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Sample records for juniper control permanent

  1. Essure Permanent Birth Control

    Science.gov (United States)

    ... Prosthetics Essure Permanent Birth Control Essure Permanent Birth Control Share Tweet Linkedin Pin it More sharing options ... System Essure is a a permanently implanted birth control device for women (female sterilization). Implantation of Essure ...

  2. Restoration of Mountain Big Sagebrush Steppe Following Prescribed Burning to Control Western Juniper

    Science.gov (United States)

    Davies, K. W.; Bates, J. D.; Madsen, M. D.; Nafus, A. M.

    2014-05-01

    Western juniper ( Juniperus occidentalis ssp. occidentalis Hook) encroachment into mountain big sagebrush ( Artemisia tridentata spp. vaseyana (Rydb.) Beetle) steppe has reduced livestock forage production, increased erosion risk, and degraded sagebrush-associated wildlife habitat. Western juniper has been successfully controlled with partial cutting followed by prescribed burning the next fall, but the herbaceous understory and sagebrush may be slow to recover. We evaluated the effectiveness of seeding perennial herbaceous vegetation and sagebrush at five sites where juniper was controlled by partially cutting and prescribed burning. Treatments tested at each site included an unseeded control, herbaceous seed mix (aerially seeded), and the herbaceous seed mix plus sagebrush seed. In the third year post-treatment, perennial grass cover and density were twice as high in plots receiving the herbaceous seed mix compared to the control plots. Sagebrush cover and density in the sagebrush seeded plots were between 74- and 290-fold and 62- and 155-fold greater than the other treatments. By the third year after treatment, sagebrush cover was as high as 12 % in the sagebrush seeded plots and between 0 % and 0.4 % where it was not seeded. These results indicate that aerial seeding perennial herbaceous vegetation can accelerate the recovery of perennial grasses which likely stabilize the site. Our results also suggest that seeding mountain big sagebrush after prescribed burning encroaching juniper can rapidly recover sagebrush cover and density. In areas where sagebrush habitat is limited, seeding sagebrush after juniper control may increase sagebrush habitat and decrease the risks to sagebrush-associated species.

  3. [Genetical control of the allozymes in juniper (Juniperus excelsa Bieb.) of the Crimea].

    Science.gov (United States)

    Korshikov, I I; Nikolaeva, A V

    2007-01-01

    Genetical control of nine enzyme systems has been studied in preserved juniper species (Juniperus excelsa Bieb.) of the natural population of the mountain Crimea. Isozymes were extracted from the haploid seed endosperms and separated elecrophoretically. As a result 16 loci have been identified. Fourteen of them were polymorphic (14--Gdh, Got-1, Mdh-1, Mdh-2, Mdh-3, Acp-1, Acp-2, Acp-3, Lap-1, Dia-1, Fdh, Sod-1, Sod-2, Sod-3). Analysis of the allele segragation of the heterozygous trees confirmed their monogenic inheritance.

  4. Impacts of pinyon and juniper control on ecosystems processes in the Porter Canyon Experimental Watershed

    Science.gov (United States)

    The opportunistic encroachment of native pinyon and juniper trees into areas formerly dominated by sagebrush has reduced the presence of shrubs and grasses, impacting critical habitat and forage availability. Pinyon and juniper currently occupy 19 million ha in the Intermountain West and prior to 18...

  5. Hart Mountain - Control of Cheatgrass in the Poker Jim Ridge Juniper Removal Area

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Since 2011 the Sheldon-Hart Mountain NWR Complex (Complex) has removed encroaching western juniper (Juniperus occidentalis) from within approximately 5,470 acres on...

  6. Pinyon-juniper woodlands

    Science.gov (United States)

    Gottfried, Gerald J.; Swetnam, Thomas W.; Allen, Craig D.; Betancourt, Julio L.; Chung-MacCoubrey, Alice L.; Finch, Deborah M.; Tainter, Joseph A.

    1995-01-01

    since the introduction of livestock and fire control. This relates to whether tree densities have been increasing or whether trees are invading grasslands and, to a lesser extent, drier ponderosa pine (Pinus ponderosa) forests. In areas where woodlands were heavily used by American Indians for fuelwood prior to European contact, the advance of pinyon and juniper could represent the slow recovery from intensive use (Samuels and Betancourt 1982). There are numerous questions regarding declines in watershed condition related to changes in pinyon-juniper tree stand densities and to the density and composition of understory vegetation. There are different opinions about proper management of woodland ecosystems. Should these lands be managed for a single resource, such as forage for livestock production, or managed for sustained production of multiple resource products and amenities? Depending on site and stand conditions, the woodlands can produce variable quantities of fuelwood, pinyon nuts, wildlife habitat, forage for livestock, and cover for watershed protection. Management must also consider increasing recreational demands, threatened and endangered species, and protection of archeological sites. Many pinyon-juniper woodland watersheds in New Mexico have unsatisfactory soil and watershed conditions (USDA Forest Service 1993); managers must develop restoration procedures that recognize the value of woodland ecosystems. The concerns, questions, and conflicts surrounding management of pinyon-juniper lands, as well as the ecological foundations of ecosystem management, require that all interested parties reevaluate attitudes toward the woodlands. Ecosystem management goals and concepts recognize diversity. Pinyonjuniper woodlands are diverse, and stand characteristics and site productivities vary. Management objectives and prescriptions must evaluate the potential of each site, and decisions must be based on sound scientific information. This information is often

  7. Sensorless Control of Permanent Magnet Synchronous Machines

    DEFF Research Database (Denmark)

    Matzen, Torben N.

    Permanent magnet machines, with either surface mounted or embedded magnets on the rotor, are becoming more common due to the key advantages of higher energy conversion efficiency and higher torque density compared to the classical induction machine. Besides energy efficiency the permanent magnet...... are dependent on the phase currents and rotor position. Based on the flux linkages the differential inductances are determined and used to establish the inductance saliency in terms of ratio and orientation. The orientation and its dependence on the current and rotor position are used to analyse the behaviour...... and establish the suitability of the machine for sensorless control using inductance saliency tracking methods. The same electromagnetic behaviour is used in the implementation of a dynamical simulation model of the machine useful for evaluation of sensorless control methods at the control design stage. Further...

  8. Biological soil crust response to late season prescribed fire in a Great Basin juniper woodland

    Science.gov (United States)

    Steven D. Warren; Larry L. St.Clair; Jeffrey R. Johansen; Paul Kugrens; L. Scott Baggett; Benjamin J. Bird

    2015-01-01

    Expansion of juniper on U.S. rangelands is a significant environmental concern. Prescribed fire is often recommended to control juniper. To that end, a prescribed burn was conducted in a Great Basin juniper woodland. Conditions were suboptimal; fire did not encroach into mid- or late-seral stages and was patchy in the early-seral stage. This study evaluated the effects...

  9. Western juniper in eastern Oregon.

    Science.gov (United States)

    Donald R. Gedney; David L. Azuma; Charles L. Bolsinger; Neil. McKay

    1999-01-01

    This report analyzes and summarizes a 1988 inventory of western juniper (Juniperus occidentalis Hook.) in eastern Oregon. This inventory, conducted by the Pacific Northwest Research Station of the USDA Forest Service, was intensified to meet increased need for more information about the juniper resource than was available in previous inventories. A...

  10. Juniper tar poisoning.

    Science.gov (United States)

    Koruk, Suda Tekin; Ozyilkan, Esin; Kaya, Pinar; Colak, Dilsen; Donderici, Omer; Cesaretli, Yildirim

    2005-01-01

    Juniper tar (cade oil) is distilled from the branches and wood of Juniperus oxycedrus. It contains etheric oils, triterpene and phenols, and is used for many purposes in folk medicine. A case is reported of a previously healthy man who ingested a spoonful of home-made extract of Juniperus oxycedrus. The poisoning caused fever, severe hypotension, renal failure, hepatotoxicity, and severe cutaneous burns on the face. After supportive and symptomatic treatment, the patient improved and was discharged in a good condition on the eleventh day.

  11. Sensorless Control of Permanent Magnet Synchronous Machines

    DEFF Research Database (Denmark)

    Matzen, Torben N.

    to appear. Sensorless control implies control of the machine without using a direct measurement of the rotor position. Instead, more information is extracted from the existing controller feedback signals - often the machine currents - and this information is used together with accurate system knowledge...... machine is also used for servo applications where higher dynamics is required, e.g. in industrial automation. The energy efficiency is essential for battery powered electric vehicles where the electric storage capacity is limited by cost, mass and volume. The control system necessary to operate...... the synchronous machine requires knowledge of the rotor shaft position due to the synchronous and undamped nature of the machine. The rotor position may be measured using a mechanical sensor, but the sensor reduces reliability and adds cost to the system and for this reason sensorless control methods started...

  12. A New Torque Control System of Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Evstratov Andrey

    2017-01-01

    Full Text Available The article describes a new approach to control of permanent magnet synchronous motor drive based on the analysis of the electromechanical transformation. The proposed control system provides quick response and low ripple of the motor torque and flux. To synthesis this control system, the authors put the electromagnetic torque and the modulus of stator flux vector as controlled values and use the Lyapunov’s second method. In addition, the stator voltage constriction and ability of low-pass filtration are taken into account. The investigation of the proposed control system has carried out with the simulation and the experimental research which have confirmed that the proposed control system correspond to all above-mentioned control tasks and the permanent magnet synchronous motor controlled under this system may be recommended to use in robotics.

  13. Permanent magnet brushless motor control based on ADRC

    Directory of Open Access Journals (Sweden)

    Li Xiaokun

    2016-01-01

    Full Text Available Permanent magnet brushless motor is a nonlinear system with multiple variables, the mathematical model of Permanent magnet brushless motor is difficult to establish, and since that the classic PID control is hard to precisely control the motor. Active disturbance rejection control (ADRC technique is a new nonlinear controller which does not depend on the system model. It is starting from the classic PID control, and establishing the loop control system by error negative feedback, the ESO(extended state observer observing system which comes from the observer theory of modern control theory to observe internal and external perturbations. ADRC inherits the advantages of PID with little overshoot, high convergence speed, high accuracy, strong anti-interference ability and other characteristics, and it has a strong disturbance adaptability and robustness as for the uncertainty perturbation and their internal disturbance of control objects. Therefore, This paper attempts to use Active disturbance rejection control(ADRC, in order to improve the control of permanent magnet brushless motor. In this design of control system, the simulation of the system is realized based on MATLAB, and then the discrete control algorithm is transplanted to the embedded system to control the permanent magnet brushless DC motor (PMBLDCM. The control system is implemented on the DSP-F28335 digital signal processor, and the DSP also provides the functions like voltage and current AD sampling, PWM driver generation, speed and rotor position calculation, etc. The simulation and experiment results indicate that, the system has good dynamic performance and anti-disturbance performance.

  14. Sage-grouse groceries: forb response to pinon-juniper treatments

    Science.gov (United States)

    In the past 150 years, juniper (Juniperus spp. L.) and piñon (Pinus spp. L.) coniferous woodlands have increased 2 to 10-fold in 9 ecoregions spanning the Intermountain area of the western United States. Control of piñon-juniper woodlands by mechanical treatments and prescribed fire have been appli...

  15. Permanent Magnetic Synchronous Motor Control System Based on ADRC

    Directory of Open Access Journals (Sweden)

    Song Wang

    2013-06-01

    Full Text Available Permanent magnetic synchronous motor (PMSM is a strong coupling and non-linear system. In the PMSM speed-regulation system, PID controller is the conventional one, it is difficult to decide the parameters of PID. Moreover, the performance of PID controller is not very well in large disturbance. In the paper, the Active Disturbance Rejection Controller (ADRC is applied to the PMSM speed-regulation system. The result of simulations and experiments show that this algorithm has better anti-load-disturbance performance than PID controller.

  16. THE CONTROL ACTIVITY EXERCISED BY PERMANENT CONTROL COMPARTIMENTS IN CREDIT INSTITUTIONS

    Directory of Open Access Journals (Sweden)

    CODRUTA DANIELA PAVEL

    2012-05-01

    Full Text Available Permanent control is defined as a permanent means acting and providing knowledge, control and monitoring of risks. Supervision of control permanent compartments includes: constant supervision through a set of dispositions applicable at the operational level to ensure legality, security and validity of transactions; control operational risks, including further activity and management of crisis situations; control of compliance, including know your customer, prevent money laundering and terrorist financing and professional ethics.Among the permanent internal control objectives in the bank network are: exercise proper permanent supervision to the bank network; identification and evaluation of operational risks; strengthening security and improving the quality of operations; respect the program of customer identification, money laundering and combating the use of bank for financing the terrorism.

  17. Soil Seed Bank Responses to Postfire Herbicide and Native Seeding Treatments Designed to Control Bromus tectorum in a Pinyon–Juniper Woodland at Zion National Park, USA

    Science.gov (United States)

    Brooks, Matthew L.; Hondo Brisbin, graduate student; Andrea Thode, Associate Professor; Karen Weber, graduate student

    2013-01-01

    The continued threat of an invasive, annual brome (Bromus) species in the western United States has created the need for integrated approaches to postfire restoration. Additionally, the high germination rate, high seed production, and seed bank carryover of annual bromes points to the need to assay soil seed banks as part of monitoring programs. We sampled the soil seed bank to help assess the effectiveness of treatments utilizing the herbicide Plateau® (imazapic) and a perennial native seed mix to control annual Bromus species and enhance perennial native plant establishment following a wildfire in Zion National Park, Utah. This study is one of few that have monitored the effects of imazapic and native seeding on a soil seed bank community and the only one that we know of that has done so in a pinyon–juniper woodland. The study made use of untreated, replicated controls, which is not common for seed bank studies. One year posttreatment, Bromus was significantly reduced in plots sprayed with herbicide. By the second year posttreatment, the effects of imazapic were less evident and convergence with the controls was evident. Emergence of seeded species was low for the duration of the study. Dry conditions and possible interactions with imazapic probably contributed to the lack of emergence of seeded native species. The perennial grass sand dropseed outperformed the other species included in the seed mix. We also examined how the treatments affected the soil seed bank community as a whole. We found evidence that the herbicide was reducing several native annual forbs and one nonnative annual forb. However, overall effects on the community were not significant. The results of our study were similar to what others have found in that imazapic is effective in providing a short-term reduction in Bromus density, although it can impact emergence of nontarget species.

  18. Bearingless Permanent Magnet Synchronous Motor using Independent Control

    Directory of Open Access Journals (Sweden)

    Normaisharah Mamat

    2015-06-01

    Full Text Available Bearingless permanent magnet synchronous motor (BPMSM combines the characteristic of the conventional permanent magent synchronous motor and magnetic bearing in one electric motor. BPMSM is a kind of high performance motor due to having both advantages of PMSM and magnetic bearing with simple structure, high efficiency, and reasonable cost. The research on BPMSM is to design and analyse BPMSM by using Maxwell 2-Dimensional of ANSYS Finite Element Method (FEM. Independent suspension force model and bearingless PMSM model are developed by using the method of suspension force. Then, the mathematical model of electromagnetic torque and radial suspension force has been developed by using Matlab/Simulink. The relation between force, current, distance and other parameter are determined. This research covered the principle of suspension force, the mathematical model, FEM analysis and digital control system of bearingless PMSM. This kind of motor is widely used in high speed application such as compressors, pumps and turbines.

  19. Discrete Current Control Strategy of Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Yan Dong

    2013-01-01

    Full Text Available A control strategy of permanent magnet synchronous motors (PMSMs, which is different from the traditional vector control (VC and direct torque control (DTC, is proposed. Firstly, the circular rotating magnetic field is analyzed on the simplified model and discredited into stepping magnetic field. The stepping magnetomotive force will drive the rotor to run as the stepping motor. Secondly, the stator current orientation is used to build the control model instead of rotor flux orientation. Then, the discrete current control strategy is set and adopted in positioning control. Three methods of the strategy are simulated in computer and tested on the experiment platform of PMSM. The control precision is also verified through the experiment.

  20. The Permanence in a Single Species Nonautonomous System with Delays and Feedback Control

    OpenAIRE

    2010-01-01

    We consider a single species nonautonomous system with delays and feedback control. A general criterion on the permanence for all positive solutions is established. The results show that the feedback control does not influence the permanence of species.

  1. Transient and permanent error control for networks-on-chip

    CERN Document Server

    Yu, Qiaoyan

    2012-01-01

    This book addresses reliability and energy efficiency of on-chip networks using a configurable error control coding (ECC) scheme for datalink-layer transient error management. The method can adjust both error detection and correction strengths at runtime by varying the number of redundant wires for parity-check bits. Methods are also presented to tackle joint transient and permanent error correction, exploiting the redundant resources already available on-chip. A parallel and flexible network simulator is also introduced, which facilitates examining the impact of various error control methods on network-on-chip performance. Includes a complete survey of error control methods for reliable networks-on-chip, evaluated for reliability, energy and performance metrics; Provides analysis of error control in various network-on-chip layers, as well as presentation of an innovative multi-layer error control coding technique; Presents state-of-the-art solutions to address simultaneously reliability, energy and performan...

  2. Using juniper berry ( Juniperus communis ) as a supplement in Japanese quail diets

    OpenAIRE

    Hakan Inci; Gokce Ozdemir; Ahmet Yusuf Sengul; Bunyamin Sogut; Hüseyin Nursoy; Turgay Sengul

    2016-01-01

    ABSTRACT The present study was conducted to determine the effects of supplemented juniper berry (Juniperus communis) on fattening performance and some carcass traits of quails. A total of 150 one-day-old Japanese quail chicks were randomly divided into five groups (one control and four treated groups) with three replicates. Four different juniper berry levels (0.5, 1, 1.5, and 2%) and a control treatment (0%) were added to the diet. Juniper berry supplementation to the diets initiated at the ...

  3. Permanence of a Single Species System with Distributed Time Delay and Feedback Control

    Directory of Open Access Journals (Sweden)

    Yali Shen

    2012-01-01

    Full Text Available We study the permanence of a classofsingle species system with distributed time delay and feedback controls. General criteria on permanence are established in this paper. A very important fact is found in our results; that is, the feedback control is harmless to the permanence of species.

  4. Controllability and Observability of 2-DOF Permanent Magnet Maglev System with Linear Control

    Institute of Scientific and Technical Information of China (English)

    CUI Tian-shi; OKa koichi; DONG Gui-ju

    2005-01-01

    A new type of 2-DOF(degree of freedom) magnetic levitation system for multi-DOF levitation is proposed. In this system, the force of permanent magnets are used for levitation and controlled by adjusting the reluctance of the magnetic circuit. Using permanent magnets, the feature of this system is effective for saving energy and avoiding heat generation. First, the principle of the levitation system and typical reluctance control methods are described. Second, an experimental device based on the principle is introduced. Finally, the feasibility of this system is considered from linear control theory.

  5. Juniper for Streambank Stabilization in Eastern Oregon

    Science.gov (United States)

    Guy R. Sheeter; Errol W. Claire

    1989-01-01

    Cut juniper trees (Juniperous osteosperma Hook.) anchored along eroded streambanks proved beneficial in stabilizing 96 percent of the erosion on eight streams evaluated in eastern Oregon over a 14-year-period. Juniper revetment was a successful substitute for costly rock structures on straight or slightly curved banks, but failed when placed on outside curves or when...

  6. Are western juniper seeds dispersed through diplochory?

    Science.gov (United States)

    Seed dispersal of western juniper (Juniperus occidentalis) appears to be convergent on a strategy utilized by fruit-bearing trees in that this conifer produces fleshy female cones (a.k.a., juniper “berries”) that are consumed by frugivorous birds, which then disperse the seeds through endozoochory b...

  7. Pinyon/juniper woodlands [Chapter 4

    Science.gov (United States)

    Robin J. Tausch; Sharon Hood

    2007-01-01

    Pinyon-juniper woodlands occur in 10 states and cover large areas in many of them. These woodlands can be dominated by several species of pinyon pine (Pinus spp. L.) and juniper (Juniperus spp. L.) (Lanner 1975; Mitchell and Roberts 1999; West 1999a). A considerable amount of information is available on the expansion of the woodlands that has occurred over large parts...

  8. Using juniper berry ( Juniperus communis as a supplement in Japanese quail diets

    Directory of Open Access Journals (Sweden)

    Hakan Inci

    2016-05-01

    Full Text Available ABSTRACT The present study was conducted to determine the effects of supplemented juniper berry (Juniperus communis on fattening performance and some carcass traits of quails. A total of 150 one-day-old Japanese quail chicks were randomly divided into five groups (one control and four treated groups with three replicates. Four different juniper berry levels (0.5, 1, 1.5, and 2% and a control treatment (0% were added to the diet. Juniper berry supplementation to the diets initiated at the end of the 1st week and sustained for seven weeks. Live weight, feed intake, and feed conversion ratio during the trial and some carcass traits after slaughter were determined. Juniper berry supplementation in the diet during seven weeks of growing period significantly increased body weight, cumulative feed intake, and feed conversion ratio of the treated groups. Carcass weight, carcass yield, and breast yield were also significantly increased by supplemented juniper berry. No significant difference was observed between viability of different groups. Supplementation of 0.5-1% juniper berry in quail diets has positive impacts on fattening performance and carcass traits.

  9. Passive control of Permanent Magnet Synchronous Motor chaotic systems

    Institute of Scientific and Technical Information of China (English)

    QI Dong-lian; WANG Jia-jun; ZHAO Guang-zhou

    2005-01-01

    Permanent Magnet Synchronous Motor model can exhibit a variety of chaotic phenomena under some choices of system parameters and external input. Based on the property of passive system, the essential conditions were studied, by which Permanent Magnet Synchronous Motor chaotic system could be equivalent to passive system. Using Lyapunov stability theory, the convergence condition deciding the system's characters was discussed. In the convergence condition area, the equivalent passive system could be globally asymptotically stabilized by smooth state feedback.

  10. Summary on Sensorless permanent magnet Brushless DC Motor Control Strategies

    OpenAIRE

    Li Hai Xia; Cao Yang

    2016-01-01

    This paper aims at discussing the development process and application of permanent magnet brushless DC motor. By referring to the related literatures, this thesis gives an overview of several common non-position sensor detection technologies, analyzing their strengths and weaknesses as well as a number of new and improved methods in practical applications. Besides, The application situation of the electric door with sensorless permanent magnet brushless DC motor was illustrated.

  11. Summary on Sensorless permanent magnet Brushless DC Motor Control Strategies

    Directory of Open Access Journals (Sweden)

    Li Hai Xia

    2016-01-01

    Full Text Available This paper aims at discussing the development process and application of permanent magnet brushless DC motor. By referring to the related literatures, this thesis gives an overview of several common non-position sensor detection technologies, analyzing their strengths and weaknesses as well as a number of new and improved methods in practical applications. Besides, The application situation of the electric door with sensorless permanent magnet brushless DC motor was illustrated.

  12. PERMANENCE OF A DISCRETE SINGLE SPECIES SYSTEM WITH DELAYS AND FEEDBACK CONTROL

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In this paper,a discrete single species system with time delays and feedback control is considered.Sufficient conditions which guarantee the permanence of all positive solutions to this discrete system are obtained.The results show that the feedback control is harmless for the permanence of the species.

  13. TAP Report - Southwest Idaho Juniper Working Group

    Energy Technology Data Exchange (ETDEWEB)

    Gresham, Garold Linn [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-01

    There is explicit need for characterization of the materials for possible commercialization as little characterization data exists. Pinyon-juniper woodlands are a major ecosystem type found in the Southwest and the Intermountain West regions of the United States including Nevada, Idaho and Oregon. These widespread ecosystems are characterized by the presence of several different species of pinyon and juniper as the dominant plant cover. Since the 1800s, pinyon-juniper woodlands have rapidly expanded their range at the expense of existing ecosystems. Additionally, existing woodlands have become denser, progressively creating potential fire hazards as seen in the Soda Fire, which burned more than 400 sq. miles. Land managers responsible for these areas often desire to reduce pinyon-juniper coverage on their lands for a variety of reasons, as stated in the Working Group objectives. However, the cost of clearing thinning pinyon-juniper stands can be prohibitive. One reason for this is the lack of utilization options for the resulting biomass that could help recover some of the cost of pinyon-juniper stand management. The goal of this TAP effort was to assess the feedstock characteristics of biomass from a juniper harvested from Owyhee County to evaluate possible fuel and conversion utilization options.

  14. Developing speed control for a permanent magnet DC motor using rapid control of prototyping techniques

    Directory of Open Access Journals (Sweden)

    Fredy Edimer Hoyos Velasco

    2010-10-01

    Full Text Available Virtually every engineering development for control systems is tested by simulation to predict performance. However, the final use of an algorithm is in its application in a real time system. Development tools using a DSP and Simulink RTW can be performed with real-time simulations (i.e. simulation interacting with physical plant. Testing the speed control loop of a DC motor with permanent magnets has thus been developed to appreciate the considerable advantages offered by these tools.

  15. Passive control of Permanent Magnet Synchronous Motor chaotic system based on state observer

    Institute of Scientific and Technical Information of China (English)

    QI Dong-lian; WANG Qiao

    2006-01-01

    Passive system theory was applied to propose a new passive control method with nonlinear observer of the Permanent Magnet Synchronous Motor chaotic system. Through constructing a Lyapunov function, the subsystem of the Permanent Magnet Synchronous Motor chaotic system could be proved to be globally stable at the equilibrium point. Then a controller with smooth state feedback is designed so that the Permanent Magnet Synchronous Motor chaotic system can be equivalent to a passive system.To get the state variables of the controller, the nonlinear observer is also studied. It is found that the outputs of the nonlinear observer can approximate the state variables of the Permanent Magnet Synchronous Motor chaotic system if the system's nonlinear function is a globally Lipschitz function. Simulation results showed that the equivalent passive system of Permanent Magnet Synchronous Motor chaotic system could be globally asymptotically stabilized by smooth state feedback in the observed parameter convergence condition area.

  16. DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)

    DEFF Research Database (Denmark)

    Swierczynski, Dariusz; Kazmierkowski, Marian P.; Blaabjerg, Frede

    2002-01-01

    DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)......DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)...

  17. DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)

    DEFF Research Database (Denmark)

    Swierczynski, Dariusz; Kazmierkowski, Marian P.; Blaabjerg, Frede

    2002-01-01

    DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)......DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)...

  18. Hybrid model predictive control for speed control of permanent magnet synchronous motor with saturation

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    A discrete-time hybrid model of a permanent magnet synchronous motor (PMSM) with saturation in voltage and current is formulated.The controller design with incorporated constraints is achieved in a systematic way from modeling to control synthesis and implementation.The Hybrid System Description Language is used to obtain a mixed-logical dynamical (MLD) model.Based on the MLD model,a model predictive controller is designed for an optimal speed regulation of the motor.For reducing computation complexity and ...

  19. Multimodel Modeling and Predictive Control for Direct-Drive Wind Turbine with Permanent Magnet Synchronous Generator

    OpenAIRE

    Lei Wang; Tao Shen; Chen Chen

    2014-01-01

    The safety and reliability of the wind turbines wholly depend on the completeness and reliability of the control system which is an important problem for the validity of the wind energy conversion systems (WECSs). A method based on multimodel modeling and predictive control is proposed for the optimal operation of direct-drive wind turbine with permanent magnet synchronous generator in this paper. In this strategy, wind turbine with direct-drive permanent magnet synchronous generator is model...

  20. Multimodel Modeling and Predictive Control for Direct-Drive Wind Turbine with Permanent Magnet Synchronous Generator

    OpenAIRE

    Lei Wang; Tao Shen; Chen Chen

    2014-01-01

    The safety and reliability of the wind turbines wholly depend on the completeness and reliability of the control system which is an important problem for the validity of the wind energy conversion systems (WECSs). A method based on multimodel modeling and predictive control is proposed for the optimal operation of direct-drive wind turbine with permanent magnet synchronous generator in this paper. In this strategy, wind turbine with direct-drive permanent magnet synchronous generator is model...

  1. Finite-Time Chaos Control of a Complex Permanent Magnet Synchronous Motor System

    Directory of Open Access Journals (Sweden)

    Xiaobing Zhou

    2014-01-01

    Full Text Available This paper investigates the finite-time chaos control of a permanent magnet synchronous motor system with complex variables. Based on the finite-time stability theory, two control strategies are proposed to realize stabilization of the complex permanent magnet synchronous motor system in a finite time. Two numerical simulations have been conducted to demonstrate the validity and feasibility of the theoretical analysis.

  2. Fuzzy Adaptive Model Following Speed Control for Vector Controlled Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Baghdad BELABES

    2008-12-01

    Full Text Available In this paper a hybrid controller combining a linear model following controller (LMFC and fuzzy logic control (FLC for speed vector controlled permanent magnet synchronous motor (PMSM is described on this study. The FLC is introduced at the adaptive mechanism level. First, an LMFC system is designed to allow the plant states to be controlled to follow the states produced by a reference model. In the nominal conditions, the model following is perfect and the adaptive mechanism based on the fuzzy logic is idle. Secondly, when parameter variations or external disturbances occur, an augmented signal will be generated by FLC mechanism to preserve the desired model following control performance. The effectiveness and robustness of the proposed controller is demonstrated by some simulation results.

  3. Rate Control Efficacy in Permanent Atrial Fibrillation : Successful and Failed Strict Rate Control Against a Background of Lenient Rate Control

    NARCIS (Netherlands)

    Groenveld, Hessel F.; Tijssen, Jan G. P.; Crijns, Harry J. G. M.; Van den Berg, Maarten P.; Hillege, Hans L.; Alings, Marco; Van Veldhuisen, Dirk J.; Van Gelder, Isabelle C.

    2013-01-01

    Objectives This study sought to investigate differences in outcome between patients treated with successful strict, failed strict, and lenient rate control. Background The RACE II (Rate Control Efficacy in Permanent Atrial Fibrillation) study showed no difference in outcome between lenient and stric

  4. Control of forced vibrations of mechanical structures by an electromagnetic controller with a permanent magnet

    DEFF Research Database (Denmark)

    Stein, George Juraj; Darula, Radoslav; Sorokin, Sergey

    2012-01-01

    A theoretical analysis of an electromagnetic vibration controller is presented. The analyzed device consists of a pot-type iron core with a coil and a permanent magnet as a source of constant magnetic flux. The magnetic circuit is closed by a yoke, excited by an external harmonic mechanical force....... Due to the hysteretic effects in the magnetic material the internal losses influence the overall system’s performance. A mathematical model of the force balance in the oscillatory system is derived in a simplified, linearised form. The electric as well as mechanical system is modelled using lumped......-parameter approach and the actuating principle for control of forced vibration is investigated....

  5. Speed Tracking of Field Oriented Control Permanent Magnet Synchronous Motor Using Neural Network

    Directory of Open Access Journals (Sweden)

    Wahyu Mulyo Utomo

    2014-05-01

    Full Text Available The field oriented control theory and space vector pulse width modulation technique make a permanent magnet synchronous motor can achieve the performance as well as a DC motor. However, due to the nonlinearity of the permanent magnet synchronous motor drive characteristics, it is difficult to control by using conventional proportional-integral-derivative controller. By this reason in this paper an online neural network controller for the permanent magnet synchronous motor is proposed. The controller is designed to tracks variations of speed references and also during load disturbance. The effectiveness of the proposed method is verified by develop simulation model in MATLAB-simulink program. The simulation results show that the proposed controller can reduce the overshoot, settling time and rise time. It can be concluded that the performance of the controller is improved.

  6. Implementation of a Fuzzy Logic Speed Controller for a Permanent ...

    African Journals Online (AJOL)

    Journal of Research in National Development. Journal Home ... Fuzzy logic controlled model of the DC motor was implemented. The purpose is to ... the proposed strategy. Keywords: Brushless DC motor, fuzzy logic control, speed controller ...

  7. Design of permanent magnet synchronous motor speed control system based on SVPWM

    Science.gov (United States)

    Wu, Haibo

    2017-04-01

    The control system is designed to realize TMS320F28335 based on the permanent magnet synchronous motor speed control system, and put it to quoting all electric of injection molding machine. The system of the control method used SVPWM, through the sampling motor current and rotating transformer position information, realize speed, current double closed loop control. Through the TMS320F28335 hardware floating-point processing core, realize the application for permanent magnet synchronous motor in the floating point arithmetic, to replace the past fixed-point algorithm, and improve the efficiency of the code.

  8. Permanent magnet brushless DC motor drives and controls

    CERN Document Server

    Xia, Chang-liang

    2012-01-01

    An advanced introduction to the simulation and hardware implementation of BLDC motor drives A thorough reference on the simulation and hardware implementation of BLDC motor drives, this book covers recent advances in the control of BLDC motor drives, including intelligent control, sensorless control, torque ripple reduction and hardware implementation. With the guidance of the expert author team, readers will understand the principle, modelling, design and control of BLDC motor drives. The advanced control methods and new achievements of BLDC motor drives, of interest to more a

  9. Predictive current control of permanent magnet synchronous motor based on linear active disturbance rejection control

    Science.gov (United States)

    Li, Kunpeng

    2017-01-01

    The compatibility problem between rapidity and overshooting in the traditional predictive current control structure is inevitable and difficult to solve by reason of using PI controller. A novel predictive current control (PCC) algorithm for permanent magnet synchronous motor (PMSM) based on linear active disturbance rejection control (LADRC) is presented in this paper. In order to displace PI controller, the LADRC strategy which consisted of linear state error feedback (LSEF) control algorithm and linear extended state observer (LESO), is designed based on the mathematic model of PMSM. The purpose of LSEF is to make sure fast response to load mutation and system uncertainties, and LESO is designed to estimate the uncertain disturbances. The principal structures of the proposed system are speed outer loop based on LADRC and current inner loop based on predictive current control. Especially, the instruction value of qaxis current in inner loop is derived from the control quantity which is designed in speed outer loop. The simulation is carried out in Matlab/Simulink software, and the results illustrate that the dynamic and static performances of proposed system are satisfied. Moreover the robust against model parameters mismatch is enhanced obviously.

  10. Pinyon-juniper woodlands [chapter 6

    Science.gov (United States)

    Gerald J. Gottfried; Thomas W. Swetnam; Craig D. Allen; Julio L. Betancourt; Alice L. Chung-MacCoubrey

    1995-01-01

    Pinyon-juniper woodlands are one of the largest ecosystems in the Southwest and in the Middle Rio Grande Basin (Fig. 1). The woodlands have been important to the region's inhabitants since prehistoric times for a variety of natural resources and amenities. The ecosystems have not been static; their distributions, stand characteristics, and site conditions have...

  11. Low Cost Sensorless Control of Permanent Magnet Motors

    DEFF Research Database (Denmark)

    Montesinos, Daniel; Galceran, Samuel; Blaabjerg, Frede

    2005-01-01

    This paper provides a review of the literature addressing sensorless operation of PM brushless machines. The methods explained are state-of-the-art of open and closed loop control strategies. The closed loop review includes those methods based on voltage and current measurements, and algebraic...... strategies....

  12. Control of Permanent Magnet Synchronous Generator for large wind turbines

    DEFF Research Database (Denmark)

    Busca, Cristian; Stan, Ana-Irina; Stanciu, Tiberiu

    2010-01-01

    converter topology was chosen for design. Parameters from a 2 MW wind turbine were used for system modeling. All the components of the wind turbine system (WTS), except the DC-link and the grid site converter were implemented in MATLAB/Simulink. The pitch controller was used to limit the output power...

  13. Low Cost Sensorless Control of Permanent Magnet Motors

    DEFF Research Database (Denmark)

    Montesinos, Daniel; Galceran, Samuel; Blaabjerg, Frede

    2005-01-01

    This paper provides a review of the literature addressing sensorless operation of PM brushless machines. The methods explained are state-of-the-art of open and closed loop control strategies. The closed loop review includes those methods based on voltage and current measurements, and algebraic ma...

  14. Impact of grazing abandonment on floristic diversity in the priority habitat type *9562 Grecian Juniper Woods

    Science.gov (United States)

    Vrahnakis, Michael; Kazoglou, Yannis; Fotiadis, George; Kakouros, Petros; Nasiakou, Stamatia; Soutsas, Konstantinos

    2017-04-01

    The habitat type *9562 Grecian juniper woods (Juniperetum excelsae) includes Greek juniper (Juniperus excelsa M. Bieb.) forests and they are found mainly in the western sector of the Prespa National Park, NW Greece. Greek juniper forests are considered extremely rare for EU-28, recommending a priority habitat type in accordance with Directive 92/43/EEC. In addition, their ecological importance is great given its high plant taxa richness; they harbor most of the 900 plant taxa found in the western sector of the Park, many of them being important for EU or global scale. The accelerated invasion of deciduous hardwoods is the most significant risk for the habitat, since its rich flora is well-adapted to open light conditions produced by the open spaced Greek junipers. Also, the dense vegetated conditions deprive the regeneration of the photophilous Greek juniper. The invasion results from the lack of its natural controller, i.e. the grazing livestock. It is estimated that the total area of juniper forests for the Devas area decreased to 89% of the area of 1945 in favor of invasive hardwoods. The paper presents the analysis of the floristic diversity of the priority habitat type *9562 Grecian Juniper Woods (Juniperetum excelsae) (GJWs). Four (4) types of juniper forest ranges (GJWs) were distinguished in terms of canopy cover: (a) pure GJWs, (b) mixed open GJWs, (c) open GJWs, and (d) mixed dense GJWs. A total of 171 plant taxa were recorded, and distributed within 43 botanical families; the largest one being Leguminosae (26 taxa). The statistically estimated plant taxa richness for pure GJWs was 116.4, for mixed open 152.6, for open 57.9, and for mixed dense 90.2 taxa. The analysis of α-diversity indices did not reveal any specific trend of diversity for the four GJWs. The behavior of the variability of diversity among the four range types of GJWs was depending on the emphasis the used indices place on properties such as taxa richness or abundance. This fact was

  15. Evaluating mountain meadow groundwater response to pinyon-juniper and temperature in a great basin watershed

    Science.gov (United States)

    Expansion of deeply-rooted Pinyon-Juniper (PJ) has altered water partitioning and reduced water availability to discharging meadows. Research highlights the development and application of GSFLOW to a semi-arid, snow-dominated watershed in the Great Basin to evaluate PJ and temperature controls on mo...

  16. MODELLING AND TORQUE TRACKING CONTROL OF PERMANENT MAGNET SYNCHRONOUS MOTOR FOR HYBRID ELECTRIC VEHICLES

    Directory of Open Access Journals (Sweden)

    Mohd Sabirin Rahmat

    2013-06-01

    Full Text Available This paper presents a detailed derivation of a permanent magnet synchronous motor, which may be used as the electric power train for the simulation of a hybrid electric vehicle. A torque tracking control of the permanent magnet synchronous motor is developed by using an adaptive proportional-integral-derivative controller. Several tests such as step function, saw tooth function, sine wave function and square wave function were used in order to examine the performance of the proposed control structure. The effectiveness of the proposed controller was verified and compared with the same system under a PID controller and the desired control. The result of the observations shows that the proposed control structure proves to be effective in tracking the desired torque with a good response. The findings of this study will be considered in the design, optimisation and experimentation of series hybrid electric vehicle.

  17. Power Control of Permanent Magnet Generator Based Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2009-01-01

    When the wind power accounts for a large portion of the grid, it will be required to regulate the active power and reactive power. This paper investigates a MWlevel variable speed wind turbine with a permanent magnet synchronous generator (PMSG). The power control capabilities of two kinds...

  18. Sensorless control of interior permanent-magnet synchronous motors with compressor load

    DEFF Research Database (Denmark)

    Huang, Shoudao; Gao, Jian; Xiao, Lei

    2013-01-01

    This paper analyzes the mathematical model of the interior permanent-magnet synchronous motors (IPMSM). Through the mathematical deformation, the paper proposes the new sensorless method based on sliding mode observer for a IPMSM. The model is only associated with the q-axis inductance, and without...... of all the control strategies....

  19. PERMANENCE AND GLOBAL STABILITY OF A FEEDBACK CONTROL SYSTEM WITH DELAYS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper considers a feedback control systems of differential equations with delays. By applying the differential inequality theorem, sufficient conditions for the permanence of the system are obtained. Also, by constructing a suitable Lyapunov functional, a criterion for the global stability of the model is obtained.

  20. CURRENT VECTOR CONTROL OF PERMANENT-MAGNET SYNCHRONOUS MOTOR OF HYBRID VEHICLE ENGINE

    Directory of Open Access Journals (Sweden)

    S. Serikov

    2009-01-01

    Full Text Available Characteristics of traction permanent-magnet synchronous motor under current vector optimum control in the possible traction-speed mode area which are relevant for hybrid vehicle engine have been investigated. As a criterion of optimality a maximum of electromagnetic moment per unit of current have been taken.

  1. Adaptive Sliding Mode Control of Chaos in Permanent Magnet Synchronous Motor via Fuzzy Neural Networks

    Directory of Open Access Journals (Sweden)

    Tat-Bao-Thien Nguyen

    2014-01-01

    Full Text Available In this paper, based on fuzzy neural networks, we develop an adaptive sliding mode controller for chaos suppression and tracking control in a chaotic permanent magnet synchronous motor (PMSM drive system. The proposed controller consists of two parts. The first is an adaptive sliding mode controller which employs a fuzzy neural network to estimate the unknown nonlinear models for constructing the sliding mode controller. The second is a compensational controller which adaptively compensates estimation errors. For stability analysis, the Lyapunov synthesis approach is used to ensure the stability of controlled systems. Finally, simulation results are provided to verify the validity and superiority of the proposed method.

  2. A Novel Maximum Power Point Tracking Control for Permanent Magnet Direct Drive Wind Energy Conversion Systems

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2012-05-01

    Full Text Available This paper proposes a novel optimal current given (OCG maximum power point tracking (MPPT control strategy based on the theory of power feedback and hill climb searching (HCS for a permanent magnet direct drive wind energy conversion system (WECS. The presented strategy not only has the advantages of not needing the wind speed and wind turbine characteristics of the traditional HCS method, but it also improves the stability and accuracy of MPPT by estimating the exact loss torque. The OCG MPPT control strategy is first carried out by simulation, then an experimental platform based on the dSPACE1103 controller is built and a 5.5 kW permanent magnet synchronous generator (PMSG is tested. Furthermore, the proposed method is compared experimentally with the traditional optimum tip speed ratio (TSR MPPT control. The experiments verify the effectiveness of the proposed OCG MPPT strategy and demonstrate its better performance than the traditional TSR MPPT control.

  3. Super-twisting sliding mode control of torque and flux in permanent magnet synchronous machine drives

    DEFF Research Database (Denmark)

    Lascu, Christian; Boldea, Ion; Blaabjerg, Frede

    2013-01-01

    This paper investigates a permanent magnet synchronous motor drive controlled by a second-order variable structure control technique, known as the super-twisting sliding modes (STSM) control. The STSM controller is designed as a direct torque and flux controller and it works in the stator flux...... reference frame, rather than the rotor frame, as a regular vector control scheme. Another second-order sliding mode controller (SMC) was developed and compared with the STSM controller. Also for comparison, a similar direct torque control scheme based on linear PI controllers was developed and tested....... The tests show that the STSM controller displays very robust behavior, like any SMC, and it works without notable chattering, like the linear PI-based controller. The paper presents theoretical aspects for the STSM control, several design and implementation details, and comparative experimental results...

  4. Avian community responses to juniper woodland structure and thinning treatments on the Colorado Plateau

    Science.gov (United States)

    Crow, Claire; van Riper, Charles

    2011-01-01

    Federal land managers are increasingly implementing fuels-reduction treatments throughout the western United States with objectives of ecological restoration and fire hazard reduction in pinyon-juniper (Pinus spp.-Juniperus spp.) woodlands. The pinyon-juniper woodland ecosystem complex is highly variable across the western landscape, as is bird community composition. We investigated relations between breeding birds and vegetation characteristics in modified pinyon-juniper woodlands at three sites (BLM, USFS, NPS) on the Colorado Plateau. During the breeding seasons of 2005 and 2006, we surveyed birds and measured vegetation in 74 study plots. These plots were each 3.1 hectares (ha; 7.6 acres), located across the range of natural variation, with 41 control sites and 33 plots in areas previously thinned by hand-cutting or chaining. We found that relations of avian pinyon-juniper specialists and priority species to vegetation characteristics were generally in agreement with the findings of previous studies and known nesting and feeding habits of those birds. Relatively high density of pinyon pines was important to species richness and abundance in 6 of 14 species. Abundance of all species was related to treatment method, and we found no difference in bird communities at chaining and hand-cut sites.

  5. A simple and robust speed control scheme of permanent magnet synchronous motor

    Institute of Scientific and Technical Information of China (English)

    Dianguo XU; Yang GAO

    2004-01-01

    This paper presents a simple and robust speed control scheme of Permanent Magnet Synchronous Motor(PMSM). It is to achieve accurate control peffommance m the presence of load torque and plant parameter variation. A robust disturbance cancellation feed forward controller is used to estimate the torque disturbance. The simple and practical control scheme is easily implemented on a PMSM driver using a TMS320LF2407 DSP. The effectiveness of the proposed robust speed control approach is demonstrated by simulation and experimental results.

  6. Permanence of a Nicholson’s Blowflies Model with Feedback Control and Multiple Time-varying Delays

    Institute of Scientific and Technical Information of China (English)

    CHEN Xiao-ying; SHI Chun-ling

    2015-01-01

    This paper covers the dynamic behaviors for a class of Nicholson’s blowflies model with multiple time-varying delay and feedback control. By using the dierential inequality theory, a set of sucient conditions are obtained to ensure the permanence of the system. Our result shows that feedback control variables have no influence on the permanence of the system.

  7. Controlling Chaos in permanent magnet synchronous motor based on finite-time stability theory

    Institute of Scientific and Technical Information of China (English)

    Wei Du-Qu; Zhang So

    2009-01-01

    This paper reports that the performance of permanent magnet synchronous motor(PMSM)degrades due to chaos when its systemic parameters fall into a certain area.To control the undesirable chaos in PMSM,a nonlinear controller,which is simple and easy to be constructed,is presented to achieve finite-time chaos control based on the finite-time stability theory.Computer simulation results show that the proposed controller is very effective.The obtained results may help to maintain the industrial servo driven system's security operation.

  8. Sensorless interior permanent magnet synchronous motor control with rotational inertia adjustment

    Directory of Open Access Journals (Sweden)

    Yongle Mao

    2016-12-01

    Full Text Available Mechanical model is generally required in high dynamic sensorless motor control schemes for zero phase lag estimation of rotor position and speed. However, the rotational inertia uncertainty will cause dynamic estimation errors, eventually resulting in performance deterioration of the sensorless control system. Therefore, this article proposes a high dynamic performance sensorless control strategy with online adjustment of the rotational inertia. Based on a synthetic back electromotive force model, the voltage equation of interior permanent magnet synchronous motor is transformed to that of an equivalent non-salient permanent magnet synchronous motor. Then, an extended nonlinear observer is designed for interior permanent magnet synchronous motor in the stator-fixed coordinate frame, with rotor position, speed and load torque simultaneously estimated. The effect of inaccurate rotational inertia on the estimation of rotor position and speed is investigated, and a novel rotational inertia adjustment approach that employs the gradient descent algorithm is proposed to suppress the dynamic estimation errors. The effectiveness of the proposed control strategy is demonstrated by experimental tests.

  9. The permanence and global attractivity of a competitive system with feedback controls and toxic substance

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, we consider a nonautonomous competitive system with feedback controls and toxic substance. Some average couditions for the permanence and global attractivity of the system are obtained. It is shown that our results are generalization or improvement of those of Zhao, Jiang and Lazer [ Nonlinear Analysis: Real World Applications, 5 ( 4 ) ( 2004 ), 265 - 276 ], Xia, Cao, Zhang and Chen [ Journal of Mathematical Analysis and Applications ,294 (2) ( 2004 ), 503 - 522 ] and Chen [ Nonlinear Analysis: Real World Applications, in press ].

  10. Script Controlled Modeling of Low Noise Permanent Magnet Synchronous Machines by using JMAG Designer

    OpenAIRE

    RUSU Tiberiu; BÎRTE Ovidiu; SZABÓ Loránd; MARŢIŞ Claudia Steluţa

    2013-01-01

    This paper deals with the parameterizedmodeling of permanent magnet synchronous machines(PMSM) by means of JMAG Designer, an advancedsimulation software for electromechanical design. Thismethod enables the designer to simulate diverse topologies ofthe machines by only changing some basic parameters of thescript controlling the preprocessing phase of the simulations.For this purpose a graphical user interface for modeling themachine was built up in Visual Basic. Thru it the users canenter the ...

  11. Study on a magnetic spiral-type wireless capsule endoscope controlled by rotational external permanent magnet

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Bo, E-mail: yebo@hubu.edu.cn [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); School of Computer Science and Information Engineering, HuBei University, Wuhan 430062 (China); Zhang, Wei [Department of Mechanical Engineering, Hubei University of Automotive Technology, Shiyan 442002 (China); Sun, Zhen-jun [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Guo, Lin [School of Computer Science and Information Engineering, HuBei University, Wuhan 430062 (China); Deng, Chao [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Chen, Ya-qi [Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030 (China); Zhang, Hong-hai [School of Mechanical Science & Engineering, Huazhong University of Science & Technology, Wuhan 430074 (China); Liu, Sheng [School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072 (China)

    2015-12-01

    In this paper, the authors propose rotating an external permanent magnet (EPM) to manipulate the synchronous rotation of a magnetic spiral-type wireless capsule endoscope (WCE), and the synchronous rotation of the WCE is converted to its translational motion in intestinal tract. In order to preliminarily verify the feasibility of this method, a handheld actuator (HA) controlled by micro controller unit, a magnetic spiral-type WCE and a bracket were fabricated, theoretical analysis and simulations about the control distance of this method were performed, and in ex-vivo tests were examined in porcine small intestine to verify the control distance and control performances of this method. It was demonstrated that this method showed good performances in controlling the translational motion of the magnetic spiral-type WCE, and this method has great potential to be used in clinical application. - Highlights: • A new magnetic control method for spiral-type wireless capsule endoscope is proposed. • Wireless capsule endoscope rotates synchronously with external permanent magnet. • The method controls the wireless capsule endoscope well in porcine small intestine. • Long control distance makes the method may be used in future medical application. • Experimental setup has great advantages: high cost performance and easy operation.

  12. Nonlinear Speed Control of Permanent Magnet Synchronous Motor with Salient Poles

    Directory of Open Access Journals (Sweden)

    K. Kyslan

    2015-12-01

    Full Text Available This paper presents the speed control of permanent magnet synchronous motor with salient poles based on two-step linearization method. In the first step, the direct compensation of the nonlinearities in the equations of current is used. In the second step, the input-output linearization in the state space is used for the decoupling of flux and torque axis. Simulated results are compared to the field oriented vector control structure with PI controllers in order to show differences in the performance of both approaches.

  13. Multi-Machine Controller Design of Permanent Magnet Wind Generators using Hamiltonian Energy Method

    Directory of Open Access Journals (Sweden)

    Bing Wang

    2013-07-01

    Full Text Available In this paper, the nonlinear control problem of permanent magnet wind generators is investigated based on Hamiltonian energy method. A nonlinear design method is proposed for the multi-machine system, such that the closed-loop system is stable simultaneously. Moreover, in the presence of disturbances, the closed-loop is finite–gain L2 stable under the action of the Hamiltonian controller. In order to illustrate the effectiveness of the proposed method, the simulations are performed which show that the gotten controller can improve the transient property and robustness of the system.  

  14. Fourier Series Learning Control for Torque Ripple Minimization in Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Eduardo Espíndola-López

    2016-09-01

    Full Text Available A new Fourier Series Learning Controller (FSLC for velocity control on a Permanent Magnet Synchronous Motor (PMSM is proposed and implemented. An analysis of the error convergence for the FSLC is presented, and the update law for the Fourier series coefficients is specified. The field-oriented control method is used as a basic element to implement three different controllers for a PMSM. The performance of the FSLC is compared with two control methods, a classical PI (Proportional Integral controller and an artificial neural network controller. The periodic nature of torque ripple in PMSMs is considered as a periodic disturbance, which must be compensated by the controller. With the FSLC implementation, a substantial reduction of the velocity ripple is obtained. Furthermore, a higher speed of learning is achieved with the FSLC in comparison with the artificial neural network.

  15. Clinical characteristics, management, and control of permanent vs. nonpermanent atrial fibrillation: insights from the RealiseAF survey.

    LENUS (Irish Health Repository)

    Murin, Jan

    2014-01-01

    Atrial fibrillation can be categorized into nonpermanent and permanent atrial fibrillation. There is less information on permanent than on nonpermanent atrial fibrillation patients. This analysis aimed to describe the characteristics and current management, including the proportion of patients with successful atrial fibrillation control, of these atrial fibrillation subsets in a large, geographically diverse contemporary sample.

  16. Multimodel Modeling and Predictive Control for Direct-Drive Wind Turbine with Permanent Magnet Synchronous Generator

    Directory of Open Access Journals (Sweden)

    Lei Wang

    2015-01-01

    Full Text Available The safety and reliability of the wind turbines wholly depend on the completeness and reliability of the control system which is an important problem for the validity of the wind energy conversion systems (WECSs. A method based on multimodel modeling and predictive control is proposed for the optimal operation of direct-drive wind turbine with permanent magnet synchronous generator in this paper. In this strategy, wind turbine with direct-drive permanent magnet synchronous generator is modeled and a backpropagation artificial neural network is designed to estimate the wind speed loaded into the turbine model in real time through the estimated turbine shaft speed and mechanical power. The nonlinear wind turbine system is presented by multiple linear models. The desired trajectory of the nonlinear system is decomposed to be suitable for the reference trajectory of multiple models that are presented by the linear models of the nonlinear system, which simplifies the nonlinear optimization problems and decreases the calculation difficulty. Then a multivariable control strategy based on model predictive control techniques for the control of variable-speed variable-pitch wind turbines is proposed. Finally, simulation results are given to illustrate the effectiveness of the proposed strategy, and the conclusion that multiple model predictive controller (MMPC has better control performance than the PI control method is obtained.

  17. Estimating juniper cover from NAIP imagery and evaluating relationships between potential cover and environmental variables

    Science.gov (United States)

    Juniper management is constrained by limited tools to estimate juniper cover and potential cover at stand closure across landscapes. We evaluated if remotely sensed imagery (NAIP) could be used to estimate juniper cover and if environmental characteristic could be used to determine potential junipe...

  18. Design,analysis and control of hybrid excited doubly salient stator-permanent-magnet motor

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    In this paper,a new hybrid excited doubly salient stator-permanent-magnet motor is proposed,where both permanent magnets and DC field windings are located in the stator.In theory,the mathematical model and design method of the motor are developed.The corresponding output power equation and the relationship between the flux control capability and the extended speed range are deduced in details.By using an efficient "one-step" three-dimensional(3D) finite element method,the electromagnetic performances are analyzed,in which the leakage flux outside the stator circumference and end-effect are taken into account.Based on the operation principle of the motor,the control strategy and scheme are developed and implemented experimentally.Both experimental results and finite element analysis show that the proposed motor not only maintains the advantages of doubly salient permanent magnet motors,but also offers high energy efficiency over a wide speed range,which makes the motor an interesting candidate for electric vehicles.

  19. Research on Operation Principle and Control of Novel Hybrid Excitation Bearingless Permanent Magnet Generator

    Directory of Open Access Journals (Sweden)

    Huangqiu Zhu

    2016-08-01

    Full Text Available Under the condition of load changing, the magnetic field of traditional permanent magnet generators (PMG is hard to be adjusted, and the mechanical bearings are significantly worn. To overcome the drawbacks above, a novel hybrid excitation bearingless permanent magnet generator (HEBPMG is proposed in this paper, which has integrated the merits of hybrid excitation permanent magnet generators and magnetic bearings. Firstly, the structure and winding configuration of the HEBPMG are introduced, and then the principles of radial suspension and power generation are presented. The suspension principle as well as power generation principle is analyzed in this paper. Then, the flux linkage and induced voltage equations are derived, and the accurate mathematical model of radial suspension force is built based on the Maxwell tensor method. Subsequently, by means of the finite element analysis software-ANSYS Maxwell, the corresponding electromagnetic characteristics are analyzed to verify the correctness of the mentioned models. In addition, a compensation control strategy based on flux-linkage observation is proposed to solve the problems of unstable suspension force and generating voltage under variable load condition in this paper. Meanwhile, the corresponding control system is constructed and its feasibility is validated by simulation results. Finally, an experimental prototype of a 2.2 kW HEBPMG is tested. Experimental researches show that the HEBPMG can operate steadily under variable load condition and possess good suspension performance and power generation quality.

  20. Direct torque control via feedback linearization for permanent magnet synchronous motor drives

    DEFF Research Database (Denmark)

    Lascu, Cristian; Boldea, Ion; Blaabjerg, Frede

    2012-01-01

    The paper describes a direct torque controlled (DTC) permanent magnet synchronous motor (PMSM) drive that employs feedback linearization and uses sliding-mode and linear controllers. We introduce a new feedback linearization approach that yields a decoupled linear PMSM model with two state...... variables, the torque and the square of stator flux magnitude. This linear model is intuitive and allows the implementation of DTC-type controllers that preserve all DTC advantages and eliminate its main drawback, the flux and torque ripple. Next, we investigate two controllers for toque and flux....... A variable structure controller (VSC) which is robust, fast, and produces low-ripple control is compared with a linear-DTC scheme which is ripple free. The torque time response is similar to a conventional DTC drive and the proposed solutions are flexible and highly tunable. We present the controller design...

  1. Modeling and control of a variable-speed wind turbine equipped with permanent magnet synchronous generator

    Energy Technology Data Exchange (ETDEWEB)

    Aliprantis, D.C.; Papathanassiou, S.A.; Papadopoulos, M.P.; Kladas, A.G. [Purdue University, Electrical and Computer Engineering, West Lafayette, IN (United States)

    2000-08-01

    In this paper the operation of a variable-speed, stall regulated wind turbine equipped with a permanent magnet synchronous generator (PMSG) is examined. The emphasis is placed on the analysis of the electric part of the system, i.e. the electrical generator, the power electronics converters and the control. The operational characteristics of the machine are investigated through a series of computer simulations and the speed control system is designed to maximize the power output and achieve a smooth torque and power profile. (orig.)

  2. Control of chaos in permanent magnet synchronous motor by using optimal Lyapunov exponents placement

    Energy Technology Data Exchange (ETDEWEB)

    Ataei, Mohammad, E-mail: ataei@eng.ui.ac.i [Department of Electrical Engineering, Faculty of Engineering, University of Isfahan, Hezar-Jerib St., Postal Code 8174673441, Isfahan (Iran, Islamic Republic of); Kiyoumarsi, Arash, E-mail: kiyoumarsi@eng.ui.ac.i [Department of Electrical Engineering, Faculty of Engineering, University of Isfahan, Hezar-Jerib St., Postal Code 8174673441, Isfahan (Iran, Islamic Republic of); Ghorbani, Behzad, E-mail: behzad.ghorbani63@gmail.co [Department of Control Engineering, Najafabad Azad University, Najafabad, Isfahan (Iran, Islamic Republic of)

    2010-09-13

    Permanent Magnet Synchronous Motor (PMSM) experiences chaotic behavior for a certain range of its parameters. In this case, since the performance of the PMSM degrades, the chaos should be eliminated. In this Letter, the control of the undesirable chaos in PMSM using Lyapunov exponents (LEs) placement is proposed that is also improved by choosing optimal locations of the LEs in the sense of predefined cost function. Moreover, in order to provide the physical realization of the method, nonlinear parameter estimator for the system is suggested. Finally, to show the effectiveness of the proposed methodology, the simulation results for applying this control strategy are provided.

  3. Juniper Pollen Hotspots in the Southwest

    Science.gov (United States)

    Bunderson, L. D.; VandeWater, P.; Luvall, J.; Levetin, E.

    2013-01-01

    Rationale: Juniperus pollen is a major allergen in Texas, Oklahoma, and New Mexico. While the bulk of pollen may be released in rural areas, large amounts of pollen can be transported to urban areas. Major juniper species in the region include: Juniperus ashei, J. virginiana, J. pinchotii, and J. monosperma. Pollen release is virtually continuous beginning in late September with J. pinchotii and ending in May with J. monosperma. Urban areas in the region were evaluated for the potential of overlapping seasons in order to inform sensitive individuals. Methods: Burkard volumetric pollen traps were established for two consecutive spring seasons at 6 sites in northern New Mexico and 6 sites for two consecutive winter and fall seasons in Texas and Oklahoma Standard methods were used in the preparation and analysis of slides. Results: The Dallas-Fort Worth Metroplex is home to over 6 million people. It is adjacent to populations of J. pinchotii, J. virginiana, and J. ashei. Peak concentration near Dallas for J. ashei in 2011 was 5891 pollen grains/m3 in January 7th. The peak date for J. pinchotii at an upwind sampling location in San Marcos, TX was November 1, 2010 and peak for J. virginiana at a nearby station in Tulsa, OK was November 1, 2010 and peak for J. virginiana at a nearby station in Tulsa, OK was February 20, 2011. Amarillo, TX is adjacent to J. pinchotii, J. ashei, and J. monosperma populations and may be subject to juniper pollen from September through May. Conclusions: Considering the overlapping distributions of juniper trees and the overlapping temporal release of pollen, sensitive patients may benefit from avoiding hotspots.

  4. Power Maximization Control of Variable Speed Wind Generation System Using Permanent Magnet Synchronous Generator

    Science.gov (United States)

    Morimoto, Shigeo; Nakamura, Tomohiko; Takeda, Yoji

    This paper proposes the sensorless output power maximization control of the wind generation system. A permanent magnet synchronous generator (PMSG) is used as a variable speed generator in the proposed system. The generator torque is suitably controlled according to the generator speed and thus the power from a wind turbine settles down on the maximum power point by the proposed MPPT control method, where the information of wind velocity is not required. Moreover, the maximum available generated power is obtained by the optimum current vector control. The current vector of PMSG is optimally controlled according to the generator speed and the required torque in order to minimize the losses of PMSG considering the voltage and current constraints. The proposed wind power generation system can be achieved without mechanical sensors such as a wind velocity detector and a position sensor. Several experimental results show the effectiveness of the proposed control method.

  5. Study on a magnetic spiral-type wireless capsule endoscope controlled by rotational external permanent magnet

    Science.gov (United States)

    Ye, Bo; Zhang, Wei; Sun, Zhen-jun; Guo, Lin; Deng, Chao; Chen, Ya-qi; Zhang, Hong-hai; Liu, Sheng

    2015-12-01

    In this paper, the authors propose rotating an external permanent magnet (EPM) to manipulate the synchronous rotation of a magnetic spiral-type wireless capsule endoscope (WCE), and the synchronous rotation of the WCE is converted to its translational motion in intestinal tract. In order to preliminarily verify the feasibility of this method, a handheld actuator (HA) controlled by micro controller unit, a magnetic spiral-type WCE and a bracket were fabricated, theoretical analysis and simulations about the control distance of this method were performed, and in ex-vivo tests were examined in porcine small intestine to verify the control distance and control performances of this method. It was demonstrated that this method showed good performances in controlling the translational motion of the magnetic spiral-type WCE, and this method has great potential to be used in clinical application.

  6. Chaos Suppression in Fractional Order Permanent Magnet Synchronous Motor and PI controlled Induction motor by Extended Back stepping Control

    Science.gov (United States)

    Rajagopal, Karthikeyan; Karthikeyan, Anitha; Duraisamy, Prakash

    2016-12-01

    In this paper we investigate the control of three-dimensional non-autonomous fractional-order model of a permanent magnet synchronous motor (PMSM) and PI controlled fractional order Induction motor via recursive extended back stepping control technique. A robust generalized weighted controllers are derived to suppress the chaotic oscillations of the fractional order model. As the direct Lyapunov stability analysis of the controller is difficult for a fractional order first derivative, we have derived a new lemma to analyze the stability of the system. Numerical simulations of the proposed chaos suppression methodology are given to prove the analytical results.

  7. A novel fault tolerant permanent magnet synchronous motor with improved optimal torque control for aerospace application

    Directory of Open Access Journals (Sweden)

    Guo Hong

    2015-04-01

    Full Text Available Improving fault tolerant performance of permanent magnet synchronous motor has always been the central issue of the electrically supplied actuator for aerospace application. In this paper, a novel fault tolerant permanent magnet synchronous motor is proposed, which is characterized by two stators and two rotors on the same shaft with a circumferential displacement of mechanical angle of 4.5°. It helps to reduce the cogging torque. Each segment of the stator and the rotor can be considered as an 8-pole/10-slot five-phase permanent magnet synchronous motor with concentrated, single-layer and alternate teeth wound winding, which enhance the fault isolation capacity of the motor. Furthermore, the motor has high phase inductance to restrain the short-circuit current. In addition, an improved optimal torque control strategy is proposed to make the motor work well under the open-circuit fault and short-circuit fault conditions. Simulation and experiment results show that the proposed fault tolerant motor system has excellent fault tolerant capacity, which is able to operate continuously under the third open-circuit fault and second short-circuit fault condition without system performance degradation, which was not available earlier.

  8. Sensorless Speed Control of Permanent Magnet Synchronous Motors by Neural Network Algorithm

    Directory of Open Access Journals (Sweden)

    Ming-Shyan Wang

    2014-01-01

    Full Text Available The sliding mode control has the merits with respect to the variation of the disturbance and robustness. In this paper, the sensorless sliding-mode observer with least mean squared error approach for permanent magnet synchronous motor (PMSM to detect the rotor position by counter electromotive force and then compute motor speed is designed and implemented. In addition, the neural network control is also used to compensate the PI gain tuning to increase the speed accuracy without regarding the errors of the current measurement and motor noise. In this paper, a digital signal processor TMS320F2812 utilizes its high-speed ADC module to get current feedback information and thus to estimate the rotor position and takes advantage of the built-in modules to achieve SVPWM current control so that the senseless speed control will be accomplished. The correctness and effectiveness of the proposed control system will be verified from the experimental results.

  9. Robust Sliding Mode Control of Permanent Magnet Synchronous Generator-Based Wind Energy Conversion Systems

    Directory of Open Access Journals (Sweden)

    Guangping Zhuo

    2016-12-01

    Full Text Available The subject of this paper pertains to sliding mode control and its application in nonlinear electrical power systems as seen in wind energy conversion systems. Due to the robustness in dealing with unmodeled system dynamics, sliding mode control has been widely used in electrical power system applications. This paper presents first and high order sliding mode control schemes for permanent magnet synchronous generator-based wind energy conversion systems. The application of these methods for control using dynamic models of the d-axis and q-axis currents, as well as those of the high speed shaft rotational speed show a high level of efficiency in power extraction from a varying wind resource. Computer simulation results have shown the efficacy of the proposed sliding mode control approaches.

  10. PERMANENCE OF A NON-AUTONOMOUS BEDDINGTON-DEANGELIS PREDATOR-PREY MODEL WITH TIME DELAY AND IMPULSIVE CONTROLS

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    A non-autonomous predator-prey delay system with Beddington-DeAngelis functional response and impulsive controls is established. A set of sufficient conditions which guarantee the prey and the predator to be permanent are obtained.

  11. Current error vector based prediction control of the section winding permanent magnet linear synchronous motor

    Energy Technology Data Exchange (ETDEWEB)

    Hong Junjie, E-mail: hongjjie@mail.sysu.edu.cn [School of Engineering, Sun Yat-Sen University, Guangzhou 510006 (China); Li Liyi, E-mail: liliyi@hit.edu.cn [Dept. Electrical Engineering, Harbin Institute of Technology, Harbin 150000 (China); Zong Zhijian; Liu Zhongtu [School of Engineering, Sun Yat-Sen University, Guangzhou 510006 (China)

    2011-10-15

    Highlights: {yields} The structure of the permanent magnet linear synchronous motor (SW-PMLSM) is new. {yields} A new current control method CEVPC is employed in this motor. {yields} The sectional power supply method is different to the others and effective. {yields} The performance gets worse with voltage and current limitations. - Abstract: To include features such as greater thrust density, higher efficiency without reducing the thrust stability, this paper proposes a section winding permanent magnet linear synchronous motor (SW-PMLSM), whose iron core is continuous, whereas winding is divided. The discrete system model of the motor is derived. With the definition of the current error vector and selection of the value function, the theory of the current error vector based prediction control (CEVPC) for the motor currents is explained clearly. According to the winding section feature, the motion region of the mover is divided into five zones, in which the implementation of the current predictive control method is proposed. Finally, the experimental platform is constructed and experiments are carried out. The results show: the current control effect has good dynamic response, and the thrust on the mover remains constant basically.

  12. A Novel Direct Torque Control Permanent Magnet Synchronous Motor Drive used in Electrical Vehicle

    Directory of Open Access Journals (Sweden)

    Yaohua Li

    2011-10-01

    Full Text Available In this paper, a modified direct torque control (DTC scheme for permanent magnet synchronous motor (PMSM is investigated, which enables low torque ripple by using an improved voltage vector selection strategy instead of switching table used in conventional DTC. Based on the control of stator flux, torque angle and torque, voltage vector selection strategy of PMSM DTC drive is proposed. In the proposed voltage vector selection strategy, the applied voltage vector is determined according to outputs of hysteresis comparators for stator flux and torque, angular position of stator flux and torque angle, which is finally synthesized by space vector modulation (SVM. Modeling and experimental results for an interior PMSM used in Honda Civic 06My Hybrid electrical vehicle are given. Simulation and experimental results show torque ripple is reduced and the total harmonics of stator current is decreased when compared those of conventional DTC. And a fixed switching frequency is obtained with the help of SVM. In addition, the proposed DTC doesn’t need any additional PI controller, which maintains the simplicity in conventional DTC. Keywords: direct torque control, permanent magnet synchronous motor, electrical vehicle, torque ripple, switching frequency

  13. UNIFIED CONTROL STRUCTURE OF MULTI-TYPE INTERIOR PERMANENT MAGNET MOTOR

    Directory of Open Access Journals (Sweden)

    M. NORHISAM

    2015-03-01

    Full Text Available This paper presents the control strategy structure to extract the speed torque characteristic for the newly designed three phase Multi Type Interior Permanent Magnet Motor. The proposed structure with the driving circuits exhibit the performance of torque characteristics of the stepper motor and brushless motor with independent coil winding per phase especially used as an in-wheel motor in agricultural applications. Brushless Direct Current motors exhibit characteristics of generating high torque at high speed while the Permanent Magnet Stepper motors has characteristic of generating high torque at low speed. The typical characteristics of the above two are integrated in the proposed structure with a complex control structure that handle the switching complexity and speed control in real time. Thus, a specially designed driving system is essential to drive and control this special motor. The evaluation of the motor mechanical characteristics when applying load torque is also presented. The result determines the practical torque range applicable for each motor configuration and as combined machine.

  14. The Effect of Rate Control on Quality of Life in Patients With Permanent Atrial Fibrillation Data From the RACE II (Rate Control Efficacy in Permanent Atrial Fibrillation II) Study

    NARCIS (Netherlands)

    Groenveld, H.F.; Crijns, H.J.G.M.; Van den Berg, M.P.; van Sonderen, E.; Alings, A.M.; Tijssen, J.G.P.; Hillege, H.L.; Tuininga, Y.S.; van Veldhuisen, D.J.; Ranchor, A.V.; Van Gelder, I.C.

    2011-01-01

    Objectives The aim of this study was to investigate the influence of rate control on quality of life (QOL). Background The RACE II (Rate Control Efficacy in Permanent Atrial Fibrillation II) trial showed that lenient rate control is not inferior to strict rate control in terms of cardiovascular morb

  15. Species Permanence Analysis of an Ecological Model with an Impulsive Control Strategy

    Institute of Scientific and Technical Information of China (English)

    Xiao Mei WANG; Shou Ming ZHONG

    2011-01-01

    In this paper,on the basis of the theories and methods of ecology and ordinary differential equations,an ecological model with an impulsive control strategy is established.By using the theories of impulsive equations,small amplitude perturbation skills and comparison technique,we get the condition which guarantees the global asymptotical stability of the prey-x-eradication and predator-y-eradication periodic solution.It is proved that the system is permanent.Furthermore,numerical simulations are also illustrated which agree well with our theoretical analysis.All these results may be useful in study of the dynamic complexity of ecosystems.

  16. Predictive control of a chaotic permanent magnet synchronous generator in a wind turbine system

    Science.gov (United States)

    Manal, Messadi; Adel, Mellit; Karim, Kemih; Malek, Ghanes

    2015-01-01

    This paper investigates how to address the chaos problem in a permanent magnet synchronous generator (PMSG) in a wind turbine system. Predictive control approach is proposed to suppress chaotic behavior and make operating stable; the advantage of this method is that it can only be applied to one state of the wind turbine system. The use of the genetic algorithms to estimate the optimal parameter values of the wind turbine leads to maximization of the power generation. Moreover, some simulation results are included to visualize the effectiveness and robustness of the proposed method. Project supported by the CMEP-TASSILI Project (Grant No. 14MDU920).

  17. Complete stability analysis of a control law for walking robots with non-permanent contacts

    OpenAIRE

    Chareyron, Sophie; Wieber, Pierre-Brice

    2005-01-01

    International audience; One of the main specificities of walking robots is their non-permanent contact with the ground which impairs their stability. The only stability analyses of control laws that have been proposed so far for walking robots have been distinctly focusing on each contact phases, with the strong assumption that these phases are never perturbated [11, 13]. In this study we aim at analysing the stability of a regulation of the position of a walking robot without any assumption o...

  18. Design and Implementation of Recursive Model Predictive Control for Permanent Magnet Synchronous Motor Drives

    Directory of Open Access Journals (Sweden)

    Xuan Wu

    2015-01-01

    Full Text Available In order to control the permanent-magnet synchronous motor system (PMSM with different disturbances and nonlinearity, an improved current control algorithm for the PMSM systems using recursive model predictive control (RMPC is developed in this paper. As the conventional MPC has to be computed online, its iterative computational procedure needs long computing time. To enhance computational speed, a recursive method based on recursive Levenberg-Marquardt algorithm (RLMA and iterative learning control (ILC is introduced to solve the learning issue in MPC. RMPC is able to significantly decrease the computation cost of traditional MPC in the PMSM system. The effectiveness of the proposed algorithm has been verified by simulation and experimental results.

  19. Adaptive fuzzy dynamic surface control for the chaotic permanent magnet synchronous motor using Nussbaum gain

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Shaohua [School of Automation, Chongqing University, Chongqing 400044, China and College of Mechanical Engineering, Hunan University of Arts and Science, Hunan 415000 (China)

    2014-09-01

    This paper is concerned with the problem of adaptive fuzzy dynamic surface control (DSC) for the permanent magnet synchronous motor (PMSM) system with chaotic behavior, disturbance and unknown control gain and parameters. Nussbaum gain is adopted to cope with the situation that the control gain is unknown. And the unknown items can be estimated by fuzzy logic system. The proposed controller guarantees that all the signals in the closed-loop system are bounded and the system output eventually converges to a small neighborhood of the desired reference signal. Finally, the numerical simulations indicate that the proposed scheme can suppress the chaos of PMSM and show the effectiveness and robustness of the proposed method.

  20. Adaptive fuzzy dynamic surface control for the chaotic permanent magnet synchronous motor using Nussbaum gain

    Science.gov (United States)

    Luo, Shaohua

    2014-09-01

    This paper is concerned with the problem of adaptive fuzzy dynamic surface control (DSC) for the permanent magnet synchronous motor (PMSM) system with chaotic behavior, disturbance and unknown control gain and parameters. Nussbaum gain is adopted to cope with the situation that the control gain is unknown. And the unknown items can be estimated by fuzzy logic system. The proposed controller guarantees that all the signals in the closed-loop system are bounded and the system output eventually converges to a small neighborhood of the desired reference signal. Finally, the numerical simulations indicate that the proposed scheme can suppress the chaos of PMSM and show the effectiveness and robustness of the proposed method.

  1. Magnetic Field Equivalent Current Analysis-Based Radial Force Control for Bearingless Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Huangqiu Zhu

    2015-05-01

    Full Text Available Bearingless permanent magnet synchronous motors (BPMSMs, with all advantages of permanent magnet motors (PMSMs and magnetic bearings, have become an important research direction in the bearingless motor field. To realize a stable suspension for the BPMSM, accurate decoupling control between the electromagnetic torque and radial suspension force is indispensable. In this paper, a concise and reliable analysis method based on a magnetic field equivalent current is presented. By this analysis method, the operation principle is analyzed theoretically, and the necessary conditions to produce a stable radial suspension force are confirmed. In addition, mathematical models of the torque and radial suspension force are established which is verified by the finite element analysis (FEA software ANSYS. Finally, an experimental prototype of a 2-4 poles surface-mounted BPMSM is tested with the customized control strategy. The simulation and experimental results have shown that the motor has good rotation and suspension performance, and validated the accuracy of the proposed analysis method and the feasibility of the control strategy.

  2. Position Sensorless Control for Permanent Magnet Synchronous Motor Using Sliding Mode Observer

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    An approach of position sensorless control for permanent magnet synchronous motor (PMSM) is put forward based on a sliding mode observer. The mathematical model of PMSM in a stationary αβ reference frame is adopted, and the system is controlled by the digital signal processor (DSP) TMS320LF2407 according to the control theory of sliding mode observer. In order to achieve closed loop operation of the motor, the stator magnetic field should be vertical with the rotor magnetic field and be synchronous with rotor rotating, so the position and speed of PMSM is estimated in real time and the estimated position is modified continuously. The simulation results indicate that the proposed observer has high precision in estimation of PMSM position and speed, and is more robust to the parametric variation and load torque disturbance.

  3. LVRT SCHEME OF WIND ENERGY SYSTEM USING PERMANENT MAGNET SYNCHRONOUS GENERATOR AND HYSTERESIS CURRENT CONTROLLER

    Directory of Open Access Journals (Sweden)

    E.RAJENDRAN

    2013-04-01

    Full Text Available In this research paper provided the information about low-voltage ride-through (LVRT scheme for the permanent magnet synchronous generator (PMSG, and wind energy conversion system. The dc-link voltage is uncomfortable by the generator side converter instead of the grid-side converter (GSC. Considering the nonlinear correlation between the generator speed (ωm and the dc-link voltage (Vdc, a dc-link Voltage controller is anticipated using a hysteresis current controller. Among all, low-voltage ride-through has been fundamental in the field, which is one of the most important challenges for wind energy conversion system. It is essential to design an included controller to protect the converter from overvoltage/overcurrent and to support the grid voltage during faults and recoveries. A unified dc-link voltage control scheme and hysteresis current controller based wind energy conversion system is proposed. The controllers for grid-side converters are coordinated to provide fault ride-through capability. The generator side is forced by space vector modulationand grid side implemented hysteresis current controller. The Grid Side Controller controls the grid active power and maximum power deliver to the grid. The ability of this control algorithm has been confirmed by simulation results.

  4. Evaluation of the seasonal and annual abortifacient risk of western juniper trees on Oregon rangelands: Abortion risk of western juniper trees

    Science.gov (United States)

    Western juniper trees can cause late term abortions in cattle, similar to ponderosa pine trees. Analyses of western juniper trees from 35 locations across the state of Oregon suggest that western juniper trees in all areas present an abortion risk in pregnant cattle. Results from this study demonstr...

  5. Magnetic Field Analysis of Interior Composite-Rotor Controllable-Flux Permanent Magnet Synchronous Machine

    Institute of Scientific and Technical Information of China (English)

    CHEN Yiguang; PAN Wei; SHEN Yonghuan; TANG Renyuan

    2006-01-01

    Conventional permanent magnet synchronous machine(PMSM)has the problem of large stator copper loss and narrow speed range. To solve this problem, an interior composite-rotor controllable-flux PMSM adaptive to multi-polar is proposed. This machine has the characteristics of low stator copper loss and wide-speed operation. The half-radial-set and half-tangential-set permanent magnets(PMs)are NdFeB that has high remanent flux density and high coercive force. The tangential-set PMs are AlNiCo that has high remanent flux density and low coercive force. By applying the pulse of d-axis stator current id, the magnetized intensity and direction of AlNiCo can be controlled. The flux created by NdFeB is repelled to stator and air-gap PM-flux is intensified, or is partially bypassed by AlNiCo in the rotor, so the air-gap PM-flux is weakened. The internal magnetic field distribution in two ultra magnetized situations is analyzed by finite element method. The dimension of PMs and magnetic structure are demonstrated. Especially when the q-axis magnetic resistance is larger and the q-axis inductance is smaller, the result of flux-weakening is better and the influence of armature reaction on air-gap PM-flux is weakened.

  6. Control of Two Permanent Magnet Machines Using a Five-Leg Inverter for Automotive Applications

    Energy Technology Data Exchange (ETDEWEB)

    Su, Gui-Jia [ORNL; Tang, Lixin [ORNL; Huang, Xianghui [GE Global Research

    2006-01-01

    This paper presents digital control schemes for control of two permanent magnet (PM) machines in an integrated traction and air-conditioning compressor drive system for automotive applications. The integrated drive system employs a five-leg inverter to power a three-phase traction PM motor and a two-phase compressor PM motor by tying the common terminal of the two-phase motor to the neutral point of the three-phase motor. Compared to a three-phase or a standalone two-phase inverter, it eliminates one phase leg and shares the control electronics between the two drives, thus significantly reducing the component count of the compressor drive. To demonstrate that the speed and torque of the two PM motors can be controlled independently, a control strategy was implemented in a digital signal processor, which includes a rotor flux field orientation based control (RFOC) for the three-phase motor, a similar RFOC and a position sensorless control in the brushless dc (BLDC) mode for the two-phase motor. Control implementation issues unique to a two-phase PM motor are also discussed. Test results with the three-phase motor running in the ac synchronous (ACS) mode while the two-phase motor either in the ACS or the BLDC mode are included to verify the independent speed and torque control capability of the integrated drive.

  7. Fractional order sliding-mode control based on parameters auto-tuning for velocity control of permanent magnet synchronous motor.

    Science.gov (United States)

    Zhang, BiTao; Pi, YouGuo; Luo, Ying

    2012-09-01

    A fractional order sliding mode control (FROSMC) scheme based on parameters auto-tuning for the velocity control of permanent magnet synchronous motor (PMSM) is proposed in this paper. The control law of the proposed F(R)OSMC scheme is designed according to Lyapunov stability theorem. Based on the property of transferring energy with adjustable type in F(R)OSMC, this paper analyzes the chattering phenomenon in classic sliding mode control (SMC) is attenuated with F(R)OSMC system. A fuzzy logic inference scheme (FLIS) is utilized to obtain the gain of switching control. Simulations and experiments demonstrate that the proposed FROSMC not only achieve better control performance with smaller chatting than that with integer order sliding mode control, but also is robust to external load disturbance and parameter variations.

  8. Applying Closing Phase-Angle Control Technique in Bounce Reduction of AC Permanent Magnet Contactor

    Directory of Open Access Journals (Sweden)

    Chieh-Tsung Chi

    2009-01-01

    Full Text Available A new low-cost electronic control circuit actuator is proposed for minimizing the bouncing times of an AC permanent magnet (PM contactor after two contacts closing. The proposed new actuator overcomes the bouncing problem of an uncontrollable restrictions imposed by previously conventional AC electromagnetic (EM contactor based on the minimization of kinetic energy prior to two contacts impact. By choosing the closing phase angle of coil voltage on purpose, the bouncing problems of the movable contact during the closing process are then overcome. The using life of contacts is then prolonged and their operating reliability is improved as well. In order to validate the feasibility and effectiveness of the proposed method here, several simulation and experimental procedures were performed on a prototype of AC PM contactor in the laboratory. Testing results actually showed that bouncing problem of contactor's contacts during the closing process was to be controlled by using the proposed technology.

  9. Swarming Speed Control for DC Permanent Magnet Motor Drive via Pulse Width Modulation Technique and DC/DC Converter

    Directory of Open Access Journals (Sweden)

    A.S. Oshaba

    2013-05-01

    Full Text Available This study presents an approach for the speed control of a permanent magnet DC motor drive via Pulse Width Modulation (PWM technique and a DC/DC converter. The Particle Swarm Optimization (PSO technique is used to minimize a time domain objective function and obtain the optimal controller parameters. The performance of the proposed technique has been evaluated using various types of disturbances including load torque variations. Simulation results illustrate clearly the robustness of the controller and validity of the design technique for controlling the speed of permanent magnet motors.

  10. A Design Fuzzy Logic Controller for a Permanent Magnet Wind Generator to Enhance the Dynamic Stability of Wind Farms

    OpenAIRE

    Marwan Rosyadi; Muyeen, S. M.; Rion Takahashi; Junji Tamura

    2012-01-01

    In this paper, a design fuzzy logic controller for a variable speed permanent magnet wind generator connected to a grid system through a LC-filter is proposed. A new current control method of grid side conversion is developed by integrating the fuzzy controller, in which both active and reactive power, delivered to a power grid system, is controlled effectively. The fuzzy logic controller is designed to adjust the gain parameters of the PI controllers under any operating conditions, so that t...

  11. Advanced Control of Permanent Magnet Synchronous Generators for Variable Speed Wind Energy Conversion Systems

    Science.gov (United States)

    Hostettler, Jacob

    Various environmental and economic factors have lead to increased global investment in alternative energy technologies such as solar and wind power. Although methodologies for synchronous generator control are well researched, wind turbines present control systems challenges not presented by traditional generation. The varying nature of wind makes achieving synchronism with the existing electrical power grid a greater challenge. Departing from early use of induction machines, permanent magnet synchronous generators have become the focus of power systems and control systems research into wind energy systems. This is due to their self excited nature, along with their high power density. The problem of grid synchronism is alleviated through the use of high performance power electronic converters. In achievement of the optimal levels of efficiency, advanced control systems techniques oer promise over more traditional approaches. Research into sliding mode control, and linear matrix inequalities with nite time boundedness and Hinfinity performance criteria, when applied to the dynamical models of the system, demonstrate the potential of these control methodologies as future avenues for achieving higher levels of performance and eciency in wind energy.

  12. A V/f= cte Control Drive for Permanent Capacitor Single-Phase Induction Motor

    Directory of Open Access Journals (Sweden)

    Pedram Shahriari Nasab

    2013-01-01

    Full Text Available Poor performance of the convectional household induction motors which used in home appliances such as refrigerator, cooler, laundry, washing machines, fans, hand-held power tools, and automotive window lift is generally caused by two main reasons. Firstly, they have high starting current which causes significant voltage drop, and secondly, they operate in a single speed mode and not in variable speed. In many home appliances, traditionally a discrete speed control method is used by changing the number of the poles. A proper solution for these problems can be achieved by using control drive systems. In this paper, a simple scalar control method is applied to control the speed of a permanent capacitor single phase induction motor (PCSPIM. The philosophy of this method is on the basis of simultaneous system’s frequency and voltage control on the machines terminals subject to V/f=cte. Simulation and practical implementation results clearly show the effectiveness of the simple V/f =cte speed control method for home appliances.

  13. Development of Digital Control for High Power Permanent-Magnet Synchronous Motor Drives

    Directory of Open Access Journals (Sweden)

    Ming-Hung Chen

    2014-01-01

    Full Text Available This paper is concerned with the development of digital control system for high power permanent-magnet synchronous motor (PMSM to yield good speed regulation, low current harmonic, and stable output speed. The design of controller is conducted by digitizing the mathematical model of PMSM using impulse invariance technique. The predicted current estimator, which is insensitive to motor feedback currents, is proposed to function under stationary frame for harmonic current suppression. In the AC/DC power converter, mathematical model and dc-link voltage limit of the three-phase switch-mode rectifier are derived. In addition, a current controller under synchronous frame is introduced to reduce the current harmonics and increase the power factor on the input side. A digital control system for 75 kW PMSM is realized with digital signal processor (R5F5630EDDFP. Experimental results indicate that the total harmonic distortion of current is reduced from 4.1% to 2.8% for 50 kW output power by the proposed predicted current estimator technique.

  14. Restoring mountain big sagebrush communities after prescribed fire in juniper encroached rangelands

    Science.gov (United States)

    Western juniper encroachment into sagebrush steppe communities has reduced livestock forage production, increased erosion and runoff risk, and degraded sagebrush-associated wildlife habitat. We evaluated seeding perennial herbaceous vegetation and sagebrush at five sites where juniper was controlle...

  15. Application of neural networks for permanent magnet synchronous motor direct torque control

    Institute of Scientific and Technical Information of China (English)

    Zhang Chunmei; Liu Heping; Chen Shujin; Wang Fangjun

    2008-01-01

    Neural networks require a lot of training to understand the model of a plant or a process. Issues such as learning speed, stability, and weight convergence remain as areas of research and comparison of many training algorithms. The application of neural networks to control interior permanent magnet synchronous motor using direct torque control (DTC) is discussed. A neural network is used to emulate the state selector of the DTC. The neural networks used are the back-propagation and radial basis function. To reduce the training patterns and increase the execution speed of the training process, the inputs of switching table are converted to digital signals, i.e., one bit represent the flux error, one bit the torque error, and three bits the region of stator flux. Computer simulations of the motor and neural-network system using the two approaches are presented and compared. Discussions about the back-propagation and radial basis function as the most promising training techniques are presented, giving its advantages and disadvantages. The system using back-propagation and radial basis function networks controller has quick parallel speed and high torque response.

  16. Optimal Velocity Control for a Battery Electric Vehicle Driven by Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Dongbin Lu

    2014-01-01

    Full Text Available The permanent magnet synchronous motor (PMSM has high efficiency and high torque density. Field oriented control (FOC is usually used in the motor to achieve maximum efficiency control. In the electric vehicle (EV application, the PMSM efficiency model, combined with the EV and road load system model, is used to study the optimal energy-saving control strategy, which is significant for the economic operation of EVs. With the help of GPS, IMU, and other information technologies, the road conditions can be measured in advance. Based on this information, the optimal velocity of the EV driven by PMSM can be obtained through the analytical algorithm according to the efficiency model of PMSM and the vehicle dynamic model in simple road conditions. In complex road conditions, considering the dynamic characteristics, the economic operating velocity trajectory of the EV can be obtained through the dynamic programming (DP algorithm. Simulation and experimental results show that the minimum energy consumption and global energy optimization can be achieved when the EV operates in the economic operation area.

  17. Development of Small-sized Fluid Control Valve with Self-holding Function Using Permanent Magnet

    Science.gov (United States)

    Akagi, Tetsuya; Dohta, Shujiro; Ueda, Hirofumi

    Recently, force feedback devices in virtual reality and power assisted nursing care systems have received much attention and active research. In such a control system, an actuator and a driving device such as a control valve are mounted on the human body. In this condition, the size and weight of the control valve become serious problems. At the same time, the valve should be operated with lower energy consumption because of using a limited electrical power. The typical electro magnetic solenoid valve drives its spool using a larger solenoid to open the valve. The complex construction of the valve for sealing makes its miniaturization and the fabrication of a low cost valve more difficult. In addition, the solenoid in the valve consumes more electrical power while the valve is kept opening. The purpose of our study is to develop a small-sized, lightweight, lower energy consumption and flexible control valve that can be safe enough to mount on the human body at a lower cost. In our pervious study, we proposed and tested the control valve that can open using a vibration motor. In this study, we propose and test a new type of fluid control valve with a self-holding function. The new valve uses a permanent magnet ball. It has a cylindrical magnet and two solenoids. The self-holding function of the valve is done as follows. When one side of the solenoid is stimulated by the current momentarily, the solenoid gives a repulsive force to the cylindrical magnet. The magnet moves toward the opposite side of the solenoid and is attracted to the iron core. Then, the magnet ball moves toward the cylindrical magnet and opens the orifice. The valve can keep open without electrical energy. As a result, the valve with the extremely lower energy consumption can be developed.

  18. Do bark beetle sprays prevent Phloeosinus species from attacking cypress and juniper?

    Science.gov (United States)

    Chris Hayes; Tom DeGomez; Karen Clancy; Joel McMillin; John Anhold

    2008-01-01

    (Please note, this is an abstract only) Phloeosinus-caused mortality of Arizona cypress, (Cupressus arizonica), oneseed juniper, (Juniperus monosperma) and alligator juniper, (J. deppeana) has been observed at high levels in Arizona during the past 3 years. Currently, there are limited preventative measures to protect high-value cypress and juniper trees against...

  19. Seed dispersal of two juniper species: Do scatter-hoarding rodents play a role?

    Science.gov (United States)

    Knowledge of seed dispersal processes is vital for understanding the ongoing expansion of the range and increase in density of juniper woodlands. Juniper seeds develop within fruit-like female cones often called “berries.” Juniper seed dispersal has largely been attributed to frugivores and endozooc...

  20. Postfire soil water repellency in piñon-juniper woodlands: Extent, severity, and thickness relative to ecological site characteristics and climate.

    Science.gov (United States)

    Zvirzdin, Daniel L; Roundy, Bruce A; Barney, Nicholas S; Petersen, Steven L; Anderson, Val J; Madsen, Matthew D

    2017-07-01

    Wildfires can create or intensify water repellency in soil, limiting the soil's capacity to wet and retain water. The objective of this research was to quantify soil water repellency characteristics within burned piñon-juniper woodlands and relate this information to ecological site characteristics. We sampled soil water repellency across forty-one 1,000 m(2) study plots within three major wildfires that burned in piñon-juniper woodlands. Water repellency was found to be extensive-present at 37% of the total points sampled-and strongly related to piñon-juniper canopy cover. Models developed for predicting SWR extent and severity had R(2)adj values of 0.67 and 0.61, respectively; both models included piñon-juniper canopy cover and relative humidity the month before the fire as coefficient terms. These results are important as they suggest that postfire water repellency will increase in the coming years as infilling processes enhance piñon-juniper canopy cover. Furthermore, reductions in relative humidity brought about by a changing climate have the potential to link additively with infilling processes to increase the frequency and intensity of wildfires and produce stronger water repellency over a greater spatial extent. In working through these challenges, land managers can apply the predictive models developed in this study to prioritize fuel control and postfire restoration treatments.

  1. Assessing Pinyon Juniper Feedstock Properties and Utilization Options

    Energy Technology Data Exchange (ETDEWEB)

    Gresham, Garold Linn [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kenney, Kevin Louis [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-08-01

    Pinyon-juniper woodlands are a major ecosystem type found in the Southwest and the Intermountain West regions of the United States. These ecosystems are characterized by the presence of several different species of pinyon pine and juniper as the dominant plant cover. Since the 1800s, pinyon-juniper woodlands have rapidly expanded their range at the expense of existing ecosystems. Additionally, existing woodlands have become more dense, potentially increasing fire hazards. Land managers responsible for these areas often desire to reduce pinyonjuniper coverage on their lands for a variety of reasons, including restoration to previous vegetative cover, mitigation of fire risk, and improvement in wildlife habitat. However, the cost of clearing or thinning pinyon-juniper stands can be prohibitive. One reason for this is the lack of utilization options for the resulting biomass that could help recover some of the cost of pinyonjuniper stand management. The goal of this project was to assess the feedstock characteristics of biomass from a pinyon-juniper harvest so that potential applications for the biomass may be evaluated.

  2. Improved inertial control for permanent magnet synchronous generator wind turbine generators

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Ziping; Gao, Wenzhong; Wang, Xiao; Kang, Moses; Hwang, Min; Kang, Yong Cheol; Gevogian, Vahan; Muljadi, Eduard

    2016-05-31

    With increasing integrations of large-scale systems based on permanent magnet synchronous generator wind turbine generators (PMSG-WTGs), the overall inertial response of a power system will tend to deteriorate as a result of the decoupling of rotor speed and grid frequency through the power converter as well as the scheduled retirement of conventional synchronous generators. Thus, PMSG-WTGs can provide value to an electric grid by contributing to the system's inertial response through the inherent kinetic energy stored in their rotating masses and fast power converter control. In this study, an improved inertial control method based on the maximum power point tracking operation curve is introduced to enhance the overall frequency support capability of PMSG-WTGs in the case of large supply-demand imbalances. Moreover, this method is implemented in the CART2-PMSG integrated model in MATLAB/Simulink to investigate its impact on the wind turbine's structural loads during the inertial response process. Simulation results indicate that the proposed method can effectively reduce the frequency nadir, arrest the rate of change of frequency, and alleviate the secondary frequency dip while imposing no negative impact on the major mechanical components of the wind turbine.

  3. Flicker Mitigation by Speed Control of Permanent Magnet Synchronous Generator Variable-Speed Wind Turbines

    Directory of Open Access Journals (Sweden)

    Yanting Hu

    2013-07-01

    Full Text Available Grid-connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a full-scale back-to-back power converter and permanent magnet synchronous generator (PMSG developed in the simulation tool of PSCAD/EMTDC. Flicker emission of this system is investigated. The 3p (three times per revolution power oscillation due to wind shear and tower shadow effects is the significant part in the flicker emission of variable speed wind turbines with PMSG during continuous operation. A new method of flicker mitigation by controlling the rotational speed is proposed. It smoothes the 3p active power oscillations from wind shear and tower shadow effects of the wind turbine by varying the rotational speed of the PMSG. Simulation results show that damping the 3p active power oscillation by using the flicker mitigation speed controller is an effective means for flicker mitigation of variable speed wind turbines with full-scale back-to-back power converters and PMSG during continuous operation.

  4. Data Quality Control of the French Permanent Broadband Network in the RESIF Framework.

    Science.gov (United States)

    Grunberg, M.; Lambotte, S.; Engels, F.

    2014-12-01

    In the framework of the RESIF (Réseau Sismologique et géodésique Français) project, a new information system is setting up, allowing the improvement of the management and the distribution of high quality data from the different elements of RESIF. Within this information system, EOST (in Strasbourg) is in charge of collecting real-time permanent broadband seismic waveform, and performing Quality Control on these data. The real-time and validated data set are pushed to the French National Distribution Center (Isterre/Grenoble) to make them publicly available. Furthermore EOST hosts the BCSF-ReNaSS, in charge of the French metropolitan seismic bulletin. This allows to benefit from some high-end quality control based on the national and world-wide seismicity. Here we present the real-time seismic data flow from the stations of the French National Broad Band Network to EOST, and then, the data Quality Control procedures that were recently installed, including some new developments.The data Quality Control consists in applying a variety of processes to check the consistency of the whole system from the stations to the data center. This allows us to verify that instruments and data transmission are operating correctly. Moreover, time quality is critical for most of the scientific data applications. To face this challenge and check the consistency of polarities and amplitudes, we deployed several high-end processes including a noise correlation procedure to check for timing accuracy (intrumental time errors result in a time-shift of the whole cross-correlation, clearly distinct from those due to change in medium physical properties), and a systematic comparison of synthetic and real data for teleseismic earthquakes of magnitude larger than 6.5 to detect timing errors as well as polarity and amplitude problems.

  5. Position Sensorless Vector Control for Permanent Magnet Synchronous Motors Based on Maximum Torque Control Frame

    Science.gov (United States)

    Hida, Hajime; Tomigashi, Yoshio; Kishimoto, Keiji

    High efficiency drive can be achieved by the maximum torque-per-ampere (MTPA) control which used reluctance torque effectively. However, the calculations for estimating rotor position and for controlling the d-axis current are required. The motor parameters of inductance etc. that are easily affected by magnetic saturation are included in those calculations. This paper proposes a new MTPA control method, which is robust against changes of motor parameters caused by magnetic saturation. In addition, complex calculation for d-axis current or reference to the table is not necessary. In this method, we define a novel coordinate frame, which has one axis aligned with the current vector of the MTPA control, and estimate the frame directly. Because the parameter Lqm for estimating the frame is less affected by the magnetic saturation than the conventional Lq, the effect of magnetic saturation on the position estimation can be greatly suppressed. First, an extended electromotive force model based on the proposed frame and a parameter Lqm for an estimation of the frame are derived. Next, the effectiveness of this proposed method is confirmed by simulations and experiments.

  6. Control of Surface Mounted Permanent Magnet Motors with Special Application to Fractional-Slot Concentrated Windings

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, J.S.

    2005-12-21

    It is well known that the ability of the permanent magnet synchronous machine (PMSM) to operate over a wide constant power speed range (CPSR) is dependent upon the machine inductance [1,2,3,4,5]. Early approaches for extending CPSR operation included adding supplementary inductance in series with the motor [1] and the use of anti-parallel thyristor pairs in series with the motor-phase windings [5]. The increased inductance method is compatible with a voltage-source inverter (VSI) controlled by pulse-width modulation (PWM) which is called the conventional phase advance (CPA) method. The thyristor method has been called the dual mode inverter control (DMIC). Neither of these techniques has met with wide acceptance since they both add cost to the drive system and have not been shown to have an attractive cost/benefit ratio. Recently a method has been developed to use fractional-slot concentrated windings to significantly increase the machine inductance [6]. This latest approach has the potential to make the PMSM compatible with CPA without supplemental external inductance. If the performance of such drive is acceptable, then the method may make the PMSM an attractive option for traction applications requiring a wide CPSR. A 30 pole, 6 kW, 6000 maximum revolutions per minute (rpm) prototype of the fractional-slot PMSM design has been developed [7]. This machine has significantly more inductance than is typical of regular PMSMs. The prototype is to be delivered in late 2005 to the Oak Ridge National Laboratory (ORNL) for testing and development of a suitable controller. In advance of the test/control development effort, ORNL has used the PMSM models developed over a number of previous studies to study the steady-state performance of high-inductance PMSM machines with a view towards control issues. The detailed steady-state model developed includes all motor and inverter-loss mechanisms and will be useful in assessing the performance of the dynamic controller to be

  7. Importance of permanent improvement of production and control of basic seed of ZP maize hybrids

    Directory of Open Access Journals (Sweden)

    Sečanski Mile

    2015-01-01

    Full Text Available High-quality seed is one of the key factors in the commercial maize grain production. In addition, hybrid seed production is conditioned by the production of basic seed of parental inbreds. According to the Law on Seed, 2005, the category of basic seed is defined as: original of self-pollinated plant species, hybrid components and potato elite, produced under control of the Ministry competent for agribusiness and is used for the production of certified seed of the first generation. This paper presents a chronological overview of the overall activity since1945. that led to the modern production of maize seed in our country. The activities have been based on scientific, technical and technological achievements within many fields, ranging from genetics and breeding, through growing practices, processing, quality control and legal regulations concerning all of this. Transition from maize breeding and production to hybrids has provided an amazing development of maize breeding and seed production and also included significant profit. Therefore, maize seed production has become high-technology industry. The scientific and professional work in improving the production of basic seed of ZP maize hybrids has been carried out in stages, and generally followed achievements in maize breeding and genetics, as well as developments in the growing practices and processing. In order to maintain a high quality of maize hybrid seed, as the end product, permanent efforts have to be invested into maize production improvement, drying, processing, storing, genetic purity of basic seed of parental inbreds of ZP maize hybrids, which are grown on the significant percentage of maize production areas not only in Serbia and countries in the region.

  8. Study on control method of running velocity for the permanent magnet-HTSC hybrid magnetically levitated conveyance system

    Science.gov (United States)

    Nishio, R.; Ikeda, M.; Sasaki, R.; Ohashi, S.

    2011-11-01

    We have developed the magnetically levitated carrying system. In this system, pinning force of high temperature bulk super conductor (HTSC) is used for the levitation and guidance. Four HTSCs are installed on the carrier. The magnetic rail is set on the ground, and flux from the magnetic rail is pinned by HTSCs. To increase levitation force, repulsive force of the permanent magnet is used. The hybrid levitation system is composed. The permanent magnet is installed under the load stage of the carrier. Repulsive force by the permanent magnet between the load stage on the carrier and the magnetic rail on the ground is used to support the load weight. Levitation and guidance one by pinning effect of the YBaCuO HTSC in the carrier is used to levitate the carrier body. The load stage is separated from the carrier flame and can move freely for vertical direction levitation. For the propulsion system, electromagnet is installed on the surface of the magnetic rail. In this paper, control method of running velocity of the carrier is studied. Propulsion force is given as follows; Air core copper coils are installed on the magnetic rail. Interaction between current of these coils and permanent magnets on the carrier generates propulsion force. Running velocity is controlled by current of the propulsion coils. It is also changed by position of the carrier and the load weight. From the results, stability of the propulsion system is given, and propulsion characteristics are improved.

  9. RESTORATION OF QUAKING ASPEN WOODLANDS INVADED BY WESTERN JUNIPER

    Science.gov (United States)

    Quaking aspen woodlands are important plant communities in the interior mountains of the western United States, providing essential habitat for many wildlife species and contain a high diversity of understory plants. Western juniper woodlands are rapidly replacing lower elevation (<6800 ft) quaking...

  10. Adsorption mechanism of cadmium on juniper bark and wood

    Science.gov (United States)

    Eun Woo Shin; K. G. Karthikeyan; Mandla A. Tshabalala

    2007-01-01

    In this study the capacity of sorbents prepared from juniper wood (JW) and bark (JB) to adsorb cadmium (Cd) from aqueous solutions at different pH values was compared. Adsorption behavior was characterized through adsorption kinetics, adsorption isotherms, and adsorption edge experiments. Results from kinetics and isotherm experiments showed that JB (76.3–91.6 lmol Cd...

  11. Development of A Super High Speed Permanent Magnet Synchronous Motor (PMSM Controller and Analysis of The Experimental Results

    Directory of Open Access Journals (Sweden)

    Limei Zhao

    2005-02-01

    Full Text Available This paper presents the design and implementation of a DSP-based controller for a super high-speed (>80,000 rpm permanent magnet synchronous motor (PMSM. The PMSM is a key component of the centrifugal compressor drive of a reverse Brayton cryocooler that is currently under development for NASA and Florida Solar Energy Center. The design of the PMSM open-loop control is presented. Experimental results with open-loop control schemes are presented. System optimization and analysis are also illustrated. They verify the effectiveness of the controller design and the optimization scheme.

  12. Non-linear control of variable-speed wind turbines with permanent magnet synchronous generators: a robust backstepping approach

    Science.gov (United States)

    Şeker, Murat; Zergeroğlu, Erkan; Tatlicioğlu, Enver

    2016-01-01

    In this study, a robust backstepping approach for the control problem of the variable-speed wind turbine with a permanent magnet synchronous generator is presented. Specifically, to overcome the negative effects of parametric uncertainties in both mechanical and electrical subsystems, a robust controller with a differentiable compensation term is proposed. The proposed methodology ensures the generator velocity tracking error to uniformly approach a small bound where practical tracking is achieved. Stability of the overall system is ensured by Lyapunov-based arguments. Comparative simulation studies with a standard proportional-integral-type controller are performed to illustrate the effectiveness, feasibility and efficiency of the proposed controller.

  13. Output Feedback Adaptive Dynamic Surface Control of Permanent Magnet Synchronous Motor with Uncertain Time Delays via RBFNN

    Directory of Open Access Journals (Sweden)

    Shaohua Luo

    2014-01-01

    Full Text Available This paper focuses on an adaptive dynamic surface control based on the Radial Basis Function Neural Network for a fourth-order permanent magnet synchronous motor system wherein the unknown parameters, disturbances, chaos, and uncertain time delays are presented. Neural Network systems are used to approximate the nonlinearities and an adaptive law is employed to estimate accurate parameters. Then, a simple and effective controller has been obtained by introducing dynamic surface control technique on the basis of first-order filters. Asymptotically tracking stability in the sense of uniformly ultimate boundedness is achieved in a short time. Finally, the performance of the proposed control has been illustrated through simulation results.

  14. Adaptive Speed Control Design for Brushed Permanent Magnet DC Motor Based on Worst-Case Analysis Approach

    Directory of Open Access Journals (Sweden)

    Sheng Zeng

    2013-01-01

    Full Text Available This paper presents the adaptive controller design for brushed permanent magnet DC motor used in velocity-tracking applications based on worst-case approach. We first formulate the robust adaptive control problem as a nonlinear H∞-control problem under imperfect state measurement, and then solve it using game-theoretic approach. The controller guarantees the boundedness of closed-loop signals with bounded exogenous disturbances, and achieves desired disturbance attenuation level with respect to the unmeasured exogenous disturbance inputs and the measured disturbance inputs. The strong robustness properties are illustrated by a simulation example.

  15. Tree Removal as a Mechanism to Reverse Ecohydrologic Thresholds in Pinyon- and Juniper-Encroached Shrublands

    Science.gov (United States)

    Williams, C. J.; Pierson, F. B.; Nouwakpo, S.; Weltz, M.

    2016-12-01

    Pinyon and juniper encroachment has altered vegetation structure, ecological condition, hydrologic function, and delivery of ecosystem goods and services on millions of hectares of sagebrush rangelands in the western US. Pinyon and juniper out-compete shrubs and herbaceous vegetation for water and nutrients and facilitate a decline in vigor and cover of understory plants. These cover declines educe a shift from biotic-controlled resource retention to abiotic-driven losses of critical soil resources over time (soil erosion feedback). Our research objective was to evaluate tree removal by mastication, burning, and cutting as a threshold-reversal mechanism for restoration of sagebrush steppe ecohydrologic resilience over a ten year period. We examined vegetation, soils, infiltration, runoff, and erosion from artificial rainfall and concentrated flow experiments across multiple scales in two late succession woodlands before and 1, 2, and 10 yr after tree removal to address two research questions: 1) Can tree removal decrease late-succession woodland ecohydrologic resilience by increasing vegetation and ground cover within the first 10 yr post-treatment?, and 2) Is the soil erosion feedback reversible in the later stages of woodland encroachment? Distributing shredded tree debris into bare areas improved infiltration and reduced soil erosion in the first few years following tree mastication. Cutting and placing downed trees in bare patches had no initial effect on runoff and erosion. Burning initially reduced infiltration and increased runoff and erosion at the sites, but favorable grass and forb cover recruitment 2 yr after burning reduced erosion from the mostly bare intercanopy between tree mounds. Our presentation of the overall study will chronicle these published pre-fire, 1 yr, and 2 yr responses and preliminary results from the 10th yr post-treatment to address the questions outlined above. The collective results advance understanding of pinyon and juniper

  16. 永磁耦合器控制系统设计%Permanent magnet coupling control system design

    Institute of Scientific and Technical Information of China (English)

    邓高见; 陆江锋; 陆江洁; 胡永冬

    2015-01-01

    永磁耦合器在传动过程中,通过永磁体磁场和电感应磁场相互作用传递扭矩 ,存在涡流热损耗,因此需要间隙控制电动执机构来控制永磁耦合器间隙大小和温度测量等参数.%In the transmission process of permanent magnetic coupling, the torque is transmitted by the interaction of permanent magnetic field and electrical magnetic and it have eddy heat losses. So we need electrical control unit to control parameters such as temperature measurement.

  17. Does woodland encroachment impact water?: An ecohydrology study of western juniper (Juniperus occidentalis) and other semi-arid conifers in the western U.S.

    Science.gov (United States)

    Niemeyer, R. J.; Link, T. E.; Heinse, R.; Seyfried, M. S.; Flerchinger, G. N.; Klos, P. Z.

    2015-12-01

    Semi-arid conifer species including western juniper (Juniperus occidentalis) among other pinyon and juniper (P-J) species have expanded into grass and shrub-dominated landscapes in the western U.S. Despite the importance of land cover changes to hydrological fluxes in these water-limited systems, there have been few process-based ecohydrology studies of western juniper encroachment. Furthermore, many conclusions about the impact of P-J encroachment on streamflow are limited to several studies in the southwestern U.S. Our objectives are to: a) assess how western juniper will impact above-ground hydrological processes, b) assess how western juniper will alter below-ground hydrological processes, c) assess how changes in P-J cover alters deep drainage across diverse climates of the western U.S. To accomplish these objectives we used a combination of continuous lysimeter and soil moisture measurements, periodic snow surveys, electrical resistivity tomography (ERT) and electromagnetic induction (EMI) surveys, simulations with the Simultaneous Heat and Water (SHAW) model and broad, spatially-coarse simulations with the atmosphere-vegetation-soil component of the HBV model. Juniper trees by both intercepting snow and increasing below-canopy snow melt caused tree wells to form throughout the winter. These tree wells increased snow redistribution to the base of the trees. Soil moisture in the interspace dominated by sagebrush, forbes, and grasses drops early in the season, but late season soil moisture changes are moderated by juniper. There is evidence that junipers continue to transpire soil moisture both late into the summer and at up to 3 meters deep. HBV simulations revealed that the potential for increases in deep drainage with a change from P-J to grass cover is principally controlled by the timing instead of the total precipitation. Simulations confirm previous empirical studies that landscapes in monsoon-dominated climates of the southwestern U.S. show negligible

  18. Ecohydrologic relationships of two juniper woodlands with different precipitation regimes

    Science.gov (United States)

    Ochoa, C. G.; Guldan, S. J.; Deboodt, T.; Fernald, A.; Ray, G.

    2015-12-01

    The significant expansion of juniper (Juniperus spp.) woodlands throughout the western U.S. during the last two centuries has disrupted important ecological functions and hydrologic processes. The relationships between water and vegetation distribution are highly impacted by the ongoing shift from shrub steppe and grassland to woodland-dominated landscapes. We investigated vegetation dynamics and hydrologic processes occurring in two distinct juniper landscapes with different precipitation regimes in the Intermountain West region: A winter snow-dominated (Oregon) and a summer rain-dominated with some winter precipitation (New Mexico) landscape. Results from the Oregon site showed marginal differences (1-2%) in soil moisture in treated vs untreated watersheds throughout the dry and wet seasons. In general, soil moisture was greater in the treated watershed in both seasons. Canopy cover affected soil moisture over time. Perennial grass cover was positively correlated with changes in soil moisture, whereas juniper cover was negatively correlated with changes in soil moisture. Shallow groundwater response observed in upland and valley monitoring wells indicate there are temporary hydrologic connections between upland and valley locations during the winter precipitation season. Results from the New Mexico site provided valuable information regarding timing and intensity of monsoon-driven precipitation and the rainfall threshold (5 mm/15 min) that triggers runoff. Long-term vegetation dynamics and hydrologic processes were evaluated based on pre- and post-juniper removal (70%) in three watersheds. In general, less runoff and greater forage response was observed in the treated watersheds. During rainfall events, soil moisture was less under juniper canopy compared with inter-canopy; this difference in soil moisture was intensified during high intensity, short duration rainstorms in the summer months. We found that winter snow precipitation helped recharge soil moisture

  19. Flicker Mitigation by Speed Control of Permanent Magnet Synchronous Generator Variable-Speed Wind Turbines

    DEFF Research Database (Denmark)

    Hu, Weihao; Zhang, Yunqian; Chen, Zhe;

    2013-01-01

    Grid-connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a full-scale back-to-back power converter and permanent magnet synchronous generator (PMSG...

  20. Sensorless control of interior permanent-magnet synchronous motors with compressor load

    DEFF Research Database (Denmark)

    Huang, Shoudao; Gao, Jian; Xiao, Lei

    2013-01-01

    This paper analyzes the mathematical model of the interior permanent-magnet synchronous motors (IPMSM). Through the mathematical deformation, the paper proposes the new sensorless method based on sliding mode observer for a IPMSM. The model is only associated with the q-axis inductance, and without...

  1. A Design Fuzzy Logic Controller for a Permanent Magnet Wind Generator to Enhance the Dynamic Stability of Wind Farms

    Directory of Open Access Journals (Sweden)

    Marwan Rosyadi

    2012-11-01

    Full Text Available In this paper, a design fuzzy logic controller for a variable speed permanent magnet wind generator connected to a grid system through a LC-filter is proposed. A new current control method of grid side conversion is developed by integrating the fuzzy controller, in which both active and reactive power, delivered to a power grid system, is controlled effectively. The fuzzy logic controller is designed to adjust the gain parameters of the PI controllers under any operating conditions, so that the dynamic stability is enhanced. A new simple method, based on frequency response of the bode diagram, is proposed in the design of the fuzzy logic controller. To evaluate the controller system capabilities, simulation analyses are performed on a small wind farm model system including an induction wind generator connected to an infinite bus. The simulations have been performed using PSCAD/EMTDC. Simulation results show that the proposed control scheme is more effective for enhancing the stability of wind farms during temporary and permanent network disturbances and randomly fluctuating wind speed, compared with that of a conventional PI controller.

  2. Effects of one-seed juniper and polyethylene glycol on intake, rumen fermentation, and plasma amino acids in sheep and goats fed supplemental protein and tannins.

    Science.gov (United States)

    We tested the effect of polyethylene glycol (PEG) on juniper and total intake, rumen fermentation, and plasma amino acids (AA) of 12 does and 12 ewes fed sudangrass and basal diets containing 10% quebracho tannins with no protein supplement (Control; 5% CP) or high rumen degradable (RDP 15% CP) or u...

  3. Study on control method of running velocity for the permanent magnet-HTSC hybrid magnetically levitated conveyance system

    Energy Technology Data Exchange (ETDEWEB)

    Nishio, R.; Ikeda, M.; Sasaki, R. [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan); Ohashi, S., E-mail: ohashi@kansai-u.ac.jp [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2011-11-15

    The hybrid magnetically levitated carrying system is developed. Control method of running velocity of the carrier is studied. Running velocity is controlled by current of the propulsion coils. Propulsion characteristcs are improved. We have developed the magnetically levitated carrying system. In this system, pinning force of high temperature bulk super conductor (HTSC) is used for the levitation and guidance. Four HTSCs are installed on the carrier. The magnetic rail is set on the ground, and flux from the magnetic rail is pinned by HTSCs. To increase levitation force, repulsive force of the permanent magnet is used. The hybrid levitation system is composed. The permanent magnet is installed under the load stage of the carrier. Repulsive force by the permanent magnet between the load stage on the carrier and the magnetic rail on the ground is used to support the load weight. Levitation and guidance one by pinning effect of the YBaCuO HTSC in the carrier is used to levitate the carrier body. The load stage is separated from the carrier flame and can move freely for vertical direction levitation. For the propulsion system, electromagnet is installed on the surface of the magnetic rail. In this paper, control method of running velocity of the carrier is studied. Propulsion force is given as follows; Air core copper coils are installed on the magnetic rail. Interaction between current of these coils and permanent magnets on the carrier generates propulsion force. Running velocity is controlled by current of the propulsion coils. It is also changed by position of the carrier and the load weight. From the results, stability of the propulsion system is given, and propulsion characteristics are improved.

  4. Optimum Density and Space Structure of Kyrgyzstan’s Juniper Stands for Identifying Water Protective Properties

    Institute of Scientific and Technical Information of China (English)

    Zayirbek; Toktoraliev; Okke; Batelaan; Pichang; YUE; Heng; ZHANG

    2014-01-01

    Central Asia including Kyrgyzstan is a disaster prone area,suffering from snow avalanches,landslides and flooding.Within the Tyan- Shan region,a mountainous region in Southern Kyrgyzstan,there is an increasing number of natural hazards over the last years.One of the possible causes of the increase in natural disasters in the region is the deterioration of the Juniper forests in the region.Juniper forests have a large economical and ecological importance for Kyrgyzstan.However,the conditions worsened for these juniper forests.Since 1980 approximately 20% of the juniper forests were lost due to intensive deforestation,forest fires and excessive cattle grazing and possibly also climate changes are affecting the juniper trees and their soil properties.The aim of this study is to investigate the impact of the juniper forest on the local hydrology and to characterize the water protective properties.

  5. Practical Wide-speed-range Sensorless Control System for Permanent Magnet Reluctance Synchronous Motor Drives via Active Flux Model

    DEFF Research Database (Denmark)

    Ancuti, Mihaela Codruta; Tutelea, Lucian; Andreescu, Gheorghe-Daniel

    2014-01-01

    This article introduces a control strategy to obtain near-maximum available torque in a wide speed range with sensorless operation via the active flux concept for permanent magnet-reluctance synchronous motor drives. A new torque dq current reference calculator is proposed, with reference torque...... digital simulation results (1–6000 rpm) and experimental results (50–3000 rpm at low inverter available DC voltage of 12 Vdc instead of 48 Vdc) demonstrate the effectiveness of the proposed sensorless control strategy in a wide speed range, with stable and reliable operations up to a speed equal to eight...

  6. Speed sensoless robust control of permanent magnet synchronous motor based on second-order sliding-mode observer

    Directory of Open Access Journals (Sweden)

    Fezzani Amor

    2014-01-01

    Full Text Available This paper is devoted to the study of the performances of a robust speed sensorless nonlinear control of permanent magnet synchronous machine. In the first part, the controllers are designed using two methods: the first one using the input output feedback linearization control and the second is a nonlinear control based on Lyapunov theory combined with sliding mode control. This second solution shows good robustness with respect to parameter variations, measurement errors and noises. In the second part, the high order sliding mode speed observer is used to overcome the occurring chattering phenomena. The super twisting algorithm is modified in order to design a speed and position observer for PMSM. Finally, simulation results are given to demonstrate the effectiveness and the good performance of the proposed control methods.

  7. Modeling and Control of a Flux-Modulated Compound-Structure Permanent-Magnet Synchronous Machine for Hybrid Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Zhiyi Song

    2012-01-01

    Full Text Available The compound-structure permanent-magnet synchronous machine (CS-PMSM, comprising a double rotor machine (DRM and a permanent-magnet (PM motor, is a promising electronic-continuously variable transmission (e-CVT concept for hybrid electric vehicles (HEVs. By CS-PMSM, independent speed and torque control of the vehicle engine is realized without a planetary gear unit. However, the slip rings and brushes of the conventional CS-PMSM are considered a major drawback for vehicle application. In this paper, a brushless flux-modulated CS-PMSM is investigated. The operating principle and basic working modes of the CS-PMSM are discussed. Mathematical models of the CS-PMSM system are given, and joint control of the two integrated machines is proposed. As one rotor of the DRM is mechanically connected with the rotor of the PM motor, special rotor position detection and torque allocation methods are required. Simulation is carried out by Matlab/Simulink, and the feasibility of the control system is proven. Considering the complexity of the controller, a single digital signal processor (DSP is used to perform the interconnected control of dual machines instead of two separate ones, and a typical hardware implementation is proposed.

  8. Enhanced Control for a Direct-driven Permanent Synchronous Generator Wind-power Generation System with Flywheel Energy Storage Unit Under Unbalanced Grid Fault

    DEFF Research Database (Denmark)

    Yao, Jun; Zhou, Te; Hu, Weihao;

    2015-01-01

    This article presents an enhanced control strategy for a direct-driven permanent synchronous generator based wind-power generation system with a flywheel energy storage unit. The behaviors of the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit under......, the DC-link voltage oscillations can be effectively suppressed during the unbalanced grid fault by controlling the flywheel energy storage unit. Furthermore, a proportional–integral-resonant controller is designed for the flywheel motor to eliminate the oscillations in the DC-link voltage. Finally......, the proposed coordinated control strategy for the direct-driven permanent magnet synchronous generator system with a flywheel energy storage unit has been validated by the simulation results of a 1-MW direct-driven permanent magnet synchronous generator wind power generation system with a flywheel energy...

  9. Accurate torque-sensorless control approach for interior permanent-magnet synchronous machine based on cascaded sliding mode observer

    Directory of Open Access Journals (Sweden)

    Kai-Hui Zhao

    2017-06-01

    Full Text Available To improve the accuracy of torque control for vector control of interior permanent-magnet synchronous machine (IPMSM, this study proposes a torque-sensorless control method based on cascaded sliding mode observer (SMO. First, the active flux model is discussed, which converts the model of IPMSM into the equivalent model of surface-mounted permanent-magnet synchronous machine. Second, to reduce chattering caused by system parameters variations and external disturbances, the cascaded observer is designed, which is composed of a variable gain adaptive SMO and an active flux SMO. The variable gain adaptive SMO is designed to estimate the speed, rotor position and stator resistance in the d–q reference frame. The active flux SMO is designed to estimate the active flux and torque in the α–β reference frame. Global asymptotic stability of the observers is guaranteed by the Lyapunov stability analysis. Finally, simulations and experiments are carried out to verify the effectiveness of the proposed control scheme.

  10. A randomized controlled trial of various MTA materials for partial pulpotomy in permanent teeth.

    Science.gov (United States)

    Kang, Chung-Min; Sun, Yeji; Song, Je Seon; Pang, Nan-Sim; Roh, Byoung-Duck; Lee, Chan-Young; Shin, Yooseok

    2017-05-01

    The aim of this study was to evaluate and compare the clinical applicability of various MTA materials as partial pulpotomy materials in permanent teeth. Partial pulpotomy was performed on 104 permanent teeth from 82 people (mean 29.3±14.8years old), who met the inclusion criteria in randomized clinical trial. The teeth were divided into three groups: ProRoot MTA (n=33), OrthoMTA (n=36), RetroMTA (n=35). Clinical examination and radiographic comparison were carried out at 1, 3, 6 and 12 months after the treatment. Survival analysis was performed using the Kaplan-Meier survival curves and log rank tests. Partial pulpotomy sustained a high success rate up to 1year with no significant differences in the outcomes treated with three MTA materials: ProRoot MTA, 96.0%; OrthoMTA, 92.8%; RetroMTA, 96.0%. The Kaplan-Meier survival function curves showed no significant differences among three groups concerning clinical and radiographic cumulative survival rates. In addition, no potential prognostic factors related to the success rate of partial pulpotomy among age, sex, tooth type, root apex status, the site and type of pulp exposure, and the type of restoration were observed in log rank analysis. Partial pulpotomy with ProRoot MTA, OrthoMTA and RetroMTA had favorable results and clinical and radiographic results were not significantly different in three groups after 1year. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. The Research on Full-speed Field Weakening Control Method of Electric Vehicle Interior Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Gao Run-Ze

    2017-01-01

    Full Text Available The motor drive system represents a key technology for development of the electrical vehicles, and the permanent magnet synchronous motor becomes the mainstream of the new energy vehicle drive motor for the superior performances in power density, low-speed torque density, efficiency and reliability. The paper studies the field weakening control strategy for the interior permanent magnet synchronous motor (IPMSM and provides a field weakening control strategy for the IPMSM at the full-speed range. By studying the mathematical IPMSM model and the methods of conventional vector control and analyzing the operating conditions of the IPMSM at the full-speed range, the paper divides the operating conditions into constant torque operation region I, constant torque operation region II, constant power field weakening operation region and high-speed field weakening operation region to confirm the control strategy algorithm in each region and the transition conditions between regions and provide the current control strategy that the d-axis current and q-axis current are confirmed by the reference torque and the feedback speed. Modeling of the field weakening control strategies in each region is made through the Matlab/Simulink, and simulation of the operating conditions with a steady-state load and a dynamic load is done to verify that the field weakening control strategy in each region is feasible. A co-simulation is made by combining the Matlab/Simulink-based control model, the RecurDyn-based virtual prototype and the RT-LAB to verify the feasible field weakening control strategy.

  12. Influence of DSP controller on performance of a permanent magnet brushless AC drive in flux-weakening mode

    Institute of Scientific and Technical Information of China (English)

    ZHU Z.Q.; SHI Y.F.; HOWE D.

    2005-01-01

    The flux-weakening performance of a permanent magnet brushless AC drive was investigated using both floating-point and fixed-point DSP controllers. A significant current oscillation was observed when the drive was operated at high-speed in the flux-weakening mode with the fixed-point DSP. The investigation showed that this was due to the on-line compensation of the winding resistance voltage drop and quantisation errors associated with the fixed-point architecture of the DSP. A simple look-up table scheme is proposed to eliminate the oscillation and to achieve extended flux-weakening capability.

  13. Off-line tuning of a PI speed controller for a permanent magnet brushless DC motor using DSP

    Energy Technology Data Exchange (ETDEWEB)

    Demirtas, Metin, E-mail: mdtas@balikesir.edu.t [Electrical and Electronics Engineering Department, Balikesir University, Balikesir (Turkey)

    2011-01-15

    In this paper, a new method of tuning Proportional Integral (PI) coefficients for a permanent magnet brushless DC (PMBLDC) motor drives is proposed. Artificial neural network is used to identify the whole system using maximum overshoot and settling time obtained from the application circuit for different K{sub p}-K{sub i} pairs. Optimal values of PI controller coefficients are obtained using genetic algorithm. Motion Control Kit (MCK243) is used to carry out digital motion control applications. The MCK243 kit includes a power module and a three-phase brushless motor. TMS320F243 programs are used for PMBLDC motor speed control. Experimental results are given to show the validity of this method.

  14. Adaptive Controllers for Permanent Magnet Brushless DC Motor Drive System using Adaptive-Network-based Fuzzy Interference System

    Directory of Open Access Journals (Sweden)

    V. M. Varatharaju

    2011-01-01

    Full Text Available Problem statement: The tuning methodology for the parameters of adaptive speed controller causes a transient deviation of the response from the set reference following variation in load torque in a permanent-magnet brushless DC (BLDC motor drive system. Approach: This study develops a mathematical model of the BLDC drive system, firstly. Secondly, discusses a design of the closed loop drive system employing the Adaptive-Network-based Fuzzy Interference System (ANFIS. The nonlinear simulation model of the BLDC motors drive system with ANFIS control based is simulated in the MATLAB/SIMULINK platform. Results: The necessitated data for training the ANFIS control is generated by simulation of the system with conventional PI controller. Conclusion: The simulated electromagnetic torque and rotor speed signify the superiority of the proposed technique over the classical method.

  15. Effects of using ground redberry juniper and dried distillers grains with solubles in lamb feedlot diets: growth, blood serum, fecal, and wool characteristics.

    Science.gov (United States)

    Whitney, T R; Lupton, C J; Muir, J P; Adams, R P; Stewart, W C

    2014-03-01

    Effects of using ground redberry juniper and dried distillers grains with solubles (DDGS) in Rambouillet lamb (n = 45) feedlot diets on growth, blood serum, fecal, and wool characteristics were evaluated. In a randomized design study with 2 feeding periods (Period 1 = 64% concentrate diet, 35 d; Period 2 = 85% concentrate diet, 56 d), lambs were individually fed 5 isonitrogenous diets: a control diet (CNTL) that contained oat hay but not DDGS or juniper or DDGS-based diets in which 0 (0JUN), 33 (33JUN), 66 (66JUN), or 100% (100JUN) of the oat hay was replaced by juniper. During Period 1, lambs fed CNTL had greater (P diets. Lamb DMI, ADG, and G:F quadratically increased (P diets. During Period 2, lambs fed CNTL had greater (P diets, but ADG was similar (P > 0.41). Compared to 0JUN, lambs fed CNTL had similar (P = 0.12) G:F and tended to have less G:F (P = 0.07) than lambs fed DDGS-based diets. Among lambs fed DDGS-based diets, DMI was similar (P > 0.19), ADG increased linearly (P = 0.03), and G:F tended to decrease quadratically (P = 0.06) as juniper increased in the diet. Serum IGF-1, serum urea N (SUN), and fecal N were greater (P 0.13) for lambs fed CNTL vs. lambs fed DDGS-based diets (CNTL). Within lambs fed DDGS-based diets, SUN increased quadratically (P = 0.01) and fecal N increased linearly (P = 0.004), which can partially be attributed to increased dietary urea and condensed tannin intake. Most wool characteristics were not affected, but wool growth per kilogram of BW decreased quadratically (P = 0.04) as percentage of juniper increased in the DDGS-based diets. When evaluating the entire 91-d feeding trial, results indicated that replacing all of the ground oat hay with ground juniper leaves and stems in lamb growing and finishing diets is not detrimental to animal performance and that DDGS-based diets can reduce total feedlot costs, as compared to sorghum grain and cottonseed meal-based diets. However, compared to using juniper or oat hay as the sole

  16. Removal of toxic heavy metal ions in runoffs by modified alfalfa and juniper

    Science.gov (United States)

    J.S. Han; J.K. Park; S.H. Min

    2000-01-01

    A series of batch isotherm tests was performed with alfalfa and juniper fibers to evaluate the effectiveness in filtering toxic heavy metals from stormwater. The adsorption of the heavy metal ions on the alfalfa and juniper fibers was strongly dependent on the equilibrium pH value of the solution. The change in sorption rate over time showed that two different sorption...

  17. Conservation opportunities in Spanish Juniper Juniperus thurifera woodlands: the case of migratory thrushes Turdus spp.

    NARCIS (Netherlands)

    Telleria, J.L.; De la Hera, I.; Ramírez, A.; Santos, T.

    2011-01-01

    Conservation opportunities in Spanish juniper Juniperus thurifera woodlands: the case of migratory thrushes Turdus spp. Spanish juniper Juniperus thurifera woodlands are the core habitat of several sites included in the Nature 2000 Network and the wintering ground of many European thrushes Turdus

  18. Digging Deeper: Analyzing root traits to characterize juniper expansion into rangelands

    Science.gov (United States)

    Juniper expansion into sagebrush communities is a widespread phenomenon occurring across large regions of the western U.S. over the past century. The primary concerns of juniper encroachment are the decrease in forage for wildlife and livestock and potential changes in water quantity. Management of ...

  19. An Optimal Integrated Control Scheme for Permanent Magnet Synchronous Generator-Based Wind Turbines under Asymmetrical Grid Fault Conditions

    Directory of Open Access Journals (Sweden)

    Dan Wang

    2016-04-01

    Full Text Available In recent years, the increasing penetration level of wind energy into power systems has brought new issues and challenges. One of the main concerns is the issue of dynamic response capability during outer disturbance conditions, especially the fault-tolerance capability during asymmetrical faults. In order to improve the fault-tolerance and dynamic response capability under asymmetrical grid fault conditions, an optimal integrated control scheme for the grid-side voltage-source converter (VSC of direct-driven permanent magnet synchronous generator (PMSG-based wind turbine systems is proposed in this paper. The optimal control strategy includes a main controller and an additional controller. In the main controller, a double-loop controller based on differential flatness-based theory is designed for grid-side VSC. Two parts are involved in the design process of the flatness-based controller: the reference trajectories generation of flatness output and the implementation of the controller. In the additional control aspect, an auxiliary second harmonic compensation control loop based on an improved calculation method for grid-side instantaneous transmission power is designed by the quasi proportional resonant (Quasi-PR control principle, which is able to simultaneously restrain the second harmonic components in active power and reactive power injected into the grid without the respective calculation for current control references. Moreover, to reduce the DC-link overvoltage during grid faults, the mathematical model of DC-link voltage is analyzed and a feedforward modified control factor is added to the traditional DC voltage control loop in grid-side VSC. The effectiveness of the optimal control scheme is verified in PSCAD/EMTDC simulation software.

  20. Adaptive two-degree-of-freedom PI for speed control of permanent magnet synchronous motor based on fractional order GPC.

    Science.gov (United States)

    Qiao, Wenjun; Tang, Xiaoqi; Zheng, Shiqi; Xie, Yuanlong; Song, Bao

    2016-09-01

    In this paper, an adaptive two-degree-of-freedom (2Dof) proportional-integral (PI) controller is proposed for the speed control of permanent magnet synchronous motor (PMSM). Firstly, an enhanced just-in-time learning technique consisting of two novel searching engines is presented to identify the model of the speed control system in a real-time manner. Secondly, a general formula is given to predict the future speed reference which is unavailable at the interval of two bus-communication cycles. Thirdly, the fractional order generalized predictive control (FOGPC) is introduced to improve the control performance of the servo drive system. Based on the identified model parameters and predicted speed reference, the optimal control law of FOGPC is derived. Finally, the designed 2Dof PI controller is auto-tuned by matching with the optimal control law. Simulations and real-time experimental results on the servo drive system of PMSM are provided to illustrate the effectiveness of the proposed strategy.

  1. A novel fuzzy logic direct torque controller for a permanent magnet synchronous motor with a field programmable gate array

    Institute of Scientific and Technical Information of China (English)

    CHEN Yong-jun; HUANG Sheng-hua; WAN Shan-ming; WU Fang

    2008-01-01

    A high-performance digital servo system built on the platform of a field programmable gate array (FPGA), a fully digitized hardware design scheme of a direct torque control (DTC) and a low speed permanent magnet synchronous motor (PMSM) is proposed. The DTC strategy of PMSM is described with Verilog hardware description language and is employed on-chip FPGA in accordance with the electronic design automation design methodology. Due to large torque ripples in low speed PMSM, the hysteresis controller in a conventional PMSM DTC was replaced by a fuzzy controller. This FPGA scheme integrates the direct torque controller strategy, the time speed measurement algorithm, the fuzzy regulating technique and the space vector pulse width modulation principle. Experimental results indicate the fuzzy controller can provide a controllable speed at 20 r min-1 and torque at 330 N m with satisfactory dynamic and static performance. Furthermore, the results show that this new control strategy decreases the torque ripple drastically and enhances control performance.

  2. Sensorless control for permanent magnet synchronous motor using a neural network based adaptive estimator

    Science.gov (United States)

    Kwon, Chung-Jin; Kim, Sung-Joong; Han, Woo-Young; Min, Won-Kyoung

    2005-12-01

    The rotor position and speed estimation of permanent-magnet synchronous motor(PMSM) was dealt with. By measuring the phase voltages and currents of the PMSM drive, two diagonally recurrent neural network(DRNN) based observers, a neural current observer and a neural velocity observer were developed. DRNN which has self-feedback of the hidden neurons ensures that the outputs of DRNN contain the whole past information of the system even if the inputs of DRNN are only the present states and inputs of the system. Thus the structure of DRNN may be simpler than that of feedforward and fully recurrent neural networks. If the backpropagation method was used for the training of the DRNN the problem of slow convergence arise. In order to reduce this problem, recursive prediction error(RPE) based learning method for the DRNN was presented. The simulation results show that the proposed approach gives a good estimation of rotor speed and position, and RPE based training has requires a shorter computation time compared to backpropagation based training.

  3. Fuzzy Adaptive Repetitive Control for Periodic Disturbance with Its Application to High Performance Permanent Magnet Synchronous Motor Speed Servo Systems

    Directory of Open Access Journals (Sweden)

    Junxiao Wang

    2016-09-01

    Full Text Available For reducing the steady state speed ripple, especially in high performance speed servo system applications, the steady state precision is more and more important for real servo systems. This paper investigates the steady state speed ripple periodic disturbance problem for a permanent magnet synchronous motor (PMSM servo system; a fuzzy adaptive repetitive controller is designed in the speed loop based on repetitive control and fuzzy information theory for reducing periodic disturbance. Firstly, the various sources of the PMSM speed ripple problem are described and analyzed. Then, the mathematical model of PMSM is given. Subsequently, a fuzzy adaptive repetitive controller based on repetitive control and fuzzy logic control is designed for the PMSM speed servo system. In addition, the system stability analysis is also deduced. Finally, the simulation and experiment implementation are respectively based on the MATLAB/Simulink and TMS320F2808 of Texas instrument company, DSP (digital signal processor hardware platform. Comparing to the proportional integral (PI controller, simulation and experimental results show that the proposed fuzzy adaptive repetitive controller has better periodic disturbance rejection ability and higher steady state precision.

  4. Comparison of Unmodulated Current Control Characteristics of Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Anwar Muqorobin

    2014-12-01

    Full Text Available This paper discusses comparison of unmodulated current controls in PMSM, more specifically, on-off, sliding mode, predictive and hybrid controls. The purpose of this study is to select the most appropriate control technique to be adopted. The comparison method is preceded by modeling the motor and entering the values of the motor parameters. PI control is used for speed control and zero d-axis current is employed. Furthermore, performing simulation for each type ofthe selected current controls and analyzing their responses in terms of dq and abc currents, q-axis current response with step reference, as well as THD. Simulation results show that the on-off control gives the best overall performance based on its abc-axis current ripple and THD at large load torque. The hybrid control shows the best response occurring only at the fastest transient time of q-axis current but its response exhibits bad qualities compared with other controls. The predictive control yields the best responses offering the smallest d-axis ripple current and THD at small load torque condition. The sliding mode control, however, does not exhibit any prominent performance compared to the others. Results presented in this paper further indicate that for the PMSM used in the simulation the most appropriate control is the predictive control.

  5. On the Permanence of a Nonautonomous Nicholson's Blowflies Model with Feedback Control and Delay

    Institute of Scientific and Technical Information of China (English)

    LAI Wei-ying

    2011-01-01

    A nonautonomous Nicholson's Blowflies model with feedback control and delay is investigated in this paper.We show that for this system,feedback control variable has no influence on the persistent property of the system.

  6. Regenerative Endodontics Versus Apexification in Immature Permanent Teeth with Apical Periodontitis: A Prospective Randomized Controlled Study.

    Science.gov (United States)

    Lin, Jiacheng; Zeng, Qian; Wei, Xi; Zhao, Wei; Cui, Minyi; Gu, Jing; Lu, Jiaxuan; Yang, Maobin; Ling, Junqi

    2017-08-29

    The aim of the study was to compare the outcomes of regenerative endodontic treatment (RET) and apexification on immature permanent teeth with pulp necrosis and apical periodontitis. A total of 118 patients (118 teeth) were recruited and randomly assigned to either RET or apexification treatment. Each treatment group was divided into 2 subgroups according to the etiology: dens evaginatus or trauma. Clinical symptoms and complications were recorded, and cone-beam computed tomographic imaging with a limited field of view was used to measure the change of root length, root thickness, and apical foramen size at the 12-month follow-up. The t test/rank sum test and Fisher exact test were applied to compare the change of root morphology between RET and apexification. One hundred three of 118 cases were completed at the 12-month follow-up. The survival rate was 100% for both treatment groups. All cases were asymptomatic with apical healing. The RET group showed a significant increase in root length and root thickness compared with the apexification group (P < .05). In the RET group, the cases caused by dens evaginatus achieved increased root length and root thickness compared with those caused by trauma (P < .05). RET and apexification achieved a comparable outcome in regard to the resolution of symptoms and apical healing. RET showed a better outcome than apexification regarding increased root thickness and root length. The etiology had an impact on the outcome of RET. Dens evaginatus cases showed better prognoses than trauma cases after RET. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  7. Adaptive Quasi-Sliding Mode Control for Permanent Magnet DC Motor

    Directory of Open Access Journals (Sweden)

    Fredy E. Hoyos

    2013-01-01

    Full Text Available The motor speed of a buck power converter and DC motor coupled system is controlled by means of a quasi-sliding scheme. The fixed point inducting control technique and the zero average dynamics strategy are used in the controller design. To estimate the load and friction torques an online estimator, computed by the least mean squares method, is used. The control scheme is tested in a rapid control prototyping system which is based on digital signal processing for a dSPACE platform. The closed loop system exhibits adequate performance, and experimental and simulation results match.

  8. Fault tolerant control with torque limitation based on fault mode for ten-phase permanent magnet synchronous motor

    Institute of Scientific and Technical Information of China (English)

    Guo Hong; Xu Jinquan

    2015-01-01

    This paper proposes a novel fault tolerant control with torque limitation based on the fault mode for the ten-phase permanent magnet synchronous motor (PMSM) under various open-circuit and short-circuit fault conditions, which includes the optimal torque control and the torque limitation control based on the fault mode. The optimal torque control is adopted to guarantee the ripple-free electromagnetic torque operation for the ten-phase motor system under the post-fault condition. Furthermore, we systematically analyze the load capacity of the ten-phase motor system under different fault modes. And a torque limitation control approach based on the fault mode is proposed, which was not available earlier. This approach is able to ensure the safety operation of the faulted motor system in long operating time without causing the overheat fault. The simulation result confirms that the proposed fault tolerant control for the ten-phase motor system is able to guarantee the ripple-free electromagnetic torque and the safety operation in long operating time under the normal and fault conditions.

  9. Fault tolerant control with torque limitation based on fault mode for ten-phase permanent magnet synchronous motor

    Directory of Open Access Journals (Sweden)

    Guo Hong

    2015-10-01

    Full Text Available This paper proposes a novel fault tolerant control with torque limitation based on the fault mode for the ten-phase permanent magnet synchronous motor (PMSM under various open-circuit and short-circuit fault conditions, which includes the optimal torque control and the torque limitation control based on the fault mode. The optimal torque control is adopted to guarantee the ripple-free electromagnetic torque operation for the ten-phase motor system under the post-fault condition. Furthermore, we systematically analyze the load capacity of the ten-phase motor system under different fault modes. And a torque limitation control approach based on the fault mode is proposed, which was not available earlier. This approach is able to ensure the safety operation of the faulted motor system in long operating time without causing the overheat fault. The simulation result confirms that the proposed fault tolerant control for the ten-phase motor system is able to guarantee the ripple-free electromagnetic torque and the safety operation in long operating time under the normal and fault conditions.

  10. Predictive control strategies for wind turbine system based on permanent magnet synchronous generator.

    Science.gov (United States)

    Maaoui-Ben Hassine, Ikram; Naouar, Mohamed Wissem; Mrabet-Bellaaj, Najiba

    2016-05-01

    In this paper, Model Predictive Control and Dead-beat predictive control strategies are proposed for the control of a PMSG based wind energy system. The proposed MPC considers the model of the converter-based system to forecast the possible future behavior of the controlled variables. It allows selecting the voltage vector to be applied that leads to a minimum error by minimizing a predefined cost function. The main features of the MPC are low current THD and robustness against parameters variations. The Dead-beat predictive control is based on the system model to compute the optimum voltage vector that ensures zero-steady state error. The optimum voltage vector is then applied through Space Vector Modulation (SVM) technique. The main advantages of the Dead-beat predictive control are low current THD and constant switching frequency. The proposed control techniques are presented and detailed for the control of back-to-back converter in a wind turbine system based on PMSG. Simulation results (under Matlab-Simulink software environment tool) and experimental results (under developed prototyping platform) are presented in order to show the performances of the considered control strategies.

  11. Sensorless control of ship propulsion interior permanent magnet synchronous motor based on a new sliding mode observer.

    Science.gov (United States)

    Ren, Jun-Jie; Liu, Yan-Cheng; Wang, Ning; Liu, Si-Yuan

    2015-01-01

    This paper proposes a sensorless speed control strategy for ship propulsion interior permanent magnet synchronous motor (IPMSM) based on a new sliding-mode observer (SMO). In the SMO the low-pass filter and the method of arc-tangent calculation of extended electromotive force (EMF) or phase-locked loop (PLL) technique are not used. The calculation of the rotor speed is deduced from the Lyapunov function stability analysis. In order to reduce system chattering, sigmoid functions with switching gains being adaptively updated by fuzzy logic systems are innovatively incorporated into the SMO. Finally, simulation results for a 4.088 MW ship propulsion IPMSM and experimental results from a 7.5 kW IPMSM drive are provided to verify the effectiveness of the proposed SMO method.

  12. Improving the Drive System of Permanent Magnet Linear Synchronous Motor Based on Direct Thrust Force Control Applying Space Vector Modulation

    Directory of Open Access Journals (Sweden)

    Mehdi Manoochehri

    2012-07-01

    Full Text Available Applying the direct thrust force control (DFC method in permanent magnet linear synchronous motor (PMLSM leads to some important problems. The most important disadvantages of applying this method are electromagnetic force and linkage flux big ripple and variable switching frequency. In this paper space vector modulation (SVM technique is applied for removing the disadvantages of classic DFC method. SVM technique makes the switching frequency constant and provides continues Voltage space compared with discrete space in classic method. Simulation results confirmed the theory. They show that combining the DFC method with SVM technique removes lots of the disadvantages of classic DFC method like big ripples and variable switching and remains the benefits of this method.

  13. A Systems Approach to the Torque Control of a Permanent Magnet Brushless Motor

    Science.gov (United States)

    1987-08-01

    Direct Drive Arm (DDArni) and is addressed kinematic and dynamnic instabilities in robot force control . An presented parameter estimation techniques and...position and therefore cannot be guaranteed to remain stable. Eppinger and Seering [861 developed a dynamic model of robot force control with force

  14. Multicore Based Open Loop Motor Controller Embedded System for Permanent Magnet Direct Current Motor

    Directory of Open Access Journals (Sweden)

    K. Baskaran

    2012-01-01

    Full Text Available Problem statement: In an advanced electronics world most of the applications are developed by microcontroller based embedded system. Approach: Multicore processor based motor controller was presented to improve the processing speed of the controller and improve the efficiency of the motor by maintaining constant speed. It was based on the combination of Cortex processor (Software core and Field Programmable Gate Arrays (FPGA, Hardware core. These multicore combination were help to design efficient low power motor controller. Results: A functional design of cortex processor and FPGA in this system was completed by using Actel libero IDE and IAR embedded IDE software PWM signal was generated by the proposed processor to control the motor driver circuit. All the function modules were programmed by Very-High-Speed Integrated Circuit Hardware Description Language (VHDL. The advantage of the proposed system was optimized operational performance and low power utility. Multicore processor was used to improve the speed of execution and optimize the performance of the controller. Conclusion: Without having the architectural concept of any motor we can control it by using this method.This is an low cost low power controller and easy to use. The simulation and experiment results verified its validity.

  15. Feedback Control Variables Have No Influence on the Permanence of a Discrete n-Species Schoener Competition System with Time Delays

    Directory of Open Access Journals (Sweden)

    Qianqian Su

    2010-01-01

    Full Text Available We consider a discrete n-species Schoener competition system with time delays and feedback controls. By using difference inequality theory, a set of conditions which guarantee the permanence of system is obtained. The results indicate that feedback control variables have no influence on the persistent property of the system. Numerical simulations show the feasibility of our results.

  16. DSP-Based Sensorless Speed Control of a Permanent Magnet Synchronous Motor using Sliding Mode Current Observer

    Directory of Open Access Journals (Sweden)

    Rachid Askour

    2014-05-01

    Full Text Available In this paper, experimental results of 3-phase permanent magnet synchronous motor (PMSM sensorless speed control are presented. To estimate the rotor position, a sliding mode current observer (SMCO was implemented. This observer estimates the back emfs of the motor in the stationary reference frame using only the measured voltages and currents of the motor. These emfs were utilized to obtain the rotor position. The speed of the motor was calculated by differentiating the rotor position angle. The stability of the proposed SMCO was verified using Lyapunov method to determine the observer gain. The saturation function was adopted in order to reduce the chattering phenomenon caused by the SMCO. A vector control method was employed to achieve the sensorless drive system. The control application was developed in C/C++ language and implemented using the Texas Instruments TMS320LF2812 digital signal processor (DSP. This new processor enables intelligent control for motors. We used to test the drive the MCK2812 which is a professional development kit available from Technosoft Company. The theoretical finding is validated with experimental results that show the effectiveness of the real-time implementation.

  17. Rotor Position Sensorless Control and Its Parameter Sensitivity of Permanent Magnet Motor Based on Model Reference Adaptive System

    Science.gov (United States)

    Ohara, Masaki; Noguchi, Toshihiko

    This paper describes a new method for a rotor position sensorless control of a surface permanent magnet synchronous motor based on a model reference adaptive system (MRAS). This method features the MRAS in a current control loop to estimate a rotor speed and position by using only current sensors. This method as well as almost all the conventional methods incorporates a mathematical model of the motor, which consists of parameters such as winding resistances, inductances, and an induced voltage constant. Hence, the important thing is to investigate how the deviation of these parameters affects the estimated rotor position. First, this paper proposes a structure of the sensorless control applied in the current control loop. Next, it proves the stability of the proposed method when motor parameters deviate from the nominal values, and derives the relationship between the estimated position and the deviation of the parameters in a steady state. Finally, some experimental results are presented to show performance and effectiveness of the proposed method.

  18. THE EFFECTS OF DIFFERENT SOWING TIMES ON GERMINATION PERCENTAGE OF MOUNTAIN JUNIPER (Juniperus communis L. subsp. nana Syme, SMALL FRUITED JUNIPER (Juniperus oxycedrus L. subsp. oxycedrus, SAVIN JUNIPER (Juniperus sabina L. SEEDS

    Directory of Open Access Journals (Sweden)

    H. Cemal Gültekin

    2005-04-01

    Full Text Available Germination is delayed in Junipers because of embriyo dormancy, and also in same cases by an impermable seedcoat, or inhibitors in the cone and seedcoat. There are a lot of non-viable or nongerminating seeds of the species like the other juniper species. Low rates of germination in a number of species are due to a large propartion of non-viable or nongerminating seed. Non-viable seed may be hollow, damaged, or immature. In this study, after the process extraction the seeds from the cones and seperation of the empty, damaged, and immature seeds, the remain full seeds has been sown to find out the effects of different sowing times on germination percent under the nursery conditions. For this reason, ten different sowing times have been applied in thirty days intervals. Germination date on sowing times were analyzed using JMP statistical software. Results of the ANOVA and LSD showed that the most suitable sowing time and greatest germination was July (62.5 % and August (61.3 % for mountain juniper, August (73.0 % for small fruited juniper, July (51.8 % and August (50.8 % for savin juniper.

  19. Control strategy for permanent magnet synchronous motor with contra-rotating rotors under unbalanced loads condition

    DEFF Research Database (Denmark)

    Cheng, Shuangyin; Luo, Derong; Huang, Shoudao;

    2015-01-01

    is developed and the instability of the system with unbalanced loads is analysed. Based on the analysis, a control strategy which can keep synchronism of the two rotors under varying load is implemented. In addition, a method for starting the motor reliably is proposed, which is applicable to ship or under...

  20. Response of bird community structure to habitat management in piñon-juniper woodland-sagebrush ecotones

    Science.gov (United States)

    Knick, Steven T.; Hanser, Steve; Grace, James B.; Hollenbeck, Jeff P.; Leu, Matthias

    2017-01-01

    Piñon (Pinus spp.) and juniper (Juniperus spp.) woodlands have been expanding their range across the intermountain western United States into landscapes dominated by sagebrush (Artemisia spp.) shrublands. Management actions using prescribed fire and mechanical cutting to reduce woodland cover and control expansion provided opportunities to understand how environmental structure and changes due to these treatments influence bird communities in piñon-juniper systems. We surveyed 43 species of birds and measured vegetation for 1–3 years prior to treatment and 6–7 years post-treatment at 13 locations across Oregon, California, Idaho, Nevada, and Utah. We used structural equation modeling to develop and statistically test our conceptual model that the current bird assembly at a site is structured primarily by the previous bird community with additional drivers from current and surrounding habitat conditions as well as external regional bird dynamics. Treatment reduced woodland cover by >5% at 80 of 378 survey sites. However, habitat change achieved by treatment was highly variable because actual disturbance differed widely in extent and intensity. Biological inertia in the bird community was the strongest single driver; 72% of the variation in the bird assemblage was explained by the community that existed seven years earlier. Greater net reduction in woodlands resulted in slight shifts in the bird community to one having ecotone or shrubland affinities. However, the overall influence of woodland changes from treatment were relatively small and were buffered by other extrinsic factors. Regional bird dynamics did not significantly influence the structure of local bird communities at our sites. Our results suggest that bird communities in piñon-juniper woodlands can be highly stable when management treatments are conducted in areas with more advanced woodland development and at the level of disturbance measured in our study.

  1. Maximum Power Point Tracking Sensorless Control of an Axial-Flux Permanent Magnet Vernier Wind Power Generator

    Directory of Open Access Journals (Sweden)

    Xiang Luo

    2016-07-01

    Full Text Available Recently, Vernier permanent magnet (VPM machines, one special case of magnetic flux-modulated (MFM machines, benefiting from their compact, simple construction and low-speed/ high-torque characteristics, have been receiving increasing interest. In this paper, the Vernier structure is integrated with an axial-flux PM machine to obtain the magnetic gear effect and produce an improved torque density for direct-drive wind power generation application. Another advantage of the proposed machine is that the stator flux rotating speed can be relatively high when the shaft speed is low. With this benefit, sensorless control strategy can be easily implemented in a wide speed range. In this paper, an improved sliding mode observer (SMO is proposed to estimate the rotor position and the speed of the proposed machine. With the estimated shaft speeds, the maximum power point tracking (MPPT control strategy is applied to maximize the wind power extraction. The machine design and the sensorless MPPT control strategy are verified by finite element analysis and experimental verification.

  2. Experimental investigation on a colloidal damper rendered controllable under the variable magnetic field generated by moving permanent magnets

    Science.gov (United States)

    Suciu, B.

    2016-09-01

    In this work, a colloidal damper rendered controllable under variable magnetic fields is proposed and its controllability is experimentally evaluated. This absorber employs a water- based ferrofluid (FERROTEC MSGW10) in association with a liquid-repellent nanoporous solid matrix, consisted of particles of gamma alumina or/and silica gel. Control of the dynamic characteristics is obtained by moving permanent neodymium annular magnets, which are placed either on the piston head (axial magnetic field) or on the external surface of the cylinder (radial magnetic field). In order to properly select these magnets, flow visualizations inside of a transparent model damper were performed, and the quantity of the displaced liquid by the magnets through the damper's filter and through the nanoporous solid matrix was determined. Experimental data concerning variation of the magnetic flux density at the magnet surface versus the height of the magnet, and versus the target distance was collected. Based on such data, the suitable magnet geometry was decided. Then, the 3D structural model of the trial colloidal damper obtained by using Solidworks, and the excitation test rig are presented. From excitation tests on a ball-screw shaker, one confirmed larger damping abilities of the proposed absorber relative to the traditional colloidal damper, and also the possibility to adjust the damping coefficient according to the excitation type.

  3. Speed Control of Matrix Converter-Fed Five-Phase Permanent Magnet Synchronous Motors under Unbalanced Voltages

    Directory of Open Access Journals (Sweden)

    Borzou Yousefi

    2017-09-01

    Full Text Available Five-phase permanent magnet synchronous motors (PMSM have special applications in which highly accurate speed and torque control of the motor are a strong requirement. Direct Torque Control (DTC is a suitable method for the driver structure of these motors. If in this method, instead of using a common five-phase voltage source inverter, a three-phase to five-phase matrix converter is used, the low-frequency current harmonics and the high torque ripple are limited, and an improved input power factor is obtained. Because the input voltages of such converters are directly supplied by input three-phase supply voltages, an imbalance in the voltages will cause problems such as unbalanced stator currents and electromagnetic torque fluctuations. In this paper, a new method is introduced to remove speed and torque oscillator factors. For this purpose, motor torque equations were developed and the oscillation components created by the unbalanced source voltage, determined. Then, using the active and reactive power reference generator, the controller power reference was adjusted in such a way that the electromagnetic torque of the motor did not change. By this means, a number of features including speed, torque, and flux of the motor were improved in terms of the above-mentioned conditions. Simulations were analyzed using Matlab/Simulink software.

  4. A New Scheme to Direct Torque Control of Matrix Converter-Fed Five-Phase Permanent Magnet Synchronous Motor

    Directory of Open Access Journals (Sweden)

    Sayyed Asghar Gholamian

    2013-07-01

    Full Text Available Multiphase machines have gained an increasing attention due to their more advantages in comparison with three-phase machines. In recent literatures, only voltage source inverters (VSIs have been used to supply five-phase drives. Matrix converters (MCs pose many advantages over conventional VSIs, such as lack of dc-bulk capacitors, high quality power output waveform and higher number of output voltages. Due to some special applications of multiphase machines such as ship propulsion and aerospace, the volume of these drives is an important challenging problem. As a consequence, using MCs can be a reasonable alternative. In this paper, a new direct torque control (DTC algorithm using a three-to-five phase MC is proposed for five-phase permanent magnet synchronous motors (PMSMs. All of output voltage space vectors of three-to-five phase MC are extracted and a new switching table is proposed. Because of higher number of output voltages in MCs, there is a degree of freedom to control input power factor to keep close to unit moreover the torque and flux control. In other words, this proposed method use the advantages of both DTC method and MCs. Simulation results show the effectiveness of presented method in different operation modes.

  5. Multivariable H Robust Controller for a Permanent Magnet Synchronous Machine (PMSM

    Directory of Open Access Journals (Sweden)

    J. Khedri

    2015-03-01

    Full Text Available Analytical modeling of the PMSM often involves many simplifying assumptions. The model thus obtained is a model where the physical phenomena and dynamics are neglected during the identification of the process such that the saturation of the magnet circuit and the skin effect. However, the variation of stator resistances, cyclic inductances and moment of inertia due to the temperature and extensive use induce a difference between the process and the nominal mathematical model. Besides since the load torque is external disturbance that can affect the PMSM model, the traditional methods (Bode, Nyquist design… fail to satisfy stability and robust performance. To solve this problem, a robust multivariable H infinity controller is used seeing that the desired performance can be merged in the design phase as performance weights. The effectiveness of the proposed controller is applied for the speed tracking during load changing of a PMSM fed by voltage inverter through experimental study.

  6. A V/f= cte Control Drive for Permanent Capacitor Single-Phase Induction Motor

    OpenAIRE

    Pedram Shahriari Nasab; Hossein SafaMehr; Majid Moazzami

    2013-01-01

    Poor performance of the convectional household induction motors which used in home appliances such as refrigerator, cooler, laundry, washing machines, fans, hand-held power tools, and automotive window lift is generally caused by two main reasons. Firstly, they have high starting current which causes significant voltage drop, and secondly, they operate in a single speed mode and not in variable speed. In many home appliances, traditionally a discrete speed control method is used by changing t...

  7. Sensorless Control of Permanent Magnet Machine for NASA Flywheel Technology Development

    Science.gov (United States)

    Kenny, Barbara H.; Kascak, Peter E.

    2002-01-01

    This paper describes the position sensorless algorithms presently used in the motor control for the NASA "in-house" development work of the flywheel energy storage system. At zero and low speeds a signal injection technique, the self-sensing method, is used to determine rotor position. At higher speeds, an open loop estimate of the back EMF of the machine is made to determine the rotor position. At start up, the rotor is set to a known position by commanding dc into one of the phase windings. Experimental results up to 52,000 rpm are presented.

  8. Impact of prostate edema on cell survival and tumor control after permanent interstitial brachytherapy for early stage prostate cancers

    Science.gov (United States)

    Chen, Zhe (Jay); Roberts, Kenneth; Decker, Roy; Pathare, Pradip; Rockwell, Sara; Nath, Ravinder

    2011-01-01

    Previous studies have shown that the procedure-induced prostate edema during permanent interstitial brachytherapy (PIB) can cause significant variations in the dose delivered to the prostate gland. Because the clinical impact of edema-induced dose variations depends strongly on the magnitude of the edema, the temporal pattern of its resolution and its interplay with the decay of radioactivity and the underlying biological processes of tumor cells (such as tumor potential doubling time), we investigated the impact of edema-induced dose variations on the tumor cell survival and tumor control probability after PIB with the 131Cs, 125I and 103Pd sources used in current clinical practice. The exponential edema resolution model reported by Waterman et al. (Int. J. Radiat. Oncol. Biol. Phys. 41, 1069–1077–1998) was used to characterize the edema evolutions observed previously during clinical PIB for prostate cancer. The concept of biologically effective dose (BED), taking into account tumor cell proliferation and sublethal damage repair during dose delivery, was used to characterize the effects of prostate edema on cell survival and tumor control probability. Our calculation indicated that prostate edema, if not taken into account appropriately, can increase the cell survival and decrease the probability of local control of PIB. The edema-induced increase in cell survival increased with increasing edema severity, decreasing half-life for radioactive decay and decreasing energy of the photons energy emitted by the source. At the doses currently prescribed for PIB and for prostate cancer cells characterized by nominal radiobiology parameters recommended by AAPM TG-137, PIB using 125I sources was less affected by edema than PIB using 131Cs or 103Pd sources due to the long radioactive decay half-life of 125I. The effect of edema on PIB using 131Cs or 103Pd was similar. The effect of edema on 103Pd PIB was slightly greater, even though the decay half-life of 103Pd (17 days

  9. The impact of prostate edema on cell survival and tumor control after permanent interstitial brachytherapy for early stage prostate cancers

    Science.gov (United States)

    (Jay Chen, Zhe; Roberts, Kenneth; Decker, Roy; Pathare, Pradip; Rockwell, Sara; Nath, Ravinder

    2011-08-01

    Previous studies have shown that procedure-induced prostate edema during permanent interstitial brachytherapy (PIB) can cause significant variations in the dose delivered to the prostate gland. Because the clinical impact of edema-induced dose variations strongly depends on the magnitude of the edema, the temporal pattern of its resolution and its interplay with the decay of radioactivity and the underlying biological processes of tumor cells (such as tumor potential doubling time), we investigated the impact of edema-induced dose variations on the tumor cell survival and tumor control probability after PIB with the 131Cs, 125I and 103Pd sources used in current clinical practice. The exponential edema resolution model reported by Waterman et al (1998 Int. J. Radiat. Oncol. Biol. Phys. 41 1069-77) was used to characterize the edema evolutions previously observed during clinical PIB for prostate cancer. The concept of biologically effective dose, taking into account tumor cell proliferation and sublethal damage repair during dose delivery, was used to characterize the effects of prostate edema on cell survival and tumor control probability. Our calculation indicated that prostate edema, if not appropriately taken into account, can increase the cell survival and decrease the probability of local control of PIB. The magnitude of an edema-induced increase in cell survival increased with increasing edema severity, decreasing half-life of radioactive decay and decreasing photon energy emitted by the source. At the doses currently prescribed for PIB and for prostate cancer cells characterized by nominal radiobiology parameters recommended by AAPM TG-137, PIB using 125I sources was less affected by edema than PIB using 131Cs or 103Pd sources due to the long radioactive decay half-life of 125I. The effect of edema on PIB using 131Cs or 103Pd was similar. The effect of edema on 103Pd PIB was slightly greater, even though the decay half-life of 103Pd (17 days) is longer than

  10. Power control for direct-driven permanent magnet wind generator system with battery storage.

    Science.gov (United States)

    Guang, Chu Xiao; Ying, Kong

    2014-01-01

    The objective of this paper is to construct a wind generator system (WGS) loss model that addresses the loss of the wind turbine and the generator. It aims to optimize the maximum effective output power and turbine speed. Given that the wind generator system has inertia and is nonlinear, the dynamic model of the wind generator system takes the advantage of the duty of the Buck converter and employs feedback linearization to design the optimized turbine speed tracking controller and the load power controller. According to that, this paper proposes a dual-mode dynamic coordination strategy based on the auxiliary load to reduce the influence of mode conversion on the lifetime of the battery. Optimized speed and power rapid tracking as well as the reduction of redundant power during mode conversion have gone through the test based on a 5 kW wind generator system test platform. The generator output power as the capture target has also been proved to be efficient.

  11. Power Control for Direct-Driven Permanent Magnet Wind Generator System with Battery Storage

    Science.gov (United States)

    Guang, Chu Xiao; Ying, Kong

    2014-01-01

    The objective of this paper is to construct a wind generator system (WGS) loss model that addresses the loss of the wind turbine and the generator. It aims to optimize the maximum effective output power and turbine speed. Given that the wind generator system has inertia and is nonlinear, the dynamic model of the wind generator system takes the advantage of the duty of the Buck converter and employs feedback linearization to design the optimized turbine speed tracking controller and the load power controller. According to that, this paper proposes a dual-mode dynamic coordination strategy based on the auxiliary load to reduce the influence of mode conversion on the lifetime of the battery. Optimized speed and power rapid tracking as well as the reduction of redundant power during mode conversion have gone through the test based on a 5 kW wind generator system test platform. The generator output power as the capture target has also been proved to be efficient. PMID:25050405

  12. Design of Parameter Independent, High Performance Sensorless Controllers for Permanent Magnet Synchronous Machines

    DEFF Research Database (Denmark)

    Xie, Ge

    parameters such as resistance and inductance are involved in many existing sensorless control algorithms. Therefore, varying machine parameters due to different operation conditions may affect the accuracy of the position estimation and the drive performance consequently. For power converter manufactures...... of the typical sensorless algorithm – the INFORM method is implemented and tested. It is demonstrated that the voltage error may seriously affect the performance of the position estimator. To overcome this difficulty, a new implementation scheme of the INFORM method with easy inverter voltage error compensation......) PWM periods. In the injection period, the voltage output from the inverter is forced to be zero. The rotor position and the speed are then estimated simply from the current changes during this zero voltage injection period. This method provides a good performance for the rotor position estimation...

  13. Direct torque control of permanent magnet synchronous machines using Matrix Converters

    OpenAIRE

    Ortega García, Carlos

    2008-01-01

    La demanda d’aplicacions industrials avançades, fa que el control de màquines elèctriques de corrent altern (AC) sigui una disciplina contínuament creixent per satisfer l’alt nivell d’exigència. Tradicionalment, la màquina d’inducció (IM) ha estat la més utilitzada en aplicacions industrials de velocitat variable, incloent-ne bombes i ventiladors, màquines tèxtils i de paper, vehicles elèctrics, generació eòlica, etc. A més dels requeriments funcionals, l’estalvi energètic és, actualment, un ...

  14. An enhanced Z-source inverter topology-based permanent magnet brushless DC motor drive speed control

    Science.gov (United States)

    Geno Peter, P.; Rajaram, M.

    2015-08-01

    In this paper, an enhanced Z-source inverter (ZSI) is introduced for controlling the speed of permanent magnet brushless DC motor (PMBLDCM) drive. It is the extension of the conventional ZSI and the elements used in the circuit are the same as those of the conventional ZSI, except that the position of Inverter Bridge and diode would be exchanged from the classical circuit diagram. This exchanged circuit avoids the startup path of the inrush current and hence reduces the inrush current and improves the motor efficiency. Different modes of enhanced ZSI are studied with PMBLDCM. The voltage polarity of Z-source capacitors in the proposed circuit is the same as that of the input voltage polarity. Furthermore, to get the same voltage boost, the capacitor voltage stress is reduced to a significant extent. The speed control capability of the proposed brushless DC motor drive is compared with that of the conventional ZSI. The proposed ZSI is implemented in MATLAB/Simulink working platform and the output performance is evaluated. Also, the performance of voltage ratio is analysed both by simulation and mathematical models. All these analyses are known to express the innovative features of the proposed system.

  15. Detection of soil erosion within pinyon-juniper woodlands using Thematic Mapper (TM) satellite data

    Science.gov (United States)

    Price, Kevin P.; Ridd, Merrill K.

    1991-01-01

    The sensitivity of Landsat TM data for detecting soil erosion within pinyon-juniper woodlands, and the potential of the spectral data for assigning the universal soil loss equation (USLE) crop managemnent (C) factor to varying cover types within the woodlands are assessed. Results show greatly accelerated rates of soil erosion on pinyon-juniper sites. Percent cover by pinyon-juniper, total soil-loss, and total nonliving ground cover accounted for nearly 70 percent of the variability in TM channels 2, 3, 4, and 5. TM spectral data were consistently better predictors of soil erosion than the biotic and abiotic field variables. Satellite data were more sensitive to vegetation variation than the USLE C factor, and USLE was found to be a poor predictor of soil loss on pinyon-juniper sites. A new string-to-ground soil erosion prediction technique is introduced.

  16. 75 FR 44281 - Public Land Order No. 7747; Partial Revocation, Juniper Butte Range; Idaho

    Science.gov (United States)

    2010-07-28

    ... United States Air Force in Owyhee County, Idaho for the Juniper Butte Range. This order also opens the.... 13, lot 1. The area described contains 5 acres, more or less, in Owyhee County. 2. At 9 a.m.,...

  17. 75 FR 27550 - Electrical Interconnection of the Juniper Canyon I Wind Project

    Science.gov (United States)

    2010-05-17

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Bonneville Power Administration Electrical Interconnection of the Juniper Canyon I Wind Project AGENCY: Bonneville Power Administration (BPA), Department of Energy (DOE). ACTION: Notice of Availability of...

  18. Geospatial analysis of western juniper (Juniperus occidentalis ) encroachment utilizing remotely sensed data

    Science.gov (United States)

    Poznanovic, Aaron James

    Utilizing remote sensing methods to assess landscape-scale ecological change are rapidly becoming a dominant force in the natural sciences. Powerful and robust non-parametric statistical methods are also actively being developed to compliment the unique characteristics of remotely sensed data. The focus of this research is to utilize these powerful, robust remote sensing and statistical approaches to shed light on woody plant encroachment into native grasslands---a troubling ecological phenomenon occurring throughout the world. Specifically, this research investigates western juniper encroachment within the sage-steppe ecosystem of the western USA. Western juniper trees are native to the intermountain west and are ecologically important by means of providing structural diversity and habitat for many species. However, after nearly 150 years of post-European settlement changes to this threatened ecosystem, natural ecological processes such as fire regimes no longer limit the range of western juniper to rocky refugia and other areas protected from short fire return intervals that are historically common to the region. Consequently, sage-steppe communities with high juniper densities exhibit negative impacts, such as reduced structural diversity, degraded wildlife habitat and ultimately the loss of biodiversity. Much of today's sage-steppe ecosystem is transitioning to juniper woodlands. Additionally, the majority of western juniper woodlands have not reached their full potential in both range and density. The first section of this research investigates the biophysical drivers responsible for juniper expansion patterns observed in the sage-steppe ecosystem. The second section is a comprehensive accuracy assessment of classification methods used to identify juniper tree cover from multispectral 1 m spatial resolution aerial imagery.

  19. 安全永续携手共赢-Juniper Solution Day Juniper Networks召开行业用户解决方案分享大会

    Institute of Scientific and Technical Information of China (English)

    罗志刚

    2007-01-01

    2007年4月3日Juniper Networks在北京新世纪只航酒店举行盛大的以“安全永续携手共赢--Juniper Solution Day”为主题的行业用户解决方案分享大会.全面展示了Juniper Networks新近推出的产品及各行业的优秀解决方案。来自于国内的政府、教育、电信、金融、石化等各行业用户参加了此次会议,会场座无虚席,气氛热烈。

  20. MODELING AND STUDY OF HYDROELECTRIC GENERATING SETS OF SMALL HYDRO POWER PLANTS WITH FREQUENCY-CONTROLLED PERMANENT MAGNET SYNCHRONOUS GENERATORS

    Directory of Open Access Journals (Sweden)

    R. I. Mustafayev

    2016-01-01

    Full Text Available Currently, the hydroelectric generating sets of small HPPs with Pelton turbines employ as their generating units conventional synchronous generators with electromagnetic excitation. To deal with the torque pulsatile behaviour, they generally install a supplementary flywheel on the system shaft that levels the pulsations. The Pelton turbine power output is adjusted by the needle changing water flow in the nozzle, whose advancement modifies the nozzle area and eventually – the flow. They limit the needle full stroke time to 20–40 sec. since quick shutting the nozzle for swift water flow reduction may result in pressure surges. For quick power adjustment so-called deflectors are employed, whose task is retraction of water jets from the Pelton turbine buckets. Thus, the mechanical method of power output regulation requires agreement between the needle stroke inside the turbine nozzles and the deflector. The paper offers employing frequency-controlled synchronous machines with permanent magnets qua generating units for the hydroelectric generating sets of small HPPs with Pelton turbines. The developed computer model reveals that this provides a higher level of adjustability towards rapid-changing loads in the grid. Furthermore, this will replace the power output mechanical control involving the valuable deflector drive and the turbine nozzle needles with electrical revolution rate and power output regulation by a frequency converter located in the generator stator circuit. Via frequency start, the controllable synchronous machine ensures stable operation of the hydroelectric generating set with negligibly small amount of water (energy carrier. Finally, in complete absence of water, the frequency-relay start facilitates shifting the generator operation to the synchronous capacitor mode, which the system operating parameter fluctograms obtained through computer modeling prove. 

  1. Western Juniper Management: Assessing Strategies for Improving Greater Sage-grouse Habitat and Rangeland Productivity

    Science.gov (United States)

    Farzan, Shahla; Young, Derek J. N.; Dedrick, Allison G.; Hamilton, Matthew; Porse, Erik C.; Coates, Peter S.; Sampson, Gabriel

    2015-09-01

    Western juniper ( Juniperus occidentalis subsp. occidentalis) range expansion into sagebrush steppe ecosystems has affected both native wildlife and economic livelihoods across western North America. The potential listing of the greater sage-grouse ( Centrocercus urophasianus) under the U.S. Endangered Species Act has spurred a decade of juniper removal efforts, yet limited research has evaluated program effectiveness. We used a multi-objective spatially explicit model to identify optimal juniper removal sites in Northeastern California across weighted goals for ecological (sage-grouse habitat) and economic (cattle forage production) benefits. We also extended the analysis through alternative case scenarios that tested the effects of coordination among federal agencies, budgetary constraints, and the use of fire as a juniper treatment method. We found that sage-grouse conservation and forage production goals are somewhat complementary, but the extent of complementary benefits strongly depends on spatial factors and management approaches. Certain management actions substantially increase achievable benefits, including agency coordination and the use of prescribed burns to remove juniper. Critically, our results indicate that juniper management strategies designed to increase cattle forage do not necessarily achieve measurable sage-grouse benefits, underscoring the need for program evaluation and monitoring.

  2. Mechanical Mastication of Utah Juniper Encroaching Sagebrush Steppe Increases Inorganic Soil N

    Directory of Open Access Journals (Sweden)

    Kert R. Young

    2014-01-01

    Full Text Available Juniper (Juniperus spp. has encroached on millions of hectares of sagebrush (Artemisia spp. steppe. Juniper mechanical mastication increases cover of understory species but could increase resource availability and subsequently invasive plant species. We quantified the effects of juniper mastication on soil resource availability by comparing total C, total N, C : N ratio, Olsen extractable P, sulfate S, and pH using soil samples and inorganic N (NO3-+NH4+ using ion exchange membranes. We compared resource availability in paired masticated and untreated areas in three juniper-dominated sagebrush and bunchgrass ecosystems in the Utah portion of the Great Basin. Inorganic N was 4.7 times higher in masticated than in untreated areas across seasons (P<0.001. Within masticated areas, tree mounds of juniper leaf scales and twigs served as resource islands with 1.9 times higher inorganic N and total C, and 2.8 times higher total N than bare interspaces across seasons (P<0.01. Bare interspaces had 3.0–3.4 times higher inorganic N than interspaces covered with masticated trees during late-summer through winter (P<0.01. Soil fertility changes associated with mastication were not considered sufficient to favor establishment of annual over perennial grasses, and we expect both to increase in cover following juniper mastication.

  3. Detection of soil erosion with Thematic Mapper (TM) satellite data within Pinyon-Juniper woodlands

    Science.gov (United States)

    Price, Kevin Paul

    1987-01-01

    Pinyon-Juniper woodlands dominate approximately 24.3 million hectares (60 million acres) in the western United States. The overall objective was to test the sensitivity of the LANDSAT Thematic Mapper (TM) spectral data for detecting varying degrees of soil erosion within the Pinyon-Juniper woodlands. A second objective was to assess the potential of the spectral data for assigning the Universal Soil Loss Equation (USLE) crop management (C) factor values to varying cover types within the woodland. Thematic Mapper digital data for June 2, 1984 on channels 2, 3, 4, and 5 were used. Digital data analysis was performed using the ELAS software package. Best results were achieved using CLUS, an unsupervised clustering algorithm. Fifteen of the 40 Pinyon-Juniper signatures were identified as being relatively pure Pinyon-Juniper woodland. Final analysis resulted in the grouping of the 15 signatures into three major groups. Ten study sites were selected from each of the three groups and located on the ground. At each site the following field measurements were taken: percent tree canopy and percent understory cover, soil texture, total soil loss, and soil erosion rate estimates. A technique for measuring soil erosion within Pinyon-Juniper woodlands was developed. A theoretical model of site degradation after Pinyon-Juniper invasion is presented.

  4. Western juniper management: assessing strategies for improving greater sage-grouse habitat and rangeland productivity

    Science.gov (United States)

    Farzan, Shahla; Young, Derek J.N.; Dedrick, Allison G.; Hamilton, Mattew; Porse, Erik C.; Coates, Peter S.; Sampson, Gabriel

    2015-01-01

    Western juniper (Juniperus occidentalis subsp. occidentalis) range expansion into sagebrush steppe ecosystems has affected both native wildlife and economic livelihoods across western North America. The potential listing of the greater sage-grouse (Centrocercus urophasianus) under the U.S. Endangered Species Act has spurred a decade of juniper removal efforts, yet limited research has evaluated program effectiveness. We used a multi-objective spatially explicit model to identify optimal juniper removal sites in Northeastern California across weighted goals for ecological (sage-grouse habitat) and economic (cattle forage production) benefits. We also extended the analysis through alternative case scenarios that tested the effects of coordination among federal agencies, budgetary constraints, and the use of fire as a juniper treatment method. We found that sage-grouse conservation and forage production goals are somewhat complementary, but the extent of complementary benefits strongly depends on spatial factors and management approaches. Certain management actions substantially increase achievable benefits, including agency coordination and the use of prescribed burns to remove juniper. Critically, our results indicate that juniper management strategies designed to increase cattle forage do not necessarily achieve measurable sage-grouse benefits, underscoring the need for program evaluation and monitoring.

  5. Western Juniper Management: Assessing Strategies for Improving Greater Sage-grouse Habitat and Rangeland Productivity.

    Science.gov (United States)

    Farzan, Shahla; Young, Derek J N; Dedrick, Allison G; Hamilton, Matthew; Porse, Erik C; Coates, Peter S; Sampson, Gabriel

    2015-09-01

    Western juniper (Juniperus occidentalis subsp. occidentalis) range expansion into sagebrush steppe ecosystems has affected both native wildlife and economic livelihoods across western North America. The potential listing of the greater sage-grouse (Centrocercus urophasianus) under the U.S. Endangered Species Act has spurred a decade of juniper removal efforts, yet limited research has evaluated program effectiveness. We used a multi-objective spatially explicit model to identify optimal juniper removal sites in Northeastern California across weighted goals for ecological (sage-grouse habitat) and economic (cattle forage production) benefits. We also extended the analysis through alternative case scenarios that tested the effects of coordination among federal agencies, budgetary constraints, and the use of fire as a juniper treatment method. We found that sage-grouse conservation and forage production goals are somewhat complementary, but the extent of complementary benefits strongly depends on spatial factors and management approaches. Certain management actions substantially increase achievable benefits, including agency coordination and the use of prescribed burns to remove juniper. Critically, our results indicate that juniper management strategies designed to increase cattle forage do not necessarily achieve measurable sage-grouse benefits, underscoring the need for program evaluation and monitoring.

  6. Canopy Interception for a Tallgrass Prairie under Juniper Encroachment.

    Science.gov (United States)

    Zou, Chris B; Caterina, Giulia L; Will, Rodney E; Stebler, Elaine; Turton, Donald

    2015-01-01

    Rainfall partitioning and redistribution by canopies are important ecohydrological processes underlying ecosystem dynamics. We quantified and contrasted spatial and temporal variations of rainfall redistribution for a juniper (Juniperus virginiana, redcedar) woodland and a tallgrass prairie in the south-central Great Plains, USA. Our results showed that redcedar trees had high canopy storage capacity (S) ranging from 2.14 mm for open stands to 3.44 mm for closed stands. The canopy funneling ratios (F) of redcedar trees varied substantially among stand type and tree size. The open stands and smaller trees usually had higher F values and were more efficient in partitioning rainfall into stemflow. Larger trees were more effective in partitioning rainfall into throughfall and no significant changes in the total interception ratios among canopy types and tree size were found. The S values were highly variable for tallgrass prairie, ranging from 0.27 mm at early growing season to 3.86 mm at senescence. As a result, the rainfall interception by tallgrass prairie was characterized by high temporal instability. On an annual basis, our results showed no significant difference in total rainfall loss to canopy interception between redcedar trees and tallgrass prairie. Increasing structural complexity associated with redcedar encroachment into tallgrass prairie changes the rainfall redistribution and partitioning pattern at both the temporal and spatial scales, but does not change the overall canopy interception ratios compared with unburned and ungrazed tallgrass prairie. Our findings support the idea of convergence in interception ratio for different canopy structures under the same precipitation regime. The temporal change in rainfall interception loss from redcedar encroachment is important to understand how juniper encroachment will interact with changing rainfall regime and potentially alter regional streamflow under climate change.

  7. Canopy Interception for a Tallgrass Prairie under Juniper Encroachment.

    Directory of Open Access Journals (Sweden)

    Chris B Zou

    Full Text Available Rainfall partitioning and redistribution by canopies are important ecohydrological processes underlying ecosystem dynamics. We quantified and contrasted spatial and temporal variations of rainfall redistribution for a juniper (Juniperus virginiana, redcedar woodland and a tallgrass prairie in the south-central Great Plains, USA. Our results showed that redcedar trees had high canopy storage capacity (S ranging from 2.14 mm for open stands to 3.44 mm for closed stands. The canopy funneling ratios (F of redcedar trees varied substantially among stand type and tree size. The open stands and smaller trees usually had higher F values and were more efficient in partitioning rainfall into stemflow. Larger trees were more effective in partitioning rainfall into throughfall and no significant changes in the total interception ratios among canopy types and tree size were found. The S values were highly variable for tallgrass prairie, ranging from 0.27 mm at early growing season to 3.86 mm at senescence. As a result, the rainfall interception by tallgrass prairie was characterized by high temporal instability. On an annual basis, our results showed no significant difference in total rainfall loss to canopy interception between redcedar trees and tallgrass prairie. Increasing structural complexity associated with redcedar encroachment into tallgrass prairie changes the rainfall redistribution and partitioning pattern at both the temporal and spatial scales, but does not change the overall canopy interception ratios compared with unburned and ungrazed tallgrass prairie. Our findings support the idea of convergence in interception ratio for different canopy structures under the same precipitation regime. The temporal change in rainfall interception loss from redcedar encroachment is important to understand how juniper encroachment will interact with changing rainfall regime and potentially alter regional streamflow under climate change.

  8. Decreased carbon limitation of litter respiration in a mortality-affected piñon–juniper woodland

    Directory of Open Access Journals (Sweden)

    E. Berryman

    2013-03-01

    Full Text Available Microbial respiration depends on microclimatic variables and carbon (C substrate availability, all of which are altered when ecosystems experience major disturbance. Widespread tree mortality, currently affecting piñon–juniper ecosystems in southwestern North America, may affect C substrate availability in several ways, for example, via litterfall pulses and loss of root exudation. To determine piñon mortality effects on C and water limitation of microbial respiration, we applied field amendments (sucrose and water to two piñon–juniper sites in central New Mexico, USA: one with a recent (2 flux on the girdled site and a non-significant increase on the control. We speculate that the reduction may have been driven by water-induced carbonate dissolution, which serves as a sink for CO2 and would reduce the net flux. Widespread piñon mortality may decrease labile C limitation of litter respiration, at least during the first growing season following mortality.

  9. Final report: Hydraulic mechanisms of survival and mortality during drought in pinon-juniper woodlands of southwestern USA

    Energy Technology Data Exchange (ETDEWEB)

    Pockman, William [Univ. of New Mexico, Albuquerque, NM (United States)

    2016-11-23

    The goal of this project was to use rainfall manipulation of an intact pinon-juniper woodland in central New Mexico to understand the mechanisms that control the response of these species to extremes of rainfall. Experimental plots were installed in a pinon-juniper woodland at the Sevilleta National Wildlife Refuge and treatments were imposed in August 2007. Treatments consisted of 1) a Drought treatment imposed by diverting approximately 45% of precipitation away from the plot, 2) and Irrigation treatment imposed by applying six 19 mm simulated rainfall events at regular intervals during the growing season, 3) a Cover Control treatment designed to assess the impact of the plastic troughs constructed on Drought plots without imposing the rainfall diversion, and 4) an untreated control that received no modification. Extensive pinon mortality was observed beginning one year after the start of drought treatment on hillslope plots, while a third drought plot on deeper soils did not exhibit pinon mortality until the fifth year of drought treatment. Pinon mortality occurred in the context of high levels of bark beetle activity, motivating the installation of two additional plots in 2010: a control plot and a drought plot built to the same standards as the original treatments but with bark beetle control maintained by pesticide application to the bole of target trees from 2010 - 2016. Although the drought treatment created similar conditions to those experienced on hillslope drought plots, the drought plot with bark beetle control exhibited no pinon mortality for 5 years even in the presence of high regional bark beetle activity in 2012/13. One of the goals of the research was to identify the mechanism of drought-induced mortality in pinon and juniper: 1) mortality due to catastrophic failure of water transport through plant tissues (hydraulic failure), 2) mortality due to limitations in carbon uptake (carbon starvation) and 3) either of the first two mechanisms with the

  10. Juniper Encroachment and Management in the Intermountain West Relative to Wildfires Utilizing Remote Sensing

    Science.gov (United States)

    Williams, J.; Howerton, R.; Ramos, S.; Simpson, Z.; Weber, K.

    2016-12-01

    One of the most pronounced vegetation changes in recent history is the expansion of junipers (Juniperus spp.) throughout the intermountain west United States. These native species have expanded from their traditional fire-safe habitats into fire-dependent communities as a result of climatic fluctuations, grazing patterns, and wildfire suppression efforts. As junipers expand their range, they begin to dominate plant communities resulting in the recession of shrubs, grasses, and forbs. Land management agencies have a strong commitment to find areas that are vulnerable to juniper encroachment, so that these areas can be studied and more effectively managed. Aiding in this effort, this project used remote sensing to develop two tools that determine fire intensity on a per pixel basis and identify different phases of juniper encroachment, respectively. Landsat 8, representing land cover data was combined with topography information (slope and aspect) in a linear regression model that quantified fire intensity on a per pixel basis, identifying areas that would burn hotter and longer based on fuel type. The overall accuracy of the model was 86% with a kappa coefficient of 0.81. Visual validation using NAIP imagery in comparison with the fuel classification result showed good visual correlation of the fuel model with dense juniper stands. The second output of the project was an image/object based classification tool that uses multispectral imagery and supervised point classification to classify different vegetation types according to the spectral detail of the objects. The goal of the model is to improve phase identification of juniper stands. Initial visual verification with NAIP shows the model to be performing very satisfactorily but is dependent on the spatial resolution of the user fed input imagery. Furnishing land managers with these tools will assist in forecasting areas prone to juniper invasion based upon surrounding seedbanks, as well as, predict the ensuing

  11. Sensorless Control of Nonsinusoidal Permanent Magnet Brushless Motor Using Selective Torque Harmonic Elimination Control Method Based on Full-Order Sliding Mode Observer

    Directory of Open Access Journals (Sweden)

    Abolfazl Halvaei Niasar

    2016-01-01

    Full Text Available Nowadays, due to excellent advantages of permanent magnet brushless (PMBL motors such as high efficiency and high torque/power density, they are used in many industrial and variable-speed electrical drives applications. If the fabricated PMBL motor has neither ideal sinusoidal nor ideal trapezoidal back-EMF voltages, it is named nonideal (or nonsinusoidal PMBL motor. Employing conventional control strategies of PMSMs and BLDCMs lowers the efficiency and leads to unwanted torque ripple, vibration, and acoustic noises. Moreover, in many applications to reduce the cost and enhance the reliability of drive, sensorless control techniques are used. This paper proposes a novel sensorless control for a nonsinusoidal PMBL motor with minimum torque ripple. To develop smooth torque, the selected torque harmonic elimination strategy is employed. Furthermore, to estimate the rotor position and speed, a novel full-order sliding mode observer is designed. Proposed observer estimates the position and speed of motor from standstill to final speed. The proposed observer is robust to uncertainty of harmonic contents in phase back-EMF voltage and able to run the motor from standstill with closed-loop control scheme. The capabilities of torque ripple minimization and sensorless strategies are demonstrated with some simulations.

  12. Transpiration and hydraulic strategies in a piñon-juniper woodland.

    Science.gov (United States)

    West, A G; Hultine, K R; Sperry, J S; Bush, S E; Ehleringer, J R

    2008-06-01

    Anthropogenic climate change is likely to alter the patterns of moisture availability globally. The consequences of these changes on species distributions and ecosystem function are largely unknown, but possibly predictable based on key ecophysiological differences among currently coexisting species. In this study, we examined the environmental and biological controls on transpiration from a piñon-juniper (Pinus edulis-Juniperus osteosperma) woodland in southern Utah, USA. The potential for climate-change-associated shifts in moisture inputs could play a critical role in influencing the relative vulnerabilities of piñons and junipers to drought and affecting management decisions regarding the persistence of this dominant landscape type in the Intermountain West. We aimed to assess the sensitivity of this woodland to seasonal variations in moisture and to mechanistically explain the hydraulic strategies of P. edulis and J. osteosperma through the use of a hydraulic transport model. Transpiration from the woodland was highly sensitive to variations in seasonal moisture inputs. There were two distinct seasonal pulses of transpiration: a reliable spring pulse supplied by winter-derived precipitation, and a highly variable summer pulse supplied by monsoonal precipitation. Transpiration of P. edulis and J. osteosperma was well predicted by a mechanistic hydraulic transport model (R2 = 0.83 and 0.92, respectively). Our hydraulic model indicated that isohydric regulation of water potential in P. edulis minimized xylem cavitation during drought, which facilitated drought recovery (94% of pre-drought water uptake) but came at the cost of cessation of gas exchange for potentially extended periods. In contrast, the anisohydric J. osteosperma was able to maintain gas exchange at lower water potentials than P. edulis but experienced greater cavitation over the drought and showed a lesser degree of post-drought recovery (55% of pre-drought uptake). As a result, these species

  13. The Study of Fuzzy Proportional Integral Controllers Based on Improved Particle Swarm Optimization for Permanent Magnet Direct Drive Wind Turbine Converters

    Directory of Open Access Journals (Sweden)

    Yancai Xiao

    2016-05-01

    Full Text Available In order to meet the requirements of high precision and fast response of permanent magnet direct drive (PMDD wind turbines, this paper proposes a fuzzy proportional integral (PI controller associated with a new control strategy for wind turbine converters. The purpose of the control strategy is to achieve the global optimization for the quantization factors, ke and kec, and scale factors, kup and kui, of the fuzzy PI controller by an improved particle swarm optimization (PSO method. Thus the advantages of the rapidity of the improved PSO and the robustness of the fuzzy controller can be fully applied in the control process. By conducting simulations for 2 MW PMDD wind turbines with Matlab/Simulink, the performance of the fuzzy PI controller based on the improved PSO is demonstrated to be obviously better than that of the PI controller or the fuzzy PI controller without using the improved PSO under the situation when the wind speed changes suddenly.

  14. Soil morphology of canopy and intercanopy sites in a pinon-Juniper woodland

    Energy Technology Data Exchange (ETDEWEB)

    Davenport, D.W.; Wilcox, B.P.; Breshear, D.D. [Los Alamos National Lab., NM (United States)

    1996-11-01

    Pinon-juniper woodlands in the semiarid western USA have expanded as much as fivefold during the last 150 yr, often accompanied by losses of understory vegetation and increasing soil erosion. We conducted this study to determine the differences in soil morphology between canopy and intercanopy locations within a pinon (Pinus edulis Engelm.)-juniper [Juniperus monosperma (Engelm.) Sarg.] woodland with uniform parent material, topography, and climate. The woodland studied, located near Los Alamos, NM, has a mean tree age of 135 yr. We examined soil morphology by augering 135 profiles in a square grid pattern and comparing soils under pinon and juniper canopies with intercanopy soils. Only two of the 17 morphological properties compared showed significant differences. The B horizons make up a slightly greater proportion of total profile thickness in intercanopy soils, and there are higher percentages of coarse fragments in the lower portions of canopy soil profiles. Canopy soils have lower mean pH and higher mean organic C than intercanopy soils. Regression analysis showed that most soil properties did not closely correspond with tree size, but total soil thickness and B horizon thickness are significantly greater under the largest pinon trees, and soil reaction is lower under the largest juniper trees. Our findings suggest that during the period in which pinon-juniper woodlands have been expanding, the trees have had only minor effects on soil morphology. 36 refs., 4 figs., 4 tabs.

  15. Modeling wind fields and fire propagation following bark beetle outbreaks in spatially-heterogeneous pinyon-juniper woodland fuel complexes

    Science.gov (United States)

    Rodman R. Linn; Carolyn H. Sieg; Chad M. Hoffman; Judith L. Winterkamp; Joel D. McMillin

    2013-01-01

    We used a physics-based model, HIGRAD/FIRETEC, to explore changes in within-stand wind behavior and fire propagation associated with three time periods in pinyon-juniper woodlands following a drought-induced bark beetle outbreak and subsequent tree mortality. Pinyon-juniper woodland fuel complexes are highly heterogeneous. Trees often are clumped, with sparse patches...

  16. Characterizating western juniper expansion via a fusion of Landsat 5 thematic mapper and LiDAR data

    Science.gov (United States)

    Juniper encroachment into shrub steppe and grassland systems is one of the most prominent changes occurring in rangelands of western North America. Most studies on juniper change are conducted over small areas, although encroachment is occurring across large regions. Development of image-based met...

  17. 75 FR 18201 - Juniper Canyon Wind Power, LLC; Supplemental Notice That Initial Market-Based Rate Filing...

    Science.gov (United States)

    2010-04-09

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Juniper Canyon Wind Power, LLC; Supplemental Notice That Initial Market... supplemental notice in the above-referenced proceeding of Juniper Canyon Wind Power, LLC's application for...

  18. Anchor chaining’s influence on soil hydrology and seeding success in burned piñon-juniper woodlands

    Science.gov (United States)

    Broadcast seeding is one of the most commonly used rehabilitation treatments for the restoration of burned piñon (Pinus ssp.) and juniper (Juniperus spp.) woodlands, but the success rate of this treatment is notoriously low. In piñon-juniper woodlands, post-fire soil water repellency can impair rese...

  19. Pinyon and juniper encroachment into sagebrush ecosystems impacts distribution and survival of greater sage-grouse

    Science.gov (United States)

    Coates, Peter S.; Prochazka, Brian; Ricca, Mark; Gustafson, K. Ben; Ziegler, Pilar T.; Casazza, Michael L.

    2017-01-01

    In sagebrush (Artemisia spp.) ecosystems, encroachment of pinyon (Pinus spp.) and juniper (Juniperus spp.; hereafter, “pinyon-juniper”) trees has increased dramatically since European settlement. Understanding the impacts of this encroachment on behavioral decisions, distributions, and population dynamics of greater sage-grouse (Centrocercus urophasianus) and other sagebrush obligate species could help benefit sagebrush ecosystem management actions. We employed a novel two-stage Bayesian model that linked avoidance across different levels of pinyon-juniper cover to sage-grouse survival. Our analysis relied on extensive telemetry data collected across 6 yr and seven subpopulations within the Bi-State Distinct Population Segment (DPS), on the border of Nevada and California. The first model stage indicated avoidance behavior for all canopy cover classes on average, but individual grouse exhibited a high degree of heterogeneity in avoidance behavior of the lowest cover class (e.g., scattered isolated trees). The second stage modeled survival as a function of estimated avoidance parameters and indicated increased survival rates for individuals that exhibited avoidance of the lowest cover class. A post hoc frailty analysis revealed the greatest increase in hazard (i.e., mortality risk) occurred in areas with scattered isolated trees consisting of relatively high primary plant productivity. Collectively, these results provide clear evidence that local sage-grouse distributions and demographic rates are influenced by pinyon-juniper, especially in habitats with higher primary productivity but relatively low and seemingly benign tree cover. Such areas may function as ecological traps that convey attractive resources but adversely affect population vital rates. To increase sage-grouse survival, our model predictions support reducing actual pinyon-juniper cover as low as 1.5%, which is lower than the published target of 4.0%. These results may represent effects of pinyon-juniper

  20. Full-order sliding mode control of uncertain chaos in a permanent magnet synchronous motor based on a fuzzy extended state observer

    Institute of Scientific and Technical Information of China (English)

    陈强; 南余荣; 郑恒火; 任雪梅

    2015-01-01

    A full-order sliding mode control based on a fuzzy extended state observer is proposed to control the uncertain chaos in the permanent magnet synchronous motor. Through a simple coordinate transformation, the chaotic PMSM model is transformed into the Brunovsky canonical form, which is more suitable for the controller design. Based on the fuzzy control theory, a fuzzy extended state observer is developed to estimate the unknown states and uncertainties, and the restriction that all the system states should be completely measurable is avoided. Thereafter, a full-order sliding mode controller is designed to ensure the convergence of all system states without any chattering problem. Comparative simulations show the effectiveness and superior performance of the proposed control method.

  1. Control of Surface Mounted Permanent Magnet Motors with Special Application to Fractional-Slot Motors with Concentrated Windings

    Energy Technology Data Exchange (ETDEWEB)

    McKeever, John W [ORNL; Patil, Niranjan [University of Tennessee, Knoxville (UTK); Lawler, Jack [ORNL

    2007-07-01

    A 30 pole, 6 kW, and 6000 maximum revolutions per minute (rpm) prototype of the permanent magnet synchronous motor (PMSM) with fractional-slot concentrated windings (FSCW) has been designed, built, and tested at the University of Wisconsin at Madison (UWM). This machine has significantly more inductance than that of regular PMSMs. The prototype was delivered in April 2006 to the Oak Ridge National Laboratory (ORNL) for testing and development of a controller that will achieve maximum efficiency. In advance of the test/control development effort, ORNL has used the PMSM models developed over a number of previous studies to study how steady state performance of high inductance PMSM machines relates to control issues. This report documents the results of this research. The amount of inductance that enables the motor to achieve infinite constant power speed ratio (CPSR) is given by L{sub {infinity}} = E{sub b}/{Omega}{sub b}I{sub R}, where E{sub b} is the root-mean square (rms) magnitude of the line-to-neutral back-electromotive force (emf) at base speed, {Omega}{sub b} is the base speed in electrical radians per second, and I{sub R} is the rms current rating of the motor windings. The prototype machine that was delivered to ORNL has about 1.5 times as much inductance as a typical PMSM with distributed integral slot windings. The inventors of the FSCW method, who designed the prototype machine, remarked that they were 'too successful' in incorporating inductance into their machine and that steps would be taken to modify the design methodology to reduce the inductance to the optimum value. This study shows a significant advantage of having the higher inductance rather than the optimal value because it enables the motor to develop the required power at lower current thereby reducing motor and inverter losses and improving efficiency. The main problem found with high inductance machines driven by a conventional phase advance (CPA) method is that the motor current

  2. Estimating pinyon and juniper cover across Utah using NAIP imagery

    Directory of Open Access Journals (Sweden)

    Darrell B. Roundy

    2016-11-01

    Full Text Available Expansion of Pinus L. (pinyon and Juniperus L. (juniper (P-J trees into sagebrush (Artemisia L. steppe communities can lead to negative effects on hydrology, loss of wildlife habitat, and a decrease in desirable understory vegetation. Tree reduction treatments are often implemented to mitigate these negative effects. In order to prioritize and effectively plan these treatments, rapid, accurate, and inexpensive methods are needed to estimate tree canopy cover at the landscape scale. We used object based image analysis (OBIA software (Feature AnalystTM for ArcMap 10.1®, ENVI Feature Extraction®, and Trimble eCognition Developer 8.2® to extract tree canopy cover using NAIP (National Agricultural Imagery Program imagery. We then compared our extractions with ground measured tree canopy cover (crown diameter and line point intercept on 309 plots across 44 sites in Utah. Extraction methods did not consistently over- or under-estimate ground measured P-J canopy cover except where tree cover was >45%. Estimates of tree canopy cover using OBIA techniques were strongly correlated with estimates using the crown diameter method (r = 0.93 for ENVI, 0.91 for Feature AnalystTM, and 0.92 for eCognition. Tree cover estimates using OBIA techniques had lower correlations with tree cover measurements using the line-point intercept method (r = 0.85 for ENVI, 0.83 for Feature AnalystTM, and 0.83 for eCognition. All software packages accurately and inexpensively extracted P-J canopy cover from NAIP imagery when the imagery was not blurred, and when P-J cover was not mixed with Amelanchier alnifolia (Utah serviceberry and Quercus gambelii (Gambel’s oak, which had similar spectral values as P-J.

  3. Direct Torque Control and Simulation of Permanent Magnet Synchronous Motor%永磁同步电机直接转矩控制及仿真

    Institute of Scientific and Technical Information of China (English)

    冯涛; 陆华

    2013-01-01

    A simple and effective direct torque control method based on permanent magnet synchronous motor was described.The direct torque control system was built by using simulink,and the performance of permanent magnet synchronous motor under different speeds and torque was analyzed.The feasibility of the method was verified through simulation analysis.This control method could satisfy the rapidity requirement,that was,it had good speed control characteristic.The results showed that stator flux and motor torque could be controlled effectively if a reasonable voltage space vector is selected.%介绍了一种基于永磁同步电机(PMSM)的简单有效的直接转矩控制(DTC)技术.利用Simulink搭建DTC系统,仿真分析了PMSM在不同转速和转矩条件下的性能,并验证算法的可行性.该控制技术能够满足系统控制快速性的要求,具有良好的速度控制特性.结果分析表明,定子磁链和电机转矩可通过选择合理的电压空间矢量得到有效控制.

  4. An adaptive radial basis function neural network (RBFNN control of energy storage system for output tracking of a permanent magnet wind generator

    Directory of Open Access Journals (Sweden)

    Abu H. M. A. Rahim

    2014-03-01

    Full Text Available The converters of a permanent magnet synchronous generator have to be properly controlled to achieve maximum transfer of energy from wind. To achiev e this goal, this article employs an energy storage device consisting of an energy capacitor interfaced through a voltage source converter which is operated through a smart adaptive radial basis function neural network (RBFNN controller. The proposed adaptive strategy employs online neural network training as opposed to conventional procedure requiring offline training of a large data-set. The RBFNN controller was tested for various contingencies in the wind generator system. Th e adaptive online controller is observed to provide excellent damping profile following low grid voltage conditions as well as for other large disturbances. The controlled converter DC capacitor voltage helps maintain a smooth flow of real and reactive power in the system.

  5. 15th March 2011 - Singapore National Research Foundation Permanent Secretary(National Research and Development)T. M. Kian signing the guest book with Head of International Relations F. Pauss and visiting CMS control centre with Collaboration Spokesperson G. Tonelli.

    CERN Multimedia

    Maximilien Brice

    2011-01-01

    15th March 2011 - Singapore National Research Foundation Permanent Secretary(National Research and Development)T. M. Kian signing the guest book with Head of International Relations F. Pauss and visiting CMS control centre with Collaboration Spokesperson G. Tonelli.

  6. Evaluating mountain meadow groundwater response to Pinyon-Juniper and temperature in a great basin watershed

    Science.gov (United States)

    Carroll, Rosemary W.H.; Huntington, Justin L.; Snyder, Keirith A.; Niswonger, Richard G.; Morton, Charles; Stringham, Tamzen K.

    2017-01-01

    This research highlights development and application of an integrated hydrologic model (GSFLOW) to a semiarid, snow-dominated watershed in the Great Basin to evaluate Pinyon-Juniper (PJ) and temperature controls on mountain meadow shallow groundwater. The work used Google Earth Engine Landsat satellite and gridded climate archives for model evaluation. Model simulations across three decades indicated that the watershed operates on a threshold response to precipitation (P) >400 mm/y to produce a positive yield (P-ET; 9%) resulting in stream discharge and a rebound in meadow groundwater levels during these wetter years. Observed and simulated meadow groundwater response to large P correlates with above average predicted soil moisture and with a normalized difference vegetation index threshold value >0.3. A return to assumed pre-expansion PJ conditions or an increase in temperature to mid-21st century shifts yielded by only ±1% during the multi-decade simulation period; but changes of approximately ±4% occurred during wet years. Changes in annual yield were largely dampened by the spatial and temporal redistribution of evapotranspiration across the watershed: Yet the influence of this redistribution and vegetation structural controls on snowmelt altered recharge to control water table depth in the meadow. Even a small-scale removal of PJ (0.5 km2) proximal to the meadow will promote a stable, shallow groundwater system resilient to droughts, while modest increases in temperature will produce a meadow susceptible to declining water levels and a community structure likely to move toward dry and degraded conditions.

  7. 双转式永磁无刷电动机的控制%Control of Dual-Rotor Permanent Magnet Brushless Motors

    Institute of Scientific and Technical Information of China (English)

    何苗

    2009-01-01

    Mathematical model and closed-loop speed control strategies of dual-rotor permanent magnet brushless motors were analyzed. A set of software and hardware control system was designed based on the chip of TMS320F2407, which was tested finally. The final testing data indicates that the control system can achieve preferable performance and high control precision.%在普通永磁无刷电动机基础上,分析了双转式永磁无刷电动机的数学模型及速度闭环控制策略,并在该基础上建立以TMS320F2407为核心的闭环控制软硬件系统,并进行了试验.试验结果表明该种控制系统控制性能较好,控制精度较高.

  8. Modeling and Maximum Power Point Tracking Control of Wind Generating Units Equipped with Permanent Magnet Synchronous Generators in Presence of Losses

    Directory of Open Access Journals (Sweden)

    Andrea Bonfiglio

    2017-01-01

    Full Text Available This paper focuses on the modeling of wind turbines equipped with direct drive permanent magnet synchronous generators for fundamental frequency power system simulations. Specifically, a procedure accounting for the system active power losses to initialize the simulation starting from the load flow results is proposed. Moreover, some analytical assessments are detailed on typical control schemes for fully rated wind turbine generators, thereby highlighting how active power losses play a fundamental role in the effectiveness of the wind generator control algorithm. Finally, the paper proposes analytical criteria to design the structure and the parameters of the regulators of the wind generator control scheme. Simulations performed with Digsilent Power Factory validated the proposed procedure, highlighting the impact of active power losses on the characterization of the initial steady state and that the simplifying assumptions done in order to synthesize the controllers are consistent with the complete modeling performed by the aforementioned power system simulator.

  9. Hydrology and ecology of pinyon-juniper woodlands: Conceptual framework and field studies

    Energy Technology Data Exchange (ETDEWEB)

    Wilcox, B.P.; Breshears, D.D.

    1994-09-01

    Pinyon-juniper woodlands represent an important ecosystem in the semiarid western United States. Concern over the sustainability of, and management approaches for, these woodlands is increasing. As in other semiarid environments, water dynamics and vegetation patterns in pinyon-juniper woodlands are highly interrelated. An understanding of these relationships can aid in evaluating various management strategies. In this paper we describe a conceptual framework designed to increase our understanding of water and vegetation in pinyon-juniper woodlands. The framework comprises five different scales, at each of which the landscape is divided into {open_quotes}functional units{close_quotes} on the basis of hydrologic characteristics. The hydrologic behavior of each unit and the connections between units are being evaluated using an extensive network of hydrological and ecological field studies on the Pajarito Plateau in northern New Mexico. Data from these studies, coupled with application of the conceptual model, have led to the development of a number of hypotheses concerning the interrelationships of water and vegetation in pinyon-juniper woodlands.

  10. The Effect of Anthropogenic Disturbance in the Ecohydrology of Pinyon Juniper Woodlands with Soil Biocrust

    Science.gov (United States)

    Lebron, I.; Chandler, D. G.; Robinson, D. A.; Belnap, J.; Madsen, M.

    2005-12-01

    The canopy and intercanopy in pinyon-juniper woodlands are intrinsically related and constitute an ecosystem of great importance in the arid lands in the United States. The integrity of this ecosystem is continually challenged by anthropogenic disturbances as oil exploration and recreation activities in these environments. An important feature in the intercanopy of pinyon juniper drylands is the soil biological crust or biocrust. Biocrust is important to the nutrient cycles and hydrology and sediment production of this system. To quantify the effect of disturbances in the soil physical properties in the interspace of a pinion-juniper woodland we measured soil bulk density, water content, and hydraulic conductivity in undisturbed and disturbed areas of sandy soil. The disturbance had minimal impact on the bulk soil properties in the interspace soils. We also analyzed chlorophyll and other pigments related with bacterial activity in top 4mm of the soil and found chlorophyll activity to be almost zero in the disturbed areas while the undisturbed ones showed several orders of magnitude higher concentrations. Subsequent analysis of the soil surface properties indicates that a drastic change in the surface roughness and structure at the surface due to disturbances can alter the microenvironment characteristics critical for the bacterial survival. Since cyanobacteria colonization is the first step in the formation of biocrust, we conclude that surface properties are critical for the preservation and establishment of biocrust in the intercanopy space of the pinyon-juniper woodlands ecosystems.

  11. Implication of Agathic Acid from Utah Juniper Bark as an Abortifacient Compound in Cattle.

    Science.gov (United States)

    Freshly ground Utah juniper (Juniperus osteosperma (Torr.) Little) bark was given via gavage at a dosage of 2.3 kg/cow twice daily to three pregnant cows starting on day 255 of gestation. All three cows aborted the calves after four, five and six days of treatment. A fourth cow was dosed Utah juni...

  12. Soil water repellency within a burned pinon-juniper woodland: spatial distribution, severity, and ecohydrologic implications

    Science.gov (United States)

    Post-fire recovery of juniper-dominated ecosystems is dependent on the extent that ecological processes have been altered. Soil water repellency is a common condition in these ecosystems that may limit site recovery. In this study we examined the extent, severity, and ecohydrologic implications of p...

  13. Influence of Prescribed Fire on Ecosystem Biomass, Carbon, and Nitrogen in a Pinyon Juniper Woodland

    Science.gov (United States)

    Pinyon and juniper woodland encroachment associated with climate change and land use history in the Great Basin is thought to provide offsets for carbon emissions. However, the largest pools of carbon in arid landscapes are typically found in soils, and aboveground biomass cannot be considered long ...

  14. Decreased carbon limitation of litter respiration in a mortality-affected pinon-juniper woodland

    Science.gov (United States)

    Erin Berryman; John D. Marshall; Thom Rahn; Marcie Litvak; John Butnor

    2013-01-01

    Microbial respiration depends on microclimatic variables and carbon (C) substrate availability, all of which are altered when ecosystems experience major disturbance. Widespread tree mortality, currently affecting pinon-juniper ecosystems in southwestern North America, may affect C substrate availability in several ways, for example, via litterfall pulses and loss of...

  15. Wildlife associations in Rocky Mountain juniper in the northern Great Plains, South Dakota

    Science.gov (United States)

    Mark A. Rumble; John E. Gobeille

    1995-01-01

    Rocky Mountain juniper is an important habitat component in the northern Great Plains. These woodlands provide vertical and horizontal vegetative structure that enhances wildlife use. Ecological approaches to managing habitats require understanding relationships between wildlife species and succession in plant communities. We determined bird, small mammals and large...

  16. Why is cultural resource site density high in the pinon-juniper woodland?

    Science.gov (United States)

    Sarah Schlanger; Signa Larralde

    2008-01-01

    (Please note, this is an extended abstract only) Hunter gatherers relied on healthy pinon-juniper woodland because it supports a wide variety of small game, large game, and bird species that shelter in the trees and forage on pinon nuts, a rich food source for humans as well as game.

  17. Western Juniper Field Guide: Asking the Right Questions to Select Appropriate Management Actions

    Science.gov (United States)

    The rapid expansion of western juniper into neighboring plant communities during the past 130 years has been linked to increased soil erosion; reduced forage production; altered wildlife habitat; changes in plant community composition, structure, and biodiversity. Impacts of post-settlement woodland...

  18. Climate Change Increases Drought Stress of Juniper Trees in the Mountains of Central Asia.

    Science.gov (United States)

    Seim, Andrea; Omurova, Gulzar; Azisov, Erlan; Musuraliev, Kanaat; Aliev, Kumar; Tulyaganov, Timur; Nikolyai, Lyutsian; Botman, Evgeniy; Helle, Gerd; Dorado Liñan, Isabel; Jivcov, Sandra; Linderholm, Hans W

    2016-01-01

    Assessments of climate change impacts on forests and their vitality are essential for semi-arid environments such as Central Asia, where the mountain regions belong to the globally important biodiversity hotspots. Alterations in species distribution or drought-induced tree mortality might not only result in a loss of biodiversity but also in a loss of other ecosystem services. Here, we evaluate spatial trends and patterns of the growth-climate relationship in a tree-ring network comprising 33 juniper sites from the northern Pamir-Alay and Tien Shan mountain ranges in eastern Uzbekistan and across Kyrgyzstan for the common period 1935-2011. Junipers growing at lower elevations are sensitive to summer drought, which has increased in intensity during the studied period. At higher elevations, juniper growth, previously favored by warm summer temperatures, has in the recent few decades become negatively affected by increasing summer aridity. Moreover, response shifts are observed during all seasons. Rising temperatures and alterations in precipitation patterns during the past eight decades can account for the observed increase in drought stress of junipers at all altitudes. The implications of our findings are vital for the application of adequate long-term measures of ecosystem conservation, but also for paleo-climatic approaches and coupled climate-vegetation model simulations for Central Asia.

  19. A demonstration project to test ecological restoration of a pinyon-juniper ecosystem

    Science.gov (United States)

    David W. Huffman; Michael T. Stoddard; Peter Z. Fule; W. Wallace Covington; H. B. Smith

    2008-01-01

    To test an approach for restoring historical stand densities and increasing plant species diversity of a pinyon-juniper ecosystem, we implemented a demonstration project at two sites (CR and GP) on the Grand Canyon-Parashant National Monument in northern Arizona. Historical records indicated that livestock grazing was intensive on the sites beginning in the late 1800s...

  20. Hysteresis Current Controller Based Grid Connected Wind Energy Conversion System for Permanent Magnet Synchronous Generator and Quasi Z-Source Inverter Using Power Quality Improvement

    Directory of Open Access Journals (Sweden)

    E.Rajendran

    2013-10-01

    Full Text Available Wind energy is a leader area of application for variable-speed generators operating on the constant grid frequency. This paper depicts the power quality enhancement in wind power system using permanent magnet synchronous generator (PMSG and Quasi Z-source Inverter. The PMSG is connected to the power network by means of a quasi z-source inverter (qZSI. The PMSG are used by these technologies due to extraordinary characteristics such as a smaller amount weight and volume, superior performance, eradicate the gear box and no need of peripheral power in permanent magnet excitation. The PMSG overcome the induction generator and other generators, because of their splendid performances without take up the grid power. But Induction Generator always needs the grid connectionfor getting power to start. In this paper the quasi Z-source inverter is a present that is a novel topology conjugated from the traditional Z source Inverter. The qZSI inherits all the advantages of the ZSI, that is performs buck-boost, inversion and power control in wind energy conversion system (WECS Moreover, the proposed qZSI the matchless advantages of less component ratings and stable dc current from the source. All over boost control methods are built for the ZSI can be used by the qZSI .This Paper presents hysteresis current control technique for the quasi Z- source inverter.

  1. Sensorless Speed Control with Initial Rotor Position Estimation for Surface Mounted Permanent Magnet Synchronous Motor Drive in Electric Vehicles

    Directory of Open Access Journals (Sweden)

    Xuan Wu

    2015-10-01

    Full Text Available The accurate information of the initial rotor position is very critical for successful starting of the Surface-mounted Permanent Magnet Synchronous Motor (SPMSM. In order to solve the problems of low accuracy and unreliability in the conventional estimation strategy, in this paper, an improved initial rotor position estimation strategy without any position sensor for SPMSM at standstill is proposed based on rectangular pulse voltage injection. In the work, when the second series of pulse voltages were applied. By the ways of strengthening the effect of weakening or strengthening magnetic fields and increasing the difference between each current of the vector. The improved strategy enhanced reliability and raised the initial position estimation accuracy from 7.5° to 1.875°. The improved strategy does not need any additional hardware. Experimental results demonstrate the validity and usefulness of the improved strategy.

  2. Conifer encroachment and hydrology: Altered above and below ground hydrologic fluxes in western juniper (Juniperus occidentalis)

    Science.gov (United States)

    Niemeyer, R. J.; Link, T. E.; Heinse, R.; Seyfried, M. S.

    2013-12-01

    Western juniper (Juniperus occidentalis) occupy 9 million acres in Oregon, California, Idaho, and Nevada. In many of these areas juniper has expanded 10-fold since Euro-American settlement into what was mostly sagebrush steppe due to grazing, changes in fire regimes, and climate. Despite the importance of elucidating if juniper encroachment appreciably changes semi-arid hydrology, there have been few process-based studies linking above and below ground hydrologic fluxes or that assess variations across a gradient of shrub to tree-dominated areas. Our objectives are to determine: A) the differences in interception and throughfall at a lower density juniper stand dominated by low sagebrush (Artemisia arbuscula) and a moderate density juniper stand dominated by juniper, B) soil moisture dynamics between lower and moderate density juniper stands, and C) how those above and below ground processes are linked. Our study area was located at the USDA-ARS Reynolds Creek Experimental Watershed in the Owyhee Mountains of southwestern Idaho. We used multiple methods to measure and estimate above and below ground hydrologic fluxes. Above ground precipitation was estimated with large (approximately 5.5 m2) precipitation lysimeters; two located under tree canopies and two in the open. Soil moisture was measured continuously at four trees and across both plots once every 1 - 2 months once snow melted. Continuous measurements under the canopy consisted of four soil moisture probes each; two outside and under the canopy at 15 cm and 60 cm. Plot wide soil moisture changes were estimated based on changes in conductivity measured with electromagnetic induction (EMI) at both 0-75 cm and 0-150 cm. Results show some clear patterns in differences in hydrologic fluxes across the two stands. Rain and snow throughfall from mid-October through mid-April under the canopy was 289 mm, compared to 381 mm outside the canopy, therefore interception was 24% of incoming precipitation. Snowmelt rates

  3. Marxism as permanent revolution

    NARCIS (Netherlands)

    van Ree, E.

    2013-01-01

    This article argues that the 'permanent revolution' represented the dominant element in Karl Marx and Friedrich Engels' political discourse, and that it tended to overrule considerations encapsulated in 'historical materialism'. In Marx and Engels's understanding, permanent revolution did not repres

  4. Marxism as permanent revolution

    NARCIS (Netherlands)

    van Ree, E.

    2013-01-01

    This article argues that the 'permanent revolution' represented the dominant element in Karl Marx and Friedrich Engels' political discourse, and that it tended to overrule considerations encapsulated in 'historical materialism'. In Marx and Engels's understanding, permanent revolution did not

  5. Responses of a Federally Endangered Songbird to Understory Thinning in Oak-Juniper Woodlands

    Science.gov (United States)

    Long, Ashley M.; Marshall, Mike E.; Morrison, Michael L.; Hays, K. Brian; Farrell, Shannon L.

    2017-04-01

    Wildlife conservation and management on military lands must be accomplished in the context of military readiness, which often includes ground-based training that is perceived to conflict with wildlife needs and environmental regulations. From 2008‒2012, we examined territory density, pairing success, and fledging success of the federally endangered golden-cheeked warbler ( Setophaga chrysoparia; hereafter warbler) in relation to removal of small-diameter trees from the understory of mature oak-juniper ( Quercus-Juniperus) woodland at the 87,890 ha Fort Hood Military Reservation in central Texas. Understory thinning created troop maneuver lanes, but left canopy vegetation intact. Warbler density, pairing success, and fledging success were similar across thinned and control sites. We found that warbler pairing and fledging success were best predicted by Ecological site (hereafter Ecosite), an indicator of hardwood tree species composition. Warbler pairing and fledging success were about 1.5 and 1.6 times higher, respectively, for territories dominated by the Low Stony Hill Ecosite than territories dominated by the Redlands Ecosite. Our results indicate that understory thinning for military training purposes did not have a negative effect on warblers at Fort Hood in the manner tested, and suggest that removal of smaller trees from the understory in a way that replicates historic conditions may elicit neutral responses from this forest-dependent songbird. Quantifying wildlife responses to military activities provides the Department of Defense and US Fish and Wildlife Service with data to guide conservation of threatened and endangered species on Department of Defense facilities while maintaining the military mission, and supports wildlife management efforts on other public and private lands.

  6. Fuzzy Adaptive Repetitive Control for Periodic Disturbance with Its Application to High Performance Permanent Magnet Synchronous Motor Speed Servo Systems

    National Research Council Canada - National Science Library

    Junxiao Wang

    2016-01-01

    .... Then, the mathematical model of PMSM is given. Subsequently, a fuzzy adaptive repetitive controller based on repetitive control and fuzzy logic control is designed for the PMSM speed servo system...

  7. Control of doxorubicin release from magnetic Poly(dl-lactide-co-glycolide) nanoparticles by application of a non-permanent magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Peça, Inês N. [Universidade Nova de Lisboa, LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia (Portugal); Bicho, A.; Gardner, Rui [Instituto Gulbenkian de Ciência (Portugal); Cardoso, M. Margarida, E-mail: margarida.cardoso@fct.unl.pt [Universidade Nova de Lisboa, LAQV, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia (Portugal)

    2015-11-15

    This work studied the effect of the application time of a non-permanent magnetic field on the rate of drug release from iron oxide polymeric nanoparticles. Magnetically responsive doxorubicin loaded poly(d-lactide-co-glycolide) (PLGA) nanoparticles were synthetized by the o/w solvent extraction/evaporation method and characterized. The produced particles show spherical shapes exhibiting a size between 200 and 400 nm, a drug loading of 3.6 % (w/w) and an iron concentration of 20.7 % (w/w). Cell cytotoxicity tests showed that unloaded magnetic PLGA nanoparticles were nontoxic. Concerning the therapeutic activity, doxorubicin-loaded magnetic particles cause a remarkable enhancement of the cell inhibition rates compared to their non-magnetic counterparts (40 against 7 % of dead cells). In vitro drug release studies performed under a non-permanent magnetic field show that the application time and the on/off cycle duration have a great influence with respect to the final amount and to the rate of drug release. The final amount and the rate of doxorubicin released increase with the time of field application reaching higher values for a higher number of pulses with a lower duration. Doxorubicin release mechanism has shown to be governed by Fickian diffusion in the absence of a magnetic field while in the presence of a magnetic field some controlled relaxation polymer chains might also be present. The results show that the drug release rate from magnetic PLGA nanoparticles can be modulated through the application time and the on/off cycles duration of a non-permanent magnetic field.

  8. Palynological evidence for the historic expansion of juniper and desert shrubs in Arizona, U.S.A.

    Science.gov (United States)

    Davis, O.K.; Turner, R.M.

    1986-01-01

    Analysis of the sediment of Pecks Lake, Yavapai County, Arizona, has permitted the first reported palynological evidence for the historic expansion of juniper and desert shrubs in the American Southwest. The palynological evidence is supported by the comparison of modern and historical photographs, which shows the regional expansion of pinyon-juniper woodland, and the local increase of mesquite and creosote bush. A gradual increase in juniper pollen percentages began over 2000 years ago, but the rate of increase abruptly accelerated after the historic introduction of grazing animals. In contrast, juniper percentages did not increase during a prehistoric interval of intense disturbance by humans, about A.D. 1200, and a different weed flora was present. Prehistorically, water depth was greatest at ca. 600 B.C. and was lowest just prior to the arrival of Europeans. Regional climate has gradually cooled since the beginning of the record at 2630 B.P. ?? 1986.

  9. 一种新型矿用真空永磁控制器设计%Design of a New Type of Mining Vacuum Permanent Magnet Controller

    Institute of Scientific and Technical Information of China (English)

    党威

    2012-01-01

    Aiming at the control need of various mining permanent magnetic vacuum circuit breakers, this stud- y realizes the new intelligent mining vacuum permanent magnet controller based on CPLD. The full electronic circuit non-contact integrated software design is adopted. The switching power with wide-range input and constant-voltage and constant-current output is adopted as the power. The voltage and current are continuously adjustable and there- fore reliable. The electronic switch comprised mainly of a transistor and an IGBT is used to control the break-brake power so that the output energy can be controlled and adjusted, and the safety of the mine and the reliability of the breaker can be ensured.%针对各种矿用永磁机构真空断路器的控制需求,实现了基于CPLD的新型智能矿用真空永磁控制器。采用全电子电路无触点软件一体化设计,电源采用宽范围输入、恒压恒流输出的开关电源设计,电压和电流连续可调,具有较高的可靠性;用三极管和IGBT组成的电子开关通断来控制钞分闸的能量,使输出能量可控、可调,保证了矿井的安全和断路器可靠工作。

  10. Casting dimensional control and fatigue life prediction for permanent mold casting dies. Technical progress report, September 29, 1993-- September 30, 1994

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-11-01

    First year efforts as part of a three year program to address metal casting dimensional control and fatigue life prediction for permanent mold casting dies are described. Procedures have been developed and implemented to collect dimensional variability data from production steel castings. The influence of process variation and casting geometry variables on dimensional tolerances have been investigated. Preliminary results have shown that these factors have a significant influence on dimensional variability, although this variability is considerably less than the variability indicated in current tolerance standards. Gage repeatability and reproducibility testing must precede dimensional studies to insure that measurement system errors are acceptably small. Also initial efforts leading to the development and validation of a CAD/CAE model to predict the thermal fatigue life of permanent molds for aluminum castings are described. An appropriate thermomechanical property database for metal, mold and coating materials has been constructed. A finite element model has been developed to simulate the mold temperature distribution during repeated casting cycles. Initial validation trials have indicated the validity of the temperature distribution model developed.

  11. Driving and control strategies in alternative current machines of permanent magnet with non-sinusoidal flux; Estrategias de acionamento e controle em maquinas CA de ima permanente com fluxo nao senoidal

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, Jose Roberto Boffino de Almeida

    1997-07-01

    The aim of this work is to study and analyze the torque performance of brush less machines with non-sinusoidal distributed magnetic fluxes. The machine type considered is a surface mount permanent magnet brush less machine. Three mathematical models for the machine are considered: the per stator phase, the vectorial and the linear second order speed-voltage models. Machines with different stator windings are compared including the permanent magnet synchronous machines with sinusoidal distributed stator windings. The torque outputs of these machines are obtained considering two kinds of open loop driving systems: one with a six-pulse waveform and other with a sinusoidal waveform. Finally, a vectorial control is proposed for the non-sinusoidal machines. The torque ripple as well the overall performance of non-sinusoidal machines with vectorial control is compared to that of sinusoidal machines. (author)

  12. Design of Permanent Magnet Synchronous Spindle Motor Control System%永磁同步主轴电动机控制系统设计

    Institute of Scientific and Technical Information of China (English)

    刘洋; 刘景林; 李欣

    2013-01-01

    A vector control system using TMS320F2812 digital signal processor (DSP) as the main chip for the permanent magnet synchronous spindle motor (PMSM) was proposed,which utilized the vector control priciple and the space vector pulse width modulation (SVPWM) method in order to decouple and control the d-q axis currents separately.Based on this,the flux-weaking control algorithm was realized through a d-axis control method based on the saturation extent of outer voltage loop,which extended the speed range of the permanent magnet synchronous spindle motor control system.The control system consists of the main power circuit,the control circuit,isolation circuit,signal detection and regulating circuit,the auxiliary power supply,display and the parameter setting circuit.It is verified through experiments that the control system is reliable,and the static and dynamic performance meets the application requirements of the CNC machine tool spindle drive.%以数字信号处理器TMS320F2812为主控芯片,根据矢量控制原理,结合空间电压矢量脉宽调制SVPWM方法,实现d-q轴电流的解耦控制,完成永磁同步主轴电动机的矢量控制.在此基础上,设计了利用外环电压饱和程度进行直轴电流弱磁控制的算法,拓宽了永磁同步主轴电机控制系统的调速范围.控制系统主要包括功率主电路、控制电路、隔离驱动电路、信号检测及调理电路、辅助电源、显示及参数设定电路.经实验验证,控制系统运行可靠、动静态性能良好,基速以下具有恒转矩特性,基速以上实现了弱磁升速,满足数控机床主轴驱动应用要求.

  13. Individualistic Response of Piñon and Juniper Tree Species Distributions to Climate Change in North America's Arid Interior West

    OpenAIRE

    Gibson, Jacob R.

    2011-01-01

    Piñon and juniper tree species have species-specific climatic requirements, resulting in unique distributions and differential responses to climate change. Piñons and junipers co-dominate the arid woodlands of North America as groups with widespread hybridization. Two piñons, Pinus edulis; P. monophylla, and four junipers, Juniperus deppeana var. deppeana; J. monosperma; J. occidentalis; J. osteosperma, are endemic to the midlatitude interior west and form three groups of hybridizing sister s...

  14. Overview on permanent magnetic actuator

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Permanent magnetic actuator (PMA), as a new electronic actuator of vacuum circuit breakers, certainly will be used to replace the traditional mechanical actuator. It has such advantages as simple structure, high reliability, free maintenance, and so on. This paper summarizes the development, structure, magnetic analysis, character analysis, and control strategy of PMA, and also predicts the future trend of PMA development

  15. Very low speed performance of active flux based sensorless control: interior permanent magnet synchronous motor vector control versus direct torque and flux control

    DEFF Research Database (Denmark)

    Paicu, M. C.; Boldea, I.; Andreescu, G. D.

    2009-01-01

    in the rotor position and speed estimation is obtained. For IPMSM, a stator-flux observer is employed based on combined current and voltage models, with speed-dependent smooth transition between them using a PI compensator of flux error. Comparative experimental results using both sensorless control systems...

  16. [Control of culicides by using Bacillus thuringiensis SH-14 var. israelensis in permanent breeding places of Fomento, province of Sancti Spiritus, Cuba].

    Science.gov (United States)

    Cruz Pineda, Carlos Alberto; Montero Lago, Grisel; Navarro Ortega, Agustín; Morejón Martín, Pedro Lorenzo

    2005-01-01

    An ecological evaluation of retrospective and descriptive temporary trend was conducted from 1999 to 2000 .in 8 water bodies of Fomento, province of Sancti Spiritus. To evaluate the effectiveness and permanence of the biolarvicide, there were used data of systematic samplings and of control actions of the provincial surveillance and antivectorial fight programs taken from the records of each breeding place in the Municipal Unit of Higiene and Epidemiology of the locality. Doses of 10 ml of active ingredient per square meter were administered. It was attained the reduction and stabilization of the larval and adult indices in human primer of important species which are vectors of malaria, phyliriasis, and Western Nile's fever. The extension of the larval recovery range up to 3 weeks was proved.

  17. Sensor-less Field Oriented Control of Wind Turbine Driven Permanent Magnet Synchronous Generator Using Flux Linkage and Back EMF Estimation Methods

    Directory of Open Access Journals (Sweden)

    Porselvi Thayumanavan

    2014-05-01

    Full Text Available The study aims at the speed control of the wind turbine driven Permanent Magnet Synchronous Generator (PMSG by sensor-less Field Oriented Control (FOC method. Two methods of sensor-less FOC are proposed to control the speed and torque of the PMSG. The PMSG and the full-scale converter have an increasing market share in variable speed Wind Energy Conversion System (WECS. When compared to the Induction Generators (IGs, the PMSGs are smaller, easier to control and more efficient. In addition, the PMSG can operate at variable speeds, so that the maximum power can be extracted even at low or medium wind speeds. Wind turbines generally employ speed sensors or shaft position encoders to determine the speed and the position of the rotor. In order to reduce the cost, maintenance and complexity concerned with the sensor, the sensor-less approach has been developed. This study presents the sensor-less control techniques using the flux-linkage and the back EMF estimation methods. Simulations for both the methods are carried out in MATLAB/SIMULINK. The simulated waveforms of the reference speed, the measured speed, the reference torque, the measured torque and rotor position are shown for both the methods.

  18. Encounters with Pinyon-Juniper influence riskier movements in Greater Sage-Grouse across the Great Basin

    Science.gov (United States)

    Prochazka, Brian; Coates, Peter S.; Ricca, Mark; Casazza, Michael L.; Gustafson, K. Ben; Hull, Josh M.

    2016-01-01

    Fine-scale spatiotemporal studies can better identify relationships between individual survival and habitat fragmentation so that mechanistic interpretations can be made at the population level. Recent advances in Global Positioning System (GPS) technology and statistical models capable of deconstructing high-frequency location data have facilitated interpretation of animal movement within a behaviorally mechanistic framework. Habitat fragmentation due to singleleaf pinyon (Pinus monophylla; hereafter pinyon) and Utah juniper (Juniperus osteosperma; hereafter juniper) encroachment into sagebrush (Artemisia spp.) communities is a commonly implicated perturbation that can adversely influence greater sage-grouse (Centrocercus urophasianus; hereafter sage-grouse) demographic rates. Using an extensive GPS data set (233 birds and 282,954 locations) across 12 study sites within the Great Basin, we conducted a behavioral change point analysis and subsequently constructed Brownian bridge movement models from each behaviorally homogenous section. We found a positive relationship between modeled movement rate and probability of encountering pinyon-juniper with significant variation among age classes. The probability of encountering pinyon-juniper among adults was two and three times greater than that of yearlings and juveniles, respectively. However, the movement rate in response to the probability of encountering pinyon-juniper trees was 1.5 times greater for juveniles. We then assessed the risk of mortality associated with an interaction between movement rate and the probability of encountering pinyon-juniper using shared frailty models. During pinyon-juniper encounters, on average, juvenile, yearling, and adult birds experienced a 10.4%, 0.2%, and 0.3% reduction in annual survival probabilities. Populations that used pinyon-juniper habitats with a frequency ≥ 3.8 times the overall mean experienced decreases in annual survival probabilities of 71.1%, 0.9%, and 0.9%. This

  19. Compatible dominant height - site index model for juniper (Juniperus deppeana Steud.)

    OpenAIRE

    Antonio Rodríguez-Carrillo; Francisco Cruz-Cobos; Benedicto Vargas-Larreta; Francisco J. Hernández

    2015-01-01

    The aim of this study was to determine the site quality of juniper (Juniperus deppeana Steud.) in the San Dimas region of the state of Durango, Mexico, using the site index method. The database comes from stem analysis of 43 trees felled in harvesting activities. The Chapman-Richards and Schumacher models, by means of the algebraic difference and generalized algebraic difference approaches, were tested to determine the site index; in addition, the error structure was modeled with a second-ord...

  20. Determine the optimum spectral reflectance of juniper and pistachio in arid and semi-arid region

    Science.gov (United States)

    Fadaei, Hadi; Suzuki, Rikie

    2012-11-01

    Arid and semi-arid areas of northeast Iran cover about 3.4 million ha are populated by two main tree species, the broadleaf Pistacia vera. L (pistachio) and the conifer Juniperus excelsa ssp. polycarpos (Persian juniper). Natural stands of pistachio in Iran are not only environmentally important but genetically essential as seed sources for pistachio production in orchards. In this study, we estimated the optimum spectral reflectance of juniper forests and natural pistachio stands using remote sensing to help in the sustainable management and production of pistachio in Iran. In this research spectral reflectance are able to specify of multispectral from Advanced Land Observing Satellite (ALOS) that provided by JAXA. These data included PRISM is a panchromatic radiometer with a 2.5 m spatial resolution at nadir, has one band with a wavelength of 0.52-0.77 μm and AVNIR-2 is a visible and near infrared radiometer for observing land and coastal zones with a 10 m spatial resolution at nadir, has four multispectral bands: blue (0.42-0.50 μm), green (0.52-0.60 μm), red (0.61-0.69 μm), and near infrared (0.76-0.89 μm). Total ratio vegetation index (TRVI) of optimum spectral reflectance of juniper and pistachio have been evaluated. The result of TRVI for Pistachio and juniper were (R2= 0.71 and 0.55). I hope this research can provide decision of managers to helping sustainable management for arid and semi-arid regions in Iran.

  1. Functional characterization of fifteen hundred transcripts from Ziarat juniper (Juniperus excelsa M.Bieb

    Directory of Open Access Journals (Sweden)

    Humaira Abdul Wahid

    2016-11-01

    Full Text Available Background: Ziarat juniper (Juniperus excelsa M.Bieb is an evergreen and dominant species of Balochistan juniper forests. This forest is providing many benefits to regional ecosystems and surrounding populations. No functional genomics study is reported for this important juniper plant. This research is aimed to characterize the Ziarat juniper functional genome based on the analyses of 1500 transcripts. Methods: Total RNA from shoot of Juniperus excelsa was extracted and subjected for transcriptome sequencing using Illumina HiSeq 2000 with the service from Macrogen, Inc., South Korea. The Illumina sequenced data was subjected to bioinformatics analysis. Quality assessment and data filtration was performed for the removal of low-quality reads, ambiguous reads and adaptor sequences. The high-quality clean reads data was deposited in the Sequence Read Archive (SRA at NCBI, and used for downstream processes. Fifteen hundred transcripts were randomly chosen and used for functional characterization. Results: As a result of homology search 80.3% transcripts showed significant similarities and were placed in significant similarities category, 19.3% transcripts showed low similarities and assigned to the ‘‘unclassified’’ category while 0.4% transcripts are defined as no hits. The functional characterization results showed that most (18% of the transcripts are involved in metabolism, followed by 11.7% in transcription and 11.5% as structural protein. 8.8% transcripts are engaged in stress response, whereas the transcripts involved in growth and development constituted 6.7%. Transcripts involved in signal transduction represented 5.6%, while 3.5% facilitating transport and 34.1% are involved in hypothetical functions. Conclusion: The functional annotation data produced in this study will be very useful for future functional genome analysis of Juniperus excelsa.

  2. Juniper tar (cade oil) poisoning in new born after a cutaneous application

    OpenAIRE

    Achour, Sanae; Abourazzak, Sana; Mokhtari, Abdelrhani; Soulaymani, Abdelmjid; Soulaymani, Rachida; Hida, Moustapha

    2011-01-01

    Juniper tar (cade oil) is distilled from the branches and wood of Juniperus oxycedrus. It contains etheric oils, triterpene and phenols, used for many purposes in folk medicine. The authors report a case of a previously healthy new born treated with a topical application of Juniperus oxycedrus for atopic dermatosis The poisoning caused convulsions, collapsus, acute pulmonary oedema, renal failure and hepatotoxicity. The newborn survived after supportive and symptomatic treatment, and discharg...

  3. Negative effects of temperature and atmospheric depositions on the seed viability of common juniper (Juniperus communis).

    Science.gov (United States)

    Gruwez, R; De Frenne, P; De Schrijver, A; Leroux, O; Vangansbeke, P; Verheyen, K

    2014-02-01

    Environmental change is increasingly impacting ecosystems worldwide. However, our knowledge about the interacting effects of various drivers of global change on sexual reproduction of plants, one of their key mechanisms to cope with change, is limited. This study examines populations of poorly regenerating and threatened common juniper (Juniperus communis) to determine the influence of four drivers of global change (rising temperatures, nitrogen deposition, potentially acidifying deposition and altering precipitation patterns) on two key developmental phases during sexual reproduction, gametogenesis and fertilization (seed phase two, SP2) and embryo development (seed phase three, SP3), and on the ripening time of seeds. In 42 populations throughout the distribution range of common juniper in Europe, 11,943 seeds of two developmental phases were sampled. Seed viability was determined using seed dissection and related to accumulated temperature (expressed as growing degree-days), nitrogen and potentially acidifying deposition (nitrogen plus sulfur), and precipitation data. Precipitation had no influence on the viability of the seeds or on the ripening time. Increasing temperatures had a negative impact on the viability of SP2 and SP3 seeds and decreased the ripening time. Potentially acidifying depositions negatively influenced SP3 seed viability, while enhanced nitrogen deposition led to lower ripening times. Higher temperatures and atmospheric deposition affected SP3 seeds more than SP2 seeds. However, this is possibly a delayed effect as juniper seeds develop practically independently, due to the absence of vascular communication with the parent plant from shortly after fertilization. It is proposed that the failure of natural regeneration in many European juniper populations might be attributed to climate warming as well as enhanced atmospheric deposition of nitrogen and sulfur.

  4. Viewpoint: Sustainability of pinon-juniper ecosystems - A unifying perspective of soil erosion thresholds

    Science.gov (United States)

    Davenport, D.W.; Breshears, D.D.; Wilcox, B.P.; Allen, C.D.

    1998-01-01

    Many pinon-juniper ecosystem in the western U.S. are subject to accelerated erosion while others are undergoing little or no erosion. Controversy has developed over whether invading or encroaching pinon and juniper species are inherently harmful to rangeland ecosystems. We developed a conceptual model of soil erosion in pinon-jumper ecosystems that is consistent with both sides of the controversy and suggests that the diverse perspectives on this issue arise from threshold effects operating under very different site conditions. Soil erosion rate can be viewed as a function of (1) site erosion potential (SEP), determined by climate, geomorphology and soil erodibility; and (2) ground cover. Site erosion potential and cove act synergistically to determine soil erosion rates, as evident even from simple USLE predictions of erosion. In pinon-juniper ecosystem with high SEP, the erosion rate is highly sensitive to ground cover and can cross a threshold so that erosion increases dramatically in response to a small decrease in cover. The sensitivity of erosion rate to SEP and cover can be visualized as a cusp catastrophe surface on which changes may occur rapidly and irreversibly. The mechanisms associated with a rapid shift from low to high erosion rate can be illustrated using percolation theory to incorporate spatial, temporal, and scale-dependent patterns of water storage capacity on a hillslope. Percolation theory demonstrates how hillslope runoff can undergo a threshold response to a minor change in storage capacity. Our conceptual model suggests that pinion and juniper contribute to accelerated erosion only under a limited range of site conditions which, however, may exist over large areas.

  5. Analysis of the control structure of wind energy generation systems based on a permanent magnet synchronous generator

    OpenAIRE

    Carranza Castillo, Oscar; Figueres Amorós, Emilio; Garcerá Sanfeliú, Gabriel; González Medina, Raul

    2013-01-01

    This paper presents the analysis of the two usual control structures for variable speed and fixed pitch wind energy generation systems, namely speed and torque control, to determine the most appropriate structure to improve both robustness and reliability of this kind of distributed generators. The study considers all the elements of a typical wind power generation system and it has been carried out in a general way, so that conclusions are independent of the kind of the AC/DC converter that ...

  6. 22 CFR 401.3 - Permanent offices.

    Science.gov (United States)

    2010-04-01

    ... Relations INTERNATIONAL JOINT COMMISSION, UNITED STATES AND CANADA RULES OF PROCEDURE General § 401.3 Permanent offices. The permanent offices of the Commission shall be at Washington, in the District of... of the Commission shall have full charge and control of said offices, respectively....

  7. Runoff and erosion from a rapidly eroding pinyon-juniper hillslope

    Energy Technology Data Exchange (ETDEWEB)

    Wilcox, B.P.; Davenport, D. W. [Los Alamos National Lab., NM (United States); Pitlick, J. [Colorado Univ., Boulder, CO (United States); Allen, C.D. [National Biological Survey, Los Alamos, NM (United States). Jemez Mountain Field Station

    1996-02-01

    The dramatic acceleration of erosion associated with the expansion of pinyon-juniper woodlands over the past 100 years has been a widely recognized but poorly understood phenomenon. A more complete understanding will come only through long-term observations of erosion and related factors. To this end, we are conducting a study of a small (1-ha) catchment in a rapidly eroding pinyon-juniper woodland. Since July 1993, we have been collecting data on runoff, erosion, and weather conditions in the catchment, as well as on the topography, soils, and vegetation. Our preliminary results suggest that (1) the catchment is currently in a cycle of accelerated erosion that began concomitant with a shift from ponderosa pine forest to pinyon-juniper woodland that was initiated by a prolonged drought; (2) the intercanopy soils cannot be sustained at the current erosion rates and will be mostly stripped away in about a century; (3) large summer thunderstorms are the most important agents of erosion (4) erosion increases dramatically as the scale increases; (5) runoff makes up <10% of the water budget.

  8. Red Mud Catalytic Pyrolysis of Pinyon Juniper and Single-Stage Hydrotreatment of Oils

    Energy Technology Data Exchange (ETDEWEB)

    Agblevor, Foster A.; Elliott, Douglas C.; Santosa, Daniel M.; Olarte, Mariefel V.; Burton, Sarah D.; Swita, Marie; Beis, Sedat H.; Christian, Kyle; Sargent, Brandon

    2016-10-20

    Pinyon juniper biomass feedstocks, which cover a large acreage of rangeland in the western United States, are being eradicated and, therefore, considered as a convenient biomass feedstock for biofuel production. Pinyon juniper whole biomass (wood, bark, and leaves) were pyrolyzed in a pilot-scale bubbling fluidized-bed reactor at 450 °C, and the noncondensable gases were recycled to fluidize the reactor. Red mud was used as the in situ catalyst for the pyrolysis of the pinyon juniper biomass. The pyrolysis products were condensed in three stages, and products were analyzed for physicochemical properties. The condenser oil formed two phases with the aqueous fraction, whereas the electrostatic precipitator oils formed a single phase. The oil pH was 3.3; the higher heating value (HHV) was 28 MJ/kg; and the viscosity was less than 100 cP. There was a direct correlation between the viscosity of the oils and the alcohol/ether content of the oils, and this was also related to the aging rate of the oils. The catalytic pyrolysis oils were hydrotreated in a continuous single-stage benchtop hydrotreater to produce hydrocarbon fuels with a density of 0.80$-$0.82 cm3/g. The hydrotreater ran continuously for over 300 h with no significant catalyst deactivation or coke formation. This is the first time that such a long single-stage hydrotreatment has been demonstrated on biomass catalytic pyrolysis oils.

  9. Sliding mode controller design for synchronous permanent magnet planar motor%永磁同步平面电动机的滑模控制器设计

    Institute of Scientific and Technical Information of China (English)

    王丽梅; 郑浩; 贾启

    2014-01-01

    To achieve high performance positioning servo control of synchronous permanent magnet planar motor( SPMPM) , the method of sliding mode motion control based on disturbance observer was proposed. On the basis of modified super-twisting algorithm, the position servo controller for SPMPM was designed. A disturbance observer( DOB) was used in the closed-loop control to estimate external disturbances and then compensate them to improve the performance and stability of the system. The SPMPM control system with the controller proposed was simulated. The simulation results show that the control strategy and algo-rithms proposed makes the system the desired performances and the control system has good robustness and stability.%为了实现永磁同步平面电动机的高性能定位伺服控制,提出了基于干扰观测器的滑模控制方法。基于改进的超螺旋算法,设计了永磁同步平面电动机的位置伺服控制器,在闭环系统中采用干扰观测器,对外部大扰动进行补偿,滑模控制器用来消除干扰观测误差,从而提高系统的鲁棒性和抗干扰能力。对所设计的控制系统进行了仿真研究,结果表明所采用的控制策略和控制算法使系统获得较好的定位精度,同时具有良好的鲁棒性和稳定性。

  10. Oscillating Permanent Magnets.

    Science.gov (United States)

    Michaelis, M. M.; Haines, C. M.

    1989-01-01

    Describes several ways to partially levitate permanent magnets. Computes field line geometries and oscillation frequencies. Provides several diagrams illustrating the mechanism of the oscillation. (YP)

  11. Global Multivariable Control of Permanent Magnet Synchronous Motor for Mechanical Elastic Energy Storage System under Multiclass Nonharmonic External Disturbances

    Directory of Open Access Journals (Sweden)

    Yang Yu

    2014-01-01

    Full Text Available For the technology of mechanical elastic energy storage utilizing spiral torsion springs as the energy storage media presented previously, a global multivariable control algorithm based on nonlinear internal model principle under multiclass external disturbances is proposed. The nonlinear external disturbances with nonharmonic periodic characteristics are generated by multiclass nonlinear external systems. New equations of nonlinear internal model are designed to estimate the multiclass external disturbances. On the basis of constructing the control law of nominal system, a state feedback controller is designed to guarantee the closed-loop system globally uniformly bounded, and a Lyapunov function is constructed to theoretically prove the global uniform boundedness of the multivariable closed-loop system signals. The simulation results verify the correctness and effectiveness of the presented algorithm.

  12. Iron loss in permanent-magnet brushless AC machines under maximum torque per ampere and flux weakening control \\ud

    OpenAIRE

    Zhu, Z.Q.; Chen, Y. S.; Howe, D.

    2002-01-01

    The airgap flux density distribution, flux density loci in the stator core, and the associated iron loss in two topologies of brushless AC motor, having a surface-mounted magnet rotor and an interior-mounted magnet rotor, respectively, are investigated when operated under maximum torque per ampere control in the constant torque mode and maximum power control in the flux-weakening mode. It is shown that whilst the interior magnet topology is known to be eminently suitable for flux-weakening op...

  13. Design and Simulation of Control Technique for Permanent Magnet Synchronous Motor Using Space Vector Pulse Width Modulation

    Science.gov (United States)

    Khan, Mansoor; Yong, Wang; Mustafa, Ehtasham

    2017-07-01

    After the rapid advancement in the field of power electronics devices and drives for last few decades, there are different kinds of Pulse Width Modulation techniques which have been brought to the market. The applications ranging from industrial appliances to military equipment including the home appliances. The vey common application for the PWM is three phase voltage source inverter, which is used to convert DC to AC in the homes to supply the power to the house in case electricity failure, usually named as Un-interrupted Power Supply. In this paper Space Vector Pulse Width Modulation techniques is discussed and analysed under the control technique named as Field Oriented Control. The working and implementation of this technique has been studied by implementing on the three phase bridge inverter. The technique is used to control the Permanente Magnet Synchronous Motor. The drive system is successfully implemented in MATLAB/Simulink using the mathematical equation and algorithm to achieve the satisfactory results. PI type of controller is used to tuned ers of the motothe parametr i.e. torque and current.

  14. Modeling and Control for Double Stator Permanent Magnetic Brushless Machine%双定子永磁无刷电机建模及其控制

    Institute of Scientific and Technical Information of China (English)

    王玉彬; 程明; 马炳荣

    2011-01-01

    推导了双定子永磁无刷( DS - PMBL)电机三相定子坐标系下的数学模型,在此基础上,基于Matlab/Simulink建立了DS - PMBL电机本体的仿真模型以及其控制系统模型,并采用id=0矢量控制策略研究了DS- PMBL电机的动态性能.试验结果验证了所搭建仿真模型的正确性.%The mathematic model of double stator permanent magnetic brushless (DS-PMBL) machine has been derived based on three-phase stator coordinate system. Accordingly, the simulation models, namely, the machine body and id = 0 vector control system, have been established using Matlab/Simulink. The dynamic performance of the proposed vector control system has been investigated. Experimental results of the prototype are given to verify the simulation model and the control strategy.

  15. On the application of permanent magnet control technology in low voltage switch%论低压开关中永磁控制技术的应用

    Institute of Scientific and Technical Information of China (English)

    龚荣福

    2016-01-01

    为了克服传统低压开关电动控制系统中所存在的诸如接触器主触头被烧、短路情况下断路器无法正常将电路分断、电机保护功能难以充分发挥等问题,可以通过永磁控制技术的应用加以实现.本文重点就低压开关的电磁控制技术进行探讨,以供参考.%In orderto overcome the traditional low voltage switch electric control system such as the main contact of the contactor is burned,short circuit breaker can not be normal circuit breaking,it is difficult to give full play to the function of protecting the motor and other issues, through permanent magnet control technology to be realized.This paper focuses on the low voltage switch electromagnetic control technology for reference.

  16. Maximum Power Point Tracking Control of Hydrokinetic Turbine and Low-speed High-Thrust Permanent Magnet Generator Design

    Science.gov (United States)

    2012-01-01

    systems as well as vortex induced vibration systems . Section 3 presents a dynamic model of the hydrokinetic turbine system based on which a MPPT...turbines. In addition, hydrokinetic current energy can be converted into electrical energy by Vortex Induced Vibration (VIV) systems , in which a cylinder...Jiang, "Doubly- fed induction generator control for variable-speed wind power generation system ," in Proc. Mechatronics and Automation, 2009. ICMA 2009

  17. Analysis and control of novel split-winding doubly salient permanent magnet motor for adjustable speed drive

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, a novel split-winding doubly salient permanentmagnet (DSPM) motor is proposed and the theoretical and experimental studies on the magnetic field, static characteristics and control strategy of this motor are carried out. The steady-state and dynamic models are presented and the output power equation is derived. The feasibility of extending the operation range of the DSPM motor by using split-windings is proved. The finite element method is used to analyze the magnetic field, in which the leakage flux outside the stator circumference is taken into account. Based on the operation principle and the static characteristics of the motor, the control strategy and scheme are developed and implemented in a microcomputer-based controller. According to the features of the 4-phase 8/6-pole DSPM motor, a half-bridge power converter without neutral is adopted to reduce the number of power devices and to eliminate the problem of voltage unbalance in the split capacitors. The experimental results on the prototype machine not only verify the theoretical analysis, but also show that the proposed DSPM motor drive possesses good steady-state and dynamic performances, offering high efficiency over wide power range, and that the split-winding topology can effectively extend the operation range of the DSPM motor.

  18. PMLSM的互补式滑模控制系统设计%Design of Complementary Sliding Mode Control System for Permanent Magnet Linear Motor

    Institute of Scientific and Technical Information of China (English)

    姚明林; 李兵

    2011-01-01

    针对永磁线性同步电动机在位置控制中易受系统参数变化、外界负载干扰以及摩擦力等不确定因素的影响,提出并设计了以径向基神经网络为预估器的互补式滑模控制器,以实现精确的位置控制.设计中利用饱和函数作为切换函数,利用径向基神经网络预测器来预测系统中的不确定项.从而减少了系统的抖振,消除稳态误差,提高了系统的暂态响应速度.通过仿真结果,验证了该控制器具有优异的跟踪能力和鲁棒性.%For the disadvantage of the permanent magnet linear synchronous motor (PMLSM), which the control system easy affected by the changes such as the parameters of the system, the influence and the unknown factors,to realize the accuracy position control in the PMLSM,a complementary sliding mode control system with radial basis function network estimator was proposed. In the design,a saturation function is used as a switching function, and use an estimator which based on radial basis function network to predict the uncertain items. It can reduce the chattering of the system,eliminate the steady-state error,and improve the speed of transient response. From the simulation,it proves that the complementary sliding mode control system with radial basis function network estimator has good performance for precision position control and robust control.

  19. Effect of using redberry juniper (Juniperus pinchotii) to reduce Haemonchus contortus in vitro motility and increase ivermectin efficacy.

    Science.gov (United States)

    Armstrong, S A; Klein, D R; Whitney, T R; Scott, C B; Muir, J P; Lambert, B D; Craig, T M

    2013-10-18

    A modified larval migration inhibition assay was used to determine if redberry juniper (Juniperus pinchotii Sudw.) can reduce Haemonchus contortus in vitro motility and increase ivermectin (IVM) efficacy. Ruminal fluid was mixed with buffer solution and either no material (CNTL) or Tifton 85 Bermudagrass hay (T85), dried juniper (DRY), fresh juniper (FRE), or distilled juniper terpenoid oil (OIL) to make treatment solutions and anaerobically incubated for 16 h. For Trial 1, larvae were incubated in CNTL, T85, DRY, or IVM. During Trial 2, larvae were incubated in CNTL, DRY, FRE, or OIL for 4h. Trials 3 (CNTL or OIL) and 4 (CNTL, DRY or FRE) evaluated larvae after incubation in treatment solution for 2h, then incubated an additional 2h in various IVM doses (0, 0.1, 1, 3, and 6 μg/mL IVM) and placed onto a screen. Larvae that passed through the 20-μm screen within a 96-well plate were considered motile. Larvae incubated in CNTL or T85 had similar (P=0.12) motility, but larvae incubated in DRY were less (PFRE, or OIL reduced (PFRE. Juniper forage material reduced in vitro H. contortus larval motility, but IVM efficacy was increased only by initially incubating larvae in DRY.

  20. Experimental Confirmation of Nonlinear-Model- Predictive Control Applied Offline to a Permanent Magnet Linear Generator for Ocean-Wave Energy Conversion

    KAUST Repository

    Tom, Nathan

    2015-01-01

    To further maximize power absorption in both regular and irregular ocean wave environments, nonlinear-model-predictive control (NMPC) was applied to a model-scale point absorber developed at the University of California Berkeley, Berkeley, CA, USA. The NMPC strategy requires a power-takeoff (PTO) unit that could be turned on and off, as the generator would be inactive for up to 60% of the wave period. To confirm the effectiveness of this NMPC strategy, an in-house-designed permanent magnet linear generator (PMLG) was chosen as the PTO. The time-varying performance of the PMLG was first characterized by dry-bench tests, using mechanical relays to control the electromagnetic conversion process. The on/off sequencing of the PMLG was tested under regular and irregular wave excitation to validate NMPC simulations using control inputs obtained from running the choice optimizer offline. Experimental results indicate that successful implementation was achieved and absorbed power using NMPC was up to 50% greater than the passive system, which utilized no controller. Previous investigations into MPC applied to wave energy converters have lacked the experimental results to confirm the reported gains in power absorption. However, after considering the PMLG mechanical-to-electrical conversion efficiency, the electrical power output was not consistently maximized. To improve output power, a mathematical relation between the efficiency and damping magnitude of the PMLG was inserted in the system model to maximize the electrical power output through continued use of NMPC which helps separate this work from previous investigators. Of significance, results from latter simulations provided a damping time series that was active over a larger portion of the wave period requiring the actuation of the applied electrical load, rather than on/off control.

  1. A New Maximum Power Point Estimator Control Strategy to Maximize Output Power of the Double Stator Permanent Magnet Generator

    Directory of Open Access Journals (Sweden)

    Norhisam Misron

    2016-08-01

    Full Text Available A new control estimator to maximize the power generated with a maximum power point estimator is introduced. The power mapping characteristics from the double-stator generator are modeled as a mathematical equation which is used to develop the estimator for maximum power tracking to maximize the generated power. The proposed estimator automatically traces the instantaneous maximum power at various load conditions. However, to stabilize the output voltage, a boost converter is used from the inverter side. The developed double-stator generator is tested with the new estimator for the maximizing power generation capability under laboratory conditions. The experimental results confirm that with the new estimator, the average power generation capability is increased by 12% and the peak value is increase by 22%.

  2. Environmental, genetic, and ecophysiological variation of western and Utah juniper and their hybrids: A model system for vegetation response to climate change. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, R.S. [Univ. of Nevada, Reno, NV (United States). Dept. of Environmental and Resource Sciences; Tausch, R.J. [Forest Service, Reno, NV (United States). Rocky Mountain Research Station

    1998-11-01

    This report focuses on the following two research projects relating to the biological effects of climate change: Hybridization and genetic diversity populations of Utah (Juniperus osteosperma) and western (Juniperus occidentalis) juniper: Evidence from nuclear ribosomal and chloroplast DNA; and Ecophysiological patterns of pinyon and juniper.

  3. Historical and modern disturbance regimes, stand structures, and landscape dynamics in pinon-juniper vegetation of the western U.S.

    Science.gov (United States)

    William H. Romme; Craig D. Allen; John D. Bailey; William L. Baker; Brandon T. Bestelmeyer; Peter M. Brown; Karen S. Eisenhart; Lisa Floyd-Hanna; Dustin W. Huffman; Brian F. Jacobs; Richard F. Miller; Esteban H. Muldavin; Thomas W. Swetnam; Robin J. Tausch; Peter J. Weisberg

    2008-01-01

    Pinon-juniper is one of the major vegetation types in western North America. It covers a huge area, provides many resources and ecosystem services, and is of great management concern. Management of pinon-juniper vegetation has been hindered, especially where ecological restoration is a goal, by inadequate understanding of the variability in historical and modern...

  4. 永磁直线同步电机无模型自适应直接推力控制%Direct Trust Control of Permanent Magnet Linear Synchronous Motor Based on Model-free Adaptive Control Method

    Institute of Scientific and Technical Information of China (English)

    崔皆凡; 闫红; 单宝钰

    2013-01-01

    For the characteristics of external disturbances and uncertain variable model parameters in permanent magnet linear synchronous motor,model-free adaptive control was firstly applied into the direct trust control of permanent magnet linear synchronous motor With this method,the differential equation between the electromagnetic force and speed was fitted in real time during the operation,and the given electromagnetic force was caculated through control law function,ultimately,direct trust control of permanent magnet linear synchronous motor based on model-free adaptive control method could be achieved.Compared with PI control,model-free adaptive control could not only eliminate the need for adjusting PI controller parameters,but also reduce the speed and force ripples caused by parameter variations and load disturbance in motor control system.,the stability of control system was ensured and robustness to internal disturbances and external disturbances was improved.%针对永磁直线同步电机模型参数不确定且时变并且在运行过程中容易受外部扰动影响的特点,首次将无模型自适应控制理论应用到永磁直线同步电机直接推力控制中.采用无模型自适应方法,实时拟合出永磁直线同步电机运行过程中电磁推力和速度之间的时变差分方程,通过控制率函数推算出给定电磁推力,实现永磁直线同步电机无模型自适应直接推力控制.与传统的PI控制相比,无模型自适应直接推力控制算法既不需要调节PI参数,又明显减少了由于电机控制系统参数变化和负载扰动引起的速度和推力脉动,在保证了系统稳定运行情况下提高了电机控制系统对内部和外部干扰的鲁棒性.

  5. Predictive value of the heart rate reserve in patients with permanent atrial fibrillation treated according to a strict rate-control strategy.

    Science.gov (United States)

    De Schryver, Nicolas; Scavée, Christophe; Marchandise, Sébastien; Pasquet, Agnès; de Meester, Christophe; le Polain de Waroux, Jean-Benoît

    2014-08-01

    Atrial fibrillation (AF) patients treated according to a rate-control strategy seem to have excellent outcomes as long as their ventricular response is kept low. However, the stringency of the rate control to adopt with pharmacologic agents is not clearly defined. In particular, the clinical importance of preserving a heart rate (HR) reserve (HRR) during exercise has not yet been investigated. We prospectively analysed the HR response profiles during exercise of 202 patients with permanent AF for whom a strict rate-control strategy was the preferred treatment option. Patients were asked to perform an exercise test on a cycle ergometer until exhaustion. The HRR was defined as the difference between the HR at peak exercise and the resting HR before exercise, divided by the resting HR. Patients were followed-up for at least 24 months or until death or hospitalization for heart failure. The mean resting HR was 80 ± 16 b.p.m. After a median follow-up period of 3 ± 1 years, 31 patients (15.3%) of our initial population (80% male, age 72 ± 12 years) presented either a hospitalization for heart failure (n = 13, 6.4%) or a death (n = 18, 8.9%). Using a univariate analysis, we found that these events correlated with a lower exercise capacity [hazard ratio, HR 0.98, 95% confidence interval, CI (0.96; 0.99), P heart failure was better in patients with a preserved HRR (HRR >40%, P rate-control strategy is associated with an increased risk of hospitalization for heart failure. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

  6. Switching Control Algorithm for the Permanent Magnet Spherical Stepper Motor%永磁球形步进电动机变结构控制算法

    Institute of Scientific and Technical Information of China (English)

    王群京; 夏鲲

    2008-01-01

    In this paper,a switching control algorithm is presented in view of controlling the permanent magnet spherical stepper motor effectively.Programmable current sources are applied to control the magnitude of the currents in the stator coils instead of controlling the motor with relays.The dynamic model of the rotor expressed with Cardan angle rotation is set up in rotor-fixed coordinates frame.One control algorithm is designed based on input-output stability theory to drive the motor without the angular accelerations feedback in unloaded mode.Then the switching control algorithm applied in the situation that the load affected the rotation inertia of the axes is developed.Finally,a boundary layer is interpolated to eliminate control chattering.Simulation results show good performance of the new control laws.It has smaller tracking errors and the steady-state errors are reduced to less than 0.01 radians.%提出了永磁球形步进电动机的一种变结构控制算法.该算法用可控电流源控制定子电磁线圈通电电流的幅值替代继电器控制方式.首先在转子固连坐标系内基于卡尔丹角旋转建立了转子动力学模型.然后在电动机空载运行的模式下,设计了一种无需角加速度反馈信号的基于输入一输出稳定性理论的控制算法.接着针对电动机负载运行,各轴向转动惯量发生变化的情况设计了变结构控制算法.最后,在变结构控制算法中插入边界层以消除抖振现象.仿真结果表明,新的控制算法具有更小的跟踪误差,稳态误差小于0.01rad.

  7. A comparison of change detection measurements using object-based and pixel-based classification methods on western juniper dominated woodlands in eastern Oregon

    Directory of Open Access Journals (Sweden)

    Ryan G. Howell

    2017-03-01

    Full Text Available Encroachment of pinyon (Pinus spp and juniper (Juniperus spp. woodlands in western North America is considered detrimental due to its effects on ecohydrology, plant community structure, and soil stability. Management plans at the federal, state, and private level often include juniper removal for improving habitat of sensitive species and maintaining sustainable ecosystem processes. Remote sensing has become a useful tool in determining changes in juniper woodland structure because of its uses in comparing archived historic imagery with newly available multispectral images to provide information on changes that are no longer detectable by field measurements. Change in western juniper (J. occidentalis cover was detected following juniper removal treatments between 1995 and 2011 using panchromatic 1-meter NAIP and 4-band 1-meter NAIP imagery, respectively. Image classification was conducted using remotely sensed images taken at the Roaring Springs Ranch in southeastern Oregon. Feature Analyst for ArcGIS (object-based extraction and a supervised classification with ENVI 5.2 (pixel-based extraction were used to delineate juniper canopy cover. Image classification accuracy was calculated using an Accuracy Assessment and Kappa Statistic. Both methods showed approximately a 76% decrease in western juniper cover, although differing in total canopy cover area, with object-based classification being more accurate. Classification results for the 2011 imagery were much more accurate (0.99 Kappa statistic because of its low juniper density and the presence of an infrared band. The development of methods for detecting change in juniper cover can lead to more accurate and efficient data acquisition and subsequently improved land management and monitoring practices. These data can subsequently be used to assess and quantify juniper invasion and succession, potential ecological impacts, and plant community resilience.

  8. Evaluation of antimicrobial and phytochemical screening of Fennel, Juniper and Kalonji essential oils against multi drug resistant clinical isolates

    Institute of Scientific and Technical Information of China (English)

    Sharmishtha Purkayastha; Rittee Narain; Praveen Dahiya

    2012-01-01

    Objective: The inhibitory effects of essential oils including fennel, juniper and kalonji from Foeniculum Vulgare, Juniperus Osteosperma and Nigella Sativa on multi drug resistant clinical isolates were investigated. All the oils have been evaluated for phytochemical constituents, antibacterial activity and TLC bioautography assay. Methods: Preliminary phytochemical analysis was performed. The antibacterial potential of essential oils from fennel, juniper and kalonji fennel, juniper and kalonji was evaluated by agar well diffusion method against multi drug resistant clinical isolates. The antibacterial effect was investigated using the TLC-bioautographic method. Results: Preliminary phytochemical analysis demonstrated the presence of most of the phytochemicals including saponins, cardiac glycosides, steroids, terpenoids, flavonoids and tannins. Antibacterial activity of essential oils was assessed on eight multi-drug resistant (MDR) clinical isolates from both Gram-positive and Gram-negative bacteria and two standard strains. All the oils tested showed significant to moderate antibacterial activity toward all tested strains except Acinetobacter sp and Staphylococcus aureus MRSA. The maximum zone of inhibition was found to be 25依0.12 mm for juniper oil followed by 21依0.085 mm for kalonji oil againstStaphylococcus aureus 2. Thin layer chromatography and bioautography assay demonstrated well-defined growth inhibition zones against Staphylococcus aureus 2 and E. coli for juniper essential oil in correspondence with tannins observed at Rf values of 0.07 and 0.57. Conclusions: Based on the present study, the essential oils from juniper and kalonji possess antibacterial activity against several multi drug resistant pathogenic bacteria and thus can be used as a base for the development of new potent drugs and phytomedicine.

  9. Permanences GAG-EPA

    CERN Multimedia

    GAC-EPA

    2015-01-01

    Le GAC organise chaque mois des permanences avec entretiens individuels. La prochaine permanence se tiendra le : Mardi 5 mai de 13 h 30 à 16 h 00 Salle de réunion de l’Association du personnel Les permanences suivantes auront lieu les mardis 2 juin, 1er septembre, 6 octobre, 3 novembre et 1er décembre 2015. Les permanences du Groupement des Anciens sont ouvertes aux bénéficiaires de la Caisse de pensions (y compris les conjoints survivants) et à tous ceux qui approchent de la retraite. Nous invitons vivement ces derniers à s’associer à notre groupement en se procurant, auprès de l’Association du personnel, les documents nécessaires.

  10. Presence and structure of the wart layer in tracheids of some junipers as visualised in the scanning electron micscope

    Directory of Open Access Journals (Sweden)

    Józef Kocoń

    2014-01-01

    Full Text Available The presence and structure of the wart layer was investigated in the tracheids of the following juniper species: J. communis L., J. communis var. saxatilis Pall., J. sabina L., J. virginiana L., J. chinensis L. and J. squamata Lamb. The wart layer was found to be present in the tracheids of the stem, roots and branches of spring and summer growths, thus, it is an integral element of their structure. It would seem that this layer is a trait of these juniper species and may be one of the taxonomic features of their wood.

  11. Multi-element determination in medicinal Juniper tree (Juniperus phoenicea by instrumental neutron activation analysis

    Directory of Open Access Journals (Sweden)

    Bouzid Nedjimi

    2015-04-01

    Full Text Available Red Juniper (Juniperus phoenicea, a local medicinal tree was collected and analyzed for 18 essential, non-essential and toxic elements using instrumental neutron activation analysis (INAA. The GBW 07605 (GSV-4 standard reference material was analyzed simultaneously with the plant samples, the results shown a good recovery and reproducibility of the method. Ca, K and Fe have been detected in good levels in this plant clarifying their possible contribution to curative properties. The data obtained in the present work will be helpful in the synthesis of new synthetic drugs which can be used for medicinal purpose.

  12. Juniper tar (cade oil) poisoning in new born after a cutaneous application.

    Science.gov (United States)

    Achour, Sanae; Abourazzak, Sana; Mokhtari, Abdelrhani; Soulaymani, Abdelmjid; Soulaymani, Rachida; Hida, Moustapha

    2011-10-28

    Juniper tar (cade oil) is distilled from the branches and wood of Juniperus oxycedrus. It contains etheric oils, triterpene and phenols, used for many purposes in folk medicine. The authors report a case of a previously healthy new born treated with a topical application of Juniperus oxycedrus for atopic dermatosis The poisoning caused convulsions, collapsus, acute pulmonary oedema, renal failure and hepatotoxicity. The newborn survived after supportive and symptomatic treatment, and discharged in a good condition on the eleventh day of hospitalisation in intensive care unit.

  13. 永磁无刷直流电机及其控制%Permanent-Magnet Brushless DC Motor and Its Control

    Institute of Scientific and Technical Information of China (English)

    夏长亮; 方红伟

    2012-01-01

    The permanent-magnet brushless DC motor(BLDC motor) has achieved a brilliant application in aerospace,military,automotive,office automation and household equipment industries,since it has the advantages of high efficiency,long lifetime,low noise and good torque-speed characteristics.The basic structure and operation of the BLDC motor is introduced,and various typical topologies of its driving circuits are also compared.Moreover,the torque ripple reduction,sensorless control,and flux-weakening speed control are investigated.Finally,the applications of BLDC motor are drawn and its development trend is discussed.%无刷直流电机因其高效率、长寿命、低噪声及良好的机械特性等优点,在航空、军事、汽车、办公自动化、家用电器等行业内得到了广泛的应用。本文系统阐述了无刷直流电机的基本结构和工作特点,比较分析了无刷直流电机几种典型的驱动电路拓扑结构。同时,对无刷直流电机的转矩波动抑制、无位置传感器控制、弱磁调速等技术进行了分析。最后,对其应用及未来发展趋势进行了探讨。

  14. 基于DSP的交流永磁同步电动机运动控制系统研究%Research on DSP-based AC permanent magnet synchronous motor motion control system

    Institute of Scientific and Technical Information of China (English)

    李文庆; 王大伟; 丁云飞; 金蒙; 林猛

    2012-01-01

    为了提高交流永磁同步电动机运动控制系统的控制精度,讨论了基于DSP的永磁同步伺服控制系统的软硬件组成及设计方案,采用转子磁场定向矢量控制和TMS320LF2812数字信号处理器,实现了对永磁同步伺服电动机的矢量控制.采用高速、高精度的DSP芯片以及矢量控制的永磁同步电动机伺服控制系统具有良好的动态响应性能和静态性能,并具有结构紧凑、设计合理和控制灵活等优点.%In order to improve the AC permanent magnet synchronous motor control precision of the motion control system based on DSP, this paper discusses the software and hardware composition and design scheme of permanent magnet synchronous servo control system, adopts the rotor field-oriented vector control, u-sing TMS320LF2812 digital signal processor, realizes the permanent magnet synchronous servo motor vector control. Adopting high speed, high precision DSP chipset, the vector control of permanent magnet synchronous motor servo control system has good dynamic response performance and static performance, and with compact structure, reasonable design, control flexible, etc.

  15. Repeat, Low Altitude Measurements of Vegetation Status and Biomass Using Manned Aerial and UAS Imagery in a Piñon-Juniper Woodland

    Science.gov (United States)

    Krofcheck, D. J.; Lippitt, C.; Loerch, A.; Litvak, M. E.

    2015-12-01

    Measuring the above ground biomass of vegetation is a critical component of any ecological monitoring campaign. Traditionally, biomass of vegetation was measured with allometric-based approach. However, it is also time-consuming, labor-intensive, and extremely expensive to conduct over large scales and consequently is cost-prohibitive at the landscape scale. Furthermore, in semi-arid ecosystems characterized by vegetation with inconsistent growth morphologies (e.g., piñon-juniper woodlands), even ground-based conventional allometric approaches are often challenging to execute consistently across individuals and through time, increasing the difficulty of the required measurements and consequently the accuracy of the resulting products. To constrain the uncertainty associated with these campaigns, and to expand the extent of our measurement capability, we made repeat measurements of vegetation biomass in a semi-arid piñon-juniper woodland using structure-from-motion (SfM) techniques. We used high-spatial resolution overlapping aerial images and high-accuracy ground control points collected from both manned aircraft and multi-rotor UAS platforms, to generate digital surface model (DSM) for our experimental region. We extracted high-precision canopy volumes from the DSM and compared these to the vegetation allometric data, s to generate high precision canopy volume models. We used these models to predict the drivers of allometric equations for Pinus edulis and Juniperous monosperma (canopy height, diameter at breast height, and root collar diameter). Using this approach, we successfully accounted for the carbon stocks in standing live and standing dead vegetation across a 9 ha region, which contained 12.6 Mg / ha of standing dead biomass, with good agreement to our field plots. Here we present the initial results from an object oriented workflow which aims to automate the biomass estimation process of tree crown delineation and volume calculation, and partition

  16. 交替极永磁无轴承电机的直接悬浮力控制%Direct Levitation Force Control of a Consequent-Pole Permanent Magnet Bearingless Motor

    Institute of Scientific and Technical Information of China (English)

    仇志坚; 邓智泉; 章跃进

    2011-01-01

    With the reference of direct torque control of conventional permanent magnet synchronous motor,a novel direct levitation force control algorithm based on space vector pulse width modulation method is proposed in this paper.To control radial magnetic levitation forces in permanent magnet-type bearingless motors directly,a profound theoretical analysis on mechanism of direct force control is presented and a real-time levitation force and torque control system is also designed.The experimental results of a consequent-pole permanent magnet bearingless machine show good performance of static and dynamic suspension and confirm the validity and availability of this new arithmetic.%通过借鉴永磁同步电机直接转矩控制(PMSM-DTC)的思想,将直接转矩控制的理论和方法应用到永磁型无轴承电机磁悬浮力的控制上去,提出了一种新颖的基于空间矢量脉宽调制(SVPWM)方法的直接悬浮力控制算法,并在一台交替极无轴承永磁电机上进行了实验验证,结果表明该控制思想的正确性和有效性。

  17. Frijolito Watershed: Integrated investigations of a rapidly eroding pinyon-juniper hillslope

    Energy Technology Data Exchange (ETDEWEB)

    Wilcox, B.P. [Los Alamos National Lab., NM (United States); Pitlick, J. [Univ. of Colorado, Boulder, CO (United States). Dept. of Geography; Allen, C.D. [National Biological Survey, Los Alamos, NM (United States)

    1995-12-31

    The dramatic acceleration of erosion associated with the expansion of pinyon-juniper woodlands over the past 100 years has been widely recognized, but few process-based studies of this phenomenon have been undertaken. In an attempt to identify the underlying causes, and the factors that affect erosion processes, we have initiated an interdisciplinary study of a rapidly eroding pinyon-juniper woodland in northern New Mexico. Since July 1993, we have collected data on runoff, erosion, and weather conditions from a 1-ha catchment study area and have conducted surveys of topography, soils, and vegetation. Our preliminary results indicate that although runoff makes up less than 10% of the annual water budget, runoff events - which are frequent in the summer - are capable of moving large amounts of sediment. We estimate that between July 1993 and October 1994, between 25,000 and 50,000 kg of sediment has eroded and been transported from the catchment. The information gained from such studies is essential to our ability to formulate effective strategies for managing these rapidly eroding woodlands.

  18. Detection of soil erosion within pinyon-juniper woodlands using Thematic Mapper (TM) data

    Science.gov (United States)

    Price, Kevin P.

    1993-01-01

    Multispectral measurements collected by Landsat Thematic Mapper (TM) were correlated with field measurements, direct soil loss estimates, and Universal Soil Loss Equation (USLE) estimates to determine the sensitivity of TM data to varying degrees of soil erosion in pinyon-juniper woodland in central Utah. TM data were also evaluated as a predictor of the USLE Crop Management C factor for pinyon-juniper woodlands. TM spectral data were consistently better predictors of soil erosion factors than any combination of field factors. TM data were more sensitive to vegetation variations than the USLE C factor. USLE estimates showed low annual rates of erosion which varied little among the study sites. Direct measurements of rate of soil loss using the SEDIMENT (Soil Erosion DIrect measureMENT) technique, indicated high and varying rates of soil loss among the sites since tree establishment. Erosion estimates from the USLE and SEDIMENT methods suggest that erosion rates have been severe in the past, but because significant amounts of soil have already been eroded, and the surface is now armored by rock debris, present erosion rates are lower. Indicators of accelerated erosion were still present on all sites, however, suggesting that the USLE underestimated erosion within the study area.

  19. Soil development mediated by traditional practices shape the stand structure of Spanish juniper woodland

    Directory of Open Access Journals (Sweden)

    Javier de la Fuente-Leon

    2014-03-01

    Full Text Available Aim of study: Assessing the effect of soil development on the stand structure of a Spanish juniper forest traditionally shaped by livestock browsing and wood extraction. Area of study: Berlanga de Duero (Soria, Castilla y León, Spain.Material and Methods: A stand inventory served to record stand structure. Tree age, height, DBH, basal area, and overbark volume were determined in each plot. Results were pooled considering two well-differentiated degrees of soil evolution. One-way ANOVAs (and Tukey’s test and regressions between growth parameters were performed to assess significant differences between growth performances on both types of soils. Research highlights: Deeper soils yielded significant higher plant density and stand stock figures than stony shallower profiles despite the intense past livestock activity in the area; and single tree-size was also significantly greater. Non-significant differences were found for merchantable junipers age (≈120-160 years. Wood extraction and livestock browsing should be limited on shallower soils to allow soil and forest evolution; as well as to preserve the genetic pool better adapted to hardest growing conditions.Keywords: livestock browsing; forest development; Juniperus thurifera L.; soil evolution; stand stock.

  20. Modeling and mapping potential distribution of Crimean juniper (Juniperus excelsa Bieb.) using correlative approaches.

    Science.gov (United States)

    Özkan, Kürşad; Şentürk, Özdemir; Mert, Ahmet; Negiz, Mehmet Güvenç

    2015-01-01

    Modeling and mapping potential distribution of living organisms has become an important component of conservation planning and ecosystem management in recent years. Various correlative and mechanistic methods can be applied to build predictive distributions of living organisms in terrestrial and marine ecosystems. Correlative methods used to predict species' potential distribution have been described as either group discrimination techniques or profile techniques. We attempted to determine whether group discrimination techniques could perform as well as profile techniques for predicting species potential distributions, using elevation (ELVN), parent material (ROCK), slope (SLOP), radiation index (RI) and topographic position index (TPI)) as explanatory variables. We compared potential distribution predictions made for Crimean juniper (Juniperus excelsa Bieb.) in the Yukan Gokdere forest district of the Mediterranean region, Turkey, applying four group discrimination techniques (discriminate analysis (DA), logistic regression analysis (LR), generalized addictive model (GAM) and classification tree technique (CT)) and two profile techniques (a maximum entropy approach to species distribution modeling (MAXENT), the genetic algorithm for rule-set prediction (GARP)). Visual assessments of the potential distribution probability of the applied models for Crimean juniper were performed by using geographical information systems (GIS). Receiver-operating characteristic (ROC) curves were used to objectively assess model performance. The results suggested that group discrimination techniques are better than profile techniques and, among the group discrimination techniques, GAM indicated the best performance.

  1. Critical phases in the seed development of common juniper (Juniperus communis).

    Science.gov (United States)

    Gruwez, R; Leroux, O; De Frenne, P; Tack, W; Viane, R; Verheyen, K

    2013-01-01

    Common juniper (Juniperus communis L.) populations in northwest European lowlands are currently declining in size and number. An important cause of this decline is a lack of natural regeneration. Low seed viability seems to be one of the main bottlenecks in this process. Previous research revealed a negative relation between seed viability and both temperature and nitrogen deposition. Additionally, the seeds of common juniper have a variable ripening time, which possibly influences seed viability. However, the underlying mechanisms remain unresolved. In order to elucidate this puzzle, it is important to understand in which phases of seed production the main defects are situated, together with the influence of ripening time. In this study, we compared seed viability of populations with and without successful recruitment. We examined three seed phases: (i) gamete development; (ii) fertilisation and early-embryo development; and (iii) late-embryo development. After the first two phases, we found no difference in the percentage viable seeds between populations with or without recruitment. After late-embryo development, populations without recruitment showed a significantly lower percentage of viable seeds. These results suggest that late-embryo development is a bottleneck in seed development. However, the complex interaction between seed viability and ripening time suggest that the causes should be in the second seed phase, as the accelerated development of male and female gametophytes may disturb the male-female synchrony for successful mating. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

  2. Antileishmanial Activities of Greek Juniper (Juniperus excelsa M.Bieb.) Against Leishmania major Promastigotes.

    Science.gov (United States)

    Moein, Mahmoodreza; Hatam, Gholamreza; Taghavi-Moghadam, Razieh; Zarshenas, Mohammad M

    2017-01-01

    Petroleum ether, chloroform, ethyl acetate, and n-butanol fractions of Greek juniper (Juniperus excelsa M.Bieb. from the family Cupressaceae) were evaluated for antileishmanial activities against Leishmania major promastigotes compared to meglumine antimoniate (Glucantime). In vitro toxicity assay was performed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and microplate ELISA reader. Extracts were prepared in ethanol/dimethyl sulfoxide (80/20) at 10 to 0.62 mg/mL. The standard was prepared in phosphate-buffered saline at 500 to 15.62 mg/mL. Both leaf and fruit extracts and related fractions showed strong inhibitory effects against promastigotes, significantly different from that of the standard. The leaf extract and the respective petroleum ether fraction showed maximum effectiveness compared to other fractions and also fruit extract and fractions (IC90 = 1.89 ± 0.03 and 0.90 ± 0.03 mg/mL, respectively). Regarding the potent activities of nonpolar fractions of Greek juniper leaf extract, these fractions can be suggested for further investigation. © The Author(s) 2016.

  3. Nature's Notebook Provides Phenology Observations for NASA Juniper Phenology and Pollen Transport Project

    Science.gov (United States)

    Luval, J. C.; Crimmins, T. M.; Sprigg, W. A.; Levetin, E.; Huete, A.; Nickovic, S.; Prasad, A.; Vukovic, A.; VandeWater, P. K.; Budge, A. M.; hide

    2014-01-01

    Phenology Network has been established to provide national wide observations of vegetation phenology. However, as the Network is still in the early phases of establishment and growth, the density of observers is not yet adequate to sufficiently document the phenology variability over large regions. Hence a combination of satellite data and ground observations can provide optimal information regarding juniperus spp. pollen phenology. MODIS data was to observe Juniperus supp. pollen phenology. The MODIS surface reflectance product provided information on the Juniper supp. cone formation and cone density. Ground based observational records of pollen release timing and quantities were used as verification. Approximately 10, 818 records of juniper phenology for male cone formation Juniperus ashei., J. monosperma, J. scopulorum, and J. pinchotti were reported by Nature's Notebook observers in 2013 These observations provided valuable information for the analysis of satellite images for developing the pollen concentration masks for input into the PREAM (Pollen REgional Atmospheric Model) pollen transport model. The combination of satellite data and ground observations allowed us to improve our confidence in predicting pollen release and spread, thereby improving asthma and allergy alerts.

  4. Utilizing national agriculture imagery program data to estimate tree cover and biomass of pinyon and juniper woodlands

    Science.gov (United States)

    With the encroachment of pinyon (Pinus ssp.) and juniper (Juniperus ssp.) (P-J) woodlands into sagebrush steppe communities, there is an increasing interest in rapid, accurate, and inexpensive quantification methods to estimate tree canopy cover and aboveground biomass over large landscapes. The o...

  5. Formation of DNA adducts in the skin of psoriasis patients, in human skin in organ culture, and in mouse skin and lung following topical application of coal-tar and juniper tar.

    Science.gov (United States)

    Schoket, B; Horkay, I; Kósa, A; Páldeák, L; Hewer, A; Grover, P L; Phillips, D H

    1990-02-01

    Preparations of coal-tar and juniper tar (cade oil) that are used in the treatment of psoriasis are known to contain numerous potentially carcinogenic polycyclic aromatic hydrocarbons (PAH). Evidence of covalent binding to DNA by components of these mixtures was sought in a) human skin biopsy samples from 12 psoriasis patients receiving therapy with these agents, b) human skin explants maintained in organ culture and treated topically with the tars, and c) the skin and lungs of mice treated with repeated doses of the formulations following the regimen used in the clinic. DNA was isolated from the human and mouse tissues and digested enzymically to mononucleotides. 32P-Post-labeling analysis revealed the presence of aromatic DNA adducts in the biopsy samples at levels of up to 0.4 fmol total adducts/microgram DNA. Treatment of human skin in organ culture produced similar levels of adducts, while treatment with dithranol, a non-mutagenic therapeutic agent, resulted in chromatograms indistinguishable from those from untreated controls. In mouse skin, coal-tar ointment and juniper tar gave similar DNA adduct levels, with a similar time-course of removal: maximum levels (0.5 fmol/microgram DNA) at 24 h after the final treatment declined rapidly to 0.05 fmol/microgram at 7 d, thereafter declining slowly over the succeeding 25 d. However, while coal-tar ointment produced only very low levels of adducts in mouse lung (less than 0.03 fmol/microgram DNA), juniper tar produced adducts at a high level (0.7 fmol/microgram DNA) that were persistent in this tissue. These results provide direct evidence for the formation of potentially carcinogenic DNA damage in human and mouse tissue by components of these therapeutic tar preparations.

  6. CRADA Final Report: Application of Dual-Mode Invertor Control to Commercially Available Radial-Gap Permanent Magnet Motors - Vol. 1

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, J.S. (U. Tennessee-Knoxville); McKeever, J.W.; Downing, M.E.; Stahlhut, R.D (John Deere); Bremmer, R. (John Deere); Shoemaker, J.M. (John Deere); Seksarian, A.K. (john Deere); Poore, B. (John Deere); Lutz, J. (UQM)

    2006-05-01

    John Deere and Company (Deere), their partner, UQM Technologies, Inc. (UQM), and the Oak Ridge National Laboratory's (ORNL's) Power Electronics and Electric Machinery Research Center (PEEMRC) recently completed work on the cooperative research and development agreement (CRADA) Number ORNL 04-0691 outlined in this report. CRADA 04-0691 addresses two topical issues of interest to Deere: (1) Improved characterization of hydrogen storage and heat-transfer management; and (2) Potential benefits from advanced electric motor traction-drive technologies. This report presents the findings of the collaborative examination of potential operational and cost benefits from using ORNL/PEEMRC dual-mode inverter control (DMIC) to drive permanent magnet (PM) motors in applications of interest to Deere. DMIC was initially developed and patented by ORNL to enable PM motors to be driven to speeds far above base speed where the back-electromotive force (emf) equals the source voltage where it is increasingly difficult to inject current into the motor. DMIC is a modification of conventional phase advance (CPA). DMIC's dual-speed modes are below base speed, where traditional pulse-width modulation (PWM) achieves maximum torque per ampere (amp), and above base speed, where six-step operation achieves maximum power per amp. The modification that enables DMIC adds two anti-parallel thyristors in each of the three motor phases, which consequently adds the cost of six thyristors. Two features evaluated in this collaboration with potential to justify the additional thyristor cost were a possible reduction in motor cost and savings during operation because of higher efficiency, both permitted because of lower current. The collaborative analysis showed that the reduction of motor cost and base cost of the inverter was small, while the cost of adding six thyristors was greater than anticipated. Modeling the DMIC control displayed inverter efficiency gains due to reduced current

  7. Permanent magnet synchronous linear motor passive control based on port-controlled Hamiltonian method%基于端口受控哈密顿方法的永磁同步直线电机无源控制

    Institute of Scientific and Technical Information of China (English)

    陈华; 程志平; 支长义; 武杰

    2015-01-01

    In view of the surface-mounted permanent magnet synchronous linear motor ( SPMSLM) for constant load obstruction under the known and unknown circumstances , using port-controlled dissipative Hamiltonian ( PCHD ) method to make the surface-mounted permanent magnet synchronous linear motor models , giving the closed-loop ex-pected Hamiltonian function , designing the desired interconnection and damping matrix of the system′s controller, and analyzing the equilibrium point of the system .However , the load resistance is unknown , and the observer is designed . The simulation results show that the proposed scheme for the load resistance under known and unknown circumstances with good position tracking performance and good disturbance resistance and strong robustness .%针对面装式永磁同步直线电机( SPMSLM)在负载阻力已知恒定和未知的情况下,采用端口受控耗散哈密顿( PCHD)方法,对面装式永磁同步直线电机进行建模,给出了闭环期望哈密顿函数,并配置了期望的互联与阻尼矩阵,设计了系统的控制器,并且在负载阻力未知时,设计了观测器,然后分析了系统平衡点的稳定性。仿真结果表明文中所提出的方案对负载阻力已知恒定和未知的情况具有很好的位置跟踪性能、很好的抗扰性能和很强的鲁棒性。

  8. 某种永磁同步发电机直接转矩控制系统设计%A Permanent Magnet Synchronous Generator Direct Torque Control System Design

    Institute of Scientific and Technical Information of China (English)

    张进超; 王玲; 郝永平; 张令涛

    2015-01-01

    Based on two dimensional trajecto-ry correction principle, a revised steering gear method of direct torque control of permanent mag-net synchronous generator is proposed.For a per-manent magnet synchronous motor model of d q coordinates,a permanent magnet synchronous mo-tor direct torque control scheme is studied.The re-sults showed that corrected steering gear direct torque control system of the generator output torque can achieve high speed rotating projectile correction.%依据二维弹道修正原理,提出修正舵机中永磁同步发电机直接转矩控制方法,针对 d q 坐标系下的永磁同步电机模型,研究了永磁同步电机直接转矩控制方案。结果表明,修正舵机中发电机直接转矩控制系统输出转矩能够达到高速旋转弹的修正效果。

  9. Application and Development of Backstepping Control in Permanent Magnet Synchronous Motor%反推控制在永磁同步电机中的应用及发展综述

    Institute of Scientific and Technical Information of China (English)

    周密; 熊微洁

    2016-01-01

    Permanent magnet synchronous motor (PMSM) has been widely used in various industrial fields due to its high power density, high torque ratio and high efficiency. In this paper, the permanent magnet synchronous motor is used as the research ob-ject, and the control strategy is summarized. The control strategy is analyzed. The control status and development of the perma-nent magnet synchronous motor are summarized.%永磁同步电机(PMSM)由于其高功率密度、高转矩惯性比和高效率等优点已经广泛应用于各种工业场所。本文以永磁同步电机为研究对象,对反推控制策略进行综述,分析了反推控制策略的原理和作用,阐述了其应用在永磁同步电机中的控制现状和发展动态,最后对反推控制技术作出总结,并展望其发展前景。

  10. Perennial vegetation data from permanent plots on the Nevada Test Site, Nye County, Nevada

    Science.gov (United States)

    Webb, Robert H.; Murov, Marilyn B.; Esque, Todd C.; Boyer, Diane E.; DeFalco, Lesley A.; Haines, Dustin F.; Oldershaw, Dominic; Scoles, Sara J.; Thomas, Kathryn A.; Blainey, Joan B.; Medica, Philip A.

    2003-01-01

    Perennial vegetation data from 68 permanent plots on the Nevada Test Site, Nye County, Nevada, are given for the period of 1963 through 2002. Dr. Janice C. Beatley established the plots in 1962 and then remeasured them periodically from 1963 through 1975. We remeasured 67 of these plots between 2000 and 2003; the remaining plot was destroyed at some time between 1975 and 1993. The plots ranged from 935 to 2,274 m in elevation and are representative of common plant associations of the Mojave Desert, the transition to Great Basin Desert, and pinyon-juniper woodlands. The purpose of this report is to describe the complete set of ecological data that Beatley collected from the Nevada Test Site from 1963 through 1975 and to present the data for perennial vegetation collected from 2000 through 2003.

  11. Landscape dynamics in aspen and western juniper woodlands on the Owyhee Plateau, Idaho

    Science.gov (United States)

    Strand, Eva K.

    A century of altered fire regimes has affected the landscape vegetation dynamics in the Intermountain West. Suppression of wildfires has resulted in increases in woody plant cover in these semi-arid ecosystems, which has resulted in land cover changes affecting biogeochemical cycling, landscape composition, and habitat diversity. Recent developments in remote sensing technology, computational power, and a rapid development of analysis techniques have enabled us to quantify such changes at the landscape scale. Wavelet analysis is a powerful image analysis technique that is here applied in a novel fashion to fine scale remote sensing imagery to automatically detect the location and crown diameter of individual western juniper plants (Juniperus occidentalis ssp. occidentalis) expanding into sagebrush (Artemisia spp.) steppe at multiple scales. The produced marked point pattern of historical and current spatial juniper distribution was compared regionally and changes in foliar cover and above ground biomass were estimated across a 330,000 ha area on the Owyhee Plateau, Idaho. The above ground carbon accumulation rate from 1946 to 1998 was estimate to be 3.3 gCm-2yr-1 and 10.0 gCm-2yr -1 employing the wavelet and conventional texture analysis methods, respectively, with an additional 25% rise in belowground carbon accumulation in root stock. This research further demonstrates that estimates of carbon accumulation rates as a result of woody encroachment are highly dependent on the spatial and temporal scales of analysis. Conifer species, western juniper and Douglas-fir (Pseudotsuga menziesii) on the Owyhee Plateau, have further expanded into the biologically important quaking aspen ( Populus tremuloides) habitats resulting in conifer dominance and occasional loss of aspen clones. Classification of remotely sensed imagery combined with spatially explicit modeling of aspen successional stages indicate that, in the absence of management activity, loss of seral aspen stands

  12. PROCEDURE FOR ESTIMATING PERMANENT TOTAL ENCLOSURE COSTS

    Science.gov (United States)

    The paper discusses a procedure for estimating permanent total enclosure (PTE) costs. (NOTE: Industries that use add-on control devices must adequately capture emissions before delivering them to the control device. One way to capture emissions is to use PTEs, enclosures that mee...

  13. Workplace bullying a risk for permanent employees.

    Science.gov (United States)

    Keuskamp, Dominic; Ziersch, Anna M; Baum, Fran E; Lamontagne, Anthony D

    2012-04-01

    We tested the hypothesis that the risk of experiencing workplace bullying was greater for those employed on casual contracts compared to permanent or ongoing employees. A cross-sectional population-based telephone survey was conducted in South Australia in 2009. Employment arrangements were classified by self-report into four categories: permanent, casual, fixed-term and self-employed. Self-report of workplace bullying was modelled using multiple logistic regression in relation to employment arrangement, controlling for sex, age, working hours, years in job, occupational skill level, marital status and a proxy for socioeconomic status. Workplace bullying was reported by 174 respondents (15.2%). Risk of workplace bullying was higher for being in a professional occupation, having a university education and being separated, divorced or widowed, but did not vary significantly by sex, age or job tenure. In adjusted multivariate logistic regression models, casual workers were significantly less likely than workers on permanent or fixed-term contracts to report bullying. Those separated, divorced or widowed had higher odds of reporting bullying than married, de facto or never-married workers. Contrary to expectation, workplace bullying was more often reported by permanent than casual employees. It may represent an exposure pathway not previously linked with the more idealised permanent employment arrangement. A finer understanding of psycho-social hazards across all employment arrangements is needed, with equal attention to the hazards associated with permanent as well as casual employment. © 2012 The Authors. ANZJPH © 2012 Public Health Association of Australia.

  14. Fictitious Reference Iterative Tuning-Based Two-Degrees-of-Freedom Method for Permanent Magnet Synchronous Motor Speed Control Using FPGA for a High-Frequency SiC MOSFET InverterMOSFET Inverter

    Directory of Open Access Journals (Sweden)

    Charles Ronald Harahap

    2016-11-01

    Full Text Available This paper proposes proportional-integral/proportional gain controller parameter tuning in a two-degrees-of-freedom (2DOF control system using the fictitious reference iterative tuning (FRIT method for permanent magnet synchronous motor (PMSM speed control using a field-programmable gate array (FPGA for a high-frequency SiC MOSFET (metal oxide semiconductor field-effect transistor inverter. The PI-P (proportional-integral/proportional controller parameters can be tuned using the FRIT method from one-shot experimental data without using a mathematical model of the plant. Particle swarm optimization is used for FRIT optimization. An inverter that uses a SiC MOSFET is presented to achieve high-frequency operation at up to100 kHz using a switching pulse-width modulation (PWM technique. As a result, a high-responsivity and high-stability PMSM (permanent magnet synchronous motor control system is achieved, where the speed response follows the ideal response characteristic for both the step response and the disturbance response. High-responsivity and optimal disturbance rejection can be achieved using the 2DOF control system. FPGA-based digital hardware control is used to maximize the switching frequency of the SiC MOSFET inverter. Finally, an experimental system is set up, and experimental results are presented to prove the viability of the proposed method.

  15. Design of a Transverse-flux Permanent-magnet Linear Generator and Controller for Use with a Free-piston Stirling Engine

    Institute of Scientific and Technical Information of China (English)

    ZHENG Jigui; HUANG Yuping; WU Hongxing; ZHENG Ping

    2016-01-01

    Transverse-flux with high efficiency has been applied in Stirling engine and permanent magnet synchronous linear generator system, however it is restricted for large application because of low and complex process. A novel type of cylindrical, non-overlapping, transverse-flux, and permanent-magnet linear motor(TFPLM) is investigated, furthermore, a high power factor and less process complexity structure research is developed. The impact of magnetic leakage factor on power factor is discussed, by using the Finite Element Analysis(FEA) model of stirling engine and TFPLM, an optimization method for electro-magnetic design of TFPLM is proposed based on magnetic leakage factor. The relation between power factor and structure parameter is investigated, and a structure parameter optimization method is proposed taking power factor maximum as a goal. At last, the test bench is founded, starting experimental and generating experimental are performed, and a good agreement of simulation and experimental is achieved. The power factor is improved and the process complexity is decreased. This research provides the instruction to design high-power factor permanent-magnet linear generator.

  16. Design of a transverse-flux permanent-magnet linear generator and controller for use with a free-piston stirling engine

    Science.gov (United States)

    Zheng, Jigui; Huang, Yuping; Wu, Hongxing; Zheng, Ping

    2016-07-01

    Transverse-flux with high efficiency has been applied in Stirling engine and permanent magnet synchronous linear generator system, however it is restricted for large application because of low and complex process. A novel type of cylindrical, non-overlapping, transverse-flux, and permanent-magnet linear motor(TFPLM) is investigated, furthermore, a high power factor and less process complexity structure research is developed. The impact of magnetic leakage factor on power factor is discussed, by using the Finite Element Analysis(FEA) model of stirling engine and TFPLM, an optimization method for electro-magnetic design of TFPLM is proposed based on magnetic leakage factor. The relation between power factor and structure parameter is investigated, and a structure parameter optimization method is proposed taking power factor maximum as a goal. At last, the test bench is founded, starting experimental and generating experimental are performed, and a good agreement of simulation and experimental is achieved. The power factor is improved and the process complexity is decreased. This research provides the instruction to design high-power factor permanent-magnet linear generator.

  17. Pinon and Juniper Field Guide: Asking the Right Questions to Select Appropriate Management Actions

    Science.gov (United States)

    Tausch, R.J.; Miller, R.F.; Roundy, B.A.; Chambers, J.C.

    2009-01-01

    Pinon-juniper woodlands are an important vegetation type in the Great Basin. Old-growth and open shrub savanna woodlands have been present over much of the last several hundred years. Strong evidence indicates these woodlands have experienced significant tree infilling and major expansion in their distribution since the late 1800s by encroaching into surrounding landscapes once dominated by shrubs and herbaceous vegetation. Both infilling and expansion affects soil resources, plant community structure and composition, water and nutrient cycles, forage production, wildlife habitat, biodiversity, and fire patterns across the landscape. Another impact is the shift from historic fire regimes to larger and more intense wildfires that are increasingly determining the future of this landscape. This publication helps biologists and land managers consider how to look at expansion of woodlands and determine what questions to ask to develop a management strategy, including prescribed fire or other practices.

  18. Permanent magnet design methodology

    Science.gov (United States)

    Leupold, Herbert A.

    1991-01-01

    Design techniques developed for the exploitation of high energy magnetically rigid materials such as Sm-Co and Nd-Fe-B have resulted in a revolution in kind rather than in degree in the design of a variety of electron guidance structures for ballistic and aerospace applications. Salient examples are listed. Several prototype models were developed. These structures are discussed in some detail: permanent magnet solenoids, transverse field sources, periodic structures, and very high field structures.

  19. Micromachined permanent magnets and their MEMS applications

    Science.gov (United States)

    Cho, Hyoung Jin

    2002-01-01

    In this research, new micromachined permanent magnets have been proposed, developed and characterized for MEMS applications. In realizing micromachined permanent magnets, a new electroplating technique using external magnetic field and a bumper filling technique using a photolithographically defined mold with resin bonded magnetic particles have been developed. The newly developed micromachining techniques allow thick film-type permanent magnet components to be integrated to magnetic MEMS devices with dimensional control and alignment. Permanent magnet arrays with the dimensions ranging from 30 mum to 200 mum have been developed with an energy density up to 2.7 kJ/m3 in precisely defined forms in the micro scale. For the applications of the permanent magnets developed in this work, three novel magnetic MEMS devices such as a bi-directional magnetic actuator, a magnetically driven optical scanner, and a magnetic cell separator have been successfully realized. After design and modeling, each device has been fabricated and fully characterized. The bi-directional actuator with the electroplated permanent magnet array has achieved bi-directional motion clearly and shown good agreement with the analytical and simulated models. The optical scanner has shown linear bi-directional response under static actuation and stable bi-directional scanning performance under dynamic actuation. As a potential BioMEMS application of the developed permanent magnet, the prototype magnetic cell separator using the electroplated permanent magnet strip array has been proposed and demonstrated for magnetic bead patterning. In conclusion, new thick film-type, electroplated CoNiMnP and epoxy resin bonded Sr-ferrite permanent magnets have been developed and characterized, and then, three new magnetic MEMS devices using the permanent magnets such as a bi-directional magnetic actuator, an optical scanner and a magnetic cell separator have been realized in this research. The new micromachined

  20. Lawful Permanent Residents - Annual Report

    Data.gov (United States)

    Department of Homeland Security — A lawful permanent resident (LPR) or 'green card' recipient is defined by immigration law as a person who has been granted lawful permanent residence in the United...

  1. Efeitos de períodos de permanência de clomazone + hexazinona no solo e na palha de cana-de-açúcar antes da ocorrência de chuvas na eficácia de controle de plantas daninhas Effects of different periods of clomazone + hexazinona permanence in soil and sugarcane mulch before the occurrence of rain on weed control efficacy

    Directory of Open Access Journals (Sweden)

    C.A. Carbonari

    2010-01-01

    Full Text Available O presente trabalho teve por objetivo avaliar a eficácia da mistura formulada de clomazone e hexazinona aplicada sobre o solo e em associação com a palha de cana-de-açúcar, após diferentes períodos de permanência sem a ocorrência de chuvas. O experimento foi conduzido em vasos em casa de vegetação, no município de Botucatu-SP. Os vasos foram preenchidos com solo, e as sementes de plantas daninhas (Brachiaria decumbens, Ipomoea grandifolia, Ipomoea hederifolia e Euphorbia heterophylla foram semeadas superficialmente e, em seguida, cobertas ou não com palha de cana-de-açúcar, dependendo do tratamento utilizado. O delineamento experimental utilizado foi o inteiramente casualizado, com quatro repetições. Os tratamentos foram dispostos em um esquema fatorial 3 x 6, sendo os fatores seis períodos sem ocorrência de chuvas (0, 3, 7, 15, 30 e 60 dias e três posicionamentos do produto (sobre o solo sem palha, sobre e sob a palha de cana. Foram realizadas avaliações de controle aos 10, 21, 35 e 42 dias após a ocorrência da chuva. A mistura de clomazone + hexazinona promoveu excelentes resultados de controle para todas as espécies estudadas quando aplicada sobre, sob ou na ausência de palha de cana-de-açúcar. No entanto, observou-se tendência de redução nos níveis de controle para períodos superiores a 60 dias sem ocorrência de chuva.The objective of this work was to evaluate the efficacy of the formulated mixture clomazone and hexazinone applied in soil or combined with sugarcane mulch, after different periods of permanence without the occurrence of rain. The experiment was carried out in vases under greenhouse conditions in Botucatu, São Paulo, Brazil. The weeds Brachiaria decumbens, Ipomoea grandifolia, Ipomoea hederifolia and Euphorbia heterophylla were sown and covered or not with sugarcane mulch. The experiment was arranged in a complete randomized design with four repetitions. The treatments were displaced in a 3x6

  2. Control system of magnetic levitation permanent magnet linear motor based on field-circuit coupling%基于场路耦合的磁悬浮永磁直线电动机控制系统

    Institute of Scientific and Technical Information of China (English)

    蓝益鹏; 张振兴; 杨波; 赵辉

    2012-01-01

    为了解决数控机床进给系统的摩擦问题,采用一种磁悬浮永磁直线电动机来实现无摩擦进给.建立磁悬浮永磁直线电动机的电压、磁链、推力和运动的数学模型及控制系统的场路耦合仿真模型,运用Ansoft软件中的Maxwell和Simplorer对磁悬浮永磁直线电动机控制系统进行场路耦合的联合仿真,并研究磁悬浮永磁直线电动机加速、刹车与反向运行过程.仿真结果表明,该磁悬浮永磁直线电动机控制系统具有良好的跟踪和抗扰性能,为深入研究整个系统的相互耦合以及搭建实验平台提供了依据.%To solve the friction problem existing in the feed system of computer numerical control (CNC) machine tool, a magnetic levitation permanent magnet linear motor was adopted to realize the friction-free feed. The mathmatical models for the voltage, flux linkage, thrust force and movement of magnetic levitation permanent magnet linear motor as well as the simulation model for the field-circuit coupling of control system were established. Maxwell and Simplorer in Ansoft software were used to carry out the co-simulation of field-circuit coupling for the control system of magnetic levitation permanent magnet linear motor. In addition, the acceleration, braking and reverse operation processes of magnetic levitation permanent magnet linear motor were studied. The simulation results show that the control system of magnetic levitation permanent magnet linear motor exhibits good tracking performance and anti-disturbance capability, which provides the basis for the research on the intercoupling of whole system and the guidance for the establishment of experiment platform.

  3. 高速永磁无刷电机设计与控制系统研究%High-speed permanent magnet motor design and control system of brushless

    Institute of Scientific and Technical Information of China (English)

    郑睿鹏

    2015-01-01

    永磁无刷电机具有结构简单、无励磁损耗、效率高等特点,适合高速场合。目前,高速永磁无刷电机已经在一些电动汽车中得到实际应用,并且在分布式发电供电系统中显示了其价值和重要性。通过对高速永磁无刷电机设计的关键性问题的探讨、对高速永磁无刷电机控制系统的研究得出,高速电机的转速非常高,而且其功率的密度非常大,其几何尺寸小于其输出功率相同的低速电机,这些特征使得它在工业领域受到了广泛的关注和应用。%Permanent magnet brushless motor has a simple structure , no excitation loss, high efficiency, suitable for high speed applications. Currently, high-speed permanent magnet brushless motor has been applied in a number of electric vehicles, and has demonstrated its value and importance in distributed power generation and distribution systems. By discussing the key issues of high-speed permanent magnet brushless motor design, the study of high-speed permanent magnet brushless motor control system derived, high-speed motor speed is very high, and its power density is very large, and its geometry is less than its the same output power low-speed motor, these features make it in the industrial sector has been widespread concern and applications.

  4. Comparative evaluation of platelet-rich fibrin, mineral trioxide aggregate, and calcium hydroxide as pulpotomy agents in permanent molars with irreversible pulpitis: A randomized controlled trial

    Science.gov (United States)

    Kumar, Varun; Juneja, Ruchi; Duhan, Jigyasa; Sangwan, Pankaj; Tewari, Sanjay

    2016-01-01

    Background: Pulpotomy has been proposed as an alternative for the management of irreversible pulpitis in permanent molars with closed apices. Aim: To compare the performances of calcium hydroxide (CH), mineral trioxide aggregate (MTA), and platelet-rich fibrin (PRF) as pulpotomy agents in mature permanent molars with irreversible pulpitis. Materials and Methods: Fifty-four permanent mandibular molars with carious exposure and symptoms of irreversible pulpitis were randomly allocated to three groups, and full pulpotomy was performed using CH, MTA, or PRF as pulpotomy agents. Pain intensity was recorded using numeric rating scale score at baseline, 24 h, 7 days, 6 months, and 1 year. Clinical and radiographic assessments were done at 6 months and 1 year. Statistical Analysis: Kruskal–Wallis test and Friedman test were used for intergroup and intragroup comparison of pain scores, respectively. The radiographic outcomes between the three study arms were compared using Chi-square test. Results: Clinical success rate was 94.4% at 7 days, which dropped to 85.4% at 12 months. All three agents were equally effective in providing pain relief at all the intervals tested, with no significant difference between them (P > 0.05 at all intervals). However, at 6 months and 12 months, 26.2% and 52.4% teeth depicted slight widening of periodontal ligament space. No significant difference was observed between the radiographic success rates observed with the three groups (P = 0.135 at 6 months, 0.717 at 12 months). Conclusion: Pulpotomy exhibited a high clinical success rate in mature molars with irreversible pulpitis and selection of biomaterial did not affect its outcome. PMID:27994420

  5. Comparative evaluation of platelet-rich fibrin, mineral trioxide aggregate, and calcium hydroxide as pulpotomy agents in permanent molars with irreversible pulpitis: A randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Varun Kumar

    2016-01-01

    Full Text Available Background: Pulpotomy has been proposed as an alternative for the management of irreversible pulpitis in permanent molars with closed apices. Aim: To compare the performances of calcium hydroxide (CH, mineral trioxide aggregate (MTA, and platelet-rich fibrin (PRF as pulpotomy agents in mature permanent molars with irreversible pulpitis. Materials and Methods: Fifty-four permanent mandibular molars with carious exposure and symptoms of irreversible pulpitis were randomly allocated to three groups, and full pulpotomy was performed using CH,MTA, or PRF as pulpotomy agents. Pain intensity was recorded using numeric rating scale score at baseline, 24 h, 7 days, 6 months, and 1 year. Clinical and radiographic assessments were done at 6 months and 1 year. Statistical Analysis: Kruskal–Wallis test and Friedman test were used for intergroup and intragroup comparison of pain scores, respectively. The radiographic outcomes between the three study arms were compared using Chi-square test. Results: Clinical success rate was 94.4% at 7 days, which dropped to 85.4% at 12 months. All three agents were equally effective in providing pain relief at all the intervals tested, with no significant difference between them (P > 0.05 at all intervals. However, at 6 months and 12 months, 26.2% and 52.4% teeth depicted slight widening of periodontal ligament space. No significant difference was observed between the radiographic success rates observed with the three groups (P = 0.135 at 6 months, 0.717 at 12 months. Conclusion: Pulpotomy exhibited a high clinical success rate in mature molars with irreversible pulpitis and selection of biomaterial did not affect its outcome.

  6. Casting Process Control of Permanent Mold with Sand Lining for Traction Sheave%曳引轮铁模覆砂铸造过程控制

    Institute of Scientific and Technical Information of China (English)

    王树成; 俞水铭; 章舟

    2012-01-01

    介绍了曳引轮铁模覆砂的生产工艺,在试生产过程中通过采取针对性措施,消除了铸件夹砂、夹渣、变形等缺陷,产品合格率大幅度提高。%The casting process of permanent mold with sand lining for traction sheave was presented. The casting defects, such as scab, slag inclusion and warping were eliminated by special measures in pilot production, and the products percent of pass were increased substantially.

  7. Permanence can be Defended.

    Science.gov (United States)

    McGee, Andrew; Gardiner, Dale

    2017-03-01

    In donation after the circulatory-respiratory determination of death (DCDD), the dead donor rule requires that the donor be dead before organ procurement can proceed. Under the relevant limb of the Uniform Determination of Death Act 1981 (USA), a person is dead when the cessation of circulatory-respiratory function is 'irreversible'. Critics of current practice in DCDD have argued that the donor is not dead at the time organs are procured, and so the procurement of organs from these donors violates the dead donor rule. We offer a new argument here in defence of current DCDD practice, and, in particular, of the interpretation of the requirement of 'irreversibility' as permanence.

  8. Pulsars: Cosmic Permanent 'Neutromagnets'?

    CERN Document Server

    Hansson, Johan

    2011-01-01

    We argue that pulsars may be spin-polarized neutron stars, i.e. cosmic permanent magnets. This would simply explain several observational facts about pulsars, including the 'beacon effect' itself i.e. the static/stable misalignment of rotational and magnetic axes, the extreme temporal stability of the pulses and the existence of an upper limit for the magnetic field strength - coinciding with the one observed in "magnetars". Although our model admittedly is speculative, this latter fact seems to us unlikely to be pure coincidence.

  9. Direct Torque Control of Permanent Magnet AC Servo Based on Active Disturbance Rejection Controller%永磁交流伺服自抗扰直接转矩控制

    Institute of Scientific and Technical Information of China (English)

    黄祯祥; 吴峻; 邓怀雄

    2012-01-01

    Based on active-disturbance rejection controller( ADRC ) theory, a direct torque control (DTC) system of permanent magnet AC servo was established. In the system uncertain external load disturbance( external disturbances) and system parameters variations (internal disturbances) were regarded as one integrated disturbance,and ADRC was used to observe and compensate this integrated disturbance. The simulation results show this system has very strong robustness not only to uncertain external load disturbance,but also to internal parameter variations such as coefficient of torque. Compared with PI controller,the system has higher dynamic performance,powerful capability of anti-interference and high control precision,etc.%设计了一种基于自抗扰控制器的永磁同步电动机直接转矩控制系统.该系统将不确定性负载扰动(外扰)和系统参数变化(内扰)视为一个综合扰动项,然后利用自抗扰控制器(ADRC)对综合扰动项进行观测和补偿.仿真结果证明,该系统不仅有效地抑制了不确定负载扰动的影响,同时对系统内部参数如电机转动惯量等摄动也具有较强的鲁棒性.该系统相比PI控制具有动态控制性能优越、抗扰能力强、控制精度高等特点.

  10. Meteorological, snow, streamflow, topographic, and vegetation height data from four western juniper-dominated experimental catchments in southwestern Idaho, USA

    Science.gov (United States)

    Kormos, Patrick R.; Marks, Danny G.; Pierson, Frederick B.; Williams, C. Jason; Hardegree, Stuart P.; Boehm, Alex R.; Havens, Scott C.; Hedrick, Andrew; Cram, Zane K.; Svejcar, Tony J.

    2017-02-01

    Meteorological, snow, streamflow, topographic, and vegetation height data are presented from the South Mountain experimental catchments. This study site was established in 2007 as a collaborative, long-term research laboratory to address the impacts of western juniper encroachment and woodland treatments in the interior Great Basin region of the western USA. The data provide detailed information on the weather and hydrologic response from four highly instrumented catchments in the late stages of woodland encroachment in a sagebrush steppe landscape. Hourly data from six meteorologic stations and four weirs have been carefully processed, quality-checked, and are serially complete. These data are ideal for hydrologic, ecosystem, and biogeochemical modeling. Data presented are publicly available from the USDA National Agricultural Library administered by the Agricultural Research Service (https://data.nal.usda.gov/dataset/data-weather-snow-and-streamflow-data-four-western-juniper-dominated-experimental-catchments" target="_blank">https://data.nal.usda.gov/dataset/data-weather-snow-and-streamflow-data-four-western-juniper-dominated-experimental-catchments, doi:10.15482/USDA.ADC/1254010).

  11. DETERMINATION OF SEED GERMINATION, OTHER SEED AND SEEDLING CHARACTERISTICS OF SYRIAN JUNIPER (Arceuthosdrupacea (Labill. Ant. et Kotschy. AND SOME RECOMMENDATIONS

    Directory of Open Access Journals (Sweden)

    H. Cemal Gültekin

    2004-04-01

    Full Text Available Syrian Juniper (Arceuthos drupacea (Labill. Antoine et Kotschy, synonym: Juniperus drupacea Labill. seeds have germination barrier due to its fleshy cone, hard seedcoat, and embryo. Germination under natural conditions can be delayed by this barrier for 4-5 years, while cone flesh alone can postpone it for 1 to 2 years. Seeds freed of this flesh (by animals usually germinate in the 3rd or 4th year. Germination can be seen in the same- or the following year if seeds are mechanically scarred by rodents. During the germination, hardened cone scales which cover the seeds fall out and the embryo becomes free to germinate. Combination used for mass production of Syrian Juniper seedling at the Egirdir Forest Nursery is as follows: Seeding in summer “after stratification at room temperature for a month x breaking of seed coats without harming the embryo” results in 53 % germination. Same seed characteristics of Syrian Juniper; time of seed ripening: October, time needed for seed fipening: 18 month,, mean weight of 1000 seeds: 2674 g, one year old seedling diameter: 3.8 mm, one year old seedling length: 16 cm.

  12. 永磁同步电动机的直接滑模电流控制研究%Study on Permanent Magnet Synchronous Machine Drive System Based on Direct Sliding Mode Current Control

    Institute of Scientific and Technical Information of China (English)

    肖甘

    2013-01-01

    本文以永磁同步电动机为基础,研究了直接滑模电流控制策略,该策略对参数变化以及外界干扰的鲁棒性较强,从而广泛应用于电气传动控制领域.设计了新颖的直接滑模电流控制器代替传统的PI电流控制器,并且采用了开关表查询方式加快了动态响应速度.最后基于TMS320DSP28335控制器对永磁同步电动机直接滑模电流控制控制系统进行实验验证,结果表明所设计的控制器动态响应较快,抗干扰能力较强.%This paper researched on direct sliding mode current control of a permanent magnet synchronous machine.Due to the robustness to parameters variations and external disturbances,sliding mode controllers were widely used for the control of electrical drives.A novel direct sliding mode current controller was designed to substitute the traditional PI current controller,and switch table was used to speed up the dynamic response.As a result,the experiment of permanent magnet synchronous machine direct sliding mode current control system based on TMS320DSP28335 controller was finished.The experimental results illustrate this designed controller has faster dynamic response and stronger anti-interference ability.

  13. Simulation research on vector control system of permanent magnet synchronous motor for ship%船用永磁同步电动机矢量控制系统仿真

    Institute of Scientific and Technical Information of China (English)

    曾礼光

    2015-01-01

    With the rapid development of high-power AC motor control technology, the electric propulsion technology replaces traditional marine power plant gradually. This paper study on the simulation vector control system of permanent magnet synchronous motor for ship. By building the mathematical model of permanent magnet synchronous motor of ship in a two-dimensional rotating coordinate system, and calculating parameters of the motor. Then a closed-loop simulation model of marine permanent magnet synchronous motor is built. Finally, simulation of the model was carried out in Matlab. The simulation results show that the model is able to fully reflect the actual system, which provides the right ideas to research and development of material object.%随着大功率交流电机控制技术的快速发展,电力推进技术逐渐取代了传统的船舶动力装置。本文对船用永磁同步电动机矢量控制系统进行仿真研究,通过在二维旋转坐标系中建立船用永磁同步电动机的数学模型,计算出电机在正常工作时的各项参数,搭建船用永磁同步电动机的闭环仿真模型。最后用Matlab对该模型进行模拟仿真。仿真结果表明,该模型能够充分反映实际系统,能够给实物开发提供正确的思路。

  14. Self-Learning Fuzzy PI Control of Permanent Magnet Brushless DC Motor%永磁无刷直流电动机的自学习模糊PI控制

    Institute of Scientific and Technical Information of China (English)

    雷金莉; 窦满峰

    2013-01-01

    The system parameters of permanent magnet brushless DC motor for aerospace are nonlinear,uncertainty,so a general PI controller is hard to achieve the satisfactory effect. A self-learning fuzzy PI controller was designed. Based on the deviation of the actual speed and the reference speed, control variables were regulated, and its control rules was modified. The PI control parameters were adjusted online. The simulation results show that the self-learning fuzzy PI controller has a strong disturbance restraining capability,fast dynamic response,no over-shoot,no steady-state error and good robustness in the motor load and electrical parameters changes in large scale. The nonlinear, uncertainty control problems of permanent magnet brushless DC motor is solved.%针对航空航天用永磁无刷直流电动机具有非线性、不确定性等特点,常规PI控制器难以取得理想的控制效果,提出了自学习模糊PI控制算法.根据实际转速与参考转速的偏差进行控制量校正,修改控制规则,从而在线调整PI控制参数.仿真验证实验表明:自学习模糊控制器对电机负载及内部参数大范围扰动具有较强的抑制能力,系统动态响应快、无超调、稳态无误差、鲁棒性强.解决了永磁无刷直流电动机非线性、不确定性的控制问题.

  15. 无位置传感器双绕组永磁BLDCM起动控制系统%Startup control system of sensorless permanent magnet BLDCM with dual windings

    Institute of Scientific and Technical Information of China (English)

    孟光伟; 李槐树

    2011-01-01

    提出了具有SVPWM控制和电流调节控制的无位置传感器双绕组无刷直流电机(BLDCM)的起动控制,其中电流调节控制采用两点式比较器控制.该起动控制方法不但能有效控制起动电流大小,而且能改善BLDCM开环起动性能.在Matlab/Simulink环境下.建立双绕组永磁BLDCM起动控制系统的仿真模型.设计了基于DSP2407A的双绕组BLDCM控制电路.并通过软件编程的方式实现了SVPWM的开环起动控制.仿真和实验结果一致.且结果表明了理论分析的正确性.%A startup control strategy with SVPWM and current regulation is proposed for the sensorless permanent magnet BLDCM(BrushLess DC Motor) with dual windings. Two-point comparator is used in its current regulation control. It controls the startup current efficiently and improves the open-loop startup performance of BLDCM. The simulation model of startup control system for permanent magnet BLDCM with dual windings is built with Matlab/Simulink software,the control circuit of BLDCM is designed based on DSP2407A chip,and the open-loop control is programmed for SVPWM. The simulative results are consistent with the experimental results,which show the correctness of the proposed control strategy.

  16. Precise control of a four degree-of-freedom permanent magnet biased active magnetic bearing system in a magnetically suspended direct-driven spindle using neural network inverse scheme

    Science.gov (United States)

    Sun, Xiaodong; Su, Bokai; Chen, Long; Yang, Zebin; Xu, Xing; Shi, Zhou

    2017-05-01

    The capacity of improving the control accuracy and dynamic performance of a four degree-of-freedom (DOF) permanent magnet biased active magnetic bearing (PMBAMB) system is critical to developing and maintaining a high precision application in a magnetically suspended direct-driven spindle system. The 4-DOF PMBAMB system, however, is a multivariable, strong coupled and nonlinear system with unavoidable and unmeasured external disturbances, in addition to having parameter variations. The satisfactory control performance cannot be obtained by using traditional strategies. Therefore, it is important to present a novel control scheme to construct a robust controller with good closed-loop capability. This paper proposes a new decoupling control scheme for a 4-DOF PMBAMB in a direct-driven spindle system based on the neural network inverse (NNI) and 2- degree-of-freedom (DOF) internal model control method. By combining the inversion of the 4-DOF PMBAMB system with its original system, a new pseudolinear system can be developed. In addition, by introducing the 2-DOF internal model controller into the pseudolinear system to design extra closed-loop controllers, we can effectively eliminate the influence of the unmodeled dynamics to the decoupling control accuracy, as well as adjust the properties of tracking and disturbance rejection independently. The experimental results demonstrate the effectiveness of the proposed control scheme.

  17. Control of Vertical Force in Flux-Reversal Permanent Magnet Linear Motor for Urban Rail Transit Applications%城轨交通用磁通反向永磁直线电机的垂向力控制

    Institute of Scientific and Technical Information of China (English)

    赵文祥; 刘虎; 吉敬华; 徐亮

    2013-01-01

    磁通反向永磁直线( FRPML)电机是一种新型的初级永磁体直线电机。在分析其电机结构特点与工作原理基础上,推导并建立了数学模型。 FRPML电机的垂向力会对其效率等产生不利影响。分析了垂向力的组成与特性,得到解析表达式。提出了电机的垂向力最优控制,使FRPML电机保持正常推力下,提高电机性能。研究结果表明,所提出的优化控制策略正确有效。%The flux-reversal permanent magnet linear ( FRPML) machine is a new class of primary permanent magnet linear machine. It can be manufactured easily and installed expediently, suitable for the long stator applications, such as urban rail transit. The mathematical model was built based on its operation principles. The vertical force would reduce the motor efficiency. Therefore, according to the physical characteristics analyses of the vertical force, its analytical model was derived. The optimal control was obtained, hence improving the motor performance. The results verified the proposed control strategy.

  18. Runoff and erosion in a pinon-juniper woodland: Influence of vegetation patches

    Energy Technology Data Exchange (ETDEWEB)

    Reid, K.D.; Wilcox, B.P.; Breshears, D.D.; MacDonald, L.

    1999-12-01

    In many semiarid regions, runoff and erosion differ according to vegetation patch type. These differences, although hypothesized to fundamentally affect ecological processes, have been poorly quantified. In a semiarid pinion-juniper woodland [Pinus edulis Engelm. and Juniperus monosperma (Engelm) Sarg.] in northern New Mexico, the authors measured runoff and erosion from the three patch types that compose these woodlands: Canopy patches (those beneath woody plants), vegetated patched in intercanopy areas, and bare patches in intercanopy areas. The bare intercanopy patches exhibited the highest rates, followed by vegetated intercanopy patches and then by canopy patches. Large convective summer storms, though relatively infrequent, generated much of the runoff and most of the sediment; prolonged frontal storms were capable of generating considerable runoff but little sediment. A portion of the runoff and most of the sediment generated from bare intercanopy patches was redistributed down-slope, probably to adjacent vegetated intercanopy patches, demonstrating connectivity between these two patch types. Their results indicate that there are significant and important differences in runoff and sediment production from the three patch types; that bare intercanopy patches act as sources of both water and sediment for the vegetated intercanopy patches; and that the transfer of water and sediment at small scales is both frequent enough and substantial enough to be considered ecologically significant.

  19. Compatible dominant height - site index model for juniper (Juniperus deppeana Steud.

    Directory of Open Access Journals (Sweden)

    Antonio Rodríguez-Carrillo

    2015-01-01

    Full Text Available The aim of this study was to determine the site quality of juniper (Juniperus deppeana Steud. in the San Dimas region of the state of Durango, Mexico, using the site index method. The database comes from stem analysis of 43 trees felled in harvesting activities. The Chapman-Richards and Schumacher models, by means of the algebraic difference and generalized algebraic difference approaches, were tested to determine the site index; in addition, the error structure was modeled with a second-order autoregressive model to remedy the dependency of existing longitudinal errors. The results showed that the Chapman-Richards model in generalized algebraic difference form provided the best fit according to the adjusted coefficient of determination (R2 adj = 0.98 and root mean square error (RMSE = 0.46 m. Plotting of the quality curves generated with this model, superimposed on the observed heights, corroborated the goodness of fit of the model selected. The equation obtained with the generalized algebraic difference approach directly estimates the dominant height and site index at any height and base age.

  20. Western juniper and ponderosa pine ecotonal climate-growth relationships across landscape gradients in southern Oregon

    Science.gov (United States)

    Knutson, K.C.; Pyke, D.A.

    2008-01-01

    Forecasts of climate change for the Pacific northwestern United States predict warmer temperatures, increased winter precipitation, and drier summers. Prediction of forest growth responses to these climate fluctuations requires identification of climatic variables limiting tree growth, particularly at limits of free species distributions. We addressed this problem at the pine-woodland ecotone using tree-ring data for western juniper (Juniperus occidentalis var. occidentalis Hook.) and ponderosa pine (Pinus ponderosa Dougl. ex Loud.) from southern Oregon. Annual growth chronologies for 1950-2000 were developed for each species at 17 locations. Correlation and linear regression of climate-growth relationships revealed that radial growth in both species is highly dependent on October-June precipitation events that recharge growing season soil water. Mean annual radial growth for the nine driest years suggests that annual growth in both species is more sensitive to drought at lower elevations and sites with steeper slopes and sandy or rocky soils. Future increases in winter precipitation could increase productivity in both species at the pine-woodland ecotone. Growth responses, however, will also likely vary across landscape features, and our findings suggest that heightened sensitivity to future drought periods and increased temperatures in the two species will predominantly occur at lower elevation sites with poor water-holding capacities. ?? 2008 NRC.

  1. Safety effects of permanent running lights for bicycles

    DEFF Research Database (Denmark)

    Madsen, Jens Chr. Overgaard; Andersen, T.; Lahrmann, Harry

    2013-01-01

    3845 cyclists was carried out in Odense, Denmark in order to examine, if permanent running lights mounted to bicycles would improve traffic safety for cyclists. The permanent running lights were mounted to 1845 bicycles and the accident rate was recorded through 12 months for this treatment group...... and 2000 other bicyclists, the latter serving as a control group without bicycle running lights. The safety effect of the running lights is analysed by comparing incidence rates – number of bicycle accidents recorded per man-month – for the treatment group and the control group. The incidence rate......, including all recorded bicycle accidents with personal injury to the participating cyclist, is 19% lower for cyclists with permanent running lights mounted; indicating that the permanent bicycle running light significantly improves traffic safety for cyclists. The study shows that use of permanent bicycle...

  2. 电动汽车用永磁同步电机驱动系统的高性能控制%High Performance Control of Permanent Magnet Synchronous Motor Drive Systems Used in Electric Car

    Institute of Scientific and Technical Information of China (English)

    朱鲁佳

    2015-01-01

    针对电动汽车用永磁同步电机驱动系统的特点,以内置式永磁同步电机为控制对象,设计了以TC1797为主控芯片的硬件驱动系统。软件控制中采用最大转矩电流控制结合电压负反馈闭环的弱磁控制的方式,使得整个驱动系统起动转矩大、调速范围宽、功率密度和效率高。搭建电动汽车用永磁同步电机驱动系统进行测试验证。试验结果表明该驱动系统弱磁扩速倍数可达3.5;系统的峰值效率达到95%,系统效率>85%的区域超过80%,验证了该控制技术的高效性和可行性。%Due to the characteristics of permanent magnet synchronous motor drive system used in electric car, with the interior permanent magnet synchronous motor as the control object, designed the hardware drive system which was used the TC1797 as main control chip, used maximum torque per ampere control and field weakening as soft control strategy, then made the whole driving system have big startup torque, wide speed range, high power density and efficiency. Finally set up the permanent magnet synchronous motor drive system which was used in electric car for test validation. The test results showed that the drive system of field weakening expansion speed ratio could reach 3. 5, system peak efficiency could reached 95% , the area which the system efficiency was more than 85% can reach more than 80% , this proved the efficiency and feasibility of the control technology.

  3. PMSM有效磁链滑模观测器及转矩精确控制%Precise torque control and active flux sliding mode observer for Permanent Magnet Synchronous Motor

    Institute of Scientific and Technical Information of China (English)

    赵凯辉; 陈特放; 张昌凡; 何静; 黄刚

    2014-01-01

    To improve the performance of the torque precision for PMSM(Permanent Magnet Synchronous Motor)of railway vehicles, a novel sliding mode observer of active flux and a precise torque control method are proposed for a vector control system of PMSM. The concept of active flux is adopted and the mathematical model of Interior Permanent Magnet Synchro-nous Motor(IPMSM)has been established. The sliding mode observer of active flux is constructed in α-β stator coordinate frame, and it is observed active flux by applying sliding mode equivalent control methodology, then it realizes the real-time estimation of torque. The precise torque closed-loop control system is constituted combining with the torque command. The simulation results verify the feasibility and effectiveness of the method. The torque control precision of the PMSM can be improved, and the driving performance of railway PMSM vehicles is fulfilled and guaranteed. This method is not only applicable to IPMSM but to Surface-mounted Permanent Magnet Synchronous Motors(SPMSM)as well.%为了改善轨道交通永磁同步电动机转矩控制的性能,提出了一种改进的有效磁链滑模观测器,实现了永磁同步电动机的精确转矩闭环控制。采用有效磁链的概念,建立了基于有效磁链的内置式永磁同步电机数学模型;在α-β静止坐标系建立了有效磁链的滑模观测器,并基于滑模等值控制方法实现了有效磁链的观测,进而进行转矩的实时估算,以此和转矩给定值形成精确转矩闭环控制。通过仿真验证该方法的可行性和有效性。结果表明提高永磁同步电动机的转矩控制精度,改善了轨道永磁同步电动机控制系统的性能。该方法不仅适用于内置式永磁同步电机,而且适用于表贴式永磁同步电机。

  4. Permanent deformation of asphalt mixes

    NARCIS (Netherlands)

    Muraya, P.M.

    2007-01-01

    This dissertation describes the results of a research that was conducted on the permanent deformation of asphalt mixtures. Central to this research was the separate characterization of the contribution of the aggregate skeleton and the bituminous mortar towards resistance to permanent deformation. T

  5. Permanent-Magnet Meissner Bearing

    Science.gov (United States)

    Robertson, Glen A.

    1994-01-01

    Permanent-magnet meissner bearing features inherently stable, self-centering conical configuration. Bearing made stiffer or less stiff by selection of magnets, springs, and spring adjustments. Cylindrical permanent magnets with axial magnetization stacked coaxially on rotor with alternating polarity. Typically, rare-earth magnets used. Magnets machined and fitted together to form conical outer surface.

  6. Soils mediate the impact of fine woody debris on invasive and native grasses as whole trees are mechanically shredded into firebreaks in piñon-juniper woodlands

    Science.gov (United States)

    Aanderud, Zachary T.; Schoolmaster, Donald R.; Rigby, Deborah; Bybee, Jordon; Campbell, Tayte; Roundy, Bruce A.

    2017-01-01

    To stem wildfires, trees are being mechanically shredded into firebreaks with the resulting fine woody debris (FWD) potentially exerting immense control over soil and plants. We linked FWD-induced changes in microbial activity and nutrient availability to the frequency of Bromus tectorum and three native, perennial grasses across 31 piñon-juniper woodlands, UT, USA. Using a series of mixed models, we found that FWD increased the frequency of three of the four grasses by at least 12%. Deep, as opposed to shallow, soils mediated frequencies following FWD additions but only partially explained the variation in Bromus and Pseudoroegneria spicata. Although fertile areas associated with tree-islands elicited no response, FWD-induced increases in nitrogen mineralization in deep soils (15–17 cm) caused the frequency of the exotic and Pseudoroegneria to rise. Higher phosphorus availability in FWD-covered surface soils (0–2 cm) had no impact on grasses. FWD altered deep soil respiration, and deep and shallow microbial biomass structuring Pseudoroegneria frequencies, suggesting that microorganism themselves regulated Pseudoroegneria. The positive effects of FWD on grass frequencies intensified over time for natives but diminished for Bromus. Our results demonstrate that microorganisms in deeper soils helped mediate species-specific responses to disturbance both facilitating exotic invasion and promoting native establishment.

  7. The "Permanent" Patient Problem.

    Science.gov (United States)

    Bruce, Courtenay R; Majumder, Mary A

    2014-01-01

    Patients who enter the health care system for acute care may become "permanent" patients of the hospital when a lack of resources precludes discharge to the next level of post-acute care. Legal, professional, and ethical norms prohibit physician and acute care hospital "dumping" of these patients. However, limitless use of hospital resources for indefinite stays is untenable. In the absence of hospital policy addressing this specific issue, the availability of financial support will be determined by health care professionals' willingness to advocate for the patient and negotiate with hospital administrators and the ability and willingness of administrators to authorize the use of hospital resources. We propose five mid-level ethical principles to guide advocacy and administrative decision-making about provision of financial support for post-acute care for those patients who cannot afford it. We use two actual, de-identified cases to illustrate how these principles can be used to make reasoned, consistent decisions about the provision of post-acute financial support.

  8. 船舶永磁同步电机网络控制延时的节能研究%Energy Saving Analysis of Permanent Magnet Synchronous Motor Network Control System

    Institute of Scientific and Technical Information of China (English)

    冯金红; 林叶锦; 贾宝柱; 张均东; 王川

    2011-01-01

    以“中铁渤海轮渡”的永磁同步电机(Permanent Magnet Synchronous Motor,PMSM)应用的直接转矩控制(Direct Torque Control,DTC)-空间矢量脉宽调制(Space Vector Pulse Width Modulation,SVPWM)系统为研究对象,设计了一个网络控制系统(Network Control System,NCS)的量化器;根据NCS的数据传输特性,推导出由传感器的数据传输延时导致的发电机组功率额外输出的延时-功率关联公式,分析了NCS中网络延时与发电机组额外输出功率之间的定量关系,并使用VS.NET编写程序进行数值仿真.仿真结果证明了网络延时可增加额外功率消耗;同时说明了:减少NCS的网络延时,对电力推进船舶节约能源消耗具有重要意义.%A NCS (Network Control System) quantizer is designed with respect to DTC-SVPWM (Direct Torque Control- Space Vector Pulse Width Modulation) of PMSM (Permanent Magnet Synchronous Motor) equipped on "china railway Bohai ferry". Based on the property of data transportation in NCS, time delay-power correlated equation is derived to quantify the relationship between time-delay and generators extra power output. Numerical simulation is carried out with VS.NET program. Simulation result indicates that it is significant for electrical propulsion ship to save energy by reducing network time-delay.

  9. 占空比调制的永磁同步电机直接转矩控制%Direct torque control of permanent magnet synchronous motor based on duty ratio control

    Institute of Scientific and Technical Information of China (English)

    杨影; 陈鑫; 涂小卫; 韩冰

    2014-01-01

    Calculation duty ratio is an important issue in Direct torque control ( DTC) of permanent mag-net synchronous motor ( PMSM) based on the duty ratio modulation. The effect of zero vector on elctro-magnetic torque during all speed range was analyzed on the basis of the relation between voltage vector and torque current component and an important phenomenon was revealed and explained that torque rip-ple in low speed range is less than that in high speed range in DTC based on the duty ratio modulation. A robust DTC method of PMSM based on the duty ratio control was designed in which the duty ratio is cal-culated with the error of torque and flux. The method is simple to implement and insensitive to motor pa-rameter error. Simulation and experiments are carried out and show that the improved DTC based on duty ratio modulation has the advantage of simplicity, robustness and improved performance in low speed.%针对如何确定占空比调制的永磁同步电机直接转矩控制的零矢量作用时间问题。根据电压矢量与电流转矩分量关系,分析了在不同转速下零矢量作用时电磁转矩的变化规律,引入占空比调制后低速区转矩脉动要小于中高速区转矩脉动。设计了基于占空比调制的永磁同步电机直接转矩控制系统,利用转矩偏差和定子磁链的偏差计算占空比,该方案易于实现,对电机参数误差不敏感。仿真和实验结果表明,该方法结构简单、鲁棒性强,能够明显改善低速性能。

  10. An Investigation on Optimization Control of the Electromagnetic Coupler in Permanent Magnet Brushless DC Motor%永磁无刷直流电机的电磁耦合器优化控制研究

    Institute of Scientific and Technical Information of China (English)

    叶伟慧

    2016-01-01

    Electromagnetic coupler of permanent magnet brushless DC motor is an important device to achieve inductive power transmission.By optimizing the control design of electromagnetic coupler the stability and output gain of the electromagnetic coupler may be improved. This article sets forth a method to optimize the control of electromagnetic coupler based on particle swarm optimization.In the first it requires to design the equivalent circuit for electromagnetic coupler of the permanent magnet brushless DC motor in order to build parameter model to constrain the control of the electromagnetic coupler which takes the output voltage gain,power consumption and efficiency as the constrain parameter to build function for the control target and achieve improved control algorithm,so that the optimal design of electromagnetic coupler of permanent magnet brushless DC motor could be realized.Simulation results show that the design method for control of the electromagnetic coupler can effectively improve the output stability of the electromagnetic coupler of the permanent magnet brushless DC motor while the current gain,voltage gain and output efficiency of the motor is higher than that of traditional methods.It should demonstrates a sound value for applications.%永磁无刷直流电机的电磁耦合器是实现感应电能传输的重要器件,通过对电磁耦合器的优化控制设计,提高电磁耦合器的稳定性和输出增益。提出一种基于优化粒子群算法的电磁耦合器优化控制方法,首先进行了永磁无刷直流电机的电磁耦合器的等效电路设计,构建电磁耦合器控制的约束参量模型,以输出电压增益、功率损耗与效率为约束参量构建控制目标函数,实现控制算法的改进,进行了永磁无刷直流电机的电磁耦合器的优化设计。仿真实验结果表明,能有效提高永磁无刷直流电机的电磁耦合的输出稳定性,电机输出的电流增益、电压增

  11. 变结构控制策略在直驱永磁同步风力发电机中的应用%Application of Variable Structure Control Strategy in Direct-Drive Permanent Magnet Synchronous Wind Turbine Generator

    Institute of Scientific and Technical Information of China (English)

    刘向向; 李新宇; 王奔; 邓大磊

    2013-01-01

    根据直驱永磁同步风力发电机的结构特点,采用双脉宽调制变流器作为其并网主电路.考虑到永磁同步发电机的数学模型在dq坐标系下是一个非线性耦合系统,不利于控制器的设计.提出了采用逆系统方法将原系统进行线性化解耦,构造出其伪线性系统模型,再运用变结构控制理论设计伪线性系统的闭环控制器.建立了基于此控制策略的仿真模型并与PI控制进行比较.仿真结果表明,该控制策略可实现发电机输出有功功率的准确控制、并网有功功率和无功功率独立调节以及变速恒频运行.变结构控制与PI控制相比,动态响应速度快、鲁棒性好.%According to the structural feature of direct-drive permanent magnet synchronous wind turbine generator, the dual pulse width modulation converter is used as the main grid-connection circuit for it Considering the fact that in synchronously rotating d-q coordinate system the mathematical model of permanent magnet synchronous generator (PMSG) is a nonlinear coupling system and is not favorable to the design of the controller, it is proposed that the original system is linearly decoupled by inverse system approach and a pseudo-linear system equation of PMSG is constructed, and then based on variable-structure control a closed-loop controller for the pseudo-linear system is designed. A simulation model based on this control strategy is built and compared with PI controller. Simulation results show that using the proposed control strategy the accurate control of active power output of PMSG, independent regulation of grid-connected active power and reactive power and variable speed constant frequency (VSCF) operation of PMSG can be implemented. Results of comparing variable structure control with PI control show that the former possesses better robustness and its dynamic response is faster.

  12. Vegetation and environmental controls on soil respiration in a pinon-juniper woodland

    Science.gov (United States)

    Sandra A. White

    2008-01-01

    Soil respiration (RS) responds to changes in plant and microbial activity and environmental conditions. In arid ecosystems of the southwestern USA, soil moisture exhibits large fluctuations because annual and seasonal precipitation inputs are highly variable, with increased variability expected in the future. Patterns of soil moisture, and periodic severe drought, are...

  13. Decreased carbon limitation of litter respiration in a mortality-affected piñon-juniper woodland

    Directory of Open Access Journals (Sweden)

    E. Berryman

    2012-10-01

    Full Text Available Microbial respiration depends on microclimatic variables and carbon (C substrate availability, all of which are altered when ecosystems experience major disturbance. Widespread tree mortality, currently affecting piñon-juniper ecosystems in Southwestern North America, may affect C substrate availability in several ways; for example, via litterfall pulses and loss of root exudation. To determine piñon mortality effects on C and water limitation of microbial respiration, we applied field amendments (sucrose and water to two piñon-juniper sites in central New Mexico, USA: one with a recent (< 1 yr, experimentally-induced mortality event and a nearby site with live canopy. We monitored the respiration response to water and sucrose applications to the litter surface and to the underlying mineral soil surface, testing the following hypotheses: (1 soil respiration in a piñon-juniper woodland is water- and labile C-limited in both the litter layer and mineral soil; (2 water and sucrose applications increase temperature sensitivity of respiration; (3 the mortality-affected site will show a reduction in C limitation in the litter; (4 the mortality-affected site will show an enhancement of C limitation in the mineral soil. Litter respiration at both sites responded to increased water availability, yet surprisingly, mineral soil respiration was not limited by water. Temperature sensitivity was enhanced by some of the sucrose and water treatments. Consistent with hypothesis 3, C limitation of litter respiration was lower at the recent mortality site compared to the intact canopy site. Results following applications to the mineral soil suggest the presence of abiotic effects of increasing water availability, precluding our ability to measure labile C limitation in soil. Widespread piñon mortality may decrease labile C limitation of litter respiration, at least during the first growing season following mortality.

  14. The use of redberry juniper (Juniperus pinchotii) to reduce Haemonchus contortus fecal egg counts and increase ivermectin efficacy.

    Science.gov (United States)

    Whitney, T R; Wildeus, S; Zajac, A M

    2013-10-18

    Objectives of this study were to determine if a redberry juniper-based diet can reduce fecal egg counts (FEC) and increase ivermectin (IVM) efficacy in IVM-resistant Haemonchus contortus. Predominant genera present were Haemonchus (range 45-100%) and Trichostrongylus (range 0-47%). The FEC reduction for IVM in the ewe flock was 25% (95% confidence intervals 79% to -162%) and confirmed IVM resistance. After natural infection was established, Barbados Blackbelly and St. Croix lambs (n=64, 6 months old) were randomly assigned to pens and fed a pelleted treatment diet (4 pens/treatment and 8 lambs/pen) consisting of traditional feed ingredients mixed with either 30% hay (CNTL) or 30% ground juniper leaves and stems (JUN). Lambs were fed during two periods: Period 1 (days 0-28) and Period 2 (days 28-42). On day 28, half of the lambs from each treatment and pen were treated with IVM orally (0.2 mg/kg), creating four treatment groups: lambs fed CNTL or JUN and either not treated (CNTLn, JUNn) or treated (CNTLi, JUNi) with IVM. During Period 1, lambs fed CNTL had greater (P0.46) FEC on days 0 and 28, but lambs fed JUN had 69.1% lower (P<0.001) FEC on day 15 as compared to lambs fed CNTL. During Period 2, CNTLi lambs had greater (P<0.05) average daily gain than JUNn and JUNi lambs. Lambs fed JUN and treated with IVM (JUNi) had 66%, 65%, and 61% lower (P<0.05) FEC as compared to CNTLn, CNTLi, and JUNn lambs, respectively. Results suggest that feeding lambs a diet containing 30% redberry juniper reduced FEC and increased IVM efficacy by 65% (JUNi vs. CNTLi). Specific mechanisms involved in increasing IVM efficacy by feeding diets containing bioactive compounds warrants further investigation. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Research of Control Method of Position Sensorless Permanent Magnet Gyro Motor Based on EKF%基于EKF的无位置传感器永磁同步陀螺电机控制方法的研究

    Institute of Scientific and Technical Information of China (English)

    黄晓凡

    2012-01-01

    无位置传感器永磁同步陀螺电机的起动及稳态运行性能取决于伺服控制系统的控制策略.以DSP芯片ADMC300为主控芯片,详细论述了将扩展卡尔曼滤波(EKF)应用于航天陀螺稳定平台中的无位置传感器两相永磁同步陀螺电机系统中的起动及稳态运行控制方法和相关软硬件设计.试验结果表明:相比较传统的利用反电势过零换相控制方法,利用EKF方法可以使电机起动更快,获得转子位置信号更多.%The starting up and steady-state operation performance of positon sensorless permanent magnet gyro motor is determined by the conrol strategy of servo control system. Base on DSP chip( ADMC300) as centre control chip,the article discussed in detail about EKF,which is used in the starting up and steady-slate operation method of positon sensorless two phase permanent magnet gyro motor used in gyro-stabilized platform in aerospace and about the related software and hardware design. The experiment result verified that EKF can make the motor starting up quiker and achieve more rotor position signals compared to what the traditional control method using Back-EMF to achieve phase convert ion can.

  16. Study on Starting Control for Sensorless Three-phase Permanent-magnet Brushless DC Motor%三相永磁无刷电机起动控制研究

    Institute of Scientific and Technical Information of China (English)

    吴强; 熊浩; 孟光伟; 让余奇; 李槐树

    2011-01-01

    本文分析了的120°导通三相逆变器的SVPWM控制特性,提出了基于SVPWM控制和电流调节控制的无位置传感器的三相永磁无刷直流电机(BLDCM)的起动控制方法。在Matlab/Simlink环境下,建立了三相永磁BLDCM起动控制系统的仿真模型并进行了仿真。仿真结果表明该起动控制方法不但能有效控制起动电流大小,而且能改善BLDCM开环起动性能。%The paper analyses the SVPWM control schema of three-phase inverter employing 120° switch-on mode,proposes a starting control method combining the SVPWM control schema with current regulation for a sensorless three-phase permanent-magnet(PM) brushless DC(BLDC) motor,establishes the simulation model of the starting control system in Matlab /Simlink environment,and implements the proposed starting control system through digital simulation.Simulation results verify that the proposed starting method can not only control the starting current effectively but also improve the open-loop starting performance of the BLDC motor.

  17. Electronic Power Transformer Control Strategy in Wind Energy Conversion Systems for Low Voltage Ride-through Capability Enhancement of Directly Driven Wind Turbines with Permanent Magnet Synchronous Generators (D-PMSGs

    Directory of Open Access Journals (Sweden)

    Hui Huang

    2014-11-01

    Full Text Available This paper investigates the use of an Electronic Power Transformer (EPT incorporated with an energy storage system to smooth the wind power fluctuations and enhance the low voltage ride-through (LVRT capability of directly driven wind turbines with permanent magnet synchronous generators (D-PMSGs. The decoupled control schemes of the system, including the grid side converter control scheme, generator side converter control scheme and the control scheme of the energy storage system, are presented in detail. Under normal operating conditions, the energy storage system absorbs the high frequency component of the D-PMSG output power to smooth the wind power fluctuations. Under grid fault conditions, the energy storage system absorbs the redundant power, which could not be transferred to the grid by the EPT, to help the D-PMSG to ride through low voltage conditions. This coordinated control strategy is validated by simulation studies using MATLAB/Simulink. With the proposed control strategy, the output wind power quality is improved and the D-PMSG can ride through severe grid fault conditions.

  18. [Genetic variability of juniper tall (Juniperus excelsa Bieb.) in the northern and southern limits of the natural distribution].

    Science.gov (United States)

    Korshikov, I I; Nikolaeva, A V

    2013-01-01

    Genetic structure, subdivision and differentiation of six populations of juniper tall (Juniperus excelsa Bieb.) of the Crimean Mountains and of one population in Lebanon were investigated using 18 polymorphic allozyme loci as genetic markers. The high level of genetic variability of J. excelsa was established in the northern and the southern limits of its natural habitat. The mean values of the main indicators of genetic polymorphism were: P99 = 1,000, A = 3,167, H(E) = 0,370, H(o) = 0,405. Subdivision and differentiation of populations were low (F(ST) = 0,032, D(N) = 0,026) indicating similarity of their gene pools.

  19. Vigilancia y control en criaderos temporales y permanentes de culícidos en Villa Clara (Vigilance and control in temporal and permanent breeding ground of mosquitoes in Villa Clara

    Directory of Open Access Journals (Sweden)

    Janhad L. Rodríguez Mendieta

    2006-07-01

    developed in the Provincial Unit of Vigilance and Vectors Against fight in Villa Clara province, between the first July to first November 2005. For the same was graphically represented the 304 permanent and 218 temporal breeding ground of mosquitoes; distributed in the 13 municipalities of this province. Were taken shows of water body (28 breeding ground existence in the 13 municipalities of the province that to detect the Density of Larva according the methodology of ladle. Were determined the species main of mosquitoes that habitat in the province and were compared two methods (Temephos 2% and fish of control for this vectors, determining the cost – risk of Temephos 2%, the Bacillus thurigiensis and fish as mosquitoes control thorough a consideration. Were primary dates process in the computerized system Excel of packet Office XP and that statistic process of effectively of each treatment was use the test of proportions comparison of packet Statgraphics plus 4.1, both systems sustained in WindowsÒ. The results showing that the mosquitoes species more disseminated in the province are: Anopheles albimanus, Aedes mediovitatus, Aedes scapularis, Aedes confinis, Culex quinquefasciatus, Culex nigripalpus and Culex corniger; besides, the results demonstrating the superiority of control with fish on the Temephos control, already that is more efficient (99% versus 87% that p < 0.01 in the mosquitoes control. The fish control (no spending in CUC and $ 1 035.08 MN is more economic than Temephos (847 500 CUC and $ 12 490.96 MN and than Bacillus thurigiensis (6 328 cuc and $ 8 280.64 MN. Was conclude that the fish constitute a control effective that the mosquitoes people, recommended the use of fish for all benefice that this represent.

  20. Net changes in aboveground woody carbon stock in western juniper woodlands, 1946-1998

    Science.gov (United States)

    Strand, Eva K.; Vierling, Lee A.; Smith, Alistair M. S.; Bunting, Stephen C.

    2008-03-01

    Although regional increases in woody plant cover in semiarid ecosystems have been identified as a worldwide phenomenon affecting the global carbon budget, quantifying the impact of these vegetation shifts on C pools and fluxes is challenging. Challenges arise because woody encroachment is governed by ecological processes that occur at fine spatial resolutions (1-10 m) and, in many cases, at slow (decadal-scale) temporal rates over large areas. We therefore analyzed time series aerial photography, which exhibits both the necessary spatial precision and temporal extent, to quantify the expansion of western juniper into sagebrush steppe landscapes in southwestern Idaho. We established upper and lower bounds of aboveground woody carbon change across the landscape via two-dimensional spatial wavelet analysis, image texture analysis, and field data collection. Forty-eight 100-ha blocks across a 330,000-ha region were stratified by topography, soil characteristics, and land stewardship for analyses. Across the area we estimate aboveground woody carbon accumulation rates of 3.3 gCm-2yr-1 and 10.0 gCm-2yr-1 using the wavelet and texture method, respectively, during the time period 1946-1998. Carbon accumulation rates were significantly affected by soil properties and were highly dependent on the spatial and temporal scales of analysis. For example, at a 100-ha scale the aboveground carbon accumulation varied from -1.7 to 9.9 gCm-2yr-1, while at the 1-ha scale the range of variability increased to -11 to 22 gCm-2yr-1. These values are an order of magnitude lower than those previously suggested due to woody encroachment, highlighting the need for examining multiple spatial scales when accounting for changes in terrestrial carbon storage.

  1. Dual extraction of essential oil and podophyllotoxin from creeping juniper (Juniperus horizontalis.

    Directory of Open Access Journals (Sweden)

    Charles L Cantrell

    Full Text Available Juniperus horizontalis Moench (Family Cupressaceae, commonly called creeping juniper, is a widely distributed species in the United States and much of Canada. It is potentially a source for two important chemical products, the anticancer drug synthetic precursor, podophyllotoxin and essential oils. The objectives of this study were to ascertain the likelihood of utilizing J. horizontalis needles for the simultaneous production of both (--podophyllotoxin and essential oil components and to determine the optimum distillation time (DT needed for the production of essential oil containing a specific ratio of constituents. Eleven different distillation times were tested in this study: 20, 40, 80, 160, 180, 240, 480, 600, 720, 840, and 960 min. Total essential oil content increased with increasing distillation time from a minimum of 0.023% at 20 min to a maximum of 1.098% at 960 min. The major constituents present in the oil were alpha-pinene, sabinene, and limonene. The percent concentration of sabinene in the essential oil varied from a high of 46.6% at 80 min to a low of 30.2% at 960 min, that of limonene changed very little as a result of distillation time and remained near 30% for all distillation times, whereas the concentration of alpha-pinene was 9.6% at 20 min DT and decreased to 4.2% at 960 min. Post distillation analysis of needles revealed elevated amounts of (--podophyllotoxin remaining in the tissue varied in the amount of podophyllotoxin present, from a low of 0.281% to a high of 0.364% as compared to undistilled needles which gave 0.217% podophyllotoxin. As a result of this study, specific essential oil components can now be targeted in J. horizontalis by varying the distillation time. Furthermore, needles can be successfully utilized as a source of both essential oil and podophyllotoxin, consecutively.

  2. Dual extraction of essential oil and podophyllotoxin from creeping juniper (Juniperus horizontalis).

    Science.gov (United States)

    Cantrell, Charles L; Zheljazkov, Valtcho D; Carvalho, Camila R; Astatkie, Tess; Jeliazkova, Ekaterina A; Rosa, Luiz H

    2014-01-01

    Juniperus horizontalis Moench (Family Cupressaceae), commonly called creeping juniper, is a widely distributed species in the United States and much of Canada. It is potentially a source for two important chemical products, the anticancer drug synthetic precursor, podophyllotoxin and essential oils. The objectives of this study were to ascertain the likelihood of utilizing J. horizontalis needles for the simultaneous production of both (-)-podophyllotoxin and essential oil components and to determine the optimum distillation time (DT) needed for the production of essential oil containing a specific ratio of constituents. Eleven different distillation times were tested in this study: 20, 40, 80, 160, 180, 240, 480, 600, 720, 840, and 960 min. Total essential oil content increased with increasing distillation time from a minimum of 0.023% at 20 min to a maximum of 1.098% at 960 min. The major constituents present in the oil were alpha-pinene, sabinene, and limonene. The percent concentration of sabinene in the essential oil varied from a high of 46.6% at 80 min to a low of 30.2% at 960 min, that of limonene changed very little as a result of distillation time and remained near 30% for all distillation times, whereas the concentration of alpha-pinene was 9.6% at 20 min DT and decreased to 4.2% at 960 min. Post distillation analysis of needles revealed elevated amounts of (-)-podophyllotoxin remaining in the tissue varied in the amount of podophyllotoxin present, from a low of 0.281% to a high of 0.364% as compared to undistilled needles which gave 0.217% podophyllotoxin. As a result of this study, specific essential oil components can now be targeted in J. horizontalis by varying the distillation time. Furthermore, needles can be successfully utilized as a source of both essential oil and podophyllotoxin, consecutively.

  3. Permanent isolation surface barrier development plan

    Energy Technology Data Exchange (ETDEWEB)

    Wing, N.R.

    1994-01-01

    The exhumation and treatment of wastes may not always be the preferred alternative in the remediation of a waste site. In-place disposal alternatives, under certain circumstances, may be the most desirable alternatives to use in the protection of human health and the environment. The implementation of an in-place disposal alternative will likely require some type of protective covering that will provide long-term isolation of the wastes from the accessible environment. Even if the wastes are exhumed and treated, a long-term barrier may still be needed to adequately dispose of the treated wastes or any remaining waste residuals. Currently, no {open_quotes}proven{close_quotes} long-term barrier is available. The Hanford Site Permanent Isolation Surface Barrier Development Program (BDP) was organized to develop the technology needed to provide a long-term surface barrier capability for the Hanford Site. The permanent isolation barrier technology also could be used at other sites. Permanent isolation barriers use engineered layers of natural materials to create an integrated structure with redundant protective features. Drawings of conceptual permanent isolation surface barriers are shown. The natural construction materials (e.g., fine soil, sand, gravel, riprap, asphalt) have been selected to optimize barrier performance and longevity. The objective of current designs is to use natural materials to develop a maintenance-free permanent isolation surface barrier that isolates wastes for a minimum of 1,000 years by limiting water drainage to near-zero amounts; reducing the likelihood of plant, animal, and human intrusion; controlling the exhalation of noxious gases; and minimizing erosion-related problems.

  4. 自适应模糊滑模变结构在永磁同步电动机的应用%Adaptive Fuzzy Sliding mode Control into Permanent Magnet Synchronous Motor

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

      针对永磁同步电动机存在参数时变、多变量耦合、负载扰动以及非线性等不确定因素,提出一种新颖的、带有扩展反馈和切换增益的自适应模糊滑模变结构控制方法。%Against the indefinite factors of the time variation of parameters, multivariable coupling, load distur-bances and nonlinear of the permanent magnet synchronous motor, an innovative approach to adaptive fuzzy sliding mode control with a new type of extended feedback and switching gains was introduced.

  5. Sliding Mode Control with Fuzzy Feedforward for Permanent Magnet Synchronous Motor%基于模糊前馈的永磁同步电动机滑模矢量控制系统

    Institute of Scientific and Technical Information of China (English)

    林辉; 吕帅帅; 樊明迪

    2013-01-01

    Combining the advantages of sliding mode control system and fuzzy control system,both of which don't rely on the model of the controlled system, the sliding mode control with fuzzy feedforward for permanent magnet synchronous motor was proposed. The robustness of the sliding mode control was ensured, the response speed of the system was improved , and the dithering was reduced. The simulation results verify the effectiveness of the method, and the structure and algorithm are simple and easy to realize for engineering.%由于滑模控制和模糊控制均不依赖被控对象系统的模型,针对这一特点,将两者的优点结合起来,提出了基于模糊前馈的永磁同步电机滑模矢量控制.该方法既保证了滑模控制的鲁棒性,又能够提高系统的响应速度,减小了抖动.仿真结果验证了该方法的有效性,且计算简单,便于工程实现.

  6. Sliding Mode Control of Permanent Magnet Synchronous Motor Based on a Novel Exponential Reaching Law%永磁同步电机滑模变结构调速系统动态品质控制

    Institute of Scientific and Technical Information of China (English)

    张晓光; 赵克; 孙力; 安群涛

    2011-01-01

    为了提高永磁同步电动机(permanent magnet synchronous motor,PMSM)调速系统的动态品质,提出了一种新型指数趋近律,与常规指数趋近律不同,该趋近律将趋近速度与系统状态量的变化相关联,克服了常规指数趋近律的缺点,有效抑制了滑模的固有抖振问题,并增大了趋近速度.将该趋近律应用于永磁同步电动机调速系统,设计了基于新型指数趋近律的滑模变结构速度控制器,以取代传统PI 调节器.仿真和实验结果表明,该速度控制器能够有效地提高系统的静态、动态特性与鲁棒性.%To improve dynamic quality of permanent magnet synchronous motor (PMSM) speed servo system, a novel exponent reaching law was proposed. Different from the conventional exponential reaching law, the reaching speed of novel reaching law was associated with the changes of the system state; the novel exponential reaching law can overcome the disadvantage of traditional reaching law, suppress the chattering and improve the reaching speed. The novel reaching law was applied to the PMSM speed servo system; a novel speed controller was designed to replace the traditional PI regulator. Simulation and experimental results show that the novel speed controller can improve steady, dynamic performances and robustness characteristics of speed servo system.

  7. Simulation on Magnetic Field Characteristics of Permanent-Magnet Seed-Metering Device

    OpenAIRE

    Wang, Jing; Hu, Jianping; Wang, Qirui; Wang, Xun

    2011-01-01

    Part 1: Simulation, Optimization, Monitoring and Control Technology; International audience; The cylindrical permanent magnet is the core part of the permanent-magnet seed-metering device, it can absorb single magnetic powder coated seed. The first, the magnetic induction intensity model of any point in the cylindrical permanent magnet external was established based on the equivalent current model of permanent magnet. The second, the mathematical formula was derived using the Biot-Savart law ...

  8. Simulation and Modeling of Servo Control System of Permanent Magnet Synchronous Machine%永磁同步电机伺服控制系统建模与仿真

    Institute of Scientific and Technical Information of China (English)

    张钊; 陈涛; 周勇

    2014-01-01

    Aiming at the complication of introducing the control theory such as adaptive, fuzzy, neural networks, etc to the permanent magnet synchronous machine (PMSM) control system, and the required control expectation can hardly be fulfilled, the vector control system of PMSM is simulated in Matlab/Simulink. Based on the analysis of PMSM model and the control theory of space vector pulse width modulation (SVPWM), the simulation model of vector control system of PMSM is designed. The simulation result shows that the system runs stably, and gains good performance of static and dynamic response, complies with the theory analysis, provides the theoretical foundation of the design and analysis of real system, it can also be taken as reference for the system debugging.%针对将自适应、模糊、神经网络等控制理论引入永磁同步电机(permanent magnet synchronous machine, PMSM)控制系统中设计太过复杂,难以达到较理想控制效果的问题,在 Matlab/Simulink 环境下,基于矢量控制策略对 PMSM 控制系统进行建模仿真。分析 PMSM 数学模型和空间电压矢量脉宽调制(space vector pulse width modulation,SVPWM)控制原理,建立基于SVPWM的PMSM控制系统仿真模型。仿真结果表明:该系统运行平稳,具有较好的静态和动态性能,符合理论分析,能为实际系统的设计与分析提供理论依据,对工程实践中系统的调试具有一定的指导意义。

  9. Modeling of cross-coupling magnetic saturation in signal-injection-based sensorless control of permanent-magnet brushless AC motors

    OpenAIRE

    Li, Y.; Zhu, Z.Q.; Howe, D.; Bingham, Chris

    2007-01-01

    An improved brushless AC motor model is proposed for use in signal-injection-based sensorless control schemes by accounting for cross-coupling magnetic saturation between the - and -axes. The incremental self- and mutual-inductance characteristics are obtained by both finite-element analysis and measurements, and have been successfully used to significantly reduce the error in the rotor position estimation of sensorless control.

  10. Simulation Research of Dual-Rotor Permanent Magnetic Brushless DC Motor by Variable Parameter PI Controlling%变参数PI控制双转永磁无刷直流电动机仿真研究

    Institute of Scientific and Technical Information of China (English)

    孙百军; 焦振宏; 丁宇汉

    2011-01-01

    双转永磁无刷直流电动机作为螺旋桨推进电机,广泛应用于无人水下航行器.基于双转永磁无刷直流电动机工作原理,建立电机数学模型,采用变参数PI控制算法设计控制器,给出相对位置检测的换相控制方案,在Matlab平台上,建立电机调速系统仿真模型.仿真结果表明,仿真建模准确,控制算法精确、稳定、可靠.%The dual-rotor permanent magnetic brushless direct current motor (dual-rotor PMBLDCM) which has two rotors running in opposite direction at any time is widely used in autonomous underwater vehicle as the driving motor of propeller. Based on the working principle, this paper built the mathematical model of dual-rotor PMBLDCM, designed controller adopting variable parameter PI control algorithm,gave a phase-change control scheme employing relative position detection and built the simulation model of the speed regulation system of dual-rotor PMBLDCM under Matlab platform. The simulation result proves that the simulation modeling and algorithm of controlling are accurate, stable and reliable.

  11. Proposal to endorse the award of a contract for the supply of a juniper T320 network router

    CERN Document Server

    2003-01-01

    This document concerns the award of a contract for the supply of a JUNIPER T320 Network Router. The Finance Committee is invited to endorse the CERN Management's decision to negotiate a contract with QWEST COMMUNICATION (USA) for the supply of a JUNIPER T320 Network Router for a total amount not exceeding 265 000 US dollars (350 000 Swiss francs). The Finance Committee is also requested to approve the negotiation of a maintenance contract for a value not exceeding 50 000 US dollars (66 000 Swiss francs) for three years and the option to purchase additional network interfaces for a value not exceeding 100 000 US dollars (132 000 Swiss francs) bringing the total amount to 415 000 US dollars (548 000 Swiss francs), not subject to revision. CERN's contribution will not exceed 90 000 Swiss francs. The amounts in Swiss francs have been calculated using the present rate of exchange. The firm has indicated the following distribution by country of the contract value covered by this adjudication proposal: CA - 100%.

  12. Detecting mortality induced structural and functional changes in a pinon-juniper woodland using Landsat and RapidEye time series

    Science.gov (United States)

    Dan J. Krofcheck; Jan U. H. Eitel; Lee A. Vierling; Urs Schulthess; Timothy M. Hilton; Eva Dettweiler-Robinson; Rosemary Pendleton; Marcy E. Litvak

    2014-01-01

    Pinon-juniper (PJ) woodlands have recently undergone dramatic drought-induced mortality, triggering broad scale structural changes in this extensive Southwestern US biome. Given that climate projections for the region suggest widespread conifer mortality is likely to continue into the next century, it is critical to better understand how this climate-induced change in...

  13. Effects of adding protein, condensed tannins, and polyethylene glycol to diets of sheep and goats fed one-seed juniper and low quality roughage

    Science.gov (United States)

    The biochemical mechanisms that limit voluntary intake of one-seed juniper by browsing ruminants are not well understood. Twelve Rambouillet ewes (78 ± 2.3 kg BW) and 12 Boer-Spanish does (54 ± 1.4 kg BW) were used in a split-plot sequence design to investigate the effects of adding protein, quebrac...

  14. Analisis Elemen Visual Pada Promosi Busana Muslimah di Instagram (Studi Kasus Merek Hijab Juniper Lane, Zaha, dan Zysku Xena di Bandung

    Directory of Open Access Journals (Sweden)

    Ramadita Fetrianggi

    2017-06-01

    Full Text Available Analysis of Visual Elements on Muslimah Clothing Promotion in Instagram (Case Study on Brands of Hijab Juniper Lane, Zaha, and Zysku Xena in Bandung. Muslim clothing in the form of hijab has become popular as a religious lifestyle and identity. The popularity of hijab is due to the promotion of marketing through instagram displaying muslim fashion clothing that is designed very interesting, so that consumers become interested and marketing becomes increasing. This study aims to examine muslim clothing photos on instagram hijab with brands of Juniper Lane, Zaha, and Zysku Xena in Bandung seen from the visual elements of photography. The research method used case study with descriptive approach through visual analysis. The research subjects are instagram photos on Juniper Lane hijab brand, Zaha, and Zysku Xena in Bandung. Data collection techniques were collected by observation, instagram photo documentation study, and interviews with local brand owners of hijab and consumers. Data were analyzed by visual analysis, content analysis, and qualitative analysis. The results show that muslim clothing photos on instagram with brands of hijab Juniper Lane, Zaha, and Zysku Xena in Bandung have fulfilled the visual elements of photography, so the photo design becomes attractive, the consumers become interested in them, and the marketing becomes increasing.

  15. The practical importance of permanent and semipermanent habitats for controlling aquatic stages of Anopheles gambiae sensu lato mosquitoes: operational observations from a rural town in western Kenya

    NARCIS (Netherlands)

    Fillinger, U.; Sonye, G.; Killeen, G.F.; Knols, B.G.J.; Becker, N.

    2004-01-01

    Control of aquatic-stage Anopheles is one of the oldest and most historically successful interventions to prevent malaria, but it has seen little application in Africa. Consequently, the ecology of immature afrotropical Anopheles has received insufficient attention. We therefore examined the populat

  16. Power Quality Control and Design of Power Converter for Variable-Speed Wind Energy Conversion System with Permanent-Magnet Synchronous Generator

    Directory of Open Access Journals (Sweden)

    Yüksel Oğuz

    2013-01-01

    Full Text Available The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5 kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%.

  17. Power quality control and design of power converter for variable-speed wind energy conversion system with permanent-magnet synchronous generator.

    Science.gov (United States)

    Oğuz, Yüksel; Güney, İrfan; Çalık, Hüseyin

    2013-01-01

    The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS) operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5 kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%.

  18. Speed anti-windup PI strategies review for field oriented control of permanent magnet synchronous machines servo drives with matrix converters

    OpenAIRE

    Espina Masramon, Jorge; Arias Pujol, Antoni; Balcells Sendra, Josep; Ortega García, Carlos; Galceran Arellano, Samuel

    2009-01-01

    When facing real systems PI tuning, the plant is modeled disregarding its physical limitations. Consequently, the PI output may increase indefinitely its value; phenomenon called Windup. This paper presents a review and a comparison between different Anti-Windup PI strategies used in speed motion and position control for Matrix Converter PMSM servo drives.

  19. Power Quality Control and Design of Power Converter for Variable-Speed Wind Energy Conversion System with Permanent-Magnet Synchronous Generator

    Science.gov (United States)

    Oğuz, Yüksel; Güney, İrfan; Çalık, Hüseyin

    2013-01-01

    The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS) operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5 kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%. PMID:24453905

  20. Control strategies and simulation research of direct-drive permanent-magnent wind power system%永磁直驱风电变流器控制策略及仿真研究

    Institute of Scientific and Technical Information of China (English)

    刘景利; 张友鹏; 高锋阳; 董唯光

    2012-01-01

    根据矢量控制原理提出了机侧和网侧PWM变流器的控制策略,分析了永磁直驱风电系统双PWM变流器的电路结构及其工作原理,建立了永磁直驱风电系统中包括风力机、传动系统、永磁同步发电机、双PWM变流器等各部分的数学模型;在MATLAB/SIMULINK仿真环境中建立了永磁直驱风电系统的仿真模型并进行了动态仿真.仿真结果表明:采用双PWM变流器的永磁直驱风电系统具有优良的动、静态性能,可以良好的控制永磁同步发电机,最终输入电网的电压、电流波形接近正弦且谐波含量小.验证了系统仿真模型的正确性和所提出双PWM变流器控制策略的有效性.%The control strategies of converters at generator and power grid sides were put forward according to the vector control method, the circuit structure and working principle of dual PWM inverters in direct-drive permanent-magnent wind power system were analyzed. The mathematical models including wind turbine model, drive train model, permanent magnet synchronous generator model and the dual PWM converter model were built. The simulation model of the wind power system was built in Matlab/Simulink software environment, and the dynamic simulations were performed. The simulation result shows that the model has good dynamic and static performance, and can control the PMSG very well. The shapes of voltage and current into the grid are close to the sine and the content of harmonic is little. The simulink result also verifies the correctness of the model and the validity of the dual PWM converter' control strategies.

  1. 永磁同步发电机与Boost斩波型变换器非线性速度控制%Nonlinear Speed Control for a Permanent Magnet Synchronous Generator and the Boost-Chopper Converter

    Institute of Scientific and Technical Information of China (English)

    耿强; 夏长亮; 王志强; 史婷娜

    2012-01-01

    直驱式永磁同步风电系统电机侧变换器的一种常见拓扑结构为二极管整流桥后接Boost斩波电路。此结构具有较强的非线性,采用普通PI控制器很难使系统在正常运行范围内保持较好的动态性能。针对其非线性特性,分区间建立了发电机与变换器整体非线性数学模型,在单区间内采用输入-输出反馈线性化方法将非线性系统转换为线性系统,在此基础上设计了转速最优控制器。该设计方法数学转换过程较为简单,参数整定方法较为成熟,且不同区间内线性控制器的参数相同。通过一套3kVA的实验系统,验证了该方法能明显改善系统动态性能,对此类风电系统电机侧变换器控制策略的设计具有一定的参考价值。%A diode bridge rectifier followed by a boost chopper circuit is a common topology of the generator side converter for a direct driven permanent magnet synchronous generator(PMSG)-based wind energy conversion system(WECS).Owing to its strong nonlinearity,it is difficult for the system to maintain good dynamic performance within a normal operating range under the ordinary proportional-integral(PI) controller.According to its nonlinear characteristics,the piecewise nonlinear mathematical model for the whole system including the surface permanent magnet synchronous generator(SPMSG) and the generator side converter is built.Then the nonlinear mathematical model is transformed into a linear one by the input-output feedback linearization(IOFL) method.In addition,a speed controller is designed based on the optimal control theory.The proposed strategy has the advantages of a simple conversion process,a relatively mature parameter tuning method and unchanged parameters for the linear optimal controller within different intervals.Experimental results are presented with a 3kVA prototype,verifying the effectiveness and practicability of the proposed strategy.

  2. Dynamic voltage decoupling compensation control of distributed DC grid converter for permanent magnet wind generator%永磁风力发电机分布式直流并网动态电压解耦补偿控制

    Institute of Scientific and Technical Information of China (English)

    唐任远; 张洪阳; 张志锋; 朱建光

    2011-01-01

    In order to satisfy the demands of distributed DC grid with permanent magnet (synchronous)wind generator, the control strategy of distributed DC grid converter based on dynamic voltage compensation is proposed and studied with wide operation range. The control principle of excitation component was analyzed, and the basis was provided for high performances and so on. The disturbance variable was defined considering the cross coupling and voltage fluctuates based on the coordinate rotary system, and then the system was compensated. The DC chopper circuit was adopted with auxiliary support capacitance for the matching of diffirent DC voltage level. Fnially, the ariable speed constant voltage control of permanent magnet wind generator was implemented. Simulation and experimental vertify the teasibility and validity of the control stategies.%针对永磁(同步)风力发电机分布式直流并网的要求,提出并研究了一种基于机侧电压动态解耦补偿的且具有宽运行范围的分布式直流并网控制策略.分析了永磁风力发电机励磁分量控制原则,进而为电机的高性能运行提供依据.基于同步旋转坐标系把宽范围运行下系统所有的交叉耦合项和电压波动等原因造成的系统扰动统一定义为一个新的变量扰动,然后对控制系统进行补偿.采用辅助支撑电容的直流斩波电路进一步实现不同直流电压等级的匹配,最终实现永磁风力发电机的变速恒压控制.通过仿真和实验验证了控制策略的可行性和有效性.

  3. A landscape-scale assessment of plant communities, hydrologic processes, and state-and-transition theory in a western juniper dominated ecosystem

    Science.gov (United States)

    Petersen, Steven L.

    Western juniper has rapidly expanded into sagebrush steppe communities in the Intermountain West during the past 120 years. This expansion has occurred across a wide range of soil types and topographic positions. These plant communities, however, are typically treated in current peer-reviewed literature generically. The focus of this research is to investigate watershed level response to Western juniper encroachment at multiple topographic positions. Data collected from plots used to measure vegetation, soil moisture, and infiltration rates show that intercanopy sites within encroached Western juniper communities generally exhibit a significant decrease in intercanopy plant density and cover, decreased infiltration rates, increased water sediment content, and lower soil moisture content. High-resolution remotely sensed imagery and Geographic Information Systems were used with these plot level measurements to characterize and model the landscape-scale response for both biotic and abiotic components of a Western juniper encroached ecosystem. These data and their analyses included an inventory of plant density, plant cover, bare ground, gap distance and cover, a plant community classification of intercanopy patches and juniper canopy cover, soil moisture estimation, solar insulation prediction, slope and aspect. From these data, models were built that accurately predicted shrub density and shrub cover throughout the watershed study area, differentiated by aspect. We propose a new model of process-based plant community dynamics associated with current state-and-transition theory. This model is developed from field measurements and spatially explicit information that characterize the relationship between the matrix mountain big sagebrush plant community and intercanopy plant community patterns occurring within a Western juniper dominated woodland at a landscape scale. Model parameters (states, transitions, and thresholds) are developed based on differences in shrub

  4. Permanent Magnet Linear Synchronous Motor Servo Control System Design Based on TMS320F2812%基于TMS320F2812的永磁同步直线电机伺服控制系统设计

    Institute of Scientific and Technical Information of China (English)

    郑俊; 曾岳南; 吴一祥

    2012-01-01

    研究永磁同步直线电机在id=0动子磁场定向矢量控制策略下的三闭环伺服控制系统设计,对动子初始磁极位置采用逐渐逼近的方法进行检测,并搭建了软硬件系统,进行相应的实验,实验证明系统动子初始磁极对位准确,具有良好的动态性能和控制精度.%This paper makes a study of the permanent magnet linear synchronous motor(PMLSM) three closed-loop servo control system design in which d-axis current of stator is set to be zero in the rotor flux-oriented control strategy. Testing the rotor initial pole position using the method of gradually approximation and set up the hardware and software system for the corresponding experiment. The experiment prove the rotor initial position testing is accurate, have good dynamic performance and control precision.

  5. Production of electron cyclotron resonance plasma by using multifrequencies microwaves and active beam profile control on a large bore electron cyclotron resonance ion source with permanent magnets.

    Science.gov (United States)

    Kato, Yushi; Watanabe, Takeyoshi; Matsui, Yuuki; Hirai, Yoshiaki; Kutsumi, Osamu; Sakamoto, Naoki; Sato, Fuminobu; Iida, Toshiyuki

    2010-02-01

    A new concept on magnetic field with all magnets on plasma production and confinement has been proposed to enhance efficiency of an electron cyclotron resonance (ECR) plasma for broad and dense ion beam source under the low pressure. The magnetic field configuration is constructed by a pair of magnets assembly, i.e., comb-shaped magnet which cylindrically surrounds the plasma chamber. The resonance zones corresponding to the fundamental ECR for 2.45 GHz and 11-13 GHz frequencies are constructed at different positions. The profiles of the plasma parameters in the ECR ion source are different from each frequency of microwave. Large bore extractor is set at the opposite side against the microwave feeds. It is found that differences of their profiles also appear at those of ion beam profiles. We conducted to launch simultaneously multiplex frequencies microwaves controlled individually, and tried to control the profiles of the plasma parameters and then those of extracted ion beam.

  6. 永磁同步风力发电机的双启发式动态规划控制%Control of Permanent Magnet Synchronous Generators Based on Dual Heuristic Programming

    Institute of Scientific and Technical Information of China (English)

    林小峰; 赵立

    2016-01-01

    Due to the fact that the power control of permanent magnet synchronous generators(PMSG)is usually based on linear control theory,its dynamic performances cannot fully satisfy the operation requirements of wind farms. In this paper,dual heuristic programming(DHP)is adopted to control the output power of PMSG. After the introduction of the working principle of PMSG,its dynamic model is established. The DHP algorithm is written using C programming lan⁃guage,and the DHP control blocks replace the PI control blocks in the dynamic model of PMSG,which is incorporated into the IEEE 10-generator 39-node system to perform time-domain simulation with adjusted parameters. Simulation re⁃sults show that the output power of PMSG can be effectively controlled with DHP,and a desired dynamic performance can be obtained.%永磁同步风力发电机(PMSG)的功率控制一般基于线性控制理论,致使其动态性能难以完全满足风电场运行的需要。本文采用双启发式动态规划(DHP)对PMSG的输出功率进行控制。首先阐述PMSG的工作原理,然后搭建动态模型,编制了DHP算法的C程序,创建DHP控制模块以更换动态模型中的PI控制模块,最终接入到IEEE 10机39节点系统进行时域仿真并调节参数。仿真结果表明,应用DHP算法有效实现了PMSG的功率控制,获得了较为理想的动态性能。

  7. Qualitative permanence of Lotka-Volterra equations.

    Science.gov (United States)

    Hofbauer, Josef; Kon, Ryusuke; Saito, Yasuhisa

    2008-12-01

    In this paper, we consider permanence of Lotka-Volterra equations. We investigate the sign structure of the interaction matrix that guarantees the permanence of a Lotka-Volterra equation whenever it has a positive equilibrium point. An interaction matrix with this property is said to be qualitatively permanent. Our results provide both necessary and sufficient conditions for qualitative permanence.

  8. Research of the Flux -weakening Control of a Permanent Magnet Synchronous Machine Used in Electric Vehicles%电动车用永磁同步电机弱磁控制策略研究

    Institute of Scientific and Technical Information of China (English)

    苏颖毅

    2012-01-01

      A layout scheme of the electric drive system of a pure electric vehicle was introduced in this paper.The longitudinal dynamics model of the electric vehicle was built , from which the driving resistance was derived and then transformed to an equivalent resistance torque on the axis of the electric machine .The mathe-matical model of a permanent magnet synchronous machine was built in the two phase rotating reference frame and the motion equation of the electric machine with respect to the driving resistance was given .The necessity of the flux -weakening control was pointed out according to the voltage and current limitations of the three phase in -verter.A surface mounted permanent magnet synchronous machine was chosen and the relative flux -weakening control was put forward.By means of the simulation in Matlab /Simulink it was concluded that the flux -weake-ning control can effectively widen the rotational speed range of the electric machine , which can raise the maxi-mum speed of the electric vehicle.%  介绍了一种纯电动车电力驱动系统布置方案。建立电动车纵向动力学模型,得出电动车行驶阻力,并将其等效到电机输出端。在两相旋转坐标系下建立永磁同步电机数学模型,结合电动车行驶阻力,推出电机运动方程。然后选用表贴式永磁同步电机,提出相应的弱磁控制策略。通过在 Matlab/Simulink 中的仿真验证,得出弱磁控制能有效拓宽永磁同步电机转速范围,提升电动车最高运行速度。

  9. Transient or permanent fisheye views

    DEFF Research Database (Denmark)

    Jakobsen, Mikkel Rønne; Hornbæk, Kasper

    2012-01-01

    , about the benefits and limitations of transient visualizations. We describe an experiment that compares the usability of a fisheye view that participants could call up temporarily, a permanent fisheye view, and a linear view: all interfaces gave access to source code in the editor of a widespread......Transient use of information visualization may support specific tasks without permanently changing the user interface. Transient visualizations provide immediate and transient use of information visualization close to and in the context of the user’s focus of attention. Little is known, however...... programming environment. Fourteen participants performed varied tasks involving navigation and understanding of source code. Participants used the three interfaces for between four and six hours in all. Time and accuracy measures were inconclusive, but subjective data showed a preference for the permanent...

  10. Lodestone: Nature's own permanent magnet

    Science.gov (United States)

    Wasilewski, P.

    1976-01-01

    Magnetic hysteresis and microstructural details are presented which explain why the class of magnetic iron ores defined as proto-lodestones, can behave as permanent magnets, i.e. lodestones. Certain of these proto-lodestones which are not permanent magnets can be made into permanent magnets by charging in a field greater than 1000 oersted. This fact, other experimental observations, and field evidence from antiquity and the middle ages, which seems to indicate that lodestones are found as localized patches within massive ore bodies, suggests that lightning might be responsible for the charging of lodestones. The large remanent magnetization, high values of coercive force, and good time stability for the remanent magnetization are all characteristics of proto-lodestone iron ores which behave magnetically as fine scale ( 10 micrometer) intergrowths when subjected to magnetic hysteresis analysis. The magnetic results are easily understood by analysis of the complex proto lodestone microstructural patterns observable at the micrometer scale and less.

  11. Topology optimized permanent magnet systems

    CERN Document Server

    Bjørk, R; Insinga, A R

    2016-01-01

    Topology optimization of permanent magnet systems consisting of permanent magnets, high permeability iron and air is presented. An implementation of topology optimization for magnetostatics is discussed and three examples are considered. First, the Halbach cylinder is topology optimized with iron and an increase of 15% in magnetic efficiency is shown, albeit with an increase of 3.8 pp. in field inhomogeneity - a value compared to the inhomogeneity in a 16 segmented Halbach cylinder. Following this a topology optimized structure to concentrate a homogeneous field is shown to increase the magnitude of the field by 111% for the chosen dimensions. Finally, a permanent magnet with alternating high and low field regions is considered. Here a $\\Lambda_\\mathrm{cool}$ figure of merit of 0.472 is reached, which is an increase of 100% compared to a previous optimized design.

  12. Connecting Temporary and Permanent Organizing

    DEFF Research Database (Denmark)

    Stjerne, Iben Sandal; Velikova, Silviya Svejenova

    2016-01-01

    This paper investigates the relationship between a permanent organization and a series of temporary organizations. It draws on an in-depth study of the process through which a Danish film production company, seeking to balance innovation and persistence in a troubled industry, struggles to realize...... a novel children’s film and its sequels. The study reveals tensions at different levels as well as boundary work and boundary roles that address them, bringing in shadows of past and future projects. The study extends the understanding of the dialectic between temporary and permanent organizing...... by emphasizing how ongoing work at different boundaries affects the permanent and temporary organizing’s connectedness and outcomes. It also challenges the overly bracketed view of temporary organizations, suggesting a temporality perspective on temporariness....

  13. New Fault-tolerant Control Strategy for Five-phase Permanent-magnet Brushless DC Motors%新型五相 BLDC 电机的容错控制策略研究

    Institute of Scientific and Technical Information of China (English)

    许晓春; 刘国海; 赵文祥

    2014-01-01

    本文针对一种具有144°平顶梯形波的五相容错永磁无刷直流(BLDC)电机提出了基于转矩等效的容错控制策略。在保证输出转矩相等的基础上,推导了故障条件下的BLDC电机容错式BLAC控制策略。仿真和试验结果表明,该容错控制策略可以保证五相DLDC电机在故障条件下保持正常运行时的转矩性能。%In this paper , a new fault-tolerant control strategy was proposed for remedial operation of a five-phase permanent-magnet brushless DC (BLDC) motor, which had 144°trapsoidal back-EMF.In order to maintain the average torque under normal condition , a remedial brushless AC ( BLAC) mode was proposed for this faulty BLDC motor.Both simulation and experimental results were given , verifying that the new con-trol strategy can enhance the torque performance of faulty operation.

  14. The Research on the Control System of Permanent Magnet Synchronous Motor Based on Fast SVPWM%基于快速SVPWM的永磁同步电机控制系统研究

    Institute of Scientific and Technical Information of China (English)

    李立; 光宣亮; 吴文贤

    2016-01-01

    This paper adopts a kind of fast SVPWM algorithm which can be applied in the control system of three-phase voltage inverter. Compared with the traditional SVPWM, this calculation method is able to realize simple and fast calculation in the microprocessor. In this paper, through establishing simulation model for control system of per-manent magnet synchronous motor in the MATLAB, the calculation methods of fast SVPWM and traditional SVPWM are compared, and the fast SVPWM algorithm is verified to be feasible and effective.%本文采用一种快速SVPWM算法,可应用于三相电压型逆变器的控制系统中,相比于常规SVPWM,该算法在微处理器上实现简单,运算速度快。本文通过在MATLAB中搭建永磁同步电机控制系统仿真模型,对比了快速SVPWM和常规SVPWM两种算法,验证了快速SVPWM算法的可行性和有效性。

  15. Study on frost damage control measures for permanent slope of a hydroelectric station in North Xinjiang%北疆某水电站永久边坡冻害治理措施研究

    Institute of Scientific and Technical Information of China (English)

    孙根民

    2012-01-01

    A water control project in Xinjiang is located in the alpine region of the North Xinjiang; of which the permanent slope of the ground powerhouse for the hydropower plant is under the impact of frost damage due to the unsmooth seepage water drainage therein, i. e. the slope surface is even covered by the ice with the thickness up to 1 m during winter, and then a Larger damage is made on both Uie slope and the ground concrete nearby. Through the relevant study, the control measures of adding drainage adits, densifying drain-holes and making heat-insulation for drainage pipelines are adopted; thereby, the ice damage is eliminated at last.%新疆某水利工程地处新疆北部严寒地区,水电站地面厂房永久边坡因排水不畅受冻害影响,冬季坡面冰盖厚度达2 m以上,并对边坡及地面混凝土造成较大破坏.经研究,采用了增设排水洞,加密排水孔,并对排水管进行保温等治理措施,最终消除了冰害影响.

  16. 永磁同步电动机直接转矩控制方法的比较研究%STUDY ON THE PERFORMANCE OF DIFFERENT DIRECT TORQUE CONTROL METHODS FOR PERMANENT MAGNET SYNCHRONOUS MACHINES

    Institute of Scientific and Technical Information of China (English)

    史涔溦; 邱建琪; 金孟加; Friedrich W.Fuchs

    2005-01-01

    提出一种用于永磁同步电动机的基于磁链误差矢量补偿的直接转矩控制(EFVC-DTC)策略,给出了磁链误差矢量的估计算法,并将该控制策略下的稳态和动态运行性能与常规DTC进行比较.仿真及实验结果表明EFVC-DTC可以使电力开关器件工作在基本固定的频率上,磁链和转矩脉动显著减小,比常规DTC具有更优越的稳态性能,而动态转矩响应几乎与常规DTC相同.%A modified direct torque control strategy based on error flux linkage vector compensation (EFVC-DTC) for permanent magnet synchronous machines (PMSM) is presented. The theoretical background of EFVC-DTC is introduced and an algorithm to estimate the flux linkage error is proposed. The steady state and dynamic performances of EFVC-DTC have been compared with those of the conventional direct torque control (DTC). The simulation and experimental results confirm that both flux linkage and torque ripples are significantly reduced in EFVC-DTC with a fixed switching frequency while the dynamic torque response isalmost as good as the basic DTC.

  17. 基于改进滑模观测器的永磁同步电动机无位置传感器控制%Vector Control for Permanent Magnet Synchronous Motors Based on Improved Sliding Mode Observer

    Institute of Scientific and Technical Information of China (English)

    孙杰; 崔巍; 范洪伟; 章跃进

    2011-01-01

    To solve the problem of sensorless vector control for permanent magnet synchronous motors, a sliding mode observer was constructed and the continuous position was obtained by means of the sliding mode control theory in this paper.The switch function was replaced by the saturation function to solve the problem of the chattering in the sliding mode observer.Finally, Simulation and experiment proves the effectiveness of the proposed improved sliding mode observer.%针对永磁同步电动机的无位置传感器矢量控制问题,借助于滑模变结构控制理论,通过构造滑模观测器的方法,实现了永磁同步电动机连续转子位置的观测.针对滑模控制固有的抖振问题,通过采用饱和函数替代切换函数的方法,有效抑制了抖振问题对转子位置观测性能的影响.最后通过仿真和实验验证了所实现的改进滑模观测器的有效性.

  18. Vector Control of Permanent Magnet Synchronous Motor Based on Sliding Mode Observer%基于滑模观测器的永磁同步电机无传感器矢量控制

    Institute of Scientific and Technical Information of China (English)

    孙杰; 崔巍; 范洪伟; 章跃进

    2011-01-01

    To solve the problem of sensorless vector control of permanent magnet synchronous motor( PMSM ), a sliding mode observer was constructed and the continuous position was obtained by means of the sliding mode control theory. The boundary layer was used to solve the problem of the chattering in the sliding mode observer. Finally, the effectiveness of the sliding mode observer improved was proved by the simulation and experimental.%根据滑模变结构控制理论,构造了滑模观测器,实现了永磁同步电机无位置传感器矢量控制.针对滑模变结构控制所固有的抖振问题,采用边界层法,有效抑制了抖振问题,提高了转子位置估算精度.通过仿真和试验,验证了所实现的改进滑模观测器的有效性.

  19. 新型开放式绕组永磁同步电机矢量控制系统研究%Research on Novel Open-End Winding Permanent Magnet Synchronous Motor Vector Control Systems

    Institute of Scientific and Technical Information of China (English)

    安群涛; 孙力; 孙立志

    2015-01-01

    双逆变器供电的开放式绕组永磁同步电机(open-end winding permanent magnet synchronous motor,OEW-PMSM)系统作为一种新型电机驱动拓扑,其直流母线电压利用率高、绕组电流控制自由度大、容错能力强,在电力拖动领域具有良好的应用价值。该文建立了OEW-PMSM的数学模型及其采用双逆变器供电的矢量控制系统,结合双逆变器工作原理和输出矢量,分析系统零序电压和零序电流问题,采用不产生零序电压的电压矢量进行空间矢量脉宽调制(space vector pulse width modulation,SVPWM)来消除零序电压,并给出实现算法。在采用消除零序电压的SVPWM 控制时,双逆变器供电的OEW-PMSM 可以将基速提高为星接绕组时的1.7倍,降低了系统弱磁设计和控制的难度。仿真和实验验证了所提方法的正确性和可行性。%Open-end winding permanent magnet synchronous motors (OEW-PMSMs) fed by dual inverters as a kind of novel drive topology have competitive application prospects in the electric drive field for their high utility of DC-link voltage, more control freedoms of currents and good fault-tolerant ability. The mathematic model and vector control system fed by the dual inverter of OEW-PMSMs were built. Based on the principle and output voltage vectors of the dual inverter, the zero-sequence voltage and current were analyzed, and a SVPWM switching strategy which employs voltage vectors that do not contribute to zero-sequence voltage was proposed to eliminate zero-sequence voltage. And, its implement algorithm was discussed. The basic speed of the OEW-PMSM fed by the dual inverter with the zero-sequence voltage eliminated SVPWM strategy can be improved to 1.7 times of the star-connected winding permanent magnet synchronous motor (SCW-PMSM). Therefore, the difficulty of their flux-weakening design and control can be reduced greatly. The proposed method is validated by simulation and experimental

  20. Electromagnetic acceleration of permanent magnets

    CERN Document Server

    Dolya, S N

    2015-01-01

    We consider the acceleration of the permanent magnets, consisting of neodymium iron boron by means of the running magnetic field gradient. It is shown that the specific magnetic moment per nucleon in neodymium iron boron is determined by the remained magnetization of the substance. The maximum accessable gradient of the magnetic field accelerating the permanent magnets is determined by the coercive force thirty kilogauss. For the neodymium iron boron magnets this gradient is equal to twenty kilogauss divided by one centimeter. The finite velocity of the magnets six kilometers per second, the length of acceleration is six hundred thirty-seven meters.

  1. Early eruption of permanent canines.

    Science.gov (United States)

    Madhu, S

    2012-01-01

    Systemic and local factors can modify the eruption time of teeth. Generalized eruption time changes could be due to some systemic diseases like hyperthyroidism, hypophosphatasia, precocious puberty, Proteus syndrome, etc. Localized early eruption of permanent teeth could be due to early extraction of deciduous teeth. Presented here is an extremely rare case of early eruption of permanent canines in a 7-year old female child. Though the number of such cases is very limited, the clinician should poses adequate knowledge and keeps an open eye to identify such cases.

  2. Early eruption of permanent canines

    Directory of Open Access Journals (Sweden)

    S Madhu

    2012-01-01

    Full Text Available Systemic and local factors can modify the eruption time of teeth. Generalized eruption time changes could be due to some systemic diseases like hyperthyroidism, hypophosphatasia, precocious puberty, Proteus syndrome, etc. Localized early eruption of permanent teeth could be due to early extraction of deciduous teeth. Presented here is an extremely rare case of early eruption of permanent canines in a 7-year old female child. Though the number of such cases is very limited, the clinician should poses adequate knowledge and keeps an open eye to identify such cases.

  3. Historical fire and multidecadal drought as context for piñon-juniper woodland restoration in western Colorado.

    Science.gov (United States)

    Shinneman, Douglas J; Baker, William L

    2009-07-01

    Fire is known to structure tree populations, but the role of broad-scale climate variability is less clear. For example, the influence of climatic "teleconnections" (the relationship between oceanic-atmospheric fluctuations and anomalous weather patterns across broad scales) on forest age structure is relatively unexplored. We sampled semiarid piñon-juniper (Pinus edulis-Juniperus osteosperma) woodlands in western Colorado, U.S.A., to test the hypothesis that woodland age structures are shaped by climate, including links to oceanic-atmospheric fluctuations, and by past fires and livestock grazing. Low-severity surface fire was lacking, as fire scars were absent, and did not influence woodland densities, but stand-replacing fires served as long-rotation (>400-600 years), stand-initiating events. Old-growth stands (>300 years old) were found in 75% of plots, consistent with a long fire rotation. Juniper and piñon age structures suggest contrasting responses during the past several centuries to dry and wet episodes linked to the Atlantic Multidecadal Oscillation (AMO) and Pacific Decadal Oscillation (PDO). Juniper density increased slightly during periods of drought, positive (warm) AMO (after approximately 10-year lag), and negative (cool) PDO. In contrast, piñon populations may still be recovering from a long, drought-filled period (AD 1620-1820), with pulses of recovery favored during cool AMO, warm PDO, and above-average moisture periods. Analysis of 20th-century tree establishment and instrumental climate data corroborate the long-term relationships between age structure and climate. After Euro-American settlement (AD 1881), livestock grazing reduced understory grasses and forbs, reducing competition with tree seedlings and facilitating climate-induced increases in piñons. Thus tree populations in these woodlands are in flux, affected by drought and wet periods linked to oceanic-atmospheric variability, Euro-American livestock grazing, and long-rotation, high

  4. Safety and efficacy of a biomimetic monolayer of permanently bound multiphosphonic acid molecules on dental implants: 3 years post-loading results from a pilot quadruple-blinded randomised controlled trial.

    Science.gov (United States)

    Esposito, Marco; Dojcinovic, Ivan; Buchini, Sabrina; Péchy, Péter; Aronsson, Björn-Owe

    To evaluate the safety and clinical efficacy of a novel surface treatment (SurfLink, Nano Bridging Molecules, Gland, Switzerland) on titanium dental implants. SurfLink consists of a monolayer of permanently bound multiphosphonic acid molecules, which mimics the surface of naturally occurring hydroxyapatite. Twenty-three patients requiring at least two single dental implants had their sites randomised according to a split-mouth design to receive one titanium grade 4 implant treated with SurfLink and one untreated control implant. Additional SurfLink-treated implants were placed if needed. Implants were submerged for 3 months in mandibles and 6 months in maxillae, then loaded with definitive metal-ceramic crowns and followed for 3 years after loading. Outcome measures were crown/implant failures, any complication, radiographic peri-implant marginal bone level changes and marginal bleeding. Three patients dropped out but all remaining patients were followed up to 3-years post-loading. No implant failed. Complications were reported for three patients, affecting both types of implant in two patients and only SurfLink implant in one patient. No differences for complications between the two implant types was observed (McNemar test, P = 1, difference in proportions = -0.04, 95% CI: -0.22 to 0.14). No bleeding was observed when a periodontal probe was run in the peri-implant soft tissues around any of the implants, with the exception of three implants affected by peri-implantitis. There were no statistically significant differences in marginal bone level changes between the two groups (at 3 years post-loading P = 0.86, mean difference = -0.05; SD = 1.15; 95% CI: -0.56 to 0.47). Medium-term data (3-years post-loading) of implants with a biomimetic monolayer of permanently bound multiphosphonic acid molecules (SurfLink surface treatment) presented no safety issues. Clinical healing in both control and SurfLink-treated implant groups was uneventful

  5. 五相容错式磁通切换永磁电机及其控制%Topology and Control of Five-phase Fault-tolerant Flux-switching Permanent-magnet Motor

    Institute of Scientific and Technical Information of China (English)

    赵文祥; 唐建勋; 吉敬华; 刘国海

    2015-01-01

    A new five-phase fault-tolerant flux-switching permanent-magnet (FT-FSPM) motor was proposed, which has odd rotor pole number. In order to improve fault tolerance, the key of the proposed motor topology is to incorporate the design method of fault-tolerant teeth to provide the desired decoupling among phases. By using the finite-element method, the electromagnetic performances of the proposed 10/19-pole FT-FSPM motor were analyzed, including the magnetic field distribution, flux density, back-EMF, and cogging torque. Particularly, the influences of odd rotor pole topology on symmetric back-EMF and low cogging torque were analyzed. Also, the control strategies of the proposed motor under normal and remedial conditions were investigated. A field-circuit co-simulation model was developed to predict torque performance of FT-FSPM motor drive under various conditions. Finally, a FT-FSPM motor was designed and prototyped. The simulated and experimental results verify the validity of the proposed topology and control method.%提出一种具有奇数转子极的新型五相容错式磁通切换永磁(fault-tolerant flux-switching permanent-magnet, FT-FSPM)电机。该电机结构通过引入容错齿设计,增强了各相之间的独立性,提高了电机容错性能。运用有限元方法,对所设计的10/19极FT-FSPM电机的磁场、气隙磁密、反电势及齿槽转矩等电磁性能进行计算,分析奇数转子极结构对反电势和齿槽转矩的影响。在此基础上,研究电机故障时的容错控制策略。运用电路、磁路瞬态联合仿真的方法,对电机的转矩进行计算,并设计加工了FT-FSPM实验样机,仿真和实验结果验证了理论分析的正确性。

  6. Design of Permanent Magnet Brushless DC Motor Control System for Air Conditioning%空调用永磁无刷直流电动机控制器设计

    Institute of Scientific and Technical Information of China (English)

    田德文; 徐奇伟; 吴世华

    2011-01-01

    永磁无刷直流电动机是新一代高性能的驱动电机,它高效、节能、控制简单,已在变频空调中得到很好的应用.传统无刷直流电动机控制器结构及控制策略复杂、成本高、节能效果不明显.文中提出了一种采用dsPIC30F2010作为控制芯片、FSBS1 0CH60SPM智能功率模块的无刷直流电机控制器设计方案.该控制器具有体积小、成本低的优点,可以广泛的应用于直流变频节能空调中.%The permanent magnet brushlese DC motor has been a very good application in variable frequency air conditioning as an advanced drive motor, with the features of high efficiency, low cost and simple operation. The traditional control strategy and structure of brushless DC motor control system are complicated, costly and power -wasting. In this paper, an control system with the control core of dsPIC30F2020 and intelligent power module FSBS10CH60SPM was designed. This design has smaller volume and lower cost, and can be widely used in variable frequency air conditioning.

  7. Coordination Control of Permanent Magnet D irect D riven Wind Turbine Based on D ual PWM Converter%基于双 PWM变换器的永磁直驱风电系统协调控制

    Institute of Scientific and Technical Information of China (English)

    刘波; 金昊

    2014-01-01

    由于双 P WM变换器的永磁直驱风电系统在常规控制策略下,当风速变化时,存在直流侧电容电压波动较大、控制系统的响应速度较慢的现象,提出有功功率前馈补偿协调控制策略。将发电机侧瞬时有功功率作为前馈信号送到网侧变换器功率控制内环,对有功功率变化扰动直接调节,协调控制双P WM变换器两侧有功功率,实现瞬时有功功率平衡,有效抑制直流侧电压的波动,同时加快控制系统的响应速度。在此基础上,在前馈控制通道中加入补偿环节,进一步提高前馈控制效果。并通过对比仿真,验证了控制策略的正确性和有效性。%Considering the fact that in conventional control strategy,the DC side capacitor voltage of dual PWM converter-based direct-drive permanent-magnet wind power system has lager fluctuation and slower con-trol system response,a coordinated control strategy of active power feed-forward compensation was proposed, in which,having motor-side instantaneous active power sent to the grid-side converter power control loop as a feed-forward signal to regulate active power change disturbance directly and to control active power of dual PWM converter on both sides coordinately so that the instantaneous active power can be balanced and the DC bus voltage fluctuation can be inhibited effectively,as well as the control system response can be accelerated. On this basis,a compensation step added in the feed-forward control channel can further improve feed-forward control.Simulation and comparison results verify both correctness and effectiveness of this control strategy.

  8. Permanent-wave dermatitis: contact allergy to cysteamine hydrochloride.

    Science.gov (United States)

    Landers, Maeran C; Law, Sandra; Storrs, Frances J

    2003-09-01

    Cysteamine hydrochloride (CHC) is a newly recognized sensitizer found in permanent-wave solutions. We report the case of a hairdresser who was found to be allergic to CHC. Our allergic patient was patch-tested to various chemicals found in permanent-wave solutions, including CHC (1.0% in petrolatum). Patch-test reactions were positive to CHC, glyceryl thioglycolate, diglyceryl thioglycolate, p-phenylenediamine (PPD), and PPD through a piece of latex glove. Sixty-four controls to CHC (1.0% in petrolatum) had negative results. Household-weight latex gloves were protective against CHC allergy. Persons with CHC-waved hair were not allergic. CHC contained in "neutral" permanent-wave preparations has been used in American beauty salons since 1993. We briefly discuss the introduction and significance of CHC in permanent waves.

  9. 27 June 2012 - Ambassador K. Pierce, Permanent Representative of the United Kingdom of Great Britain and Northern Ireland to the United Nations Office and other international organisations in Geneva visiting the LHC tunnel at Point 5 with Department Head P. Collier and CMS control room with Former Collaboration Spokesperson J. Virdee.

    CERN Document Server

    Laurent Egli

    2012-01-01

    27 June 2012 - Ambassador K. Pierce, Permanent Representative of the United Kingdom of Great Britain and Northern Ireland to the United Nations Office and other international organisations in Geneva visiting the LHC tunnel at Point 5 with Department Head P. Collier and CMS control room with Former Collaboration Spokesperson J. Virdee.

  10. 28 June 2012 - Ambassador I. Piperkov, Permanent Representative of Bulgaria to the United Nations Office and other international organisations in Geneva and Spouse visiting CMS experimental area with Collaboration Deputy Spokesperson T. Camporesi and CERN Control Centre with M. Benedikt.Senior physicist L. Litov accompanies the delegation throughout.

    CERN Multimedia

    Jean-Claude Gadmer

    2012-01-01

    28 June 2012 - Ambassador I. Piperkov, Permanent Representative of Bulgaria to the United Nations Office and other international organisations in Geneva and Spouse visiting CMS experimental area with Collaboration Deputy Spokesperson T. Camporesi and CERN Control Centre with M. Benedikt.Senior physicist L. Litov accompanies the delegation throughout.

  11. Magnetic Fields: Visible and Permanent.

    Science.gov (United States)

    Winkeljohn, Dorothy R.; Earl, Robert D.

    1983-01-01

    Children will be able to see the concept of a magnetic field translated into a visible reality using the simple method outlined. Standard shelf paper, magnets, iron filings, and paint in a spray can are used to prepare a permanent and well-detailed picture of the magnetic field. (Author/JN)

  12. PWM Control of Directly-driven Permanent Magnet Synchronous Wind Turbines in Motor Side%直驱式永磁同步风电机组机侧PWM控制

    Institute of Scientific and Technical Information of China (English)

    孙延昭; 黄守道; 黄科元; 佘峰

    2009-01-01

    在介绍永磁同步发电机(PMSG)d,q轴数学模型和矢量控制理论基础上,提出在直驱式永磁同步风电系统机侧采用PWM控制方式,通过转子磁场定向控制策略.实现有功无功功率解耦控制,减小了损耗,并且较好地控制了转速.利用Matlab/Simulink进行仿真,并给出了仿真结果.同时搭建了基于TMS320F2808控制器的试验平台,对该控制策略进行了实验,实验结果验证了该控制系统的正确性与可行性.%The PWM control strategy of directly-driven permanent magnet synchronous wind turbine sys-tem in motor-side was presented,which based on the dq-axis mathematical model of PMSG and the vector con-trol theory, by using the strategy of rotor field oriented, the active power and reactive power can be deeoupled, while the loss can be decreased, and the rotor speed is controlled very well. Matlab/Simulink was carried out to prove the validity of the system, and the simulating results was given. An experimental system based on TMS320F2808 was set up to verify the validity and the feasibility.

  13. Permanent Magnet Brushless Motor Control Strategy Based on Switching System Theory%基于切换系统理论的永磁无刷电动机控制策略

    Institute of Scientific and Technical Information of China (English)

    吕永健; 李飞; 李子龙

    2011-01-01

    The switching system is one of the important models which describe the hybrid dynamical systems. Different models and the switching rules are adopted to better describe the motion of the actual complicated systems. Combined with advantages of the PMSM and BLDCM.the paper proposed the switching control strategy for brushless permanent magnet motor with the rule of output feedback based on switching system theory. Then the linear model of the switching control system was obtained and the stability of it was analyzed. The results of the simulation and the experiment show that the switching control strategy is stable and could effectively improve the efficiency and the function of the motor in full speed range.%切换系统是描述混杂动态系统的重要模型之一,采用不同的模态和切换规则可以更好地刻画一个实际复杂动态系统的运行轨迹.基于切换系统理论,结合正弦波和方波电流驱动的永磁无刷电动机的各自优势,提出了按输出状态反馈切换的永磁无刷电动机切换控制策略,建立了切换系统的线性化模型并对其稳定性进行了分析.仿真和实验结果表明,切换控制系统运行稳定,可有效地提高电机全速度范围内的运行效率和性能.

  14. 基于自抗扰控制器的直驱式永磁同步风电系统双PWM控制%Direct-drive permanent magnet synchronous wind power generation system based on active disturbance rejection controller

    Institute of Scientific and Technical Information of China (English)

    伍亮; 杨金明; 贾盼盼

    2013-01-01

    Based on the mathematical model of direct-drive permanent magnet synchronous wind power generation system,the active disturbance rejection controllers (ADRC) are designed for the generator-side converter and the grid-side converter respectively.Using the ADRC,the wind power generation system with dual PWM converter can track maximum power point by the generator-side converter and maintain a constant voltage of DC capacitor by the grid-side converter under rated wind speed.The simulation result shows that comparing with the traditional PI controller,wind power generation system with ADRC can track the reference turbine speed quickly without overshoot.At the same time,voltage disturbance on DC capacitor caused by the variation of wind speed and grid voltage disturbance is effectively restrained.So the wind power generation system with ADRC has outstanding control performance.%针对直驱式永磁同步风力发电机组,分别设计了电机侧和电网侧的变换器自抗扰控制器,从而实现在额定风速以下对电机侧的最大风能跟踪控制、电网侧直流电容电压恒定控制.与常规PI控制器相比,采用自抗扰控制器的直驱动式永磁同步发电系统,能够实现对指令转速快速及无超调跟踪、有效抑制风速变化及电网电压扰动对电容电压的影响,具有较为优秀的控制性能.

  15. 基于最大转矩电流比的永磁同步电动机矢量控制%Vector Control for Permanent Magnet Synchronous Motor Based on Maximum Torque Per Ampere

    Institute of Scientific and Technical Information of China (English)

    田以涛; 王英

    2013-01-01

    在分析永磁同步电动机数学模型基础上,通过极值原理推导出基于最大转矩电流比控制方法下电磁转矩与d、q轴电流之间的关系式,给出了一种关系式的工程近似求解方法,分析了3次拟合多项式与5次拟合多项式下的拟合特点.分析结果表明5次拟合情况下的电机空载运行电流明显小于3次拟合情况下的电机空载运行电流,有利于降低电机空载运行时的损耗.仿真对比了两种拟合多项式控制下的电机运行状态,仿真结果与理论分析相符.%Based on the mathematical model of permanent magnet synchronous motor (PMSM),the relational expression between electromagnetic torque and d-axes,q-axes current,was controlled based on maximum torque per ampere (MTPA),which was deduced according to extremal principle.An engineering approximate algorithm for the maximum torque per ampere control was given.And the fitting characteristic of three times fitting polynomial and five times fitting polynomial was analyzed.The current of the motor no-load running under five times polynomial was obviously lower than that under three times polynomial,which helped to reduce the motor no-load running loss.The motor operation under the control of two fitting polynomial was compared by the simulation.The simulation result was consistent with the theoretical analysis.

  16. 基于永磁同步电机模型辨识与补偿的自抗扰控制器%Active Disturbance Rejection Controller Based on Permanent Magnetic Synchronous Motor Model Identification and Compensation

    Institute of Scientific and Technical Information of China (English)

    刘志刚; 李世华

    2008-01-01

    在用1阶自抗扰(active disturbance rejection controller,ADRC)控制的永磁同步电机(permanent magnetic synchr-onous motor,PMSM)调速系统中,当扰动变化大时,扩张的状态观测器(extended State observer,ESO)难以保证对扰动的估计精度.为了使ESO对扰动有更好的估计,提高1阶自抗扰控制器的性能,提出了PMSM调速系统的模型补偿自抗扰控制器方案.辨识出系统的部分模型,利用部分模型信息在一阶自抗扰控制器对扰动进行部分补偿,从而减小了ESO对扰动估计的压力,使得扰动估计精度提高.仿真结果表明,该算法具有更好的抗负载扰动能力.

  17. 电流型多相永磁同步电动机调速系统的换相转矩脉动%Commutation Torque Ripple Analysis of Current-Type Multiphase Permanent Magnet Synchronous Motor Speed Control System

    Institute of Scientific and Technical Information of China (English)

    周羽; 李槐树; 苏广东

    2013-01-01

    为了研究多相梯形波永磁同步电动机(以下简称TPMSM)的换流转矩脉动,基于Y-Y移30°电角度的六相TPMSM建立电流型调速系统的数学模型,给出了换流重叠角的计算公式,并利用仿真分析了换相超前角和换流重叠角之间的关系以及换相超前角和转矩脉动之间的关系.结果表明,减小换相超前角有利于减小转矩脉动,但是会增加换流重叠角,甚至导致换流失败.%In order to study the commutation torque ripple of multiphase trapezia-wave permanent magnet synchronous motor (TPMSM) ,the mathematical model of current-type speed control system was established based on the six-phase TPMSM with Y-Y winding shifting 30° electric-degree. The calculating formula of commutating angular overlap was given. And the relationship of commutating angle and commutating angular overlap and relationship of commutating angular overlap and torque ripple were analyzed. The results show that reducing commutating angle is beneficial to reducing torque ripple, but it will increase commutating angular overlap,even bring on the failure of commutation.

  18. Ecohydrologic Implications and Management of Post-fire Soil Water Repellency in Burned Pinon-Juniper Woodlands

    Science.gov (United States)

    Madsen, Matthew; Zvirzdin, Daniel; Fernelius, Kaitlynn; McMillan, Mica; Kostka, Stanley

    2014-05-01

    Erosion and weed dominance often limit the recovery of piñon-juniper woodlands of western North America after high intensity wildfires. Soil water repellency (SWR) is one factor that may promote overland flow and impede seedling establishment. In spite of these effects, the influence of post-fire SWR on site recovery is poorly understood. Our presentation summarizes data collected within studies on burned piñon-juniper woodlands that provide new insight on: 1) the spatial distribution and severity of SWR, 2) influence of SWR on soil hydrology, nitrogen cycling, and site revegetation, and 3) the suitability of soil surfactants as a post-fire restoration tool. We demonstrate how patterns of SWR are highly correlated to pre-fire woodland canopy structure. At sites where SWR is present, infiltration, soil water content, and plant establishment is significantly less than at non-hydrophobic sites. We show how newly developed soil surfactants can significantly improve ecohydrologic properties required for plant growth by overcoming SWR; thus, increasing the amount and duration of available water for seed germination and plant growth. However, the application of soil surfactants in wildfire-affected ecosystems has been limited due to logistical and economic constraints associated with the standard practice of using large quantities of irrigation water as the surfactant carrier. We have developed a potential solution to this problem by using seed coating technology to use the seed as the carrier for the delivery of soil surfactant. Through this approach, precipitation leaches the surfactant from the seed into the soil where it absorbs onto the soil particles and ameliorates water repellency within the seeds microsite. We present findings from laboratory and field evaluations of surfactant seed coatings, which provide evidence that it may be plausible for the technology to improve post-fire seeding efforts by restoring soil hydrologic function and increasing seedling

  19. The Impact of Ozone Treatment in Dynamic Bed Parameters on Changes in Biologically Active Substances of Juniper Berries.

    Science.gov (United States)

    Brodowska, Agnieszka Joanna; Śmigielski, Krzysztof; Nowak, Agnieszka; Czyżowska, Agata; Otlewska, Anna

    2015-01-01

    The development of the parameters of ozone decontamination method assuring the least possible losses of biologically active substances (essential oils and polyphenols) and their activity in common juniper (Juniperus communis (L.)) berries was studied. Ozone treatment in dynamic bed was conducted 9 times. The process was conducted under different ozone concentrations (100.0; 130.0; 160.0 g O3/m3) and times (30, 60, 90 min). After each decontamination, the microbiological profile of the juniper berries was studied, and the contaminating microflora was identified. Next to the microbiological profile, the phenolic profile, as well as antioxidant activity of extracts and essential oils were determined. The total polyphenol content (TPC), composition of essential oils, free radical-scavenging capacity, total antioxidant capacity, ferric-reducing antioxidant power (FRAP), beta-carotene bleaching test (BCB) and LC-MS polyphenol analysis were carried out. The study reveals that during short ozone contact times, higher amounts of TPC, 15.47 and 12.91 mg CE/g of extract, for samples 100/30 and 130/30, respectively, were demonstrated. Whereas samples 100/60, 130/60, 100/90, and 160/90 exhibited the lowest amount of phenolics. The highest antioxidant activity was found in the methanol extract obtained from ozonated berries which exhibited the lowest IC50 in all the antioxidant assays, such as DPPH, FRAP, and BCB assays. Ozone treatment showed noteworthy potential and its usage in food manufacturing and as an alternative decontamination method should be considered.

  20. The Impact of Ozone Treatment in Dynamic Bed Parameters on Changes in Biologically Active Substances of Juniper Berries.

    Directory of Open Access Journals (Sweden)

    Agnieszka Joanna Brodowska

    Full Text Available The development of the parameters of ozone decontamination method assuring the least possible losses of biologically active substances (essential oils and polyphenols and their activity in common juniper (Juniperus communis (L. berries was studied. Ozone treatment in dynamic bed was conducted 9 times. The process was conducted under different ozone concentrations (100.0; 130.0; 160.0 g O3/m3 and times (30, 60, 90 min. After each decontamination, the microbiological profile of the juniper berries was studied, and the contaminating microflora was identified. Next to the microbiological profile, the phenolic profile, as well as antioxidant activity of extracts and essential oils were determined. The total polyphenol content (TPC, composition of essential oils, free radical-scavenging capacity, total antioxidant capacity, ferric-reducing antioxidant power (FRAP, beta-carotene bleaching test (BCB and LC-MS polyphenol analysis were carried out. The study reveals that during short ozone contact times, higher amounts of TPC, 15.47 and 12.91 mg CE/g of extract, for samples 100/30 and 130/30, respectively, were demonstrated. Whereas samples 100/60, 130/60, 100/90, and 160/90 exhibited the lowest amount of phenolics. The highest antioxidant activity was found in the methanol extract obtained from ozonated berries which exhibited the lowest IC50 in all the antioxidant assays, such as DPPH, FRAP, and BCB assays. Ozone treatment showed noteworthy potential and its usage in food manufacturing and as an alternative decontamination method should be considered.

  1. Modeling the shrub and juniper encroachment in the western north America grasslands with a Cellular Automata model

    Science.gov (United States)

    Caracciolo, D.; Istanbulluoglu, E.; Noto, L. V.

    2013-12-01

    Arid and semiarid grasslands of western North America have experienced dramatic changes over the last 150 years as a result of woody plant encroachment (WPE). WPE is characterized as increase in density, cover and biomass of indigenous tree or shrubby plants in grasslands. In this study we examine the environmental factors that trigger and further the progress of WPE at two semiarid sites using the CATGraSS ecohydrologic plant coexistence model. CATGraSS is a spatially distributed model driven by spatially explicit irradiance and runs on a fine-resolution gridded domain. In CATGraSS each cell can hold a single plant type or can remain empty. Plant competition is modeled by keeping track of mortality and establishment of plants, both calculated probabilistically based on soil moisture stress. For this study CATGraSS is improved with a stochastic fire and a grazing function, and its plant establishment algorithm is modified. Using CATGraSS shrub encroachment is studied in the Sevilleta National Wildlife Refuge (SNWR), New Mexico, located in the northern Chihuahuan desert. The area shows a dramatic encroachment front of Larrea tridentata (shrub) into native desert grassland. The model is implemented in a small area (7.3 km2) in SNWR. The second study site is a small catchment (11.8 km2) located within the Ochoco National Forest, Crook County, OR, where Juniper encroachment has been observed since the mid 1800s. The outcome of the changes in observed climate, fire frequency, and grazing intensity are investigated through numerical modeling scenarios. While in the Ochoco National Forest basin, the Western Juniper encroaches all the study area and the shrub disappears. In the SNWR basin, the model is able to reproduce the encroachment, simulating an increasing of the shrub from 2% in 1860 to 42% in 2010 (actual shrub percentage) highlighting as more influent factors the reduced fire frequency and the increased grazing intensity.

  2. PERMANENT-MAGNET INDUCTION GENERATORS: AN OVERVIEW

    Directory of Open Access Journals (Sweden)

    K. S. S. RAMAKRISHNAN

    2011-06-01

    Full Text Available The advantage of using a permanent-magnet induction generator (PMIG instead of a conventional induction generator is its ability to suppress inrush current during system linking when synchronous input is performed. Induction machines excited with permanent-magnet (PM are called permanent-magnet induction generators. This paper presents an exhaustive survey of the literature discussing the classification of permanent-magnet machines, process of permanent-magnet excitation and voltage build-up, modelling, steady-state and performance analysis of the permanent-magnet induction generators.

  3. Effects of garlic and juniper berry essential oils on ruminal fermentation and on the site and extent of digestion in lactating cows.

    Science.gov (United States)

    Yang, W Z; Benchaar, C; Ametaj, B N; Chaves, A V; He, M L; McAllister, T A

    2007-12-01

    The objective of this study was to evaluate the effects of feeding essential oils from garlic (GAR) and juniper berry (JUN), or monensin (MO) on feed intake, ruminal fermentation, the site and extent of digestion, microbial protein synthesis, milk production, and immune status in dairy cows. Four midlactating Holstein cows fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square design with 21-d periods and 4 treatments: control (no additive), MO (330 mg/cow per d), GAR (5 g/cow per d), and JUN (2 g/cow per d). Cows were fed ad libitum a TMR consisting of 40% forage and 60% barley-based concentrate. Dry matter intake averaged 20.4 kg/d and was not affected by dietary additives. Total tract digestibilities of dry matter, organic matter, fiber, and starch were not affected by experimental treatments. However, ruminal digestibilities of dry matter and organic matter were higher (+13%) for GAR and JUN than for the control diet, mainly because of increased crude protein digestion in the rumen. Feeding GAR and JUN increased ruminal digestion of dietary protein by 11% as compared with the control. In contrast, ruminal digestion of dietary protein was reduced by 11% with MO as compared with the control. Milk fat content was lower for MO (2.68%) than for the GAR (3.46%), JUN (3.40%), and control (3.14%) diets. No effects of GAR, JUN, or MO were observed on milk production, ruminal microbial protein synthesis, ruminal pH, and ruminal concentrations of volatile fatty acids and ammonia N. The total and differential numbers of white blood cells as well as serum amyloid A and haptoglobin were not affected by the treatments, suggesting that additives had no effect on the immune status of cows. Results of this study indicate that supplementing dairy cows with GAR (5 g/d) and JUN (2 g/d) essential oils improved feed digestibility in the rumen, but possibly at the expense of a reduction in the flow of bypass protein to the small intestine. Feeding monensin could

  4. Sensorless control and start-up strategy of permanent magnet synchronous motor%永磁同步电机无传感器控制及其启动策略

    Institute of Scientific and Technical Information of China (English)

    张耀中; 黄进; 康敏

    2015-01-01

    In order to realize sensorless vector control of permanent magnet synchronous motor, a novel method based on improved flux observer was adopted. A low-pass filter was used instead of a pure inte-grator, which reduced the errors caused by the initial value and DC offset. The magnitude and phase er-rors of the stator flux linkage introduced by the low-pass filters were compensated in the polar coordinate to make accurate estimation of speed and rotor position. In order to start motor successfully under the load conditions, a start-up method called I-f control was used, which can avoid the problem of overcurrent. A new switching strategy was also adopted. The given position was switched to the estimated according to weighting function. At the same time the given stator current was changed accordingly. It ensured that motors could switch from I-f control mode to vector control mode smoothly and reliably. The experimental results verify that the sensorless control system can work reliably and stably with smooth switching process and good control performance.%为了实现永磁同步电机的无速度传感器矢量控制,采用改进的磁链观测器法,用低通滤波环节代替纯积分环节,减小了初值误差及直流偏置误差,同时在极坐标系下对定子磁链幅值及相位进行补偿,实现转速和转子位置的准确估算。针对带载情况下无法自启动的问题,采用I-f控制自启动方法,避免了启动过程中出现过流情况。设计了一种新的切换方式,给定坐标角度按加权函数切换至位置观测值,同时相应改变定子电流给定值,保证电机平滑可靠地从I-f控制方式切换为矢量控制方式。实验表明,控制系统能够可靠稳定运行,切换过程平滑,控制性能良好。

  5. Decoupling control for permanent magnet synchronous motor based on single neuron%基于单神经元的永磁同步电机解耦控制

    Institute of Scientific and Technical Information of China (English)

    李晓宁; 赵现枫; 黄大贵; 邵伟

    2012-01-01

    The conventional decoupling strategy for the magnetic field-oriented control of permanent magnet synchronous motors (PMSM) is difficult to achieve high performances. To deal with this problem, we put forward a decoupling control strategy based on the single neuron, by exploiting the independency of neural network on the object model as well as its excellent learning ability. On the basis of the model of traditional magnetic field-oriented control, we build a single neuron decoupling control system for the PMSM, and perform the simulation as well as the experimental tests on the platform with digital signal processor (DSP) as the core element. The experimental results show that the PMSM control system based on the single neuron decoupling has rapid response ability and is almost with no static error and overshoot. It realizes high performance in PMSM control.%针对永磁同步电机(PMSM)磁场定向控制为代表的传统解耦策略难以实现高性能控制的问题,本文利用神经网络不依赖对象模型的特点以及出色的学习能力,提出了一种基于单神经元的永磁同步电机解耦控制策略.在传统磁场定向控制模型的基础上,构建了基于单神经元的永磁同步电机解耦控制系统,进行了仿真,并搭建以数字信号处理器为核心的电机控制实验平台上进行实验论证.结果表明,基于单神经元解耦的永磁同步电机控制系统具有快速响应能力,并且几乎达到无静差、无超调,实现了PMSM的高性能控制.

  6. Dynamic Analysis of Permanent Magnet Synchronous Generator with Power Electronics

    Directory of Open Access Journals (Sweden)

    OZCIRA, S.

    2010-05-01

    Full Text Available Permanent magnet DC motor-generators (PMDC, PMSG have been widely used in industrial and energy sectors recently. Power control of these systems can be achieved by controlling the output voltage. In this study, PMDC-PMSG systems are mathematically modeled and simulated in MATLAB and Simulink software. Then the results are discussed. A low power permanent magnet synchronous generator is driven by a permanent magnet DC motor and the output voltage is controlled by a frequency cycle-converter. The output of a half-wave uncontrolled rectifier is applied to an SPWM inverter and the power is supplied to a 300V, 50Hz load. The load which is connected to an LC filter is modeled by state-space equations. LC filter is utilized in order to suppress the voltage oscillations at the inverter output.

  7. 基于模糊控制的新型永磁开关磁阻电机控制系统研究与设计%Research and Design of the Permanent Switched Reluctance Motor Control System Based on Fuzzy Control

    Institute of Scientific and Technical Information of China (English)

    卫鹏; 张俊芳

    2013-01-01

    提出了一种新型永磁式开关磁阻电机.通过对传统电机结构上进行了改进,在定子上加入永磁材料,使得电机成为混合励磁电机,分析了其结构及原理等,并探讨了其调速方式,把模糊控制运用于调速系统,设计了其调速系统的软硬件,最后对其样机进行了试验,对开关磁阻电机的改进具有一定指导意义.%Based on an in-depth analysis of the new structure of the switched reluctance motor at home and abroad,this paper presents a new type of permanent magnet switched reluctance motor.The structure of the traditional motor is improved with permanent magnet materials adding to the stator to make the motor a hybrid excitation motor.This paper analyzes the structure and principles of the new permanent switched reluctance motor,and discusses the speed control method.By applying the fuzzy control to the speed control system,the hardware and software of the system are designed.Finally,the prototype of the system is tested,and the result of the test shows that the research has certain significance on improvement of switched reluctance motors.

  8. Dynamic Risk Analysis of Permanent Deformation of Sea Embankment

    Institute of Scientific and Technical Information of China (English)

    高玉峰; 刘汉龙; 余湘娟

    2001-01-01

    For evaluation of the permanent deformation of a sea embankment under stochastic earthquake excitation, a robust dynamic risk analytical method is presented based on conventional permanent deformation analysis and stochastic seismic response analysis. This method can predict not only the mean value of maximum permanent deformation but also the reliability corresponding to different deformation control standards. The earthquake motion is modelled as a stationary Gaussian filtered white noise random process. The predicted average maximum horizontal permanent displacement is in agreement with the conventional result. Further studied are the reliability of permanent deformation due to stochastic wave details at one seismic motion level and the risk of permanent deformation due to stochastic seismic strength, i. e., the maximum acceleration in a long period. Therefore, it is possible to make the optimal design in terms of safety and economy according to the importance of a sea embankment. It is suggested that the improved stochastic seismic model that can catch the behavior of the non-stationary random process for sea embankments should be further studied in future.

  9. 基于锁相环原理的永磁同步电机无传感器控制方法%Sensorless Control Method of Permanent Magnet Synchronous Motor Based on Principle of Phase-Locked Loop

    Institute of Scientific and Technical Information of China (English)

    郑昌陆; 胡月波; 耿宇翔

    2015-01-01

    研究了一种基于锁相环原理的转子位置估计方法。该方法的实际转子位置与估计转子位置间的比较环节相当于锁相环模型中的鉴相器,从转速到转子位置的一次积分相当于锁相环模型中的压控振荡,通过系统输入信号和输出信号之间的误差来调整电机的转速。仿真结果表明采用该转子位置和转速估计的PMSM无传感器矢量控制系统表现出较好的动静态性能,基于锁相环原理的PMSM调速系统具有优良的性能。%A rotor position estimation method based on the principle of phase-locked loop was studied. In the method,compare link between actual rotor position and the estimated rotor position was equivalent to the phase detector in the phase-locked loop model and an integral from speed to the rotor position was equivalent to the voltage-controlled oscillator phase-locked loop model. The speed of the motor was adjusted through the error between the input signal and the output signal of the system. The simulation results showed that sensorless permanent magnet synchronous motor vector control system which used the rotor position and speed estimation showed good performance.

  10. Sensorless Control of Permanent Magnet Synchronous Motor Based on Least Square Algorithm%基于最小二乘法的永磁同步电机无传感器控制

    Institute of Scientific and Technical Information of China (English)

    杨丙洲; 彭达洲

    2012-01-01

    A new rotor position and speed observer of permanent magnet synchronous motor was proposed based on the least square algorithm to accurately estimate the rotor position and speed and achieve sensorless control. Observer used the voltage equation in the synchronous rotating coordinate system, saw the voltage and current as the information variables and the rotor speed as parameter variables, used identification model of the least squares algorithm for online identification of the speed. The algorithm was simple and the computation cost was small. The results of MATLAB simulation showed that this control method was effective with its rapid response speed and strong robustness.%为准确估计永磁同步电机的转子位置和转速,实现无传感器控制,提出了一种基于最小二乘法的转子位置和转速观测器.观测器采用同步旋转坐标系下的电压方程,将电压、电流视为信息量,转子转速视为参数量,利用最小二乘法的辨识模型对转速进行在线辨识.该算法简单明了,计算量小.Simulink仿真结果表明该算法具有响应速度快、鲁棒性强,是一种有效的控制方法.

  11. Manganese-based Permanent Magnets

    Directory of Open Access Journals (Sweden)

    Ian Baker

    2015-08-01

    Full Text Available There is a significant gap between the energy product, BH, where B is the magnetic flux density and H is the magnetic field strength, of both the traditional ferrite and AlNiCo permanent magnets of less than 10 MGOe and that of the rare earth magnets of greater than 30 MGOe. This is a gap that Mn-based magnets could potentially, inexpensively, fill. This Special Issue presents work on the development of both types of manganese permanent magnets. Some of the challenges involved in the development of these magnets include improving the compounds’ energy product, increasing the thermal stability of these metastable compounds, and producing them in quantity as a bulk material.[...

  12. Automated phenotyping of permanent crops

    Science.gov (United States)

    McPeek, K. Thomas; Steddom, Karl; Zamudio, Joseph; Pant, Paras; Mullenbach, Tyler

    2017-05-01

    AGERpoint is defining a new technology space for the growers' industry by introducing novel applications for sensor technology and data analysis to growers of permanent crops. Serving data to a state-of-the-art analytics engine from a cutting edge sensor platform, a new paradigm in precision agriculture is being developed that allows growers to understand the unique needs of each tree, bush or vine in their operation. Autonomous aerial and terrestrial vehicles equipped with multiple varieties of remote sensing technologies give AGERpoint the ability to measure key morphological and spectral features of permanent crops. This work demonstrates how such phenotypic measurements combined with machine learning algorithms can be used to determine the variety of crops (e.g., almond and pecan trees). This phenotypic and varietal information represents the first step in enabling growers with the ability to tailor their management practices to individual plants and maximize their economic productivity.

  13. 永磁同步发电机的无传感器滑模辨识及控制%Speed sensorless sliding mode observer and control of permanent magnet synchronous generator

    Institute of Scientific and Technical Information of China (English)

    史旺旺; 刘超

    2012-01-01

    针对坐标旋转法永磁同步发电机无速度传感器控制中忽略定子电流微分项带来的估计偏差大等问题,提出基于旋转坐标系的自适应锁相环和滑模辨识方法.采用近似滑模控制对模型电机定子电流进行控制,使发电机和模型电机电流相等,从而获得两电机转子相位差的正弦和余弦分量.建立直驱式永磁同步电机无速度传感器辨识模型和自适应锁相环模型,并利用基于反步法的自适应锁相环进行速度和相位观测,在此基础上利用Lyapunov函数设计法设计控制器.采用近似滑模辨识使模型电机电流快速逼近原电机电流且到近似正弦的控制量,自适应数字锁相环相位收敛快,采用Lyapunov函数设计的控制器能保证系统收敛.仿真结果验证了该方法的可行性和有效性.%Aiming at the big error problem of speed sensorless permanent magnet synchronous generator (PMSG) control with rotating frame by omitting differential component in direct-driven wind power system , a sliding mode observer with adaptive phase-locked loop( PLL) was presented. Model PMSG current was controlled to keep track of PMSG current by approximate sliding mode observer ( SMO) and rotor phase difference of two machine were acquired. Speed and phase were observed by adaptive PLL with acquired sine and cosine component. The sensorless model for PMSG and adaptive PLL model were presented and controller was designed with Lyapunov function method. Simulation results show that the model based on model machine observer with approximation SMO and PLL can accurately control current with quick response and fine static dynamic performance, and controller designed by Lyapunov function can ganrantee convergence.

  14. Trans-permanent magnetic actuation

    Science.gov (United States)

    Farmer, Daniel Jay

    The demands for an actuator to deploy, position and shape large spaced-based structures form a unique set of design criteria. In many applications it is desirable to hold displacements or forces between two points to within specified requirements (the regulation problem) and to periodically to change position (the tracking problem). Furthermore, the interest generally lies in satisfying the dynamic performance requirements while expending minimal power, while meeting tight tolerances and while experiencing little wear and fatigue. The actuator must also be able to withstand a variety of operational conditions such as impacts and thermal changes over an extended period of time. Current trends in large-scale structures have addressed the demands by using conventional actuators and motors, along with elaborate linkages or mechanisms to shape, position, protect and deploy. The developed designs use unique characteristics of permanent magnets to create simple direct-acting actuators and motors very suitable for space based structures. The developed trans-permanent magnetic (T-PM) actuators and motors are systems consisting of one or more permanent magnets, some of whose magnetic strengths can be switched on-board by surrounding pulse-coils. The T-PM actuator and motors expend no power during regulation. The T-PM can periodically change or remove the strength of its own magnets thereby enabling both fine-tune adjustments (microsteps) and large-scale adjustments (rotation). The fine (microstep) adjustments are particularly helpful in thermally varying space environments. The large-scale adjustments (rotation) are particularly helpful in deployment where the structure or antenna must experience large-angle rotations and/or large displacements. T-PM concepts are illustrated in direct acting actuators and built into stepper motor and permanent magnet motor applications. Several examples of design, analysis and testing are developed to verify the technology and supporting

  15. The cycloid Permanent Magnetic Gear

    DEFF Research Database (Denmark)

    Rasmussen, Peter Omand; Andersen, Torben Ole; Jørgensen, Frank T.

    2008-01-01

    This paper presents a new permanent-magnet gear based on the cycloid gearing principle. which normally is characterized by an extreme torque density and a very high gearing ratio. An initial design of the proposed magnetic gear was designed, analyzed, and optimized with an analytical model...... regarding torque density. The results were promising as compared to other high-performance magnetic-gear designs. A test model was constructed to verify the analytical model....

  16. Research of active disturbance rejection controller of direct torque control system of permanent magnet synchronous motor based on parameter optimization%基于参数优化的永磁同步电动机直接转矩控制系统自抗扰控制器研究

    Institute of Scientific and Technical Information of China (English)

    杨杰; 黄坤

    2013-01-01

    针对基于PI控制器的永磁同步电动机直接转矩控制系统存在转矩波动大、易受负载变化影响的问题,设计了一种基于转速外环的自抗扰控制器,代替PI控制器以改善永磁同步电动机直接转矩控制系统的性能;采用粒子群优化算法对自抗扰控制器的相关参数进行了优化计算,改进了控制器的调节性能.仿真和实验结果表明,基于参数优化自抗扰控制器的永磁同步电动机直接转矩控制系统具有较高的抗负载扰动能力,更快的响应速度和良好的动、静态性能.%In view of problems of big torque fluctuation and easy to be influenced by load change existed in direct torque control system of permanent magnet synchronous motor based on PI controller,the paper designed an active disturbance rejection controller based on speed loop to replace PI controller to improve performances of direct torque control system of permanent magnet synchronous motor.It used particle swarm optimizer algorithm to make optimization calculation for the parameters of the active disturbance rejection controller and improved adjustment performance of the controller.The simulation and experimental results show that the system based on the active disturbance rejection controller with parameters optimization has higher ability of anti-disturbance of load,faster response speed and good dynamic and static performance.

  17. Permanent magnets including undulators and wigglers

    OpenAIRE

    Bahrdt, J.

    2011-01-01

    After a few historic remarks on magnetic materials we introduce the basic definitions related to permanent magnets. The magnetic properties of the most common materials are reviewed and the production processes are described. Measurement techniques for the characterization of macroscopic and microscopic properties of permanent magnets are presented. Field simulation techniques for permanent magnet devices are discussed. Today, permanent magnets are used in many fields. This article concentrat...

  18. EDITORIAL: Permanent revolution - or evolution?

    Science.gov (United States)

    Dobson, Ken

    1998-03-01

    Honorary Editor It was that temporary Bolshevik Leon Trotsky who developed the principle of `permanent revolution', a principle that perhaps characterizes the recent history of education in (south) Britain more than does, say, principles traditionally associated with the Conservative or Labour parties. As this editorial is being written, changes are being made to primary school education, and the long-awaited details of the post-Dearing reorganizing of post-16 education are yet to hit the overful bookshelves and filing cabinets of school heads and examination board officials. But something unique has happened recently which might have surprised even Trotsky. The Secretary of State for Education has set up targets for primary school pupils' attainment and threatened (or promised) to resign if they are not met within the lifetime of our newly elected parliament. Of course, if Mr Blunkett is still in a position to resign at that stage he will have been the longest serving Secretary of State since time immemorial. But we should not carp: this is truly a revolutionary idea. Not the promise to resign - although this idea is not so fashionable now as it once was. The revolutionary idea is that a major change to an educational process is actually being made that carries with it a predicted and testable outcome. By contrast, when school physics was refreshed a generation ago by the introduction of Nuffield courses at both pre- and post-16 stages, no `targets' were set. I and many other physics teachers certainly preferred teaching these to teaching their predecessor syllabuses, and might even dare to assert that the pupils liked them too. But we still don't really know whether or not they learned more - or even better - physics. Very little happened as far as the outside world was concerned: the usual fraction of students gave up physics at the usual ages, and those who were examined didn't really get a better reward for their more up-to-date and more enjoyably learned

  19. Bulanık Kazanç Ayarlamalı Nonlineer PI Kontrolörün Kalıcı Mıknatıslı Doğru Akım Motor-Dinamo Sistemine Uygulanması = Applying the Fuzzy Gain Scheduling Nonlinear PI Controller to Permanent Magnet Direct Current Motor - Dynamo System

    Directory of Open Access Journals (Sweden)

    Kamil Burak DALCI

    2004-01-01

    Full Text Available This paper describes the realization of a fuzzy gain scheduling scheme of a PI controller using a RISC microcontroller. Fuzzy rules and reasoning are utilised on-line to determine the PI controller parameters based on the error signal and its first difference. The Fuzzy control algorithm is implemented in the RISC microcontroller to regulate the speed of a permanent magnet DC motor (PMDC and works on-line. The microcontroller directly tunes the motor speed with a chopper converter which changes the motor terminal voltage. Application results demonstrate that better control performance can be achieved in comparison with traditional PI controllers.

  20. 基于开绕组结构的永磁风力发电机控制策略%Control strategy of permanent magnet wind generator based on open winding configuration

    Institute of Scientific and Technical Information of China (English)

    年珩; 周义杰; 李嘉文

    2013-01-01

    Aimed at the operation demands on the large capacity and high performance of permanent mag net synchronous generator (PMSG) for wind power generation system, the generation system with open winding based PMSG and two cascaded two-level converter is built, in which the vector control, position sensorless control, space vector modulation are investigated. By analyzing the mathematic model of the open winding PMSG, the vector control strategy based on the rotor flux orientation and the sensorless op eration technique based on the back electromotive force estimation was implemented, and then the target vector assignment method and the corresponding space vector modulation strategy for the two generator-side converter were also studied. The analysis results indicate that the proposed open winding PMSG sys tem can not only decrease the generator-side converter capacity, but achieve the three-level modulation effect. The correctness and availability of the proposed system and control strategy are validated by the experimental results.%为了实现永磁风力发电机组大容量、高性能的运行需求,建立一种基于开绕组结构的永磁同步发电机和两个级联两电平变流器组成的风力发电系统.对该系统所采用的矢量控制、无位置传感器运行、空间矢量调制等技术进行了研究.通过建立开绕组永磁同步发电机的数学模型,得出基于转子磁场定向的矢量控制策略,进而结合基于反电势估算法的无位置传感器运行技术,研究了开绕组永磁同步发电机在两个机侧变流器下的目标矢量分配方法及对应的空间矢量调制策略.分析结果表明,所提出的开绕组永磁同步发电系统不仅降低了机侧变流器的容量,还起到了三电平的调制效果.实验结果验证了所提结构及控制策略的正确性和可行性.

  1. 直驱永磁同步风力发电机控制策略的研究%Control Strategy Research of Permanent-magnetic Direct-drive Wind Power Generator

    Institute of Scientific and Technical Information of China (English)

    鞠天广; 任永峰; 刘峰; 关勇; 丛雨

    2012-01-01

    Compare with AC excitation doubly fed wind energy generation system, direct -drive permanent magnet synchronous wind power system has the advantages of simple structure, power efficiency and high reliability. In this paper, a new generation of electric power system simulation software PSCAD/EMTDC was used as the base, simulation model for 1. 5 MW PMSG wind power generation system was established; Below the rated wind speed, the characteristics of PMSG wind power generation system under the control strategy of the optimum tip speed ratio was studied, Using space vector modulation method, maximum wind power tracking control was a-chieved; VSCF and the decoupled control of active power and reactive power of nets side converter grid-connected was also achieved. Finally the simulation result was analyzed; to verify the validity of control strategy.%与双馈交流励磁风力发电系统相比,直驱永磁同步风力发电系统具有结构简单、发电效率及运行可靠性高等优点.本文利用电力系统仿真工具PSCAD/EMTDC为基础,建立了1.5 MW直驱永磁同步风力发电系统的仿真模型;在低于额定风速下,研究了最佳叶尖速比控制策略下直驱永磁同步风力发电系统的特性,采用空间矢量调制方法实现了风力发电机最大风能跟踪的控制;网侧变换器并网实现了变速恒频和有功功率与无功功率的解耦控制;最后对仿真结果进行分析,验证了控制策略的正确性.

  2. Data Report: Meteorological and Evapotranspiration Data from Sagebrush and Pinyon Pine/Juniper Communities at Pahute Mesa, Nevada National Security Site, 2011-2012

    Energy Technology Data Exchange (ETDEWEB)

    Jasoni, Richard L [DRI; Larsen, Jessica D [DRI; Lyles, Brad F. [DRI; Healey, John M [DRI; Cooper, Clay A [DRI; Hershey, Ronald L [DRI; Lefebre, Karen J [DRI

    2013-04-01

    Pahute Mesa is a groundwater recharge area at the Nevada National Security Site. Because underground nuclear testing was conducted at Pahute Mesa, groundwater recharge may transport radionuclides from underground test sites downward to the water table; the amount of groundwater recharge is also an important component of contaminant transport models. To estimate the amount of groundwater recharge at Pahute Mesa, an INFIL3.0 recharge-runoff model is being developed. Two eddy covariance (EC) stations were installed on Pahute Mesa to estimate evapotranspiration (ET) to support the groundwater recharge modeling project. This data report describes the methods that were used to estimate ET and collect meteorological data. Evapotranspiration was estimated for two predominant plant communities on Pahute Mesa; one site was located in a sagebrush plant community, the other site in a pinyon pine/juniper community. Annual ET was estimated to be 310±13.9 mm for the sagebrush site and 347±15.9 mm for the pinyon pine/juniper site (March 26, 2011 to March 26, 2012). Annual precipitation measured with unheated tipping bucket rain gauges was 179 mm at the sagebrush site and 159 mm at the pinyon pine/juniper site. Annual precipitation measured with bulk precipitation gauges was 222 mm at the sagebrush site and 227 mm at the pinyon pine/juniper site (March 21, 2011 to March 28, 2012). A comparison of tipping bucket versus bulk precipitation data showed that total precipitation measured by the tipping bucket rain gauges was 17 to 20 percent lower than the bulk precipitation gauges. These differences were most likely the result of the unheated tipping bucket precipitation gauges not measuring frozen precipitation as accurately as the bulk precipitation gauges. In this one-year study, ET exceeded precipitation at both study sites because estimates of ET included precipitation that fell during the winter of 2010-2011 prior to EC instrumentation and the precipitation gauges started

  3. 21 CFR 886.4445 - Permanent magnet.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Permanent magnet. 886.4445 Section 886.4445 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4445 Permanent magnet. (a) Identification. A permanent magnet is a nonelectric device that generates a magnetic field intended to find and remove...

  4. Comparing the above-ground component biomass estimates of western junipers using airborne and full-waveform terrestrial laser scanning data

    Science.gov (United States)

    Shrestha, R.; Glenn, N. F.; Spaete, L.; Hardegree, S. P.

    2012-12-01

    With the rapid expansion into shrub steppe and grassland ecosystems over the last century, western juniper (Juniperus occidentalis var. occidentalis Hook) is becoming a major component of the regional carbon pool in the Intermountain West. Understanding how biomass is allocated across individual tree components is necessary to understand the uncertainties in biomass estimates and more accurately quantify biomass and carbon dynamics in these ecosystems. Estimates of component biomass are also important for canopy fuel load assessment and predicting rangeland fire behavior. Airborne LiDAR can capture vegetation structure over larger scales, but the high crown penetration and sampling density of terrestrial laser scanner (TLS) instruments can better capture tree components. In this study, we assessed the ability of airborne LiDAR to estimate biomass of tree components of western juniper with validation data from field measured tees and a full-waveform TLS. Sixteen juniper trees (height range 1.5-10 m) were randomly selected using a double sampling strategy from different height classes in the Reynolds Creek Experimental Watershed in the Owyhee Mountains, southwestern Idaho, USA. Each tree was scanned with a full-waveform TLS, and the dry biomass of each component (foliage, branches and main stem) were measured by destructive harvesting of the trees. We compare the allometric relationships of biomass estimates of the tree components obtained from field-measured trees and TLS-based estimates with the estimates from discrete-return airborne-LiDAR based estimates.

  5. Chemical Composition and Antioxidant Properties of Juniper Berry (Juniperus communis L.) Essential Oil. Action of the Essential Oil on the Antioxidant Protection of Saccharomyces cerevisiae Model Organism

    Science.gov (United States)

    Höferl, Martina; Stoilova, Ivanka; Schmidt, Erich; Wanner, Jürgen; Jirovetz, Leopold; Trifonova, Dora; Krastev, Lutsian; Krastanov, Albert

    2014-01-01

    The essential oil of juniper berries (Juniperus communis L., Cupressaceae) is traditionally used for medicinal and flavoring purposes. As elucidated by gas chromatography/flame ionization detector (GC/FID) and gas chromatography/mass spectrometry (GC/MS methods), the juniper berry oil from Bulgaria is largely comprised of monoterpene hydrocarbons such as α-pinene (51.4%), myrcene (8.3%), sabinene (5.8%), limonene (5.1%) and β-pinene (5.0%). The antioxidant capacity of the essential oil was evaluated in vitro by 2,2-Diphenyl-1-picrylhydrazyl (DPPH) scavenging, 2,2-azino-bis-3-ethylbenzothiazoline-6 sulfonic acid (ABTS) radical cation scavenging, hydroxyl radical (ОН•) scavenging and chelating capacity, superoxide radical (•O2−) scavenging and xanthine oxidase inhibitory effects, hydrogen peroxide scavenging. The antioxidant activity of the oil attributable to electron transfer made juniper berry essential oil a strong antioxidant, whereas the antioxidant activity attributable to hydrogen atom transfer was lower. Lipid peroxidation inhibition by the essential oil in both stages, i.e., hydroperoxide formation and malondialdehyde formation, was less efficient than the inhibition by butylated hydroxytoluene (BHT). In vivo studies confirmed these effects of the oil which created the possibility of blocking the oxidation processes in yeast cells by increasing activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). PMID:26784665

  6. Development of a permanently controllable rotating biopsy device. Pt. 2. competitive in-vitro testing of a cannula-like prototype compared to established end-cut and side-notch biopsy devices

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, P.J.; Schaefer, F.K.; Strutz, A.; Heller, M.; Jahnke, T. [Universitaetsklinikum Schleswig-Holstein, Kiel (Germany). Klinik fuer Diagnostische Radiologie; Kurz, B. [Kiel Univ. (Germany). Inst. fuer Anatomie; Hedderich, J. [Universitaetsklinikum Schleswig-Holstein, Kiel (Germany). Inst. fuer Medizinische Statistik und Informatik

    2010-01-15

    To evaluate the quantitative and qualitative efficiency of a permanently controllable biopsy-cannula prototype with lancet-like helically bent cutting edge for safer biopsy compared to established end-cut and side-notch biopsy devices. Each of the n = 100 specimens per organ and system were obtained by the prototype, an end-cut device and a side-notch device (18 gauge each) using a bovine liver, kidney and myocardium as the biopsy tissue. Quantitatively, the number of fragments, length in mm and weight in mg of the specimen were analyzed. Qualitatively, a histopathological analysis was performed with respect to tissue fragmentation, crush artifact and adequacy of tissue (score per category min. 1 and max 3). To identify significant differences (p < 0.025), chi-square and Kruskal-Wallis tests were calculated in the statistical analysis. For each of the n = 300 specimens, the one-piece fragment/mean length/mean weight were n = 232 / 10.34 mm/ 4.86 mg for the prototype, n = 210 / 12.16 mm/ 5.35 mg for the end-cut system and n = 248 / 11.63 mm/ 4.08 mg for the side-notch system. The differences reached a level of significance with p < 0.001. The mean histopathological score for the prototype/end-cut system/side-notch system was 5.60 / 5.60 / 5.25 for the liver, 5.65 / 4.65 / 4.60 for the kidney and 5.05 / 5.35 / 4.85 for the myocardium. The differences did not reach a level of significance for the liver/kidney/myocardium with p = 0.665 /p = 0.186 /p = 0.436. Compared to established core biopsy systems, the biopsy-cannula prototype offers diagnostically equivalent biopsy specimen quality in an in-vitro setting in bovine liver, kidney and myocardium. (orig.)

  7. Sensorless Control of Permanent Magnet Synchronous Motor Based on Extended Sliding Mode Observer%基于扩展滑模观测器的永磁同步电动机无传感器控制

    Institute of Scientific and Technical Information of China (English)

    李冉; 赵光宙; 徐绍娟

    2012-01-01

    针对传统滑模观测器在估计电机转速时存在的抖动问题,本文通过永磁同步电机扩展状态方程以及扩展滑模观测器,将滑模控制和模型参考自适应结合在一起,来提取电机转速。从仿真和实验两方面,对新方法与传统滑模观测器方法作了详细的比较,结果验证了新方法可以避免传统滑模参数估计时存在的抖动问题,同时具有良好的动静态性能以及更高的估计精度。%Aiming at the chattering problem arising from the estimation of rotor velocity by using traditional sliding mode observer(SMO),the paper combines sliding mode control with model reference adaptive systems by the extended state equations of permanent magnet synchronous motor(PMSM) and the equations of extended sliding mode observer of PMSM,and then the new estimation method of rotor velocity is presented.The detailed comparison between the proposed method and the traditional one is introduced according to simulation analysis and experimental validation.The simulation and experimental results show the superiority of the proposed method which avoid the chattering problem of the traditional one and better estimated precision,moreover,good dynamic and static performance are achieved.

  8. 双三电平永磁直驱风力发电系统控制策略研究%Dual Three-level Permanent Magnet Direct Drive Wind Power System Control Strategy

    Institute of Scientific and Technical Information of China (English)

    王斌; 王峰; 刘毅; 张杰

    2011-01-01

    为满足变流器容量需求并获取较低的电流谐波指标,降低开关损耗,达到良好的并网要求,直驱式风力发电系统采用永磁同步发电机(PMSG)和双三电平变流器相结合的拓扑结构.基于PMSG d,q坐标系下的数学模型,机侧变换器运用简化的空间矢量脉宽调制技术并结合PMSG的最大转矩电流比控制策略,充分利用凸极效应,提高系统运行效率,网侧变换器采用电压电流双闭环控制策略.利用Matlab软件建立直驱式永磁同步风力发电系统的仿真模型,并对风速突变时系统的动态特性进行研究.仿真结果表明,所建立模型具有较好的动态特性并验证了控制系统的正确性及有效性.%To meet the requirement for the capacity, low current harmonic level and low switching loss, direct-drive wind power generation system employed the topology which combined the permanent magnet synchronous generator (PMSG) and dual three-level PWM full-size converter.Based on d,q axis mathematical model of PMSG,in order to take full advantages of saliency effects, improve efficiency, the generator side adopts simplified space vector pulse width modulation technology combined with maximum torque per ampere control scheme.The grid side employes the dual close-loop control strategy which are the inner current-loop and the outer voltage-loop. The model of direct-drive wind power generation system is realized with the engineering software, Matlab for the case of wind speed stepping change shows the excellent dynamic performance of the model, in the same time, verifies the correctness and feasibili ty of the control strategy.

  9. A Direct Torque Control Algorithm of Five-phase Permanent-magnet Machines With Multi-objective Optimization%五相永磁同步电机多目标优化直接转矩控制算法

    Institute of Scientific and Technical Information of China (English)

    薛诚; 宋文胜; 冯晓云

    2016-01-01

    The multi-phase permanent magnet synchronous machine (PMSM) has the property of small size, low noise and high power density, so it has been widely used in high-power and low-voltage occasion. Based on the analysis of traditional direct torque control (DTC) models and space vector pulse width modulation (SVPWM) technologies, a fixed switching frequency modified DTC algorithm of five-phase PMSM with multi-objective optimization was proposed, which aims at improving the trajectory of stator flux effectively, reducing torque ripples and low harmonic components of stator currents. The proposed algorithm brings the following benefits: such as fast torque control dynamic response, the fixed switching frequency, the optimization control of torque, stator flux and stator phase currents. Simulation and experimental results show the feasibility and effectiveness of the proposed algorithm.%多相永磁同步电机驱动系统因具有体积小、噪声低、功率密度高等诸多优点,在低压、大功率输出及可靠性要求高的场合已得到了广泛关注和应用。该文以五相永磁同步电机为研究对象,分析并建立传统直接转矩控制(direct torque control,DTC)算法数学模型,在此基础上,以进一步优化转矩纹波及磁链轨迹,降低定子电流低次谐波为控制目标,结合空间矢量脉宽调制(space vector pulse width modulation, SVPWM)技术,提出改进DTC的定频多目标优化控制模型。该算法不仅保持了传统DTC快速的转矩控制动态响应,实现了开关频率恒定及转矩的无稳态误差,同时也兼顾了定子磁链以及相电流的优化控制。仿真和实验结果均表明该算法的正确性和有效性。

  10. Position-Sensorless Vector Control of Permanent Magnet Synchronous Motor at Full Speed Range%永磁同步电机在全速范围内的无位置传感器矢量控制

    Institute of Scientific and Technical Information of China (English)

    张海燕; 刘军; 兖涛; 赵瑶瑶

    2014-01-01

    提出一种混合控制策略以实现永磁同步电机在全速范围内的无速度传感器控制,在中、高速范围内,采用基于基波模型的滑模观测器法估算电机转子速度与位置。在零速、低速范围内,为避免滑模法的缺陷则切换到高频信号注入法。实现了滑模观测器法的应用,测算出滑模法的应用速度下限,确立混合模式下速度切换区的依据。试验仿真结果表明:结合滑模观测器法与高频注入法的混合模式能够有效降低算法切换过程中的抖振,实现了永磁同步电机在全速范围内的无速度传感器控制。%A hybrid control strategy was proposed, in order to realize the position-sensorless vector control of permanent magnet synchronous motor ( PMSM ) at full speed range. The sliding mode observer method based on fundamental wave model was used for estimating the motor rotor speed and position at medium and high speed range. While at low or zero speed range, in order to avoid the defects of sliding mode observer, it switches to the high frequency injection method. The application of sliding mode observer was achieved. And the speed limit of sliding mode observer was measured, which is used as basis for establishing a speed switching area of mixed mode. The experiment simulation results show that the mixed mode of sliding mode observer and high frequency injection can effectively reduce the chatter in the process of switching of algorithm, and the control of PMSM is realized at full speed range.

  11. Permanent-File-Validation Utility Computer Program

    Science.gov (United States)

    Derry, Stephen D.

    1988-01-01

    Errors in files detected and corrected during operation. Permanent File Validation (PFVAL) utility computer program provides CDC CYBER NOS sites with mechanism to verify integrity of permanent file base. Locates and identifies permanent file errors in Mass Storage Table (MST) and Track Reservation Table (TRT), in permanent file catalog entries (PFC's) in permit sectors, and in disk sector linkage. All detected errors written to listing file and system and job day files. Program operates by reading system tables , catalog track, permit sectors, and disk linkage bytes to vaidate expected and actual file linkages. Used extensively to identify and locate errors in permanent files and enable online correction, reducing computer-system downtime.

  12. Performance of repulsive type magnetic bearing system under nonuniform magnetization of permanent magnet

    OpenAIRE

    Ohji, T.; Mukhopadhyay, S. C.; Iwahara, Masayoshi; Yamada, Sotoshi

    2000-01-01

    Permanent magnet bearing system utilizes the repulsive forces between the stator and rotor permanent magnets (PM) for the levitation of the system and it results a simplified axial control scheme. A repulsive type magnetic bearing system based on the above principle was fabricated in our laboratory. Material characteristics and the configuration of the permanent magnets are the central component for this type of bearing system. Due to aging or as both the magnets are repelling each other, the...

  13. CERN Permanent exhibitions short version

    CERN Multimedia

    2016-01-01

    Visits Explore by yourself the issues CERN's physicists are trying to solve: given that the entire universe is made of particles, where do they come from? Why do they behave in the way they do? Discover the massive apparatus used by physicists at CERN, like the LHC, and see how each part works. CERN invites the public to discover the mysteries of the Universe and the work of the world's biggest physics laboratory through free of charge guided tours and permanent exhibitions. As a group, with friends, individually, on foot, on your bike, come and discover CERN or explore it virtually. Welcome!

  14. Sensorless Control of Permanent Magnet Synchronous Motor Based on Improved Sliding-Mode Observer%基于改进型滑模观测器的PMSM无位置控制

    Institute of Scientific and Technical Information of China (English)

    刘昇; 卢广山; 徐瑜; 刘闯

    2013-01-01

    In order to realize the permanent magnet synchronous motor (PMSM) sensorless control with high performance,which cannot be reached by conventional sliding-mode observer algorithm with defects of violent chattering phenomena,slow convergence speed and relatively low steady state accuracy,an improved sliding-mode observer algorithm using the saturated function as reaching law is put forward.By using saturated function instead of traditional switch function,and combined with the corresponding filter link and compensation link,the accuracy and the robustness of the observer are greatly improved.As a result,this algorithm provides conditions for the realization of PMSM space vector sensorless control.In the actual system,linear approximation method is used to simulate saturated function.Related simulation and experiment prove that this method provides better performance than the traditional sliding-mode observer.%为了实现永磁同步电机的高性能无位置控制,针对传统滑模观测器算法抖振现象剧烈、收敛速度慢、稳态精度不高的特点,提出了一种基于饱和函数趋近律的改进型滑模观测器无位置算法.由饱和函数取代传统的开关函数,并结合相应的滤波环节、补偿环节,提高了观测器的准确性和鲁棒性,为实现永磁同步电机的无位置矢量控制提供了条件.在实际系统中采用线性逼近的方法模拟饱和函数.相关的仿真和实验证明了该方法比传统滑模观测器具有更好的性能.

  15. Soil moisture, temperature, and carbon substrate influences on soil respiration in a piñon-juniper woodland

    Science.gov (United States)

    Berryman, E.; Marshall, J. D.; Rahn, T.; Litvak, M. E.

    2010-12-01

    Arid and semi-arid ecosystems may be more vulnerable to climate change than mesic systems, having potentially large consequences for ecosystem carbon balance of the US southwest. Specifically, piñon-juniper woodlands cover much of the land area in the SW US, and they have experienced widespread piñon mortality in the past ten years. The impact of this mortality on carbon cycling in these ecosystems has yet to be fully examined. Of particular current interest is how soil temperature, soil moisture, and substrate availability interact to influence short-term variability of soil respiration rates. In this study, we examined the dependence of soil respiration on recent piñon photosynthate, temperature, and moisture in a piñon-juniper woodland in central New Mexico. We utilized phloem-girdling to study the importance of recently-fixed photosynthate as substrate for respiration, and we treated the stable carbon isotope ratio of soil respiration as indicative of different substrate sources contributing to soil respiration. Due to the presence of C3, C4, and CAM photosynthetic pathways in the ecosystem, we were able to infer changing contribution of different sources to soil respiration. We found that soil-respired δ13C depended on both soil moisture and lagged precipitation, although in dissimilar manners, suggesting different mechanisms are triggered by rainfall events compared to elevated soil moisture. C3-source respiration responded quickly to precipitation events. Over a ten-day period following girdling of piñon trees, soil-respired δ13C did not significantly change compared to a reference plot. There were also distinct differences in carbon isotope signatures and temporal patterns of such signatures of soil respiration collected in open spaces compared to underneath piñon canopies, emphasizing the importance of considering spatial variability when sampling soil-respired CO2 in patchy ecosystems. Overall, we found little evidence that soil respiration in

  16. Magnetostatic interactions and forces between cylindrical permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Vokoun, David [Institute of Physics ASCR, v.v.i., Prague (Czech Republic)], E-mail: vokoun@fzu.cz; Beleggia, Marco [Institute for Materials Research, University of Leeds, Leeds LS2 9JT (United Kingdom); Heller, Ludek; Sittner, Petr [Institute of Physics ASCR, v.v.i., Prague (Czech Republic)

    2009-11-15

    Permanent magnets of various shapes are often utilized in magnetic actuators, sensors or releasable magnetic fasteners. Knowledge of the magnetic force is required to control devices reliably. Here, we introduce an analytical expression for calculating the attraction force between two cylindrical permanent magnets on the assumption of uniform magnetization. Although the assumption is not fulfilled exactly in cylindrical magnets, we obtain a very good agreement between the calculated and measured forces between two identical cylindrical magnets and within an array of NdFeB cylindrical magnets.

  17. Magnetostatic interactions and forces between cylindrical permanent magnets

    Science.gov (United States)

    Vokoun, David; Beleggia, Marco; Heller, Luděk; Šittner, Petr

    2009-11-01

    Permanent magnets of various shapes are often utilized in magnetic actuators, sensors or releasable magnetic fasteners. Knowledge of the magnetic force is required to control devices reliably. Here, we introduce an analytical expression for calculating the attraction force between two cylindrical permanent magnets on the assumption of uniform magnetization. Although the assumption is not fulfilled exactly in cylindrical magnets, we obtain a very good agreement between the calculated and measured forces between two identical cylindrical magnets and within an array of NdFeB cylindrical magnets.

  18. Analysis and Design of Hybrid Excitation Permanent Magnet Synchronous Generators

    Institute of Scientific and Technical Information of China (English)

    JIN Wan-bing; ZHANG Dong; AN Zhong-liang; TAN Ren-yuan

    2006-01-01

    On the basis of a conventional permanent magnet (PM) synchronous generator's construction,a novel kind of Hybrid Excitation Permanent Magnet Synchronous Generator (HEPMSG) is introduced by inserting exciting winding in the stator or rotor.Firstly,the construction of HEPMSG is improved with the addition of PM excitation on the ferromagnetic pole,and its working principle and design method are studied in detail.Then,an appropriate exciting current control system is presented considering the characteristics of HEPMSG.Finally,a prototype is made,and test results confirm the analysis and design.

  19. Variable-period permanent-magnet helical undulator

    OpenAIRE

    Jungho Mun; Young Uk Jeong; Vinokurov, Nikolay A.; Kitae Lee; Kyu-Ha Jang; Seong Hee Park; Min Yong Jeon; Sang-In Shin

    2014-01-01

    We realized a variable-period permanent-magnet helical undulator with high (∼1  T) field amplitude, which is almost constant over undulator periods of 23–26 mm. Each undulator period has four modular sections of iron poles and permanent magnets embedded in nonmagnetic disks with holes along the undulator axis. Modular plates undergo a longitudinal repulsive force from the magnetic field pressure and the spring coils between modular plates. The undulator period can thus be controlled by mechan...

  20. Magnetic forces between arrays of cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, D.; Tomassetti, G.; Beleggia, Marco

    2011-01-01

    Permanent magnet arrays are often employed in a broad range of applications: actuators, sensors, drug targeting and delivery systems, fabrication of self-assembled particles, just to name a few. An estimate of the magnetic forces in play between arrays is required to control devices and fabrication...... procedures. Here, we introduce analytical expressions for calculating the attraction force between two arrays of cylindrical permanent magnets and compare the predictions with experimental data obtained from force measurements with NdFeB magnets. We show that the difference between predicted and measured...

  1. Improved Design of Hoisting Equipment with Permanent Magne

    Directory of Open Access Journals (Sweden)

    S. S. Stoyanova

    2010-01-01

    Full Text Available Hoisting equipment for lifting ferromagnetic loads can be designed while using electromagnets and permanent magnets. The second variant finds wider application due to great successes in creation of hard magnetic materials and significantly less electric power consumption. A shortcoming of this design is in the fact that under operational conditions magnetization and demagnetization processes take place in magnetic circuits with various magnetic resistance due to differences in the attracted loads. The proposed design presupposes that load attraction and lowering are controlled without magnetization and demagnetization of the permanent magnet. This effect is achieved by the following way: a strict permanent magnetic flux is directed to a ferromagnetic load or the flux is deviated from it.

  2. Sealants for preventing dental decay in the permanent teeth

    DEFF Research Database (Denmark)

    Ahovuo-Saloranta, Anneli; Forss, Helena; Walsh, Tanya

    2013-01-01

    in preventing caries in children and adolescents when compared to no sealants. Their effectiveness may be related to the caries prevalence in the population. OBJECTIVES: To compare the effects of different types of fissure sealants in preventing caries in permanent teeth in children and adolescents. SEARCH...... of age. DATA COLLECTION AND ANALYSIS: Two review authors independently screened search results, extracted data and assessed trial quality. We calculated the odds ratio (OR) for caries or no caries on occlusal surfaces of permanent molar teeth. For trials with a split-mouth design, the Becker...... or the baseline caries prevalence.- Resin-based sealant compared with no sealant: Compared to control without sealant, second or third or fourth generation resin-based sealants prevented caries in first permanent molars in children aged 5 to 10 years (at 2 years of follow-up odds ratio (OR) 0.12, 95% confidence...

  3. Special-Purpose High-Torque Permanent-Magnet Motors

    Science.gov (United States)

    Doane, George B., III

    1995-01-01

    Permanent-magnet brushless motors that must provide high commanded torques and satisfy unusual heat-removal requirement are developed. Intended for use as thrust-vector-control actuators in large rocket engines. Techniques and concepts used to design improved motors for special terrestrial applications. Conceptual motor design calls for use of rotor containing latest high-energy-product rare-earth permanent magnets so that motor produces required torque while drawing smallest possible currents from power supply. Torque generated by electromagnetic interaction between stator and permanent magnets in rotor when associated electronic circuits applied appropriately temporally and spatially phased currents to stator windings. Phase relationships needed to produce commanded torque computed in response to torque command and to electronically sensed angular position of rotor relative to stator.

  4. Permanent cortical blindness after bronchial artery embolization.

    Science.gov (United States)

    van Doorn, Colette S; De Boo, Diederick W; Weersink, Els J M; van Delden, Otto M; Reekers, Jim A; van Lienden, Krijn P

    2013-12-01

    A 35-year-old female with a known medical history of cystic fibrosis was admitted to our institution for massive hemoptysis. CTA depicted a hypertrophied bronchial artery to the right upper lobe and showed signs of recent bleeding at that location. Bronchial artery embolization (BAE) was performed with gelfoam slurry, because pronounced shunting to the pulmonary artery was present. Immediately after BAE, the patient developed bilateral cortical blindness. Control angiography showed an initially not opacified anastomosis between the embolized bronchial artery and the right subclavian artery, near to the origin of the right vertebral artery. Cessation of outflow in the bronchial circulation reversed the flow through the anastomosis and allowed for spill of embolization material into the posterior circulation. Unfortunately the cortical blindness presented was permanent.

  5. Permanent Cortical Blindness After Bronchial Artery Embolization

    Energy Technology Data Exchange (ETDEWEB)

    Doorn, Colette S. van, E-mail: cvandoorn@gmail.com; De Boo, Diederick W., E-mail: d.w.deboo@amc.uva.nl [Academic Medical Centre, Department of Radiology (Netherlands); Weersink, Els J. M., E-mail: e.j.m.weersink@amc.uva.nl [Academic Medical Centre, Department of Pulmonology (Netherlands); Delden, Otto M. van, E-mail: o.m.vandelden@amc.uva.nl; Reekers, Jim A., E-mail: j.a.reekers@amc.uva.nl; Lienden, Krijn P. van, E-mail: k.p.vanlienden@amc.uva.nl [Academic Medical Centre, Department of Radiology (Netherlands)

    2013-12-15

    A 35-year-old female with a known medical history of cystic fibrosis was admitted to our institution for massive hemoptysis. CTA depicted a hypertrophied bronchial artery to the right upper lobe and showed signs of recent bleeding at that location. Bronchial artery embolization (BAE) was performed with gelfoam slurry, because pronounced shunting to the pulmonary artery was present. Immediately after BAE, the patient developed bilateral cortical blindness. Control angiography showed an initially not opacified anastomosis between the embolized bronchial artery and the right subclavian artery, near to the origin of the right vertebral artery. Cessation of outflow in the bronchial circulation reversed the flow through the anastomosis and allowed for spill of embolization material into the posterior circulation. Unfortunately the cortical blindness presented was permanent.

  6. Stability and Control Technology of Surrounding Rock under Permanent Coal Pillar%永久煤柱下巷道围岩稳定性及控制技术分析

    Institute of Scientific and Technical Information of China (English)

    孙明磊; 李佳丽

    2016-01-01

    Broken influence elements and mechanism of special return air entry of Daihe coal mine were analyzed, which included supporting pressure of coal pillar, surrounding rock strength and supporting way. Detailed numerical modeling of FLAC2D was conducted to evaluate surrounding rock stress distribution that influence by horizontal distance of roadway to coal pillar edge and supporting way. These papers studied the characters of roadway moment distribution and surrounding rock displacement that influenced by three different supporting way, which included U style steel supporting, grouting reinforcement and compensate supporting with cable, put forward grouting and compensate supporting with cable should be used on the basis of U style steel supporting in roadway under the per-manent coal pillar, then stability supporting body would formed, and roadway deformation could be controlled effectively.%以岱河煤矿Ⅳ1专用回风巷变形破坏为研究对象,从煤柱支承压力、围岩强度、现有支护措施3个方面分析了其破坏影响因素和机理,通过建立FLAC2D 模拟模型明确了巷道与煤柱边缘水平距离、巷道支护方式对围岩应力分布的影响。研究了U型钢、注浆及锚索结构补偿支护3种作用下的巷道弯矩分布、围岩位移等特点,提出了永久煤柱下的巷道在U型钢基础上应进行注浆加固,再用锚索进行针对性支护结构补偿,形成稳定的共同承载体,有效地控制巷道变形。

  7. 永磁同步电机静止及低速下无传感器控制研究%Sensorless Control of Permanent Magnet Synchronous Motor at Zero Speed and Low Speed

    Institute of Scientific and Technical Information of China (English)

    干瑞; 朱元; 王双全

    2012-01-01

    In order to achieve the estimation of rotor position of IPMSM at low speed and zero speed, a scheme based on high frequency injection method for sensorless control of permanent magnet synchronous motor was presented. The basic principal of high frequency injection method was discussed combined with the mathematical model of PMSPM in detail. In consideration of the magnetically saturated saliency, the high frequency response character of PMSM was studied, based on which a new method extracting the DC component of high frequency current was proposed for distinguishing the rotor polarity at zero speed. The impact and compensation of phase deviation of high frequency current was also discussed. The experiment result shows that the methods adopted have satisfies performance at both zero speed and low speed.%研究了一种基于高频注入法的永磁同步电机无传感器控制技术,以实现内埋式永磁同步电机在静止及低速下转子位置的估算.结合电机数学模型阐述了脉振注入法的原理.利用电机的饱和凸极性,分析了电机在静止时的高频响应特性,并提出了一种通过提取高频电流直流分量来判断电机转子极性的方法.为r解决响应电流存在相位偏移的问题,将d轴高频电流作为输入量,通过锁相环得到响应电流的相位偏移值,并做出相应的补偿.实验结果表明,采用的方法跟踪性能良好,适用于电机的静止以及低速运行阶段.

  8. 基于锁相环的永磁同步电机无传感器控制%Sensorless Control of Permanent Magnet Synchronous Motor Based on Phase-locked Loop

    Institute of Scientific and Technical Information of China (English)

    李冉; 龙雪涛; 陈辉

    2013-01-01

    Sliding mode observer has been successfully applied to sensorless control of permanent magnet synchronous motor,however,the side effect of the sliding mode method caused chattering due to its mechanism,so the estimation errors of rotor position and velocity would be increased.To solve the chattering problem,a new approach was presented by combining sliding mode observer with phase-locked loop.Firstly,back electromotive force was estimated by means of sliding mode observer,then rotor position detected system based on phase-locked loop was designed,furthermore,the rotor position and velocity signal could be extracted from estimated back electromotive force.The proposed approach could instead of the traditional sliding mode observer,which obtained the rotor position and velocity signal directly by means of numerical operation.So it could effectively reduce the affect of the sliding mode chattering and improve the estimation precision of rotor position and velocity.The results of experimental and simulation show the proposed approach is correct and feasible.%基于滑模观测器的永磁同步电机无传感器控制系统中由于滑模自身机制带来的高频抖动,会使电机转子位置以及速度估计时存在很大的误差.为了解决这一问题,将滑模观测器与锁相环技术结合起来,先通过滑模观测器估计电机反电动势,然后再构造基于锁相环结构的转子位置检测单元,从估计的反电动势中提取电机转子位置和速度信号.这种方法能够避免滑模观测器直接通过数值关系运算得到转子位置和速度存在的抖动现象,从而一定程度上削弱估计反电动势中的高频抖动分量对系统被估量的影响,提高了估计精度,仿真分析和实验结果均表明该方法的正确性和可行性.

  9. Levitation decoupling control for permanent-magnet bearingless synchronous motors based on speed information observation%基于速度信息观测的无轴承永磁同步电机悬浮解耦控制

    Institute of Scientific and Technical Information of China (English)

    王晓琳; 丁强

    2011-01-01

    无轴承永磁同步电机以转子位置信息为媒介实现解耦控制,整个算法复杂且依赖速度传感器.本文研究电机无传感器运行及解耦算法简化的方法.首先将传统扩张状态观测算法简化为线性形式.然后将二、三阶线性扩张状态观测器分别加入转矩和悬浮系统电流环和位移环,并定义电角速度与转矩d-q轴电流乘积以及转矩系统q轴磁链与悬浮d-q轴电流乘积为扰动项,利用观测器辨识转速信息及悬浮扰动力.接着对转速信息进行处理、对悬浮扰动力进行补偿从而实现无速度传感器运行并简化悬浮解耦算法.最后通过仿真验证所提控制策略能够实现电机无速度传感器运行,保证额定转速下稳定悬浮.%The conventional decoupling control of permanent-magnet bearingless synchronous motors depends on the rotor-position information. This control algorithm is complex and dependent on speed-sensor. We propose a decoupling control algorithm with no speed-sensor working for the motor. First, the traditional extended state observer(ESO) algorithm is simplified to a linear form, and then, the second-order and third-order linear-ESO algorithms are added respectively to the current-loop in the torque system and the displacement-loop in the suspension system. The product of the electrical angular speed and the d-q axis current in the torque system, and the product of the q-axis flux in the torque system and the d-q axis current in the suspension system are defined as disturbances to the linear-ESO in identifying the speed information and the levitation disturbance force. Thirdly, the speed information is processed, and the levitation disturbance force is simplified, thus realizing the operation without the speed-sensor, and the simplication of the levitation decoupling algorithm. Finally, the simulation results show that the proposed control strategy can achieve the operation with no speed-sensor and guarantee the

  10. Annual precipitation since 515 BC reconstructed from living and fossil juniper growth of northeastern Qinghai Province, China

    Energy Technology Data Exchange (ETDEWEB)

    Sheppard, P.R.; Graumlich, L.J. [University of Arizona, Laboratory of Tree-Ring Research, AZ (United States); Tarasov, P.E. [Alfred-Wegener-Institute for Polar and Marine Research, Potsdam Department, Potsdam (Germany); Heussner, K.-U.; Wagner, M. [German Archaeological Institute, Department of Eurasian Archaeology, Berlin (Germany); Oesterle, H. [Potsdam Institute for Climate Impact Research, Telegrafenberg, P. O. Box 60 12 03, Potsdam (Germany); Thompson, L.G. [Ohio State University, Byrd Polar Research Center, Columbus, OH (United States)

    2004-12-01

    Annual precipitation for the last 2,500 years was reconstructed for northeastern Qinghai from living and archaeological juniper trees. A dominant feature of the precipitation of this area is a high degree of variability in mean rainfall at annual, decadal, and centennial scales, with many wet and dry periods that are corroborated by other paleoclimatic indicators. Reconstructed values of annual precipitation vary mostly from 100 to 300 mm and thus are no different from the modern instrumental record in Dulan. However, relatively dry years with below-average precipitation occurred more frequently in the past than in the present. Periods of relatively dry years occurred during 74-25 BC, AD51-375, 426-500, 526-575, 626-700, 1100-1225, 1251-1325, 1451-1525, 1651-1750 and 1801-1825. Periods with a relatively wet climate occurred during AD376-425, 576-625, 951-1050, 1351-1375, 1551-1600 and the present. This variability is probably related to latitudinal positions of winter frontal storms. Another key feature of precipitation in this area is an apparently direct relationship between interannual variability in rainfall with temperature, whereby increased warming in the future might lead to increased flooding and droughts. Such increased climatic variability might then impact human societies of the area, much as the climate has done for the past 2,500 years. (orig.)

  11. Difference in Tree Growth Responses to Climate at the Upper Treeline: Qilian Juniper in the Anyemaqen Mountains

    Institute of Scientific and Technical Information of China (English)

    Jianfeng Peng; Xiaohua Gou; Fahu Chen; Jinbao Li; Puxing Liu; Yong Zhang; Keyan Fang

    2008-01-01

    Three ring-width chronologies were developed from Qilian Juniper (Sabina przewalskii Kom.) at the upper treeline along a west-east gradient in the Anyemaqen Mountains.Most chronological statistics,except for mean sensitivity (MS),decreased from west to east.The first principal component (PC1) Ioadings indicated that stands in a similar climate condition were most important to the variability of radial growth.PC2 Ioadings decreased from west to east,suggesting the difference of tree-growth between eastern and western Anyemaqen Mountains.Correlations between standard chronologies and climatic factors revealed different climatic influences on radial growth along a west-east gradient in the study area.Temperature of warm season (July-August) was important to the radial growth at the upper treeline in the whole study area.Precipitation of current May was an important limiting factor of tree growth only in the western (drier) upper treeline,whereas precipitation of current September limited tree growth in the eastern (wetter) upper treeline.Response function analysis results showed that there were regional differences between tree growth and climatic factors in various sampling sites of the whole study area.Temperature and precipitation were the important factors influencing tree growth in western (drier) upper treeline.However,tree growth was greatly limited by temperature at the upper treeline in the middle area,and was more limited by precipitation than temperature in the eastern (wetter) upper treeline.

  12. Difference in tree growth responses to climate at the upper treeline: Qilian Juniper in the Anyemaqen Mountains.

    Science.gov (United States)

    Peng, Jianfeng; Gou, Xiaohua; Chen, Fahu; Li, Jinbao; Liu, Puxing; Zhang, Yong; Fang, Keyan

    2008-08-01

    Three ring-width chronologies were developed from Qilian Juniper (Sabina przewalskii Kom.) at the upper treeline along a west-east gradient in the Anyemaqen Mountains. Most chronological statistics, except for mean sensitivity (MS), decreased from west to east. The first principal component (PC1) loadings indicated that stands in a similar climate condition were most important to the variability of radial growth. PC2 loadings decreased from west to east, suggesting the difference of tree-growth between eastern and western Anyemaqen Mountains. Correlations between standard chronologies and climatic factors revealed different climatic influences on radial growth along a west-east gradient in the study area. Temperature of warm season (July-August) was important to the radial growth at the upper treeline in the whole study area. Precipitation of current May was an important limiting factor of tree growth only in the western (drier) upper treeline, whereas precipitation of current September limited tree growth in the eastern (wetter) upper treeline. Response function analysis results showed that there were regional differences between tree growth and climatic factors in various sampling sites of the whole study area. Temperature and precipitation were the important factors influencing tree growth in western (drier) upper treeline. However, tree growth was greatly limited by temperature at the upper treeline in the middle area, and was more limited by precipitation than temperature in the eastern (wetter) upper treeline.

  13. New permanent magnets; manganese compounds.

    Science.gov (United States)

    Coey, J M D

    2014-02-12

    The exponential growth of maximum energy product that prevailed in the 20th century has stalled, leaving a market dominated by two permanent magnet materials, Nd2Fe14B and Ba(Sr)Fe12O19, for which the maximum theoretical energy products differ by an order of magnitude (515 kJ m(-3) and 45 kJ m(-3), respectively). Rather than seeking to improve on optimized Nd-Fe-B, it is suggested that some research efforts should be devoted to developing appropriately priced alternatives with energy products in the range 100-300 kJ m(-3). The prospects for Mn-based hard magnetic materials are discussed, based on known Mn-based compounds with the tetragonal L10 or D022 structure or the hexagonal B81 structure.

  14. CHALLENGES OF PERMANENT TEACHER TRAINING

    Directory of Open Access Journals (Sweden)

    María Manuela Valles-Ornelas

    2015-07-01

    Full Text Available The new challenges for teachers and managers require to assume permanent formation as a tool for responding effectively and efficiently to them, different perspective to strengthen from the initial teacher education programs. The research was done in a primary school in the state of Chihuahua. The method used was research action, the question was: How can we encourage the lifelong learning and training of the staff of this school, with the purpose to assist them in these processes to improve the service that the school provides to students. The school group is the center of the process, the cooperative and collaborative work accompanied by educational leadership and persuasive provide better results, and all accompanied by the professional selfinvitation.

  15. 可控整流缩短连续极永磁发电机电压恢复时间%Method of controllable rectification to shorten voltage recovery time of consequent-pole permanent magnet generator

    Institute of Scientific and Technical Information of China (English)

    梁学修; 许家群; 蒋杰; 赵博; 孙荣毅

    2016-01-01

    To realize the function of automotive engine stop-start, it is promising that traditional independent starter and generator in automobile are replaced by the integrated starter/generator (ISG), which contributes to energy conservation and emission reduction. Hybrid excitation starter/generator is a potential selection for the ISG, which has high efficiency over extensive working range, high power density, low maintenance, and high reliability without brushes. The consequent-pole permanent magnet (CPPM) brushless direct-current generator (BLDCG) electromotive force (EMF) is designed to the trapezoidal wave. The trapezoidal wave electromotive force CPPM motor is different from the existing sine wave electromotive force CPPM motor. It has the advantages of high power density, small direct-current (DC) voltage harmonic ripple, only requiring low cost and low resolution Holzer position sensor, simple control and other advantages. The CPPM motor can output stable voltage in the wide speed range. However, the normal brushless DC generator needs to match the complex power converter. Therefore, The CPPM motor is a new type of motor used for electric vehicle. This kind of motor has a good prospect in the application of the ISG of automobile. Generally, the excitation current regulation combined with diode rectification is adopted to meet the requirement of alternator technical specification. However, the large time constant of about 100 ms in excitation winding will cause DC-link voltage drop and lead to abnormal operation of automotive sensitive device, such as engine control unit, and radio. In generating mode, the CPPM BLDCG can be seen as hybrid excitation brushless DC generator. In view of relatively low time constant in armature winding of CPPM BLDCG, it is possible to improve DC-link voltage dynamic performance by regulating armature winding current. This paper takes CPPM BLDCG of 14 V as the research object and aims to shorten the time of voltage recovery. With the

  16. Intrusive luxation of 60 permanent incisors

    DEFF Research Database (Denmark)

    Tsilingaridis, Georgios; Malmgren, Barbro; Andreasen, Jens O;

    2012-01-01

      Intrusive luxation in the permanent dentition is an uncommon injury but it is considered one of the most severe types of dental trauma because of the risk for damage to the periodontal ligament, pulp and alveolar bone. Management of intrusive luxation in the permanent dentition is controversial....... The purpose of this study was to evaluate pulp survival and periodontal healing in intrusive luxated permanent teeth in relation to treatment alternatives, degree of intrusion and root development....

  17. Dental Interventions on First Permanent Molars

    OpenAIRE

    2016-01-01

    The first permanent molars have the biggest dental morbidity and mortality of all permanent teeth. The main aim was to evaluate of the most common dental problems and procedures that are performed on the first permanent molars. Material and method: examination was performed in three private dental offices, two from urban and one from rural region, over a period of 2 years. The data was obtained by using dental charts from the patients and by the ambulatory register for performe...

  18. Permanence of Stochastic Lotka-Volterra Systems

    Science.gov (United States)

    Liu, Meng; Fan, Meng

    2017-04-01

    This paper proposes a new definition of permanence for stochastic population models, which overcomes some limitations and deficiency of the existing ones. Then, we explore the permanence of two-dimensional stochastic Lotka-Volterra systems in a general setting, which models several different interactions between two species such as cooperation, competition, and predation. Sharp sufficient criteria are established with the help of the Lyapunov direct method and some new techniques. This study reveals that the stochastic noises play an essential role in the permanence and characterize the systems being permanent or not.

  19. Diagnostics Systems for Permanent Hall Thrusters Development

    Science.gov (United States)

    Ferreira, Jose Leonardo; Soares Ferreira, Ivan; Santos, Jean; Miranda, Rodrigo; Possa, M. Gabriela

    -Effect Thruster (PMHET), developed at the Plasma Physics Laboratory of UnB. The idea of using an array of permanent magnets, instead of an electromagnet, to produce a radial magnetic field inside the cylindrical plasma drift channel of the thruster is very attractive, especially because of the possibility of developing a HET with power consumption low enough to be used in small satellites or medium-size satellites with low on board power. Hall-Effect Thrusters are now a very good option for spacecraft primary propulsion and also for station-keeping of medium and large satellites. This is because of their high specific impulse, efficient use of propellant mass and combined low and precise thrust capabilities, which are related to an economy in terms of propellant mass utilization , longer satellite lifetime and easier spacecraft maneuvering in microgravity environment. The first HETs were developed in the mid 1950’s, and they were first called Closed Drift Thrusters. Today, the successful use of electric thrusters for attitude control and orbit modification on hundreds of satellites shows the advanced stage of development of this technology. In addition to this, after the success of space missions such as Deep Space One and Dawn (NASA), Hayabusa (JAXA) and Smart-1 (ESA), the employment of electric thrusters is also consolidated for the primary propulsion of spacecraft. This success is mainly due to three factors: reliability of this technology; efficiency of propellant utilization, and therefore reduction of the initial mass of the ship; possibility of operation over long time intervals, with practically unlimited cycling and restarts. This thrusting system is designed to be used in satellite attitude control and long term space missions. One of the greatest advantage of this kind of thruster is the production of a steady state magnetic field by permanent magnets providing electron trapping and Hall current generation within a significant decrease on the electric energy supply

  20. 应用双级矩阵变换器的永磁直驱风力发电系统集成控制策略%INTEGRATED CONTROL STRATEGY FOR PERMANENT MAGNET DIRECT-DRIVE WIND TURBINE WITH TWO-STAGE MATRIX CONVERTER

    Institute of Scientific and Technical Information of China (English)

    邓文浪; 倪泽平

    2012-01-01

    The control strategy of permanent magnet direct-drive wind turbine was investigated based on two-stage matrix converter(TSMC) in this paper.The model of grid-connected inverter-stage was developed,a novel interg-rated control strategy of TSMC permanent magnet direct-drive wind turbine was proposed,in which the maximum wind energy tracking,output power control and variable speed constant frequency (VSCF) were realized by interg-rated control at the inverter-stage,and there was no need of power-balancing control strategy to decrease the dc-bus voltage fluctuation,which reduced the control complexity.Simulation results verify the validity of the proposed control strategy.%以基于TSMC的永磁直驱型风力发电系统为研究对象,建立TSMC并网逆变级的数学模型,提出TSMC直驱型风力发电系统的集成控制策略,将最大风能跟踪、输出功率调节、变速恒频控制通过网侧逆变级的集成控制实现,且无需进行稳定直流电压的功率平衡控制,系统控制复杂度降低.仿真结果验证了该控制策略的有效性.

  1. Effect of the repulsive force in the HTSC-permanent magnet hybrid bearing system

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, S., E-mail: ohashi@ipcku.kansai-u.ac.j [Kansai University, 3-3-35, Yamate-cho, Suita, Osaka 564-8680 (Japan); Kobayashi, S. [Kansai University, 3-3-35, Yamate-cho, Suita, Osaka 564-8680 (Japan)

    2009-10-15

    Magnetic levitation using the pinning force of the YBaCuO high-T{sub c} bulk superconductor (HTSC) materials has an advantage to achieve stable levitation without control. To increase levitation force, the HTSC-permanent magnet hybrid magnetic bearing system is introduced. A circular shaped three phase Nd-Fe-B permanent magnet is installed on the rotor, and HTSC bulk superconductor is set on the stator. The additional permanent magnet is installed under the HTSC. Repulsive force of the permanent magnet is used for levitation, and pinning force between the HTSC and permanent magnet is used for guidance force of the bearing. In this system, relationship between permanent magnet and the HTSC is important. When repulsive force of the permanent magnet is large, pinning force of superconductor is used to keep the rotor position. As a result, stability for the lateral direction is decreased with hybrid system. For levitation force, effect of the hybrid system is not observed with column HTSC. Compared with the ring HTSC results, the following thing is considered. Because there is no space that flux of one permanent magnet acts on the other one with the column HTSC configuration, interaction between two permanent magnets becomes small.

  2. Effect of the repulsive force in the HTSC-permanent magnet hybrid bearing system

    Science.gov (United States)

    Ohashi, S.; Kobayashi, S.

    2009-10-01

    Magnetic levitation using the pinning force of the YBaCuO high- Tc bulk superconductor (HTSC) materials has an advantage to achieve stable levitation without control. To increase levitation force, the HTSC-permanent magnet hybrid magnetic bearing system is introduced. A circular shaped three phase Nd-Fe-B permanent magnet is installed on the rotor, and HTSC bulk superconductor is set on the stator. The additional permanent magnet is installed under the HTSC. Repulsive force of the permanent magnet is used for levitation, and pinning force between the HTSC and permanent magnet is used for guidance force of the bearing. In this system, relationship between permanent magnet and the HTSC is important. When repulsive force of the permanent magnet is large, pinning force of superconductor is used to keep the rotor position. As a result, stability for the lateral direction is decreased with hybrid system. For levitation force, effect of the hybrid system is not observed with column HTSC. Compared with the ring HTSC results, the following thing is considered. Because there is no space that flux of one permanent magnet acts on the other one with the column HTSC configuration, interaction between two permanent magnets becomes small.

  3. COMMANDE NON LINEAIRE SANS CAPTEUR DE LA MACHINE SYNCHRONE A AIMANTS PERMANENTS

    OpenAIRE

    Ezzat, Marwa

    2011-01-01

    The permanent magnet synchronous motor when compared to other electric machines, is very present in motion control industrial applications. This is mainly because of its compactness, low inertia, dynamics performances, robustness, power density and simplicity of operation with mechanical sensor. However, sensorless control of this machine is always a difficult problem because of the observability loss problem. The aim of this thesis is to propose control laws for mechanical sensorless permane...

  4. Physico-mechanical properties of Spanish juniper wood considering the effect of heartwood formation and the presence of defects and imperfections

    Directory of Open Access Journals (Sweden)

    Javier de la Fuente-Leon

    2014-04-01

    Full Text Available Aim of study: Determining the main physical and mechanical properties of Spanish juniper wood from Soria (Spain considering the effects of heartwood formation and the presence of defects and imperfections; and comparing the resulting characteristics with similar existing data for other regional softwood species of commercial interest. Area of study: Berlanga de Duero (Soria, Castilla y León, Spain.Material and Methods: Wood physico-mechanical performance was determined by Spanish UNE standards in order to provide proper comparisons to other regional softwood species. An individual tree representing average plot characteristics was selected in all eight 10 m radius circular plots that were established well-representing the heterogeneity of this woodland. The age of every tree was determined reading the number of growth rings at the base of each sampled tree. Every physico-mechanical property was assessed at least 4 times for every wood sample type (sapwood and heartwood, whether clear or with the presence of defects of each tree. Two-way ANOVA was run to assess significant differences in the results. Post hoc all pairwise comparisons were performed using Tukey's test (p < 0.05.Research highlights: Spanish juniper wood resulted harder than other regional commercial conifers, and showed semi-heavyweight heartwood and lightweight sapwood; whereas shrinkage figures remarked its great dimensional stability. The high presence of knots within heartwood made it even heavier, harder, and more resistant to compression parallel to grain. A commercial use of this rare precious wood may contribute to juniper forests preservation in the frame of forest sustainable management plans. Key words: heartwood effect; Juniperus thurifera L.; physico-mechanical wood properties; wood classification; wood defects.

  5. Investigating uranium distribution in surface sediments and waters: a case study of contamination from the Juniper Uranium Mine, Stanislaus National Forest, CA.

    Science.gov (United States)

    Kayzar, Theresa M; Villa, Adam C; Lobaugh, Megan L; Gaffney, Amy M; Williams, Ross W

    2014-10-01

    The uranium concentrations and isotopic compositions of waters, sediment leachates and sediments from Red Rock Creek in the Stanislaus National Forest of California were measured to investigate the transport of uranium from a point source (the Juniper Uranium Mine) to a natural surface stream environment. The ((234)U)/((238)U) composition of Red Rock Creek is altered downstream of the Juniper Mine. As a result of mine-derived contamination, water ((234)U)/((238)U) ratios are 67% lower than in water upstream of the mine (1.114-1.127 ± 0.009 in the contaminated waters versus 1.676 in the clean branch of the stream), and sediment samples have activity ratios in equilibrium in the clean creek and out of equilibrium in the contaminated creek (1.041-1.102 ± 0.007). Uranium concentrations in water, sediment and sediment leachates are highest downstream of the mine, but decrease rapidly after mixing with the clean branch of the stream. Uranium content and compositions of the contaminated creek headwaters relative to the mine tailings of the Juniper Mine suggest that uranium has been weathered from the mine and deposited in the creek. The distribution of uranium between sediment surfaces (leachable fraction) and bulk sediment suggests that adsorption is a key element of transfer along the creek. In clean creek samples, uranium is concentrated in the sediment residues, whereas in the contaminated creek, uranium is concentrated on the sediment surfaces (∼70-80% of uranium in leachable fraction). Contamination only exceeds the EPA maximum contaminant level (MCL) for drinking water in the sample with the closest proximity to the mine. Isotopic characterization of the uranium in this system coupled with concentration measurements suggest that the current state of contamination in Red Rock Creek is best described by mixing between the clean creek and contaminated upper branch of Red Rock Creek rather than mixing directly with mine sediment.

  6. resonant inverter supplied interior permanent magnet (ipm)

    African Journals Online (AJOL)

    user

    Permanent Magnet (IPM) or Surface Permanent. Magnet ... desired torque is produced to rotate the motor in the desired ... u axis, and the direct-axis of the rotor is at angle θ from the ..... Based Stator Flux Estimator” International. Journal of ...

  7. Comparison of adjustable permanent magnetic field sources

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders

    2010-01-01

    A permanent magnet assembly in which the flux density can be altered by a mechanical operation is often significantly smaller than comparable electromagnets and also requires no electrical power to operate. In this paper five permanent magnet designs in which the magnetic flux density can...

  8. Magnetic guns with cylindrical permanent magnets

    DEFF Research Database (Denmark)

    Vokoun, David; Beleggia, Marco; Heller, Luděk

    2012-01-01

    The motion of a cylindrical permanent magnet (projectile) inside a tubular permanent magnet, with both magnets magnetized axially, illustrates nicely the physical principles behind the operation of magnetic guns. The force acting upon the projectile is expressed semi-analytically as derivative...

  9. Sensorless operation of surface mount permanent magnet AC (PMAC) motors

    Energy Technology Data Exchange (ETDEWEB)

    Toliyat, H.A.; Rahman, K.M.; Shet, D.S.

    1999-12-01

    A sensorless field oriented control scheme for surface mount permanent magnet ac (PMAC) motor with split phase stator windings is presented. This motor is obtained by splitting the phase windings of a conventional three phase motor. The six-phase motor, however is run as a three-phase motor by connecting the split phase stator windings in series, while the taps are made available for voltage measurements. By measuring the terminal voltages and the line currents, absolute position of the permanent magnet ac motor driven by a current regulated PWM inverter with a hysteresis controller is estimated. The estimated position information is independent of the stator resistance, thus this scheme is even applicable at low speeds. Results are presented to show the effectiveness of the new controller, and it is also shown that the position error is negligible.

  10. Consequences of Widespread Piñon Mortality for Water Availability and Water Use Dynamics in Piñon-Juniper Woodlands

    Science.gov (United States)

    Morillas, L.; Pangle, R. E.; Krofcheck, D. J.; Pockman, W.; Litvak, M. E.

    2014-12-01

    Tree die-off events have showed a rapid increase in the last decade as a result of warmer temperatures and more severe drought. In the southwestern US, where piñon-juniper (PJ) woodlands occupy 24 million ha, the turn of the century drought (1999-2002) triggered 40-95% mortality of piñon pine (Pinus edulis) and 2-25% mortality of juniper (Juniperous monosperma). To determine the consequences of this disturbance on surface water balance we conducted a girdling experiment where all piñon trees above 7 cm of diameter at breast height in an area of 200 m2 were girdled in September 2009. We compared water and energy fluxes in this girdled site (PJG) using open-path eddy covariance (EC) to fluxes measured simultaneously in an intact PJ woodland less than 3 km away (PJC). In addition to evapotranspiration (ET) measurements from EC, canopy transpiration (ETc) was measured using sap flow probes (Granier thermal dissipation method) installed on five juniper and five piñon trees at each site. Soil water content (SWC) was also monitored using TDR probes (CS610, Campbell Scientific) under the three main cover types ( bare soil, under juniper and under piñon) and at three depths (5,10 and 30 cm depths) in both sites. Total ET at PJG decreased slowly, but progressively, relative to PJC following the girdling, with annual ET 5%, 10% and 19% lower in 2010, 2011 and 2012, respectively, in the girdled site. Following the girdling, canopy transpiration was significantly reduced at PJG, with an observed reduction of annual ETc at PJG of 45%, 59% and 71% from 2010 to 2012 compared to the PJC site. Our results suggest that girdling triggered a significant increase of soil evaporation and understory transpiration (not directly measured) as a result of canopy cover loss. This agrees with significant higher establishment of annual forbs seen at PJG relative to PJC and the increase of solar radiation reaching the soil surface as a result of canopy cover loss. Our results suggest pi

  11. Leadership in a (permanent) crisis.

    Science.gov (United States)

    Heifetz, Ronald; Grashow, Alexander; Linsky, Marty

    2009-01-01

    The current economic crisis is not just another rough spell. Today's mix of urgency, high stakes, and uncertainty will continue even after the recession ends. The immediate crisis--which we will get through with policy makers' expert technical adjustments--sets the stage for a sustained, or even permanent, crisis, a relentless series of challenges no one has encountered before. Instead of hunkering down and relying on their familiar expertise to deal with the sustained crisis, people in positions of authority--whether they are CEOs or managers heading up a company initiative--must practice what the authors call adaptive leadership. They must, of course, tackle the underlying causes of the crisis, but they must also simultaneously make the changes that will allow their organizations to thrive in turbulent environments. Adaptive leadership is an improvisational and experimental art, requiring some new practices. Like Julie Gilbert, who overcame internal resistance to reorient Best Buy toward female purchasers, adaptive leaders get things done to meet today's challenges and then modify those things to thrive in tomorrow's world. They also embrace disequilibrium, using turbulence as an opportunity to build crucial new capacities, as Paul Levy did to rescue Beth Israel Deaconess Medical Center from a profound financial crisis. Finally, adaptive leaders, such as Egon Zehnder, the founder of an executive search firm, draw out the leadership skills that reside deep in the organization, recognizing the interdependence of all employees and mobilizing everyone to generate solutions.

  12. Finite element modeling of permanent magnet devices

    Science.gov (United States)

    Brauer, J. R.; Larkin, L. A.; Overbye, V. D.

    1984-03-01

    New techniques are presented for finite element modeling of permanent magnets in magnetic devices such as motors and generators. These techniques extend a previous sheet-current permanent magnet model that applies only for straight line B-H loops and rectangular-shaped magnets. Here Maxwell's equations are used to derive the model of a permanent magnet having a general curved B-H loop and any geometric shape. The model enables a nonlinear magnetic finite element program to use Newton-Raphson iteration to solve for saturable magnetic fields in a wide variety of devices containing permanent magnets and steels. The techniques are applied to a brushless dc motor with irregular-shaped permanent magnets. The calculated motor torque agrees well with measured torque.

  13. Gating of Permanent Molds for ALuminum Casting

    Energy Technology Data Exchange (ETDEWEB)

    David Schwam; John F. Wallace; Tom Engle; Qingming Chang

    2004-03-30

    This report summarizes a two-year project, DE-FC07-01ID13983 that concerns the gating of aluminum castings in permanent molds. The main goal of the project is to improve the quality of aluminum castings produced in permanent molds. The approach taken was determine how the vertical type gating systems used for permanent mold castings can be designed to fill the mold cavity with a minimum of damage to the quality of the resulting casting. It is evident that somewhat different systems are preferred for different shapes and sizes of aluminum castings. The main problems caused by improper gating are entrained aluminum oxide films and entrapped gas. The project highlights the characteristic features of gating systems used in permanent mold aluminum foundries and recommends gating procedures designed to avoid common defects. The study also provides direct evidence on the filling pattern and heat flow behavior in permanent mold castings.

  14. Stu dy on Control Technology of Single Potr R egulated Speed Flux-switchi ng Permanent Magnet Generator System%变速磁通切换型永磁发电机系统中单端口稳压控制技术研究

    Institute of Scientific and Technical Information of China (English)

    张文昌; 刘海鹏; 于功山; 王怀杰

    2013-01-01

    变速、变负载的磁通切换型永磁发电机一般需要电力电子装置进行整流与直流稳压,由此构成了基本的磁通切换型永磁发电机系统。该系统既可提供直流电源,也可经逆变后提供交流电源。对磁通切换型永磁发电机系统的控制技术进行研究,并设计了宽范围输入电压高精度自动稳压输出电路。%magnetic flux switching type variable speed , variable load of permanent magnet generator generally requires a power electronic device for rectifier and DC voltage ,thus forming the flux-switching permanent magnet generator system basic .The system can provide the DC power supply , can also provide AC power supply with in-verter .Study on control technology of flux-switching permanent magnet generator system ,and design a wide input voltage range and high precision automatic voltage output circuit .

  15. Research on the controlling of rare earth permanent magnet brushless DC motor based on TMS320C242%基于TMS320C242的稀土永磁无刷直流电机控制系统研究

    Institute of Scientific and Technical Information of China (English)

    董艺

    2012-01-01

    对用TMS320C242控制稀土永磁无刷直流电机(REPMBLDCM)进行了深入的探讨。作为驱动设备,稀土永磁无刷直流电机在很多方面性能优于普通直流电机;作为控制核心,TMS320C242无论是集成度还是控制速度都远超普通的单片机。所以用TMS320C242控制REPMBLDCM可获得极为优秀的控制效果和驱动性能。%A deep discussion has been made on how to control rare earth permanent magnet brushless DC motor with TMS320C242. As a driving device, rare earth permanent magnet brushless DC motor is superior to the common DC motor in many ways. As a core of the control system, TMS320C242 is far more superior to the common single chip microcontroller unit whether on its integration or its controlling speed. Therefore, excellent control effects and driving properties can be obtained by adopting TMS320C242 to control REPMBLDCM.

  16. Environmental Monitoring Supported by Aerial Photography – a Case Study of the Burnt Down Bugac Juniper Forest, Hungary

    Directory of Open Access Journals (Sweden)

    Szatmári József

    2016-06-01

    Full Text Available Wildfire poses a serious risk in several regions of the world threatening urban, agricultural areas and natural ecosystems as well. Nature conservation has important role to be prepared for the management of postfire environmental degradation and restoration for protected areas preserving valuable ecosystems. The improving temporal and spatial resolution of remote sensing and GIS methods significantly contributes to map the changes for accelerating management steps of restoration. In this study a severe wildfire and its impacts were assessed in case of a protected area of the Kiskunság National Park in Hungary, which was partly burnt down in 2012. The aim of this research was to efficiently and accurately assess the damages and to plan and execute the restoration works using remote sensing tools. Aerial data collection was performed one month, and one year after the fire. In 2014 the regenerated vegetation was surveyed and mapped in the field. Using the aerial photographs and the field data, the degree and extent of the fire damages, the types and the state of the vegetation and the presence and proportion of the invasive species were determined. Semi-automatic methods were used for the classification of completely, partially damaged and undamaged areas. Based on the results, the reforestation of the burnt area is suggested to prevent the overspreading of white poplar against common junipers and to clean the area from the most frequent invasive species. To monitor the regeneration of the vegetation and the spreading of the invasive species, further aerial photography and field campaigns are planned.

  17. 改进滑模变结构永磁电机控制器研发%Control design for permanent magnet synchronous motors based on improved sliding mode variable structure control

    Institute of Scientific and Technical Information of China (English)

    张自友; 周大鹏

    2013-01-01

    In order to overcome the defects of chattering and the inaccuracy estimation of rotor position when the traditional sliding mode observer was used to control the PMSM,a design method based on improved sliding mode observer was proposed.Firstly,the mathematical model of PMSM was given and the rotor position estimation principle and its defects of the traditional sliding mode observer were analyzed.Then,the low pass filter was used to filter the current error switch signal and compensate the rotor angle,and the saturation function was used to replace the switch function for reducing the chattering.Finally,the stability was proved to build the equation.Experimental results show that this method can estimate the speed and rotor position with high accuracy.It is proved as an effective control method for PMSM.%为克服传统滑模观测器对永磁同步电机进行无传感器控制时存在高频抖振和转子位置估算不精确的缺陷,提出一种基于改进滑模观测器的PMSM控制器设计方法.首先,建立PMSM的数学模型并分析传统滑模观测器转子位置估计原理和缺陷,然后,采用低通滤波器对电流误差开关信号进行滤波并对转角进行补偿,采用饱和函数代替开关函数以减少滑模运动的高频抖动,最后,采用李亚普若夫稳态判定方程证明设计的改进观测器的稳定性.系统测试表明:该方法能较为准确地对PMSM的转子位置和速度进行估算,具有较高的估算精度.

  18. Research on Magnetic Levitation Permanent Magnet Linear Motor and Its Control System%磁悬浮永磁直线电动机及其控制系统研究

    Institute of Scientific and Technical Information of China (English)

    蓝益鹏; 刘宇菲

    2015-01-01

    According to the special structure and operation mechanism of the maglev permanent magnet linear motor,a mathematical model of electromagnetic thrust and levitation force of the motor was given.The finite element calculation model of maglev permanent magnet linear motor was estab-lished.The air gap flux density,magnetic thrust and levitation force were calculated by finite element method,and the air gap flux density was carried out by harmonic analysis method.A research proto-type of the maglev permanent magnet linear motor was design.The magnetic suspension subsystem and the feed servo subsystem were made.The results of the magnetic suspension subsystem and feed subsystem were obtained by experiments.Experimental results show that adopting the maglev perma-nent magnet linear motor can achieve the feasibility of direct drive and frictionless operation.%根据磁悬浮永磁直线电动机的特殊结构与运行机理,给出了电动机电磁推力和悬浮力的数学模型。建立了磁悬浮永磁直线电动机的有限元计算模型,对气隙磁密、电磁推力和悬浮力进行了有限元计算,并对气隙磁密作了谐波分析。设计了磁悬浮永磁直线电动机的研究样机,制作了磁悬浮子系统和进给伺服子系统,对系统进行实验研究,获得了磁悬浮子系统和进给子系统运行的实验结果。实验研究结果表明,该磁悬浮永磁直线电动机可实现直接驱动与无摩擦运行。

  19. Permanency and the Foster Care System.

    Science.gov (United States)

    Lockwood, Katie K; Friedman, Susan; Christian, Cindy W

    2015-10-01

    Each year over 20,000 youth age out of the child welfare system without reaching a permanent placement in a family. Certain children, such as those spending extended time in foster care, with a diagnosed disability, or adolescents, are at the highest risk for aging out. As young adults, this population is at and increased risk of incarceration; food, housing, and income insecurity; unemployment; educational deficits; receipt of public assistance; and mental health disorders. We reviewed the literature on foster care legislation, permanency, outcomes, and interventions. The outcomes of children who age out of the child welfare system are poor. Interventions to increase permanency include training programs for youth and foster parents, age extension for foster care and insurance coverage, an adoption tax credit, and specialized services and programs that support youth preparing for their transition to adulthood. Future ideas include expanding mentoring, educational support, mental health services, and post-permanency services to foster stability in foster care placements and encourage permanency planning. Children in the child welfare system are at a high risk for physical, mental, and emotional health problems that can lead to placement instability and create barriers to achieving permanency. Failure to reach the permanency of a family leads to poor outcomes, which have negative effects on the individual and society. Supporting youth in foster care throughout transitions may mediate the negative outcomes that have historically followed placement in out-of-home care. Copyright © 2015 Mosby, Inc. All rights reserved.

  20. A Practical Permanent Magnetic Motor Drive for Hybrid Motorcycle

    Institute of Scientific and Technical Information of China (English)

    崔巍; 江建中; 邵定国; 杨斌

    2003-01-01

    A novel embedded-type permanent magnetic motor for hybrid motorcycle, which employs asymmetric design of eccentric air-gap, is proposed in the paper. This special design of air-gap well conforms to the mono-directional operation characteristic of motorcycle and effectively suppresses the distortion of air-gap magnetic field caused by armature reaction. Hence the torque ripple is reduced. A drive system consisting of the newly-designed Nd-Fe-B permanent magnet synchronous motor and parallel-MOSFET threephase inverter for hybrid motorcycle propulsion is established. Wide-range speed operation is realized through a simple and novel control strategy. Computer simulation is described and experimental results given to verify the practicality of the proposed motor design and control strategy.