Stability analysis of linear switching systems with time delays

International Nuclear Information System (INIS)

Li Ping; Zhong Shouming; Cui Jinzhong

2009-01-01

The issue of stability analysis of linear switching system with discrete and distributed time delays is studied in this paper. An appropriate switching rule is applied to guarantee the stability of the whole switching system. Our results use a Riccati-type Lyapunov functional under a condition on the time delay. So, switching systems with mixed delays are developed. A numerical example is given to illustrate the effectiveness of our results.

Actinide isotopic analysis systems

International Nuclear Information System (INIS)

Koenig, Z.M.; Ruhter, W.D.; Gunnink, R.

1990-01-01

This manual provides instructions and procedures for using the Lawrence Livermore National Laboratory's two-detector actinide isotope analysis system to measure plutonium samples with other possible actinides (including uranium, americium, and neptunium) by gamma-ray spectrometry. The computer program that controls the system and analyzes the gamma-ray spectral data is driven by a menu of one-, two-, or three-letter options chosen by the operator. Provided in this manual are descriptions of these options and their functions, plus detailed instructions (operator dialog) for choosing among the options. Also provided are general instructions for calibrating the actinide isotropic analysis system and for monitoring its performance. The inventory measurement of a sample's total plutonium and other actinides content is determined by two nondestructive measurements. One is a calorimetry measurement of the sample's heat or power output, and the other is a gamma-ray spectrometry measurement of its relative isotopic abundances. The isotopic measurements needed to interpret the observed calorimetric power measurement are the relative abundances of various plutonium and uranium isotopes and americium-241. The actinide analysis system carries out these measurements. 8 figs

Organization of the channel-switching process in parallel computer systems based on a matrix optical switch

Science.gov (United States)

Golomidov, Y. V.; Li, S. K.; Popov, S. A.; Smolov, V. B.

1986-01-01

After a classification and analysis of electronic and optoelectronic switching devices, the design principles and structure of a matrix optical switch is described. The switching and pair-exclusion operations in this type of switch are examined, and a method for the optical switching of communication channels is elaborated. Finally, attention is given to the structural organization of a parallel computer system with a matrix optical switch.

Incremental passivity and output regulation for switched nonlinear systems

Science.gov (United States)

Pang, Hongbo; Zhao, Jun

2017-10-01

This paper studies incremental passivity and global output regulation for switched nonlinear systems, whose subsystems are not required to be incrementally passive. A concept of incremental passivity for switched systems is put forward. First, a switched system is rendered incrementally passive by the design of a state-dependent switching law. Second, the feedback incremental passification is achieved by the design of a state-dependent switching law and a set of state feedback controllers. Finally, we show that once the incremental passivity for switched nonlinear systems is assured, the output regulation problem is solved by the design of global nonlinear regulator controllers comprising two components: the steady-state control and the linear output feedback stabilising controllers, even though the problem for none of subsystems is solvable. Two examples are presented to illustrate the effectiveness of the proposed approach.

Theoretical analysis of balanced truncation for linear switched systems

DEFF Research Database (Denmark)

Petreczky, Mihaly; Wisniewski, Rafal; Leth, John-Josef

2012-01-01

In this paper we present theoretical analysis of model reduction of linear switched systems based on balanced truncation, presented in [1,2]. More precisely, (1) we provide a bound on the estimation error using L2 gain, (2) we provide a system theoretic interpretation of grammians and their singu......In this paper we present theoretical analysis of model reduction of linear switched systems based on balanced truncation, presented in [1,2]. More precisely, (1) we provide a bound on the estimation error using L2 gain, (2) we provide a system theoretic interpretation of grammians...... for showing this independence is realization theory of linear switched systems. [1] H. R. Shaker and R. Wisniewski, "Generalized gramian framework for model/controller order reduction of switched systems", International Journal of Systems Science, Vol. 42, Issue 8, 2011, 1277-1291. [2] H. R. Shaker and R....... Wisniewski, "Switched Systems Reduction Framework Based on Convex Combination of Generalized Gramians", Journal of Control Science and Engineering, 2009....

New stability and stabilization for switched neutral control systems

International Nuclear Information System (INIS)

Xiong Lianglin; Zhong Shouming; Ye Mao; Wu Shiliang

2009-01-01

This paper concerns stability and stabilization issues for switched neutral systems and presents new classes of piecewise Lyapunov functionals and multiple Lyapunov functionals, based on which, two new switching rules are introduced to stabilize the neutral systems. One switching rule is designed from the solution of the so-called Lyapunov-Metzler linear matrix inequalities. The other is based on the determination of average dwell time computed from a new class of linear matrix inequalities (LMIs). And then, state-feedback control is derived for the switched neutral control system mainly based on the state switching rules. Finally, three examples are given to demonstrate the effectiveness of the proposed method.

A prototype switched Ethernet data acquisition system

International Nuclear Information System (INIS)

Ye Gaoying; Deng Huichen; Chen Liaoyuan; Liu Li; Wang Xinhui

1999-01-01

A prototype switched Ethernet data acquisition system has been built up and successfully operated in HL-1M tokamak experiments. The system is based on a switched high bandwidth Ethernet network with which the CAMAC crates are directly interfaced. It takes the advanced features of LAN switch and Ethernet CAMAC controller (ECC 1365 MK III, HYTEC product) to avoid the rewriting of CAMAC driver for an individual computer system and to ensure high data transmission rate between CAMAC system and host computers on the network. It is a new approach to DAS system architecture and provides a solution for a well-known bottleneck problem in traditional distributed DAS system for fusion research. An average throughput of the test system reaches over 100 Mbps. The system features also an easy and low cost migration from traditional distributed DAS system. In the paper, the hardware configuration, software structure, performance of the system and the method of migrating from current DAS system are discussed in detail. (orig.)

Stability analysis of switched linear systems defined by graphs

OpenAIRE

Athanasopoulos, Nikolaos; Lazar, Mircea

2015-01-01

We present necessary and sufficient conditions for global exponential stability for switched discrete-time linear systems, under arbitrary switching, which is constrained within a set of admissible transitions. The class of systems studied includes the family of systems under arbitrary switching, periodic systems, and systems with minimum and maximum dwell time specifications. To reach the result, we describe the set of rules that define the admissible transitions with a weighted directed gra...

Distributed Consensus of Stochastic Delayed Multi-agent Systems Under Asynchronous Switching.

Science.gov (United States)

Wu, Xiaotai; Tang, Yang; Cao, Jinde; Zhang, Wenbing

2016-08-01

In this paper, the distributed exponential consensus of stochastic delayed multi-agent systems with nonlinear dynamics is investigated under asynchronous switching. The asynchronous switching considered here is to account for the time of identifying the active modes of multi-agent systems. After receipt of confirmation of mode's switching, the matched controller can be applied, which means that the switching time of the matched controller in each node usually lags behind that of system switching. In order to handle the coexistence of switched signals and stochastic disturbances, a comparison principle of stochastic switched delayed systems is first proved. By means of this extended comparison principle, several easy to verified conditions for the existence of an asynchronously switched distributed controller are derived such that stochastic delayed multi-agent systems with asynchronous switching and nonlinear dynamics can achieve global exponential consensus. Two examples are given to illustrate the effectiveness of the proposed method.

The experimental optical burst switching system

Science.gov (United States)

Li, Xinwan; Chen, Jian-Ping; Wu, Guiling; Wang, Hui; Lu, Jialin; Ye, Ailun

2005-02-01

The first optical burst switching (OBS) system has been demonstrated in China, which includes three edge routers and one core-node. A kind of fast wavelength selective optical switching was used in the system. The core OBS node consists of a kind of wavelength selective optical switch we developed. It consists of two SOA switches and one wavelength selective thin film filter with centre wavelength at one wavelength. There are one input optical fiber and two output fibers, each fiber carries two wavelengths. The Dell PE2650 servers act as the edge OBS routers. The wavelength of each data channel is located in C-band and the bit rate is at 1.25Gbps. The control channel uses bit rate of 100Mbps at wavelength of 1310 nm. A novel effective scheme for Just-In-Time (JIT) protocol was proposed and implemented. OBS services, such as Video on Demand (VOD) and file transfer protocol (FTP), have been demonstrated. Assembling and scheduling methods that are capable to guarantee the QoS (quality of service) of the transported service are studied.

MOBS - A modular on-board switching system

Science.gov (United States)

Berner, W.; Grassmann, W.; Piontek, M.

The authors describe a multibeam satellite system that is designed for business services and for communications at a high bit rate. The repeater is regenerative with a modular onboard switching system. It acts not only as baseband switch but also as the central node of the network, performing network control and protocol evaluation. The hardware is based on a modular bus/memory architecture with associated processors.

A Fast Channel Switching Method in EPON System for IPTV Service

Science.gov (United States)

Nie, Yaling; Yoshiuchi, Hideya

This paper presents a fast channel switching method in Ethernet Passive Optical Network (EPON) system for IPTV service. Fast channel switching is one of the important features of successful IPTV systems. Users surely prefer IPTV systems with small channel switching time rather than a longer one. Thus a channel switching control module and a channel/permission list in EPON system’s ONU or OLT is designed. When EPON system receives channel switching message from IPTV end user, the channel switching control module will catch the message and search the channel list and permission list maintained in EPON system, then got the matching parameter of EPON for the new channel. The new channel’s data transmission will be enabled by directly updating the optical filter of the ONU that end user connected. By using this method in EPON system, it provides a solution for dealing with channel switching delays in IPTV service.

Design of convergent switched systems

NARCIS (Netherlands)

Berg, van den R.A.; Pogromsky, A.Y.; Leonov, G.A.; Rooda, J.E.; Pettersen, K.Y.; Gravdahl, J.T.; Nijmeijer, H.

2006-01-01

In this paper we deal with the problem of rendering hybrid/nonlinear systems into convergent closed-loop systems by means of a feedback law or switching rules. We illustrate our approach to this problem by means of two examples: the anti-windup design for a marginally stable system with input

Time-dependent switched discrete-time linear systems control and filtering

CERN Document Server

Zhang, Lixian; Shi, Peng; Lu, Qiugang

2016-01-01

This book focuses on the basic control and filtering synthesis problems for discrete-time switched linear systems under time-dependent switching signals. Chapter 1, as an introduction of the book, gives the backgrounds and motivations of switched systems, the definitions of the typical time-dependent switching signals, the differences and links to other types of systems with hybrid characteristics and a literature review mainly on the control and filtering for the underlying systems. By summarizing the multiple Lyapunov-like functions (MLFs) approach in which different requirements on comparisons of Lyapunov function values at switching instants, a series of methodologies are developed for the issues on stability and stabilization, and l2-gain performance or tube-based robustness for l∞ disturbance, respectively, in Chapters 2 and 3. Chapters 4 and 5 are devoted to the control and filtering problems for the time-dependent switched linear systems with either polytopic uncertainties or measurable time-varying...

Isotopic ratios in the solar system

International Nuclear Information System (INIS)

1985-01-01

This colloquium is aimed at presentation of isotope ratio measurements in different objects of solar system and surrounding interstellar space and evaluation of what information on composition and structure of primitive solar nebula and on chemical evolution of interstellar space in this part of the galaxy can be deduced from it. Isotope ratio in solar system got from laboratory study of extraterrestrial materials is a subject of this colloquium. Then isotope ratio measured in solar wind, planets and comets. Measurements either are made in-situ by mass spectrometry of ions in solar wind or planetery atmosphere gases either are remote measurements of spectra emitted by giant planets and comets. At last, planetology and astrophysics implications are presented and reviewed. Consraints for solar system formation model can be deduced from isotope ratio measurement. Particularly, isotope anomalies are marks of the processes, which have influenced the primitive solar nebula contraction [fr

Multiuser hybrid switched-selection diversity systems

KAUST Repository

Shaqfeh, Mohammad

2011-09-01

A new multiuser scheduling scheme is proposed and analyzed in this paper. The proposed system combines features of conventional full-feedback selection-based diversity systems and reduced-feedback switch-based diversity systems. The new hybrid system provides flexibility in trading-off the channel information feedback overhead with the prospected multiuser diversity gains. The users are clustered into groups, and the users\\' groups are ordered into a sequence. Per-group feedback thresholds are used and optimized to maximize the system overall achievable rate. The proposed hybrid system applies switched diversity criterion to choose one of the groups, and a selection criterion to decide the user to be scheduled from the chosen group. Numerical results demonstrate that the system capacity increases as the number of users per group increases, but at the cost of more required feedback messages. © 2011 IEEE.

Fractionation of boron isotopes in Icelandic hydrothermal systems

International Nuclear Information System (INIS)

Aggarwal, J.K.

1995-01-01

Boron isotope ratios have been determined in a variety of different geothermal waters from hydrothermal systems across Iceland. Isotope ratios from the high temperature meteoric water recharged systems reflect the isotope ratio of the host rocks without any apparent fractionation. Seawater recharged geothermal systems exhibit more positive δ 1 1B values than the meteoric water recharged geothermal systems. Water/rock ratios can be assessed from boron isotope ratios in the saline hydrothermal systems. Low temperature hydrothermal systems also exhibit more positive δ 1 1B than the high temperature systems, indicating fractionation of boron due to absorption of the lighter isotope onto secondary minerals. Fractionation of boron in carbonate deposits may indicate the level of equilibrium attained within the systems. (author). 14 refs., 2 figs

Robust filtering and fault detection of switched delay systems

CERN Document Server

Wang, Dong; Wang, Wei

2013-01-01

Switched delay systems appear in a wide field of applications including networked control systems, power systems, memristive systems. Though the large amount of ideas with respect to such systems have generated, until now, it still lacks a framework to focus on filter design and fault detection issues which are relevant to life safety and property loss. Beginning with the comprehensive coverage of the new developments in the analysis and control synthesis for switched delay systems, the monograph not only provides a systematic approach to designing the filter and detecting the fault of switched delay systems, but it also covers the model reduction issues. Specific topics covered include: (1) Arbitrary switching signal where delay-independent and delay-dependent conditions are presented by proposing a linearization technique. (2) Average dwell time where a weighted Lyapunov function is come up with dealing with filter design and fault detection issues beside taking model reduction problems. The monograph is in...

Evaluating prey switching in wolf-ungulate systems.

Science.gov (United States)

Garrott, Robert A; Bruggeman, Jason E; Becker, Matthew S; Kalinowski, Steven T; White, P J

2007-09-01

Wolf restoration has become a widely accepted conservation and management practice throughout North America and Europe, though the ecosystem effects of returning top carnivores remain both scientific and societal controversies. Mathematical models predicting and describing wolf-ungulate interactions are typically limited to the wolves' primary prey, with the potential for prey switching in wolf-multiple-ungulate systems only suggested or assumed by a number of investigators. We used insights gained from experiments on small taxa and field data from ongoing wolf-ungulate studies to construct a model of predator diet composition for a wolf-elk-bison system in Yellowstone National Park, Wyoming, USA. The model explicitly incorporates differential vulnerability of the ungulate prey types to predation, predator preference, differences in prey biomass, and the possibility of prey switching. Our model demonstrates wolf diet shifts with changes in relative abundance of the two prey, with the dynamics of this shift dependent on the combined influences of preference, differential vulnerability, relative abundances of prey, and whether or not switching occurs. Differences in vulnerability between elk and bison, and strong wolf preference for elk, result in an abrupt dietary shift occurring only when elk are very rare relative to bison, whereas incorporating switching initiates the dietary shift more gradually and at higher bison-elk ratios. We demonstrate how researchers can apply these equations in newly restored wolf-two-prey systems to empirically evaluate whether prey switching is occurring. Each coefficient in the model has a biological interpretation, and most can be directly estimated from empirical data collected from field studies. Given the potential for switching to dramatically influence predator-prey dynamics and the wide range of expected prey types and abundances in some systems where wolves are present and/or being restored, we suggest that this is an

An integrated circuit/packet switched video conferencing system

Energy Technology Data Exchange (ETDEWEB)

Kippenhan Junior, H.A.; Lidinsky, W.P.; Roediger, G.A. [Fermi National Accelerator Lab., Batavia, IL (United States). HEP Network Resource Center; Waits, T.A. [Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy

1996-07-01

The HEP Network Resource Center (HEPNRC) at Fermilab and the Collider Detector Facility (CDF) collaboration have evolved a flexible, cost-effective, widely accessible video conferencing system for use by high energy physics collaborations and others wishing to use video conferencing. No current systems seemed to fully meet the needs of high energy physics collaborations. However, two classes of video conferencing technology: circuit-switched and packet-switched, if integrated, might encompass most of HEPS's needs. It was also realized that, even with this integration, some additional functions were needed and some of the existing functions were not always wanted. HEPNRC with the help of members of the CDF collaboration set out to develop such an integrated system using as many existing subsystems and components as possible. This system is called VUPAC (Video conferencing Using Packets and Circuits). This paper begins with brief descriptions of the circuit-switched and packet-switched video conferencing systems. Following this, issues and limitations of these systems are considered. Next the VUPAC system is described. Integration is accomplished primarily by a circuit/packet video conferencing interface. Augmentation is centered in another subsystem called MSB (Multiport MultiSession Bridge). Finally, there is a discussion of the future work needed in the evolution of this system. (author)

An integrated circuit/packet switched video conferencing system

International Nuclear Information System (INIS)

Kippenhan Junior, H.A.; Lidinsky, W.P.; Roediger, G.A.; Waits, T.A.

1996-01-01

The HEP Network Resource Center (HEPNRC) at Fermilab and the Collider Detector Facility (CDF) collaboration have evolved a flexible, cost-effective, widely accessible video conferencing system for use by high energy physics collaborations and others wishing to use video conferencing. No current systems seemed to fully meet the needs of high energy physics collaborations. However, two classes of video conferencing technology: circuit-switched and packet-switched, if integrated, might encompass most of HEPS's needs. It was also realized that, even with this integration, some additional functions were needed and some of the existing functions were not always wanted. HEPNRC with the help of members of the CDF collaboration set out to develop such an integrated system using as many existing subsystems and components as possible. This system is called VUPAC (Video conferencing Using Packets and Circuits). This paper begins with brief descriptions of the circuit-switched and packet-switched video conferencing systems. Following this, issues and limitations of these systems are considered. Next the VUPAC system is described. Integration is accomplished primarily by a circuit/packet video conferencing interface. Augmentation is centered in another subsystem called MSB (Multiport MultiSession Bridge). Finally, there is a discussion of the future work needed in the evolution of this system. (author)

Constructing large scale SCI-based processing systems by switch elements

International Nuclear Information System (INIS)

Wu, B.; Kristiansen, E.; Skaali, B.; Bogaerts, A.; Divia, R.; Mueller, H.

1993-05-01

The goal of this paper is to study some of the design criteria for the switch elements to form the interconnection of large scale SCI-based processing systems. The approved IEEE standard 1596 makes it possible to couple up to 64K nodes together. In order to connect thousands of nodes to construct large scale SCI-based processing systems, one has to interconnect these nodes by switch elements to form different topologies. A summary of the requirements and key points of interconnection networks and switches is presented. Two models of the SCI switch elements are proposed. The authors investigate several examples of systems constructed for 4-switches with simulations and the results are analyzed. Some issues and enhancements are discussed to provide the ideas behind the switch design that can improve performance and reduce latency. 29 refs., 11 figs., 3 tabs

Mode switching control of dual-evaporator air-conditioning systems

International Nuclear Information System (INIS)

Lin, J.-L.; Yeh, T.-J.

2009-01-01

Modern air-conditioners incorporate variable-speed compressors and variable-opening expansion valves as the actuators for improving cooling performance and energy efficiency. These actuators have to be properly feedback-controlled; otherwise the systems may exhibit even poorer performance than the conventional machines which use fixed-speed compressors and mechanical expansion valves. Particularly for an air-conditioner with multiple evaporators, there are occasions that the machine is operated in a mode that only selected evaporator(s) is(are) turned on, and switching(s) between modes occurs(occur) during the control process. In this case, one needs to have more carefully designed control and switching strategies to ensure the system performance. In this paper, a framework for mode switching control of the dual-evaporator air-conditioning (DEAC) system is proposed. The framework is basically an integration of a controller and a dynamic compensator. The controller, which possesses the flow-distribution capability and assumes both evaporators are on throughout the control process, is intended to provide nominal performance. While mode switching is achieved by varying the reference settings in the controller, the dynamic compensator is used to improve the transient responses immediately after the switching. Experiments indicate that the proposed framework can achieve satisfactory indoor temperature regulation and provide bumpless switching between different modes of operation.

High Performance Gigabit Ethernet Switches for DAQ Systems

CERN Document Server

Barczyk, Artur

2005-01-01

Commercially available high performance Gigabit Ethernet (GbE) switches are optimized mostly for Internet and standard LAN application traffic. DAQ systems on the other hand usually make use of very specific traffic patterns, with e.g. deterministic arrival times. Industry's accepted loss-less limit of 99.999% may be still unacceptably high for DAQ purposes, as e.g. in the case of the LHCb readout system. In addition, even switches passing this criteria under random traffic can show significantly higher loss rates if subject to our traffic pattern, mainly due to buffer memory limitations. We have evaluated the performance of several switches, ranging from "pizza-box" devices with 24 or 48 ports up to chassis based core switches in a test-bed capable to emulate realistic traffic patterns as expected in the readout system of our experiment. The results obtained in our tests have been used to refine and parametrize our packet level simulation of the complete LHCb readout network. In this paper we report on the...

Isotope anomalies in oxygen isotope exchange equilibrium systems

International Nuclear Information System (INIS)

Kotaka, M.

1997-01-01

The purpose of the present work is to elucidate the isotope anomalies in oxygen isotope exchange equilibrium systems, according to the calculations of the equilibrium constants for oxygen isotopic exchange reactions, and the calculations of the oxygen isotope separation factors between two phases. The equilibrium constants (K65, K67, K68 and K69) of 16 O- 15 O, 16 O 17 O, 16 O- 18 O, and 16 O- 19 O exchange reactions between diatomic oxides were calculated in a wide temperature range on the basis of quantum statistical mechanics. Many equilibrium constants showed the anomalous mass effects, and then had the crossover temperatures and the mass independent fractionation (MIF) temperatures which held K67 = K65, K67 = K68, or K67 = K69, etc. For example, the equilibrium constants for the reactions between OH and the other diatomic oxides (MO) showed the anomalous mass effects, when M was Li, Na, Mg, K, Fe, Al, Ge, Zr, Pt, etc. The 16 O 15 O, 16 O 17 O, 16 O- 18 O, and 16 O- 19 O oxygen isotope separation factors (S65, S67, S68 and S69) between two phases were calculated, when OH and CO were in the first phase, and SiO was in the second phase. Although the oxygen isotopic exchange equilibria in the two phases had no MIF and crossover temperatures, the separation factors showed the anomalous mass effects and had the temperatures. According to what is called the normal mass effects for the equilibrium constant of isotopic exchange reaction, the value of InK68/InK67 is 1.885. Therefore, the value of InS68/InS67 should be 1.885 too. The value calculated, however, widely changed. It can be concluded from the results obtained in the present work that some oxygen isotopic exchange equilibria cause the anomalous mass effects, the anomalous oxygen isotope separation factors, and then isotope anomalies

Protection and switching system for the RFX power supply

International Nuclear Information System (INIS)

Browning, J.L.; Gray, J.W.; Mace, T.A.; Varley, G.L.

1986-01-01

The RFX toroidal field power supply comprises a large 4.8MJ (max) modular capacitor bank and four 14MW AC/DC converter flat-top power supply modules. The high fault level associated with the capacitor banks presents a problem in the design of the switching system, since mistiming could produce large currents in the flat-top supplies. The poloidal circuit consists of four groups of magnetising windings connected in series, each with its own flat-top convertor supply and opening switch transfer system. The flat-top converter supplies are needed when the transfer voltage has fallen from approximately 40kV to 1kV. Solutions to the problem of designing a fault-tolerant system which presents no danger to the flat-top converters are described in the paper. The adopted methods make use of hybrid ignitron/mechanical switches to give the required combination of switching speed and current carrying capacity, together with careful attention to the circuit layout of different switching elements. (author)

Switched periodic systems in discrete time: stability and input-output norms

Science.gov (United States)

Bolzern, Paolo; Colaneri, Patrizio

2013-07-01

This paper deals with the analysis of stability and the characterisation of input-output norms for discrete-time periodic switched linear systems. Such systems consist of a network of time-periodic linear subsystems sharing the same state vector and an exogenous switching signal that triggers the jumps between the subsystems. The overall system exhibits a complex dynamic behaviour due to the interplay between the time periodicity of the subsystem parameters and the switching signal. Both arbitrary switching signals and signals satisfying a dwell-time constraint are considered. Linear matrix inequality conditions for stability and guaranteed H2 and H∞ performances are provided. The results heavily rely on the merge of the theory of linear periodic systems and recent developments on switched linear time-invariant systems.

Optimal control of switched systems arising in fermentation processes

CERN Document Server

Liu, Chongyang

2014-01-01

The book presents, in a systematic manner, the optimal controls under different mathematical models in fermentation processes. Variant mathematical models – i.e., those for multistage systems; switched autonomous systems; time-dependent and state-dependent switched systems; multistage time-delay systems and switched time-delay systems – for fed-batch fermentation processes are proposed and the theories and algorithms of their optimal control problems are studied and discussed. By putting forward novel methods and innovative tools, the book provides a state-of-the-art and comprehensive systematic treatment of optimal control problems arising in fermentation processes. It not only develops nonlinear dynamical system, optimal control theory and optimization algorithms, but can also help to increase productivity and provide valuable reference material on commercial fermentation processes.

Isotope separation system

International Nuclear Information System (INIS)

Lehmann, J.-C.

1975-01-01

A description is given of an isotope separation device comprising a system for converting into gaseous form a first and second isotope to be separated, a monochromatic excitation light source to excite the gaseous molecules of these two isotopes in a distinct manner, a first and second receiver to collect selectively the molecules of the first and second distinctly excited isotopes. The frequency FL of the excitation light is selected between a lower limit and a higher limit F2 + 1/2 LD, depending on the frequences F1 and F2 of two absorption lines near this first and second isotope. The difference DF between these two frequencies F1 and F2 is less than the Doppler width LD of each one of these lines and greater than the natural width LN of each of these two lines and also the width of line LR of the excitation light source. The probability that the molecules will be excited by this light depends on the direction of their displacement to a major and different extent for both isotopes. An ionising light source LI is set up to irradiate the seat of interaction between the excitation light and the gaseous molecules with an ionisation light able to ionise the excited molecules without ionising the molecules that are not excited. The receivers are able to collect selectively the ionised molecules. A sufficiently low gas pressure is selected for the distance between the place of interaction and the first receiver to be less than double the free mean travel of the molecules in the gas [fr

Control of delay dominant systems with costs related to switching

DEFF Research Database (Denmark)

Deng, Honglian; Larsen, Lars Finn Sloth; Stoustrup, Jakob

2010-01-01

The objective of this paper is to extend a novel low complexity method for optimizing switch control developed by the authors earlier to work with delay dominant systems and demonstrate that the method works in practice with a refrigeration test system. The extended method solves switching problems...... controller with fixed bounds shows that the optimizing switch control outperforms the baseline....

Three-tier multi-granularity switching system based on PCE

Science.gov (United States)

Wang, Yubao; Sun, Hao; Liu, Yanfei

2017-10-01

With the growing demand for business communications, electrical signal processing optical path switching can't meet the demand. The multi-granularity switch system that can improve node routing and switching capabilities came into being. In the traditional network, each node is responsible for calculating the path; synchronize the whole network state, which will increase the burden on the network, so the concept of path calculation element (PCE) is proposed. The PCE is responsible for routing and allocating resources in the network1. In the traditional band-switched optical network, the wavelength is used as the basic routing unit, resulting in relatively low wavelength utilization. Due to the limitation of wavelength continuity, the routing design of the band technology becomes complicated, which directly affects the utilization of the system. In this paper, optical code granularity is adopted. There is no continuity of the optical code, and the number of optical codes is more flexible than the wavelength. For the introduction of optical code switching, we propose a Code Group Routing Entity (CGRE) algorithm. In short, the combination of three-tier multi-granularity optical switching system and PCE can simplify the network structure, reduce the node load, and enhance the network scalability and survivability. Realize the intelligentization of optical network.

Switching Systems: Controllability and Control Design

Science.gov (United States)

2009-04-25

both continuous and discrete dynamics, are abundant in essentially all areas of engineering and scientific endeavor. Hybrid systems can switch between...TERMS EOARD, Navigation, Comunications & Guidance, Complex Systems 16. SECURITY CLASSIFICATION OF: 19a. NAME OF RESPONSIBLE PERSON JAMES LAWTON Ph

Petrological, geochemical, isotopic, and geochronological constraints for the Late Devonian-Early Carboniferous magmatism in SW Gondwana (27-32°LS): an example of geodynamic switching

Science.gov (United States)

Dahlquist, Juan A.; Alasino, Pablo H.; Basei, Miguel A. S.; Morales Cámera, Matías M.; Macchioli Grande, Marcos; da Costa Campos Neto, Mario

2018-04-01

We report a study integrating 13 new U-Pb LA-MC-ICP-MS zircon ages and Hf-isotope data from dated magmatic zircons together with complete petrological and whole-rock geochemistry data for the dated granitic rocks. Sample selection was strongly based on knowledge reported in previous investigations. Latest Devonian-Early Carboniferous granite samples were collected along a transect of 900 km, from the inner continental region (present-day Eastern Sierras Pampeanas) to the magmatic arc (now Western Sierras Pampeanas and Frontal Cordillera). Based on these data together with ca. 100 published whole-rock geochemical analyses we conclude that Late Devonian-Early Carboniferous magmatism at this latitude represents continuous activity (ranging from 322 to 379 Ma) on the pre-Andean margin of SW Gondwana, although important whole-rock and isotopic compositional variations occurred through time and space. Combined whole-rock chemistry and isotope data reveal that peraluminous A-type magmatism started in the intracontinental region during the Late Devonian, with subsequent development of synchronous Carboniferous peraluminous and metaluminous A-type magmatism in the retro-arc region and calc-alkaline magmatism in the western paleomargin. We envisage that magmatic evolution was mainly controlled by episodic fluctuations in the angle of subduction of the oceanic plate (between flat-slab and normal subduction), supporting a geodynamic switching model. Subduction fluctuations were relatively fast (ca. 7 Ma) during the Late Devonian and Early Carboniferous, and the complete magmatic switch-off and switch-on process lasted for 57 Ma. Hf T DM values of zircon (igneous and inherited) from some Carboniferous peraluminous A-type granites in the retro-arc suggest that Gondwana continental lithosphere formed during previous orogenies was partly the source of the Devonian-Carboniferous granitic magmas, thus precluding the generation of the parental magmas from exotic terranes.

1.114-gb/s time/space division switch system

Science.gov (United States)

Pawelski, Robert L.; Nordin, Ronald A.; Huisman, R. F.; Kelly, S.; Payne, William A.; Veach, R. S.

1990-10-01

Advanced digital communication services11 such as Broadband ISDN High Definition Television (HDTV) and enhanced data networking are expected to require high bandwidth and fast reconfiguration time switching centers available in the 1990''s. Digital GaAs IC''s can allow the implementation of these switching centers providing these services efficiently and at a low cost. The low cost arises from the reduction in hardware power maintenance etc. when the switch is designed to operate at the incoming data rate instead of at a lower rate. In order to utilize the capacity of a high bandwidth data link time division multiplexing is employed. This is a technique where multiple digital signals are interleaved (bit byte or block) on one data link. Clearly it is advantageous to have a switch that not only has a large bandwidth but can reconfigure at the data rate so as to provide bit byte or block switching functions thus being compatible with many different transmission formats. We present an experimental Time/Space Division Switch System capable of operating at over 1 Gb/s. Both custom and commercial Gallium Arsenide (GaAs) devices are used in the design of the various system functional blocks. These functional blocks include a Time Slot Interchanger (TSI) Time Multiplexed Switch (TMS) TMS Controller Multiplexer and Demultiplexers. In addition to the system overview we discuss such issues as printed circuit board microwave interconnections and CAD tools for high speed

Switched-Observer-Based Adaptive Neural Control of MIMO Switched Nonlinear Systems With Unknown Control Gains.

Science.gov (United States)

Long, Lijun; Zhao, Jun

2017-07-01

In this paper, the problem of adaptive neural output-feedback control is addressed for a class of multi-input multioutput (MIMO) switched uncertain nonlinear systems with unknown control gains. Neural networks (NNs) are used to approximate unknown nonlinear functions. In order to avoid the conservativeness caused by adoption of a common observer for all subsystems, an MIMO NN switched observer is designed to estimate unmeasurable states. A new switched observer-based adaptive neural control technique for the problem studied is then provided by exploiting the classical average dwell time (ADT) method and the backstepping method and the Nussbaum gain technique. It effectively handles the obstacle about the coexistence of multiple Nussbaum-type function terms, and improves the classical ADT method, since the exponential decline property of Lyapunov functions for individual subsystems is no longer satisfied. It is shown that the technique proposed is able to guarantee semiglobal uniformly ultimately boundedness of all the signals in the closed-loop system under a class of switching signals with ADT, and the tracking errors converge to a small neighborhood of the origin. The effectiveness of the approach proposed is illustrated by its application to a two inverted pendulum system.

Progress in switching technology for METS systems

International Nuclear Information System (INIS)

Honig, E.M.; Swannack, C.E.; Warren, R.W.; Whitaker, D.H.

1977-01-01

Three distinct sets of switching requirements have emerged from design optimization studies of large superconducting magnetic energy storage systems, such as the METS system to power the adiabatic plasma compression field in the proposed theta-pinch SFTR. Extremely low joule loss cryogenic disconnects are required between storage coils in the liquid helium environment to allow charging the coils in series over a prolonged time, then to isolate the coils for parallel fast discharging into the load. Another switch must break the current in the series charging loop and absorb the energy from the stray inductance. This action will allow the subsequent opening of the cryogenic disconnects under near zero current condition. The current now has been transferred to the many paralleled circuits, each containing a high current, high voltage interrupter. The opening and arc commutation of the interrupter starts the energy transfer into the load. The primary activities associated with cryogenic disconnect have been testing and development of contact materials, configurations, and closing forces for carrying 26 kA with a resistance less than 40 nΩ, and development of an actuating system that is both reliable and fast acting in a liquid helium environment. The charging loop switch will include a continuous duty switch and a vacuum interrupter. The continuous duty switch resistance can be an order of magnitude larger than that of the cryogenic disconnect because it does not present a refrigeration load. The HVDC interrupter must break 26 kA and withstand 60 kV during the energy transfer time of 700 μs. Testing in progress already has shown successful interruption using single vacuum interrupters up to 31 kA and 66 kV

Forward modeling of fluctuating dietary 13C signals to validate 13C turnover models of milk and milk components from a diet-switch experiment.

Directory of Open Access Journals (Sweden)

Alexander Braun

Full Text Available Isotopic variation of food stuffs propagates through trophic systems. But, this variation is dampened in each trophic step, due to buffering effects of metabolic and storage pools. Thus, understanding of isotopic variation in trophic systems requires knowledge of isotopic turnover. In animals, turnover is usually quantified in diet-switch experiments in controlled conditions. Such experiments usually involve changes in diet chemical composition, which may affect turnover. Furthermore, it is uncertain if diet-switch based turnover models are applicable under conditions with randomly fluctuating dietary input signals. Here, we investigate if turnover information derived from diet-switch experiments with dairy cows can predict the isotopic composition of metabolic products (milk, milk components and feces under natural fluctuations of dietary isotope and chemical composition. First, a diet-switch from a C3-grass/maize diet to a pure C3-grass diet was used to quantify carbon turnover in whole milk, lactose, casein, milk fat and feces. Data were analyzed with a compartmental mixed effects model, which allowed for multiple pools and intra-population variability, and included a delay between feed ingestion and first tracer appearance in outputs. The delay for milk components and whole milk was ~12 h, and that of feces ~20 h. The half-life (t½ for carbon in the feces was 9 h, while lactose, casein and milk fat had a t½ of 10, 18 and 19 h. The (13C kinetics of whole milk revealed two pools, a fast pool with a t½ of 10 h (likely representing lactose, and a slower pool with a t½ of 21 h (likely including casein and milk fat. The diet-switch based turnover information provided a precise prediction (RMSE ~0.2 ‰ of the natural (13C fluctuations in outputs during a 30 days-long period when cows ingested a pure C3 grass with naturally fluctuating isotope composition.

A switched state feedback law for the stabilization of LTI systems.

Energy Technology Data Exchange (ETDEWEB)

Santarelli, Keith R.

2009-09-01

Inspired by prior work in the design of switched feedback controllers for second order systems, we develop a switched state feedback control law for the stabilization of LTI systems of arbitrary dimension. The control law operates by switching between two static gain vectors in such a way that the state trajectory is driven onto a stable n - 1 dimensional hyperplane (where n represents the system dimension). We begin by briefly examining relevant geometric properties of the phase portraits in the case of two-dimensional systems to develop intuition, and we then show how these geometric properties can be expressed as algebraic constraints on the switched vector fields that are applicable to LTI systems of arbitrary dimension. We then derive necessary and sufficient conditions to ensure stabilizability of the resulting switched system (characterized primarily by simple conditions on eigenvalues), and describe an explicit procedure for designing stabilizing controllers. We then show how the newly developed control law can be applied to the problem of minimizing the maximal Lyapunov exponent of the corresponding closed-loop state trajectories, and we illustrate the closed-loop transient performance of these switched state feedback controllers via multiple examples.

Balanced truncation for linear switched systems

DEFF Research Database (Denmark)

Petreczky, Mihaly; Wisniewski, Rafal; Leth, John-Josef

2013-01-01

In this paper, we present a theoretical analysis of the model reduction algorithm for linear switched systems from Shaker and Wisniewski (2011, 2009) and . This algorithm is a reminiscence of the balanced truncation method for linear parameter varying systems (Wood et al., 1996) [3]. Specifically...

An approach to evaluate switching overvoltages during power system restoration

Directory of Open Access Journals (Sweden)

Sadeghkhani Iman

2012-01-01

Full Text Available Transformer switching is one of the important stages during power system restoration. This switching can cause harmonic overvoltages that might damage some equipment and delay power system restoration. Core saturation on the energisation of a transformer with residual flux is a noticeable factor in harmonic overvoltages. This work uses artificial neural networks (ANN in order to estimate the temporary overvoltages (TOVs due to transformer energisation. In the proposed methodology, the Levenberg-Marquardt method is used to train the multilayer perceptron. The developed ANN is trained with the worst case of switching condition, and tested for typical cases. Simulated results for a partial 39-bus New England test system, show the proposed technique can accurately estimate the peak values and durations of switching overvoltages.

A study on switched linear system identification using game ...

African Journals Online (AJOL)

A study on switched linear system identification using game-theoretic strategies and neural computing. ... This study deals with application of game-theoretic strategies and neural computing to switched linear ... AJOL African Journals Online.

A packet switched communications system for GRO

Science.gov (United States)

Husain, Shabu; Yang, Wen-Hsing; Vadlamudi, Rani; Valenti, Joseph

1993-11-01

This paper describes the packet switched Instrumenters Communication System (ICS) that was developed for the Command Management Facility at GSFC to support the Gamma Ray Observatory (GRO) spacecraft. The GRO ICS serves as a vital science data acquisition link to the GRO scientists to initiate commands for their spacecraft instruments. The system is ready to send and receive messages at any time, 24 hours a day and seven days a week. The system is based on X.25 and the International Standard Organization's (ISO) 7-layer Open Systems Interconnection (OSI) protocol model and has client and server components. The components of the GRO ICS are discussed along with how the Communications Subsystem for Interconnection (CSFI) and Network Control Program Packet Switching Interface (NPSI) software are used in the system.

Isotope hydrology of catchment basins: lithogenic and cosmogenic isotopic systems

Energy Technology Data Exchange (ETDEWEB)

Nimz, G. J., LLNL

1998-06-01

A variety of physical processes affect solute concentrations within catchment waters. The isotopic compositions of the solutes can indicate which processes have determined the observed concentrations. These processes together constitute the physical history of the water. Many solutes in natural waters are derived from the interaction between the water and the rock and/or soil within the system - these are termed `lithogenic` solutes. The isotopic compositions of these solutes provide information regarding rock-water interactions. Many other solutes have their isotopic compositions determined both within and outside of the catchment - i.e., in addition to being derived from catchment rock and soil, they are solutes that are also transported into the catchment. Important members of this group include solutes that have isotopic compositions produced by atomic particle interactions with other nuclides. The source of the atomic particles can be cosmic radiation (producing `cosmogenic` nuclides in the atmosphere and land surface), anthropogenic nuclear reactions (producing `thermonuclear` nuclides), or radioactive and fission decay of naturally-occurring elements, principally {sup 238}U (producing `in-situ` lithogenic nuclides in the deep subsurface). Current language usage often combines all of the atomic particle-produced nuclides under the heading `cosmogenic nuclides`, and for simplicity we will often follow that usage here, although always indicating which variety is being discussed. This paper addresses the processes that affect the lithogenic and cosmogenic solute concentrations in catchment waters, and how the isotopic compositions of the solutes can be used in integrative ways to identify these processes, thereby revealing the physical history of the water within a catchment system. The concept of a `system` is important in catchment hydrology. A catchment is the smallest landscape unit that can both participate in all of the aspects of the hydrologic cycle and

Effect of switching surges on ehv system design

Energy Technology Data Exchange (ETDEWEB)

Baril, G A; McGillis, D

1966-01-01

The presence of switching surges imposes certain conditions on the design of ehv system and certain resulting requirements in the basic components of these systems. At extra high voltage, it becomes both a practical as well as an economic necessity to limit the magnitude of switching surge overvoltages. This can be accomplished by the installation of suitable terminal equipment, and for the 735 kV system it was found necessary to install permanently connected shunt reactors on the transmission lines and to provide for the installation of closing resistors on the circuit breakers.

Synchronization of switched system and application in communication

International Nuclear Information System (INIS)

Yu Wenwu; Cao Jinde; Yuan Kun

2008-01-01

In this Letter, synchronization of switched system is investigated based on Lyapunov method. A sufficient condition is derived to ensure the synchronization between two switched systems, and a new communication scheme is also proposed based on this. Furthermore, some secure analysis works, such as return map attack and moving average error attack, are also given to show the security of the proposed scheme. Finally, simulation examples are constructed to verify the theoretical analysis and its application for communication

Switch/router architectures shared-bus and shared-memory based systems

CERN Document Server

Aweya, James

2018-01-01

A practicing engineer's inclusive review of communication systems based on shared-bus and shared-memory switch/router architectures. This book delves into the inner workings of router and switch design in a comprehensive manner that is accessible to a broad audience. It begins by describing the role of switch/routers in a network, then moves on to the functional composition of a switch/router. A comparison of centralized versus distributed design of the architecture is also presented. The author discusses use of bus versus shared-memory for communication within a design, and also covers Quality of Service (QoS) mechanisms and configuration tools. Written in a simple style and language to allow readers to easily understand and appreciate the material presented, Switch/Router Architectures: Shared-Bus and Shared-Memory Based Systems discusses the design of multilayer switches—starting with the basic concepts and on to the basic architectures. It describes the evolution of multilayer switch designs and highli...

Global dynamics for switching systems and their extensions by linear differential equations.

Science.gov (United States)

Huttinga, Zane; Cummins, Bree; Gedeon, Tomáš; Mischaikow, Konstantin

2018-03-15

Switching systems use piecewise constant nonlinearities to model gene regulatory networks. This choice provides advantages in the analysis of behavior and allows the global description of dynamics in terms of Morse graphs associated to nodes of a parameter graph. The parameter graph captures spatial characteristics of a decomposition of parameter space into domains with identical Morse graphs. However, there are many cellular processes that do not exhibit threshold-like behavior and thus are not well described by a switching system. We consider a class of extensions of switching systems formed by a mixture of switching interactions and chains of variables governed by linear differential equations. We show that the parameter graphs associated to the switching system and any of its extensions are identical. For each parameter graph node, there is an order-preserving map from the Morse graph of the switching system to the Morse graph of any of its extensions. We provide counterexamples that show why possible stronger relationships between the Morse graphs are not valid.

Global dynamics for switching systems and their extensions by linear differential equations

Science.gov (United States)

Huttinga, Zane; Cummins, Bree; Gedeon, Tomáš; Mischaikow, Konstantin

2018-03-01

Switching systems use piecewise constant nonlinearities to model gene regulatory networks. This choice provides advantages in the analysis of behavior and allows the global description of dynamics in terms of Morse graphs associated to nodes of a parameter graph. The parameter graph captures spatial characteristics of a decomposition of parameter space into domains with identical Morse graphs. However, there are many cellular processes that do not exhibit threshold-like behavior and thus are not well described by a switching system. We consider a class of extensions of switching systems formed by a mixture of switching interactions and chains of variables governed by linear differential equations. We show that the parameter graphs associated to the switching system and any of its extensions are identical. For each parameter graph node, there is an order-preserving map from the Morse graph of the switching system to the Morse graph of any of its extensions. We provide counterexamples that show why possible stronger relationships between the Morse graphs are not valid.

Radiogenic isotope geochemistry of sedimentary and aquatic systems

International Nuclear Information System (INIS)

Stille, P.; Shields, G.

1997-01-01

The following topics are discussed: Basic principles of isotopic geochemistry; weathering; isotopic geochemistry of river water; isotopic geochemistry in the environment; isotopic composition of seawater past and present (Sr, Nd, Pb, Os, Ce); isotope geochemistry of detrital and authigenic clay minerals in marine sediemnts (Rb-Sr, K-Ar, O); the Sm-N isotope system in detrital and authigenic argillaceous sediments. (SR), provided they are of exceptional interest and focused on a single topic. (orig./SR)

Radiogenic isotope geochemistry of sedimentary and aquatic systems

Energy Technology Data Exchange (ETDEWEB)

Stille, P.; Shields, G. [Centre National de la Recherche Scientifique (CNRS), 67 - Strasbourg (France). Centre de Sedimentologie et Geochimie de la Surface

1997-12-31

The following topics are discussed: Basic principles of isotopic geochemistry; weathering; isotopic geochemistry of river water; isotopic geochemistry in the environment; isotopic composition of seawater past and present (Sr, Nd, Pb, Os, Ce); isotope geochemistry of detrital and authigenic clay minerals in marine sediemnts (Rb-Sr, K-Ar, O); the Sm-N isotope system in detrital and authigenic argillaceous sediments. (SR), provided they are of exceptional interest and focused on a single topic. (orig./SR)

Modeling and Analysis of Modal Switching in Networked Transport Systems

International Nuclear Information System (INIS)

Hante, Falk M.; Leugering, Guenter; Seidman, Thomas I.

2009-01-01

We consider networked transport systems defined on directed graphs: the dynamics on the edges correspond to solutions of transport equations with space dimension one. In addition to the graph setting, a major consideration is the introduction and propagation of discontinuities in the solutions when the system may discontinuously switch modes, naturally or as a hybrid control. This kind of switching has been extensively studied for ordinary differential equations, but not much so far for systems governed by partial differential equations. In particular, we give well-posedness results for switching as a control, both in finite horizon open loop operation and as feedback based on sensor measurements in the system

A Time-Measurement System Based on Isotopic Ratios

International Nuclear Information System (INIS)

Vo, Duc T.; Karpius, P.J.; MacArthur, D.W.; Thron, J.L.

2007-01-01

A time-measurement system can be built based on the ratio of gamma-ray peak intensities from two radioactive isotopes. The ideal system would use a parent isotope with a short half-life decaying to a long half-life daughter. The activities of the parent-daughter isotopes would be measured using a gamma-ray detector system. The time can then be determined from the ratio of the activities. The best-known candidate for such a system is the 241 Pu- 241 Am parent-daughter pair. However, this 241 Pu- 241 Am system would require a high-purity germanium detector system and sophisticated software to separate and distinguish between the many gamma-ray peaks produced by the decays of the two isotopes. An alternate system would use two different isotopes, again one with a short half-life and one with a half-life that is long relative to the other. The pair of isotopes 210 Pb and 241 Am (with half-lives of 22 and 432 years, respectively) appears suitable for such a system. This time-measurement system operates by measuring the change in the ratio of the 47-keV peak of 210 Pb to the 60-keV peak of 241 Am. For the system to work reasonably well, the resolution of the detector would need to be such that the two gamma-ray peaks are well separated so that their peak areas can be accurately determined using a simple region-of-interest (ROI) method. A variety of detectors were tested to find a suitable system for this application. The results of these tests are presented here.

The transport of oxygen isotopes in hydrothermal systems

International Nuclear Information System (INIS)

McKibbin, R.; Absar, A.; Blattner, P.

1986-01-01

As groundwater passes through porous rocks, exchange of oxygen between the fluid and the solid matrix causes a change in the oxygen isotope concentrations in both water and rock. If the rate at which the exchange takes place can be estimated (as a function of the isotope concentrations and temperature) then the time taken for a rock/water system to come to equilibrium with respect to isotope concentration might be calculated. In this paper, the equation for isotope transport is derived using conservation laws, and a simple equation to describe the rate of isotope exchange is proposed. These are combined with the equations for fluid flow in a porous medium, to produce a general set of equations describing isotope transport in a hydrothermal system. These equations are solved numerically, using typical parameters, for the one-dimensional case. Oxygen isotope data from the basement rocks underlying Kawerau geothermal field are modelled. The results indicate that the time taken for exchange of 18 O to present-day values is less than the postulated age of hydrothermal alteration in that field. This suggests that, although controlled by similar parameters, oxygen isotope exchange, in felsic rocks at least, is much faster than hydrothermal alteration. This conclusion is consistent with the petrographic observations from the Kawerau system as well as other geothermal fields

Non-traditional Stable Isotope Systematics of Seafloor Hydrothermal Systems

Science.gov (United States)

Rouxel, O. J.

2009-05-01

Seafloor hydrothermal activity at mid-ocean ridges is one of the fundamental processes controlling the chemistry of the oceans and the altered oceanic crust. Past studies have demonstrated the complexity and diversity of seafloor hydrothermal systems and have highlighted the importance of subsurface environments in controlling the composition of hydrothermal fluids and mineralization types. Traditionally, the behavior of metals in seafloor hydrothermal systems have been investigated by integrating results from laboratory studies, theoretical models, mineralogy and fluid and mineral chemistry. Isotope ratios of various metals and metalloids, such as Fe, Cu, Zn, Se, Cd and Sb have recently provided new approaches for the study of seafloor hydrothermal systems. Despite these initial investigations, the cause of the isotopic variability of these elements remains poorly constrained. We have little understanding of the isotope variations between vent types (black or white smokers) as well as the influence of source rock composition (basalt, felsic or ultrabasic rocks) and alteration types. Here, I will review and present new results of metal isotope systematics of seafloor hydrothermal systems, in particular: (1) determination of empirical isotope fractionation factors for Zn, Fe and Cu-isotopes through isotopic analysis of mono-mineralic sulfide grains lining the internal chimney wall in contact with hydrothermal fluid; (2) comparison of Fe- and Cu-isotope signatures of vent fluids from mid- oceanic and back-arc hydrothermal fields, spanning wide ranges of pH, temperature, metal concentrations and contributions of magmatic fluids enriched in SO2. Ultimately, the use of complementary non-traditional stable isotope systems may help identify and constrain the complex interactions between fluids,minerals, and organisms in seafloor hydrothermal systems.

Utilizing Stable Isotopes and Isotopic Anomalies to Study Early Solar System Formation Processes

Science.gov (United States)

Simon, Justin

2017-01-01

Chondritic meteorites contain a diversity of particle components, i.e., chondrules and calcium-, aluminum-rich refractory inclusions (CAIs), that have survived since the formation of the Solar System. The chemical and isotopic compositions of these materials provide a record of the conditions present in the protoplanetary disk where they formed and can aid our understanding of the processes and reservoirs in which solids formed in the solar nebula, an important step leading to the accretion of planetesimals. Isotopic anomalies associated with nucleosynthetic processes are observed in these discrete materials, and can be compared to astronomical observations and astrophysical formation models of stars and more recently proplyds. The existence and size of these isotopic anomalies are typically thought to reflect a significant state of isotopic heterogeneity in the earliest Solar System, likely left over from molecular cloud heterogeneities on the grain scale, but some could also be due to late stellar injection. The homogenization of these isotopic anomalies towards planetary values can be used to track the efficiency and timescales of disk wide mixing,

Disturbance Decoupling of Switched Linear Systems

NARCIS (Netherlands)

Yurtseven, E.; Heemels, W.P.M.H.; Camlibel, M.K.

2010-01-01

In this paper we consider disturbance decoupling problems for switched linear systems. We will provide necessary and sufficient conditions for three different versions of disturbance decoupling, which differ based on which signals are considered to be the disturbance. In the first version the

Microprocessor Controlled Capacitor Bank Switching System for ...

African Journals Online (AJOL)

In this work, analysis and development of a microprocessor controlled capacitor bank switching system for deployment in a smart distribution network was carried out. This system was implemented by the use of discreet components such as resistors, capacitors, transistor, diode, automatic voltage regulator, with the ...

Atomic switch networks as complex adaptive systems

Science.gov (United States)

Scharnhorst, Kelsey S.; Carbajal, Juan P.; Aguilera, Renato C.; Sandouk, Eric J.; Aono, Masakazu; Stieg, Adam Z.; Gimzewski, James K.

2018-03-01

Complexity is an increasingly crucial aspect of societal, environmental and biological phenomena. Using a dense unorganized network of synthetic synapses it is shown that a complex adaptive system can be physically created on a microchip built especially for complex problems. These neuro-inspired atomic switch networks (ASNs) are a dynamic system with inherent and distributed memory, recurrent pathways, and up to a billion interacting elements. We demonstrate key parameters describing self-organized behavior such as non-linearity, power law dynamics, and multistate switching regimes. Device dynamics are then investigated using a feedback loop which provides control over current and voltage power-law behavior. Wide ranging prospective applications include understanding and eventually predicting future events that display complex emergent behavior in the critical regime.

A Class of Stochastic Hybrid Systems with State-Dependent Switching Noise

DEFF Research Database (Denmark)

Leth, John-Josef; Rasmussen, Jakob Gulddahl; Schiøler, Henrik

2012-01-01

In this paper, we develop theoretical results based on a proposed method for modeling switching noise for a class of hybrid systems with piecewise linear partitioned state space, and state-depending switching. We devise a stochastic model of such systems, whose global dynamics is governed...

Continuous-flow isotope ratio mass spectrometry method for carbon and hydrogen isotope measurements on atmospheric methane

Directory of Open Access Journals (Sweden)

M. Brass

2010-12-01

Full Text Available We describe a continuous-flow isotope ratio mass spectrometry (CF-IRMS technique for high-precision δD and δ¹³C measurements of atmospheric methane on 40 mL air samples. CH₄ is separated from other air components by utilizing purely physical processes based on temperature, time and mechanical valve switching. Chemical agents are avoided. Trace amounts of interfering compounds can be separated by gas chromatography after pre-concentration of the CH₄ sample. The purified sample is then either combusted to CO₂ or pyrolyzed to H₂ for stable isotope measurement. Apart from connecting samples and refilling liquid nitrogen as coolant the system is fully automated and allows an unobserved, continuous analysis of samples. The analytical system has been used for analysis of air samples with CH₄ mixing ratios between ~100 and ~10 000 ppb, for higher mixing ratios samples usually have to be diluted.

Study on improvement of laser system performance for uranium isotope separation

International Nuclear Information System (INIS)

Fujii, Takashi

1998-01-01

For the purpose of reducing the cost of Atomic Vapor Laser Isotope Separation (AVLIS), I developed the following laser technologies. (1) I developed a solid-state pulse power supply, of which output power was the almost highest value achieved for a copper vapor laser in 1989, using a GTO as a switching device and a magnetic pulse compression circuit. (2) I developed a new technique of tuning the laser wavelength to an atomic absorption band using high-speed wavelength shift of a laser diode by direct modulation. (3) I developed a new technique of stabilizing the laser wavelength at an absorption band of a target atom, by locking the sideband generated by phase modulation of a laser beam to a Fabry-Perot interferometer. (4) I proposed the Cr 4+ -doped forsterite laser system as an all solid-state laser system for the AVLIS. I obtained the slope efficiency of 25%, which was the highest value achieved in the case of pulse operation of the Cr 4+ -doped forsterite laser in 1995, using the forsterite with high Cr 4+ -ion concentration. (author)

Problems and solutions of the IFSMTF power and switch system

International Nuclear Information System (INIS)

Wood, R.J.; Wintenberg, R.E.; Googe, J.M.; Nickels, L.E.

1985-01-01

Solutions have been found for the problems encountered with the coil power and switching systems of the International Fusion Superconducting Magnet Test Facility (IFSMTF). The coil power system provides the filtered dc sources (+- 12 V dc; 25,000 A) for charging and discharging the coils of the IFSMTF experiment. The switching system provides the means of transferring the coil current into a dump resistor when a rapid discharge of a coil is required due to a coil failure (quench) or other system abnormalities

Kilowatt Isotope Power System: component report for the Ground Demonstration System Accumulator

International Nuclear Information System (INIS)

Brainard, E.L.

1978-01-01

The Model Number ORC1A3A01 System Accumulator for the Kilowatt Isotope Power System was expulsion tested and demonstrated to be in compliance with the requirements of Sundstrand Explusion Test Procedure, TP 400. Test requirements of TP 400 were extracted from the Kilowatt Isotope Power System, Ground Demonstration System Test Plan

Small-scale computerized isotope record monitoring system

Energy Technology Data Exchange (ETDEWEB)

Richards, L [Queen Elizabeth Coll., London (UK)

1979-05-01

A system in use at Queen Elizabeth College for monitoring the isotopes used by radiation workers and the precautionary medical screening of the workers is described. It consists of a PDP-11 minicomputer and flexible disk storage system. The machine is run under a single-user, real-time operating system and is linked on-line to a teleprinter and a VDU. Data is stored as a series of files, each relating to an individual worker, which can be updated individually from the VDU. The files contain information on the worker's project and medical screening records, and his holdings of isotopes and their use and disposal. A warning is printed automatically if a worker's holding exceeds the allowed maximum. The total quantity of isotopes held and their distribution in an institution such as a university can easily be monitored so that legal limits can be adhered to. The system is inexpensive and can be used by personnel not familiar with computer systems.

Stabilization of switched nonlinear systems with unstable modes

CERN Document Server

Yang, Hao; Cocquempot, Vincent

2014-01-01

This book provides its reader with a good understanding of the stabilization of switched nonlinear systems (SNS), systems that are of practical use in diverse situations: design of fault-tolerant systems in space- and aircraft; traffic control; and heat propagation control of semiconductor power chips. The practical background is emphasized throughout the book; interesting practical examples frequently illustrate the theoretical results with aircraft and spacecraft given particular prominence. Stabilization of Switched Nonlinear Systems with Unstable Modes treats several different subclasses of SNS according to the characteristics of the individual system (time-varying and distributed parameters, for example), the state composition of individual modes and the degree and distribution of instability in its various modes. Achievement and maintenance of stability across the system as a whole is bolstered by trading off between individual modes which may be either stable or unstable, or by exploiting areas of part...

Quadratic stabilisability of multi-agent systems under switching topologies

Science.gov (United States)

Guan, Yongqiang; Ji, Zhijian; Zhang, Lin; Wang, Long

2014-12-01

This paper addresses the stabilisability of multi-agent systems (MASs) under switching topologies. Necessary and/or sufficient conditions are presented in terms of graph topology. These conditions explicitly reveal how the intrinsic dynamics of the agents, the communication topology and the external control input affect stabilisability jointly. With the appropriate selection of some agents to which the external inputs are applied and the suitable design of neighbour-interaction rules via a switching topology, an MAS is proved to be stabilisable even if so is not for each of uncertain subsystem. In addition, a method is proposed to constructively design a switching rule for MASs with norm-bounded time-varying uncertainties. The switching rules designed via this method do not rely on uncertainties, and the switched MAS is quadratically stabilisable via decentralised external self-feedback for all uncertainties. With respect to applications of the stabilisability results, the formation control and the cooperative tracking control are addressed. Numerical simulations are presented to demonstrate the effectiveness of the proposed results.

Ages of the solar system: Isotopic dating

International Nuclear Information System (INIS)

Turner, G.

1982-01-01

The major concern of this section will be to outline the ways in which measurements of isotope abundances have been used to determine the chronology of the origin and evolution of the solar system. In passing it should be remembered that the use of isotopic information is by no means restricted simply to the measurement of time scales and, particularly in recent years, isotope abundances have been used to investigate problems as diverse as the heat sources in the early solar nebula and the chemical evolution of the Earth's mantle. The fundamental property of isotopes which makes them especially useful for dating and other applications is the fact that, apart from a limited amount of mass fractionation, the composition of an isotopic mixture is unaffected by chemical processes. In those cases where mass fractionation does occur this effect may itself be useful, particularly as a source of information on temperatures. Since our main theme is time the events discussed in this section will be most conveniently presented as a chronological sequence, progressing from some time before the solar system existed down to the present day. (orig./WL)

Switched generalized function projective synchronization of two identical/different hyperchaotic systems with uncertain parameters

International Nuclear Information System (INIS)

Li Hongmin; Li Chunlai

2012-01-01

In this paper, we investigate two switched synchronization schemes, namely partial and complete switched generalized function projective synchronization, by using the adaptive control method. Partial switched synchronization of chaotic systems means that the state variables of the drive system synchronize with partial different state variables of the response system, whereas complete switched synchronization of chaotic systems means that all the state variables of the drive system synchronize with complete different state variables of the response system. Because the switched synchronization scheme exists in many combinations, it is a promising type of synchronization as it provides greater security in secure communications. Based on the Lyapunov stability theory, the adaptive control laws and the parameter update laws are derived to make the states of two identical/different hyperchaotic systems asymptotically synchronized up to a desired scaling function. Finally, numerical simulations are performed to verify and illustrate the analytical results.

Lithium isotope separation factors of some two-phase equilibrium systems

International Nuclear Information System (INIS)

Palko, A.A.; Drury, J.S.; Begun, G.M.

1976-01-01

Isotope separation factors of seventeen two-phase equilibrium systems for lithium isotope enrichment have been determined. In all cases, lithium amalgam was used as one of the lithium-containing phases and was equilibrated with an aqueous or organic phase containing a lithium compound. In all systems examined, isotopic exchange was found to be extremely rapid, and 6 Li was concentrated in the amalgam phase. The isotopic separation factor for the LiOH(aqueous) vs Li(amalgam) system has been studied as a function of temperature from -2 to 80 degreeC. The values obtained have been compared with the ''electrolysis'' and exchange separation factors given in the literature. The two-phase systems, LiCl(ethylenediamine) vs Li(amalgam) and LiCl(propylenediamine) vs Li(amalgam), have been studied, and the isotopic separation factors have been determined as functions of the temperature. The factors for the two systems have been found to be substantially the same (within limits of the errors involved) over the temperature range studied (0 to 100 degreeC) as those for the aqueous system. The isotopic separation factors for the seventeen systems have been tabulated, and correlations have been drawn that show the salt and solvent effects upon the values obtained

On the observer design problem for continuous-time switched linear systems with unknown switchings

Czech Academy of Sciences Publication Activity Database

Gómez–Gutiérrez, D.; Čelikovský, Sergej; Ramírez–Trevino, A.; Castillo-Toledo, B.

2015-01-01

Roč. 352, č. 4 (2015), s. 1595-1612 ISSN 0016-0032 R&D Projects: GA ČR GA13-20433S Institutional support: RVO:67985556 Keywords : observer design * switched systems Subject RIV: BC - Control Systems Theory Impact factor: 2.327, year: 2015 http://library.utia.cas.cz/separaty/2015/TR/celikovsky-0442959.pdf

Mean Square Exponential Stability of Stochastic Switched System with Interval Time-Varying Delays

Directory of Open Access Journals (Sweden)

Manlika Rajchakit

2012-01-01

Full Text Available This paper is concerned with mean square exponential stability of switched stochastic system with interval time-varying delays. The time delay is any continuous function belonging to a given interval, but not necessary to be differentiable. By constructing a suitable augmented Lyapunov-Krasovskii functional combined with Leibniz-Newton’s formula, a switching rule for the mean square exponential stability of switched stochastic system with interval time-varying delays and new delay-dependent sufficient conditions for the mean square exponential stability of the switched stochastic system are first established in terms of LMIs. Numerical example is given to show the effectiveness of the obtained result.

Output regulation control for switched stochastic delay systems with dissipative property under error-dependent switching

Science.gov (United States)

Li, L. L.; Jin, C. L.; Ge, X.

2018-01-01

In this paper, the output regulation problem with dissipative property for a class of switched stochastic delay systems is investigated, based on an error-dependent switching law. Under the assumption that none subsystem is solvable for the problem, a sufficient condition is derived by structuring multiple Lyapunov-Krasovskii functionals with respect to multiple supply rates, via designing error feedback regulators. The condition is also established when dissipative property reduces to passive property. Finally, two numerical examples are given to demonstrate the feasibility and efficiency of the present method.

Software development for a switch-based data acquisition system

Energy Technology Data Exchange (ETDEWEB)

Booth, A. (Superconducting Super Collider Lab., Dallas, TX (United States)); Black, D.; Walsh, D. (Fermi National Accelerator Lab., Batavia, IL (United States))

1991-12-01

We report on the software aspects of the development of a switch-based data acquisition system at Fermilab. This paper describes how, with the goal of providing an integrated systems engineering'' environment, several powerful software tools were put in place to facilitate extensive exploration of all aspects of the design. These tools include a simulation package, graphics package and an Expert System shell which have been integrated to provide an environment which encourages the close interaction of hardware and software engineers. This paper includes a description of the simulation, user interface, embedded software, remote procedure calls, and diagnostic software which together have enabled us to provide real-time control and monitoring of a working prototype switch-based data acquisition (DAQ) system.

Solid-state Marx based two-switch voltage modulator for the On-Line Isotope Mass Separator accelerator at the European Organization for Nuclear Research.

Science.gov (United States)

Redondo, L M; Silva, J Fernando; Canacsinh, H; Ferrão, N; Mendes, C; Soares, R; Schipper, J; Fowler, A

2010-07-01

A new circuit topology is proposed to replace the actual pulse transformer and thyratron based resonant modulator that supplies the 60 kV target potential for the ion acceleration of the On-Line Isotope Mass Separator accelerator, the stability of which is critical for the mass resolution downstream separator, at the European Organization for Nuclear Research. The improved modulator uses two solid-state switches working together, each one based on the Marx generator concept, operating as series and parallel switches, reducing the stress on the series stacked semiconductors, and also as auxiliary pulse generator in order to fulfill the target requirements. Preliminary results of a 10 kV prototype, using 1200 V insulated gate bipolar transistors and capacitors in the solid-state Marx circuits, ten stages each, with an electrical equivalent circuit of the target, are presented, demonstrating both the improved voltage stability and pulse flexibility potential wanted for this new modulator.

Control of systems with costs related to switching: applications to air-condition systems

DEFF Research Database (Denmark)

Thybo (Deng), Honglian; Larsen, Lars Finn Sloth; Stoustrup, Jakob

2009-01-01

The objective of this paper is to investigate a low complexity method for controlling systems with binary inputs that have costs related to switching. The control objective for this type of systems is often a trade off between the deviation from the reference and the number of switches (weariness...... energy efficiency etc.). For such systems a steady state solution might never be attained, but rather the optimal behavior might be constituted by a limit cycle. In this paper we consider the problem of finding and controlling the system towards an optimal limit cycle. A low complexity approach giving...

Isotopic coherence of refractory inclusions from CV and CK meteorites: Evidence from multiple isotope systems

Science.gov (United States)

Shollenberger, Quinn R.; Borg, Lars E.; Render, Jan; Ebert, Samuel; Bischoff, Addi; Russell, Sara S.; Brennecka, Gregory A.

2018-05-01

Calcium-aluminum-rich inclusions (CAIs) are the oldest dated materials in the Solar System and numerous previous studies have revealed nucleosynthetic anomalies relative to terrestrial rock standards in many isotopic systems. However, most of the isotopic data from CAIs has been limited to the Allende meteorite and a handful of other CV3 chondrites. To better constrain the isotopic composition of the CAI-forming region, we report the first Sr, Mo, Ba, Nd, and Sm isotopic compositions of two CAIs hosted in the CK3 desert meteorites NWA 4964 and NWA 6254 along with two CAIs from the CV3 desert meteorites NWA 6619 and NWA 6991. After consideration of neutron capture processes and the effects of hot-desert weathering, the Sr, Mo, Ba, Nd, and Sm stable isotopic compositions of the samples show clearly resolvable nucleosynthetic anomalies that are in agreement with previous results from Allende and other CV meteorites. The extent of neutron capture, as manifested by shifts in the observed 149Sm-150Sm isotopic composition of the CAIs is used to estimate the neutron fluence experienced by some of these samples and ranges from 8.40 × 1013 to 2.11 × 1015 n/cm2. Overall, regardless of CAI type or host meteorite, CAIs from CV and CK chondrites have similar nucleosynthetic anomalies within analytical uncertainty. We suggest the region that CV and CK CAIs formed was largely uniform with respect to Sr, Mo, Ba, Nd, and Sm isotopes when CAIs condensed and that CAIs hosted in CV and CK meteorites are derived from the same isotopic reservoir.

Study of solar array switching power management technology for space power system

Science.gov (United States)

Cassinelli, J. E.

1982-01-01

This report documents work performed on the Solar Array Switching Power Management Study. Mission characteristics for three missions were defined to the depth necessary to determine their power management requirements. Solar array switching concepts which could satisfy the mission requirements were identified. The switching concepts were compared with a conventional buck regulator system for cost, weight and volume, reliability, efficiency and thermal control. Solar array switching provided significant advantages in all areas of comparison for the reviewed missions.

Original models of NGN/IMS-networks surrounded by circuit-switched systems

OpenAIRE

Kulikov, Nikolay

2014-01-01

On obtaining of the Alexander Graham Bell a patent for invention of the telephone in 1987, the communication system consistently has gone through several evolutionary stages: from analog lines and manual switches to video telephony and IMS architecture. Each of the stages can be described by specific switching systems, data transmission systems and types of transmitted information. After implementation of such solution, it is possible to create a number of access nodes in the Operators IMS-ne...

A small-scale computerized isotope record monitoring system

International Nuclear Information System (INIS)

Richards, L.

1979-01-01

A system in use at Queen Elizabeth College for monitoring the isotopes used by radiation workers and the precautionary medical screening of the workers is described. It consists of a PDP-11 minicomputer and flexible disk storage system. The machine is run under a single-user, real-time operating system and is linked on-line to a teleprinter and a VDU. Data is stored as a series of files, each relating to an individual worker, which can be updated individually from the VDU. The files contain information on the worker's project and medical screening records, and his holdings of isotopes and their use and disposal. A warning is printed automatically if a worker's holding exceeds the allowed maximum. The total quantity of isotopes held and their distribution in an institution such as a university can easily be monitored so that legal limits can be adhered to. The system is inexpensive and can be used by personnel not familiar with computer systems. (author)

Exponential Stability of Time-Switched Two-Subsystem Nonlinear Systems with Application to Intermittent Control

Directory of Open Access Journals (Sweden)

Huang Tingwen

2009-01-01

Full Text Available This paper studies the exponential stability of a class of periodically time-switched nonlinear systems. Three cases of such systems which are composed, respectively, of a pair of unstable subsystems, of both stable and unstable subsystems, and of a pair of stable systems, are considered. For the first case, the proposed result shows that there exists periodically switching rule guaranteeing the exponential stability of the whole system with (sufficient small switching period if there is a Hurwitz linear convex combination of two uncertain linear systems derived from two subsystems by certain linearization. For the second case, we present two general switching criteria by means of multiple and single Lyapunov function, respectively. We also investigate the stability issue of the third case, and the switching criteria of exponential stability are proposed. The present results for the second case are further applied to the periodically intermittent control. Several numerical examples are also given to show the effectiveness of theoretical results.

Mixed H∞ and passive control for linear switched systems via hybrid control approach

Science.gov (United States)

Zheng, Qunxian; Ling, Youzhu; Wei, Lisheng; Zhang, Hongbin

2018-03-01

This paper investigates the mixed H∞ and passive control problem for linear switched systems based on a hybrid control strategy. To solve this problem, first, a new performance index is proposed. This performance index can be viewed as the mixed weighted H∞ and passivity performance. Then, the hybrid controllers are used to stabilise the switched systems. The hybrid controllers consist of dynamic output-feedback controllers for every subsystem and state updating controllers at the switching instant. The design of state updating controllers not only depends on the pre-switching subsystem and the post-switching subsystem, but also depends on the measurable output signal. The hybrid controllers proposed in this paper can include some existing ones as special cases. Combine the multiple Lyapunov functions approach with the average dwell time technique, new sufficient conditions are obtained. Under the new conditions, the closed-loop linear switched systems are globally uniformly asymptotically stable with a mixed H∞ and passivity performance index. Moreover, the desired hybrid controllers can be constructed by solving a set of linear matrix inequalities. Finally, a numerical example and a practical example are given.

Switched Systems With Multiple Invariant Sets

Science.gov (United States)

2015-05-06

from [9]. Choose ẋp = Axp + bp, (15) but with A = [ −1 −10 10 −1 ] (16) b1 = [ 10 1 ] , b2 = [ −1 10 ] , b3 = [ 1 −10 ] . We are able to use the same...This amounted to a generalization and refinement of the argument presented in [9] and is in the spirit of dwell time methods for switched systems. This

An improved data acquisition system for isotopic ratio mass spectrometers

International Nuclear Information System (INIS)

Saha, T.K.; Reddy, B.; Nazare, C.K.; Handu, V.K.

1999-01-01

Isotopic ratio mass spectrometers designed and fabricated to measure the isotopic ratios with a precision of better than 0.05%. In order to achieve this precision, the measurement system consisting of ion signal to voltage converters, analog to digital converters, and data acquisition electronics should be at least one order better than the overall precision of measurement. Using state of the art components and techniques, a data acquisition system, which is an improved version of the earlier system, has been designed and developed for use with multi-collector isotopic ratio mass spectrometers

Adaptive Neural Tracking Control for Discrete-Time Switched Nonlinear Systems with Dead Zone Inputs

Directory of Open Access Journals (Sweden)

Jidong Wang

2017-01-01

Full Text Available In this paper, the adaptive neural controllers of subsystems are proposed for a class of discrete-time switched nonlinear systems with dead zone inputs under arbitrary switching signals. Due to the complicated framework of the discrete-time switched nonlinear systems and the existence of the dead zone, it brings about difficulties for controlling such a class of systems. In addition, the radial basis function neural networks are employed to approximate the unknown terms of each subsystem. Switched update laws are designed while the parameter estimation is invariable until its corresponding subsystem is active. Then, the closed-loop system is stable and all the signals are bounded. Finally, to illustrate the effectiveness of the proposed method, an example is employed.

Development of high electrical resistance persistent current switch for high speed energization system

International Nuclear Information System (INIS)

Jizo, Y.; Furuta, Y.; Nakashima, H.

1986-01-01

Japanese National Railways is now developing a superconducting magnetically-levitated train system. A persistent current switch is incorporated in the super-conducting magnet used in the magnetically-levitated train. In recent years, the switch has been required to have higher electrical resistance during its off-state in order to realize the high speed energization/de-energization system of the superconducting magnets. The system aims to decrease evaporation volume of liquid helium during the energization/de-energization of the magnet, by means of energizing the superconducting magnet with high current increasing/decreasing rate. Consequently, it would be possible to decrease the dependence of the on-board magnet system upon the ground cooling system. Through the development of a stable superconductive wire material and a coil structure for the persistent current switch using many small model switches which were produced in order to improve their current carrying capacities, the authors have succeeded in manufacturing the high electrical resistance persistent current switch whose electrical resistance was 5 ohms. The switch, of cylindrical shape, has a diameter of about 100mm, a length of about 100mm. These 5 ohm PCSs are now functioning in stable conditions being incorporated in the superconducting magnets of No.2 vehicle of MLU001 at the JNR's Miyazaki test track. Further, the authors are now developing the PCS of still higher resistance values, such as 50 ohms, through studies for stabilization in structural aspects of the winding and obtaining results therefrom

Inherently safe SNR shutdown system with Curie point controlled sensor/switch unit

International Nuclear Information System (INIS)

Mueller, K.; Norajitra, P.; Reiser, H.

1987-02-01

Inherent shutdown due to increase in the sodium temperature at the core outlet is triggered by interruption of the current supply to the electromagnet coupling of absorber elements via curie point controlled sensor/switch units. These switches are arranged above suitable fuel element positions and spatially independent of the shutdown elements. Compared with other similar systems very short response times are achieved. A prototype switch unit has already undergone extensive testing. These tests have confirmed that switching takes place in a very narrow temperature range. (orig./HP) [de

SOS switch system (SSS) in the radiation treatment room

International Nuclear Information System (INIS)

Komiyama, Takafumi; Motoyama, Tsuyoshi; Nakamura, Koji; Onishi, Hiroshi; Araya, Masayuki; Sano, Naoki

2009-01-01

We applied patient's self-breath hold irradiation system to a device to declare the patient's intentions (SOS switch system: SSS) in the radiation room and examined a utility for problem recognition and improvement of risk management during radiation therapy by induction of SSS. Between May 2005 and October 2006, we used SSS with 65 patients. The study involved 32 men and 33 women with a median age of 65 (range, 26-88) years. The reason for using SSS was as a shell in 57, a history of laryngectomy in 2, a cough in 6, convulsions in 1, and anxiety in 3. The treatment with SSS was performed 1,120 times. The hand switch was pushed 11 times. The reasons the switch was pushed were for nausea, aspiration, pain, and cough one time each. For the others, the reasons were unclear, and it was thought due to the clouding of consciousness from brain metastases. No problems were observed with the use of SSS. SSS was a useful device for improvement of risk management during the radiation therapy. (author)

H/D Isotope Effects in Hydrogen Bonded Systems

Directory of Open Access Journals (Sweden)

Aleksander Filarowski

2013-04-01

Full Text Available An extremely strong H/D isotope effect observed in hydrogen bonded A-H…B systems is connected with a reach diversity of the potential shape for the proton/deuteron motion. It is connected with the anharmonicity of the proton/deuteron vibrations and of the tunneling effect, particularly in cases of short bridges with low barrier for protonic and deuteronic jumping. Six extreme shapes of the proton motion are presented starting from the state without possibility of the proton transfer up to the state with a full ionization. The manifestations of the H/D isotope effect are best reflected in the infra-red absorption spectra. A most characteristic is the run of the relationship between the isotopic ratio nH/nD and position of the absorption band shown by using the example of NHN hydrogen bonds. One can distinguish a critical range of correlation when the isotopic ratio reaches the value of ca. 1 and then increases up to unusual values higher than . The critical range of the isotope effect is also visible in NQR and NMR spectra. In the critical region one observes a stepwise change of the NQR frequency reaching 1.1 MHz. In the case of NMR, the maximal isotope effect is reflected on the curve presenting the dependence of Δd (1H,2H on d (1H. This effect corresponds to the range of maximum on the correlation curve between dH and ΔpKa that is observed in various systems. There is a lack in the literature of quantitative information about the influence of isotopic substitution on the dielectric properties of hydrogen bond except the isotope effect on the ferroelectric phase transition in some hydrogen bonded crystals.

Packet-switched data communication system of the Paks Nuclear Power Plant, Hungary

International Nuclear Information System (INIS)

Szuegyi, M.

1991-01-01

Data communication systems are inherent components of the computer network of nuclear power plants. In the PNPP, Hungary, a new packet-switched network has been installed, based on the X25 protocol. It was developed in the framework of the Information Infrastructure Development project of the country. The most important system and software components of the new packet-switched communication system and computer network installed at PNPP are described. (R.P.) 4 refs.; 1 fig

Switching control of linear systems for generating chaos

International Nuclear Information System (INIS)

Liu Xinzhi; Teo, Kok-Lay; Zhang Hongtao; Chen Guanrong

2006-01-01

In this paper, a new switching method is developed, which can be applied to generating different types of chaos or chaos-like dynamics from two or more linear systems. A numerical simulation is given to illustrate the generated chaotic dynamic behavior of the systems with some variable parameters. Finally, a circuit is built to realize various chaotic dynamical behaviors

Energy reversible switching from amorphous metal based nanoelectromechanical switch

KAUST Repository

Mayet, Abdulilah M.; Smith, Casey; Hussain, Muhammad Mustafa

2013-01-01

We report observation of energy reversible switching from amorphous metal based nanoelectromechanical (NEM) switch. For ultra-low power electronics, NEM switches can be used as a complementary switching element in many nanoelectronic system applications. Its inherent zero power consumption because of mechanical detachment is an attractive feature. However, its operating voltage needs to be in the realm of 1 volt or lower. Appropriate design and lower Young's modulus can contribute achieving lower operating voltage. Therefore, we have developed amorphous metal with low Young's modulus and in this paper reporting the energy reversible switching from a laterally actuated double electrode NEM switch. © 2013 IEEE.

Energy reversible switching from amorphous metal based nanoelectromechanical switch

KAUST Repository

Mayet, Abdulilah M.

2013-08-01

We report observation of energy reversible switching from amorphous metal based nanoelectromechanical (NEM) switch. For ultra-low power electronics, NEM switches can be used as a complementary switching element in many nanoelectronic system applications. Its inherent zero power consumption because of mechanical detachment is an attractive feature. However, its operating voltage needs to be in the realm of 1 volt or lower. Appropriate design and lower Young\\'s modulus can contribute achieving lower operating voltage. Therefore, we have developed amorphous metal with low Young\\'s modulus and in this paper reporting the energy reversible switching from a laterally actuated double electrode NEM switch. © 2013 IEEE.

Isotopic study of some fossil and actual hydrothermal systems

International Nuclear Information System (INIS)

Demont, J.M.

1981-07-01

Oxygen and hydrogen isotopic compositions of rocks from the INAG no 1 drillhole provide evidence of a fossil hydrothermal system in the Ceyssat region of the Massif Central. Oxygen isotope temperatures for the mineral paragenesis are about 275 0 C and the water is of marine origin. Measurements have also been made of delta 13 C values of dissolved carbon and gaseous CO 2 from several hot springs in the Pyrenees and Massif Central. The carbon isotopic composition of the total systems have been calculated from the gas-liquid ratios at the emergence sites and these results are discussed in terms of the origin of the carbon. Most of the hydrothermal carbon is of deep origin. The observed variations in isotopic compositions may be explained by the behavior of the fluids during their ascent to the surface [fr

Assessment of Stable Isotope Distribution in Complex Systems

Science.gov (United States)

He, Y.; Cao, X.; Wang, J.; Bao, H.

2017-12-01

Biomolecules in living organisms have the potential to approach chemical steady state and even apparent isotope equilibrium because enzymatic reactions are intrinsically reversible. If an apparent local equilibrium can be identified, enzymatic reversibility and its controlling factors may be quantified, which helps to understand complex biochemical processes. Earlier research on isotope fractionation tends to focus on specific process and compare mostly two different chemical species. Using linear regression, "Thermodynamic order", which refers to correlated δ13C and 13β values, has been proposed to be present among many biomolecules by Galimov et al. However, the concept "thermodynamic order" they proposed and the approach they used has been questioned. Here, we propose that the deviation of a complex system from its equilibrium state can be rigorously described as a graph problem as is applied in discrete mathematics. The deviation of isotope distribution from equilibrium state and apparent local isotope equilibrium among a subset of biomolecules can be assessed using an apparent fractionation difference matrix (|Δα|). Applying the |Δα| matrix analysis to earlier published data of amino acids, we show the existence of apparent local equilibrium among different amino acids in potato and a kind of green alga. The existence of apparent local equilibrium is in turn consistent with the notion that enzymatic reactions can be reversible even in living systems. The result also implies that previous emphasis on external carbon source intake may be misplaced when studying isotope distribution in physiology. In addition to the identification of local equilibrium among biomolecules, the difference matrix approach has the potential to explore chemical or isotope equilibrium state in extraterrestrial bodies, to distinguish living from non-living systems, and to classify living species. This approach will benefit from large numbers of systematic data and advanced pattern

New Isotopic clues to solar system formation

International Nuclear Information System (INIS)

Lee, T.

1979-01-01

The presence of two new extinct nuclides 26 Al and 107 Pd with half-lives approx.10 6 years in the early solar system implies that there were nucleosynthetic activities involving a great many elements almost at the instant of solar system formation. Rare gas and oxygen isotopic abundance variations [''anomalies''] relative to the ''cosmic'' composition were observed in a variety of planetary objects indicating that isotopic heterogeneities caused by the incomplete mixing of distinct nucleosynthetic components permeate of the entire solar system. The correlated nuclear [''FUN''] anomalies in O, Mg, Si, Ca, Sr, Ba, Nd, and Sm were found in three rare inclusions in the Allende meteorite, which show large mass-dependent isotopic fractionation effects. The signature of the nuclear component required to explain these anomalies suggests a source which has received a catastrophic neutron burst [e.g., an r-process event]. These extinct nuclides and nucleosynthetic anomalies provide new clues to solar system formation. In particular, these results have led to the speculation that a nearby supernova had injected freshly synthesized material into the early solar nebula and possibly triggered the collapse of the proto-solar interstellar cloud. Furthermore, these new results have major implications on cosmochronology, nucleosynthesis theory, star formation, planetary heating, and the genetic relationship between different planetary bodies

Tritium isotope fractionation in biological systems and in analytical procedures

International Nuclear Information System (INIS)

Kim, M.A.; Baumgaertner, Franz

1989-01-01

The organically bound tritium (OBT) is evaluated in biological systems by determining the tritium distribution ratio (R-value), i.e. tritium concentrations in organic substance to cell water. The determination of the R-value always involves isotope fractionation is applied analytical procedures and hence the evaluation of the true OBT -value in a given biological system appears more complicated than hitherto known in the literature. The present work concentrates on the tritium isotope fractionation in the cell water separation and on the resulting effects on the R-value. The analytical procedures examined are vacuum freeze drying under equilibrium and non-equilibrium conditions and azeotropic distillation. The vaporization isotope effects are determined separately in the phase transition of solid or liquid to gas in pure tritium water systems as well as in real biological systems, e.g. corn plant. The results are systematically analyzed and the influence of isotope effects on the R-value is rigorously quantified

On the asymptotic stability of nonlinear mechanical switched systems

Science.gov (United States)

Platonov, A. V.

2018-05-01

Some classes of switched mechanical systems with dissipative and potential forces are considered. The case, where either dissipative or potential forces are essentially nonlinear, is studied. It is assumed that the zero equilibrium position of the system is asymptotically stable at least for one operating mode. We will look for sufficient conditions which guarantee the preservation of asymptotic stability of the equilibrium position under the switching of modes. The Lyapunov direct method is used. A Lyapunov function for considered system is constructed, which satisfies the differential inequality of special form for every operating mode. This inequality is nonlinear for the chosen mode with asymptotically stable equilibrium position, and it is linear for the rest modes. The correlations between the intervals of activity of the pointed mode and the intervals of activity of the rest modes are obtained which guarantee the required properties.

Global Uniform Asymptotic Stability of a Class of Switched Linear Systems with an Infinite Number of Subsystems

Directory of Open Access Journals (Sweden)

L. F. Araghi

2014-01-01

Full Text Available Stability of switching systems with an infinite number of subsystems is important in some structure of systems, like fuzzy systems, neural networks, and so forth. Because of the relationship between stability of a set of matrices and switching systems, this paper first studies the stability of a set of matrices, then and the results are applied for stability of switching systems. Some new conditions for globally uniformly asymptotically stability (GUAS of discrete-time switched linear systems with an infinite number of subsystems are proposed. The paper considers some examples and simulation results.

Digital switched hydraulics

Science.gov (United States)

Pan, Min; Plummer, Andrew

2018-06-01

This paper reviews recent developments in digital switched hydraulics particularly the switched inertance hydraulic systems (SIHSs). The performance of SIHSs is presented in brief with a discussion of several possible configurations and control strategies. The soft switching technology and high-speed switching valve design techniques are discussed. Challenges and recommendations are given based on the current research achievements.

Automatic limit switch system for scintillation device and method of operation

International Nuclear Information System (INIS)

Brunnett, C.J.; Ioannou, B.N.

1976-01-01

A scintillation scanner is described having an automatic limit switch system for setting the limits of travel of the radiation detection device which is carried by a scanning boom. The automatic limit switch system incorporates position responsive circuitry for developing a signal representative of the position of the boom, reference signal circuitry for developing a signal representative of a selected limit of travel of the boom, and comparator circuitry for comparng these signals in order to control the operation of a boom drive and indexing mechanism. (author)

A Microcontroller-Based Automatic Transfer Switching System for a ...

African Journals Online (AJOL)

Michael

2015-06-01

Jun 1, 2015 ... Most industries still employ the manual method of power supply changeover, ... This paper presents a Microcontroller-Based Automatic Transfer Switching System ..... and currently has special research interest in Wireless.

100 kV solid-state switch for fusion heating systems

International Nuclear Information System (INIS)

Beaumont, B.; Bertrand, E.; Brugnetti, R.; Chatroux, D.; Kazarian, F.; Milly, R.; Prou, M.; Rigole, H.

2005-01-01

Power switching in RF heating systems is a delicate function as it is often linked to high power tube protection. In most RF systems, the end stage power tube is fed by a high voltage power supply (HVPS), which connection to the tube has to be interrupted in case of arc suspicion. The amount of energy that is allowable to be dissipated in the arc is in the range of 10-50 J, to limit the degradations observed on the tube structures. The protection function is usually performed by a crowbar. Furthermore, the HVPS is often shared by several power tubes, and the loss of all the power from the group of tubes is to be avoided to minimize the perturbation on the plasma experiment. A description of a 40 kV thyristor based crowbar and a 100 kV, 25 A MOSFET switch is given, as well as the contours of the existing components for high power switching applications. By combining small components, such as thyristors or MOSFET, in matrix, highly compact and reliable units have been built and implemented in Tore Supra RF systems

Development of the switch requirements and architecture of a safety data communication system

International Nuclear Information System (INIS)

Jeong, K.I.; Lee, J.K.; Park, H.Y.; Koo, I.S.

2004-12-01

In accordance with digitalising the Instrumentation and Control(I and C) systems in the integral reactor, a communication network is required for effective information exchanges between the different equipment, an enhancement of the design flexibility, a simple installation and cost reduction. Generally, a communication network consists of a topology, the protocol, a communication medium, an interconnection device, etc. In this report, the development methods of switch and the architecture of a Safety Data Communication System(SDCS) are investigated and analyzed. In this report, the design requirements for switch are presented, which are the essential requirements to develop the switch in a SDCS of the SMART-P. To establish these requirements, the evaluation and analysis of the design and implementation method of the COTS switches, the architecture of SDCS and the design requirements of a SDCS were performed. At the detail design stage, these requirements will be used for the top-tier requirements, especially the design target and design basis. To develop the detail design requirements in the future, more quantitative and qualitative analyses are required. In the case of selecting the COTS switch and developing the switch, these requirements will also be used for the evaluation guide

Development of the switch requirements and architecture of a safety data communication system

Energy Technology Data Exchange (ETDEWEB)

Jeong, K.I.; Lee, J.K.; Park, H.Y.; Koo, I.S

2004-12-01

In accordance with digitalising the Instrumentation and Control(I and C) systems in the integral reactor, a communication network is required for effective information exchanges between the different equipment, an enhancement of the design flexibility, a simple installation and cost reduction. Generally, a communication network consists of a topology, the protocol, a communication medium, an interconnection device, etc. In this report, the development methods of switch and the architecture of a Safety Data Communication System(SDCS) are investigated and analyzed. In this report, the design requirements for switch are presented, which are the essential requirements to develop the switch in a SDCS of the SMART-P. To establish these requirements, the evaluation and analysis of the design and implementation method of the COTS switches, the architecture of SDCS and the design requirements of a SDCS were performed. At the detail design stage, these requirements will be used for the top-tier requirements, especially the design target and design basis. To develop the detail design requirements in the future, more quantitative and qualitative analyses are required. In the case of selecting the COTS switch and developing the switch, these requirements will also be used for the evaluation guide.

Unconventional isotope systems applied to enhancing the petrogenesis of uranium deposits

International Nuclear Information System (INIS)

Voignot, A.; Chipley, D.; Kyser, K.; Uvarova, Y.

2014-01-01

Among the new techniques applied to the petrogenesis and evolution of uranium deposits from their formation to later alteration is isotope tracing. The isotope systems being used include Li, C, N, Fe, Mo, Tl, Pb and U, all of which reflect different, but overlapping, processes. Although Pb isotopes have been used to understand the temporal evolution and migration of radiogenic Pb from the deposits, Li, C, N, Mo, Tl and U isotope systems are new ways to analyze deposits and barren areas and to reveal their precise redox mechanisms. Geochemical technologies for exploration include "2"3"8U/"2"3"5U ratios of uranium minerals, which vary as a function of the type of uranium deposit and the efficiency of the redox processes. Lithium isotope ratios in muscovite and chlorite associated with mineralizing events are distinct from background ratios, with the lowest values reflecting the beginning of hydrothermal alteration systems and the highest values indicative of the terminal flow of hydrothermal fluids. Carbon and N reflect the influence of biospheric processes on the deposits and dispersion of elements that can be used for exploration. Iron, Mo and Tl are common elements in many uranium deposits and are among the most redox active elements. Their isotopes separate among phases having different oxidation potentials. They reflect the efficiency of the redox systems associated with fixing the uranium and the subsequent processes involved in mobilizing elements from the deposits. Isotopes add benefits to refining genetic models for uranium deposits, thereby enhancing our exploration models as well. An additional goal of applying isotope geochemistry to uranium deposits is to be able to use them to reflect a definitive process that occurs in the deposit and not in barren systems, and then to relate these to something that is easier to measure, namely elemental concentrations. (author)

Phase-controlled all-optical switching based on coherent population oscillation in a two-level system

International Nuclear Information System (INIS)

Liao, Ping; Yu, Song; Luo, Bin; Shen, Jing; Gu, Wanyi; Guo, Hong

2011-01-01

We theoretically propose a scheme of phase-controlled all-optical switching due to the effect of degenerate four-wave mixing (FWM) and coherent population oscillation (CPO) in a two-level system driven by a strong coupling field and two weak symmetrically detuned fields. The results show that the phase of the FWM field can be utilized to switch between constructive and destructive interference, which can lead to the transmission or attenuation of the probe field and thus switch the field on or off. We also find the intensity of the coupling field and the propagation distance have great influence on the performance of the switching. In our scheme, due to the quick response in semiconductor systems, a fast all-optical switching can be realized at low light level. -- Highlights: ► We study a new all-optical switching based on coherent population oscillation. ► The phase of the FWM field can be utilized to switch the probe field on or off. ► A fast and low-light-level switching can be realized in semiconductors.

Program plan for the Brayton Isotope Power System. Phase I. Design, fabrication and test of the Brayton Isotope Power System

International Nuclear Information System (INIS)

1975-01-01

Phase I of an overall program for the development of a 500 to 2000 W(e) (EOM), 7-y life, power system for space vehicles is discussed. The system uses a closed Brayton dynamic system to convert energy from an isotope heat source at a net efficiency greater than 25 percent. This first phase, a 35-month effort, is for the conceptual design of a 1300 W(e), 450 lb flight system and the design, fabrication, and test of a ground demonstration system. The flight system will use, for the baseline design, two of the multihundred-watt (MHW) heat sources being developed. The Ground Demonstration System will simulate, as closely as possible, the Brayton Isotope Power Flight System and will utilize components and technology being developed for the Mini-Brayton rotating unit, recuperator and heat source assembly, respectively. The Ground Demonstration System includes a performance test and a 1000-h endurance test

Measurement of stable isotope ratio of organic carbon in water samples

International Nuclear Information System (INIS)

Fujii, Toshihiro; Otsuki, Akira

1977-01-01

A new method for the measurement of stable isotope ratios was investigated and applied to organic carbon's isotope ratio measurements in water samples. A few river water samples from Tsuchiura city were tested. After the wet oxidation of organic carbons to carbon dioxide in a sealed ampoule, the isotope ratios were determined with the gas chromatograph-quadrupole mass spectrometer combined with a total organic carbon analyser, under the dynamic conditions. The GC-MS had been equipped with the multiple ion detector-digital integrator system. The ion intensities at m/e 44 and 45 were simultaneously measured at a switching rate of 1 ms. The measurements with carbon dioxide acquired from sodium carbonate (53 μg) gave the isotope ratios with the variation coefficient of 0.62%. However, the variation coefficients obtained from organic carbons in natural water samples were 2 to 3 times as high as that from sodium carbonate. This method is simple and rapid and may be applied to various fields especially in biology and medicine. (auth.)

Dual temperature isotope exchange system

International Nuclear Information System (INIS)

Spevack, J.S.

1976-01-01

Improvements in the method for isotope concentration by dual temperature exchange between feed and auxiliary fluids in a multistage system are described. In a preferred embodiment the first is a vaporizable liquid and the auxiliary fluid a gas, comprising steps for improving the heating and/or cooling and/or humidifying and/or dehumidifying operations

Design study of fuel circulating system using Pd-alloy membrane isotope separation method

International Nuclear Information System (INIS)

Naito, T.; Yamada, T.; Yamanaka, T.; Aizawa, T.; Kasahara, T.; Nishikawa, M.; Asami, N.

1980-01-01

Design study on the fuel circulating system (FCS) for a tokamak experimental fusion reactor (JXFR) has been carried out to establish the system concept, to plan the development program, and to evaluate the feasibility of diffusion system. The FCS consists of main vacuum system, fuel gas refiners, isotope separators, fuel feeders, and auxiliary systems. In the system design, Pd-alloy membrane permeation method is adopted for fuel refining and isotope separating. All impurities are effectively removed and hydrogen isotopes are sufficiently separated by Pd-alloy membrane. The isotope separation system consists of 1st (47 separators) and 2nd (46 separators) cascades for removing protium and separating deuterium, respectively. In the FCS, while cryogenic distillation method appears to be practicable, Pd-alloy membrane diffusion method is attractive for isotope separation and refining of fuel gas. The choice will have to be based on reliability, economic, and safety analyses

Input and output constraints-based stabilisation of switched nonlinear systems with unstable subsystems and its application

Science.gov (United States)

Chen, Chao; Liu, Qian; Zhao, Jun

2018-01-01

This paper studies the problem of stabilisation of switched nonlinear systems with output and input constraints. We propose a recursive approach to solve this issue. None of the subsystems are assumed to be stablisable while the switched system is stabilised by dual design of controllers for subsystems and a switching law. When only dealing with bounded input, we provide nested switching controllers using an extended backstepping procedure. If both input and output constraints are taken into consideration, a Barrier Lyapunov Function is employed during operation to construct multiple Lyapunov functions for switched nonlinear system in the backstepping procedure. As a practical example, the control design of an equilibrium manifold expansion model of aero-engine is given to demonstrate the effectiveness of the proposed design method.

Design and construction of the advanced photon source 352-MHz rf system switching control

International Nuclear Information System (INIS)

Horan, D.; Solita, L.; Reigle, D.; Dimonte, N.

1997-01-01

A switching control system has been designed and built to provide the capability of rapidly switching the waveguide and low-level cabling between different klystrons to operate the Advanced Photon Source storage ring in the event of a failure of a klystron system or to perform necessary repairs and preventative maintenance. The twelve possible modes of operation allow for complete redundancy of the booster synchrotron rf system and either a maximum of two storage ring rf systems to be completely off-line or one system to be used as a power source for an rf test stand. A programmable controller is used to send commands to intermediate control panels which interface to WR2300 waveguide switches and phase shifters, rf cavity interlock and low-level rf distribution systems, and klystron power supply controls for rapid reconfiguration of the rf systems in response to a mode-selection command. Mode selection is a local manual operation using a keyswitch arrangement which prevents more than one mode from being selected at a time. The programmable controller also monitors for hardware malfunction and guards against open-quotes hot-switchingclose quotes of the rf systems. The rf switching controls system is monitored via the Experimental Physics and Industrial Control System (EPICS) for remote system status check

Method and system for a gas tube switch-based voltage source high voltage direct current transmission system

Science.gov (United States)

She, Xu; Chokhawala, Rahul Shantilal; Zhou, Rui; Zhang, Di; Sommerer, Timothy John; Bray, James William

2016-12-13

A voltage source converter based high-voltage direct-current (HVDC) transmission system includes a voltage source converter (VSC)-based power converter channel. The VSC-based power converter channel includes an AC-DC converter and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and a DC-AC inverter include at least one gas tube switching device coupled in electrical anti-parallel with a respective gas tube diode. The VSC-based power converter channel includes a commutating circuit communicatively coupled to one or more of the at least one gas tube switching devices. The commutating circuit is configured to "switch on" a respective one of the one or more gas tube switching devices during a first portion of an operational cycle and "switch off" the respective one of the one or more gas tube switching devices during a second portion of the operational cycle.

Parameter study on Japanese proposal of ITER hydrogen isotope separation system

International Nuclear Information System (INIS)

Yoshida, Hiroshi; Enoeda, Mikio; Tanaka, Shigeru; Ohokawa, Yoshinao; Ohara, Atsushi; Nagakura, Masaaki; Naito, Taisei; Nagashima, Kazuhiro.

1991-01-01

As part of Japanese design contribution in the ITER activity, conceptual design of an entire ITER tritium system and their safety analysis have been carried out through the three-year period since 1988. The tritium system includes the following subsystems; - Fuelling (gas puffing and pellet injection) subsystem, - Torus vacuum pumping subsystem, - Plasma exhaust gas purification subsystem, - Hydrogen isotope separation subsystem, - NBI gas processing subsystem, - Blanket tritium recovery subsystem, - Tritiated water processing subsystem, - Tritium safety subsystem. Hydrogen isotope separation system is a key subsystem in the ITER tritium system because it is connected to all above subsystems. This report describes an analytical study on the Japanese concept of hydrogen isotope separation system. (author)

Simulation and Analysis of Isotope Separation System for Fusion Fuel Recovery System

Science.gov (United States)

Senevirathna, Bathiya; Gentile, Charles

2011-10-01

This paper presents results of a simulation of the Fuel Recovery System (FRS) for the Laser Inertial Fusion Engine (LIFE) reactor. The LIFE reaction will produce exhaust gases that will need to be recycled in the FRS along with xenon, the chamber's intervention gas. Solids and liquids will first be removed and then vapor traps are used to remove large gas molecules such as lead. The gas will be reacted with lithium at high temperatures to extract the hydrogen isotopes, protium, deuterium, and tritium in hydride form. The hydrogen isotopes will be recovered using a lithium blanket processing system already in place and this product will be sent to the Isotope Separation System (ISS). The ISS will be modeled in software to analyze its effectiveness. Aspen HYSYS was chosen for this purpose for its widespread use industrial gas processing systems. Reactants and corresponding chemical reactions had to be initialized in the software. The ISS primarily consists of four cryogenic distillation columns and these were modeled in HYSYS based on design requirements. Fractional compositions of the distillate and liquid products were analyzed and used to optimize the overall system.

Proposed configuration for ITER hydrogen isotope separation system (ISS)

International Nuclear Information System (INIS)

Lazar, A.; Brad, S.; Sofalca, N.; Vijulie, M.; Cristescu, I.; Doer, L; Wurster, W.

2008-01-01

Full text: The isotope separation system utilizes cryogenic distillation and catalytic reaction for isotope exchange to separate elemental hydrogen isotope gas mixtures. The ISS shall separate hydrogen isotope mixtures from two sources to produce up to five different products. These are: protium, effluent for discharge to the atmosphere, deuterium for fuelling, deuterium for NB injector (NBI) source gas, 50 % and 90% T fuelling streams. The concept of equipment 3D layout for the ISS main components were developed using the Part Design, Assembly Design, Piping Design, Equipment Arrangement and Plant Layout application from CATIA V5. The 3D conceptual layouts for ISS system were created having as reference the DDD -32-B report, the drawings 0028.0001.2D. 0100. R 'Process Flow Diagram'; 0029.0001.2D. 0200.R 'Process Instrumentation Diagram -1' (in the cold box); 0030.0001.2D. 0100. R 'Process Instrumentation Diagram -2' (in the hard shell confinement) and imputes from TLK team. The main components designed for ISS are: ISS cold box system (CB) with cryogenic distillation columns (CD) and recovery heat exchangers (HX), ISS hard shell containment (HSC) system with metals bellow pumps (MB) and chemical equilibrators (RC), valve box system, instrumentation box system, vacuum system and hydrogen expansion vessels. Work related to these topics belongs to the contract FU06-CT-2006-00508 (EFDA 06-1511) from the EFDA Technology Workprogramm 2006 and was done in collaboration with FZK Association team during the period January 2007 - September 2008. (authors)

System design specification Brayton Isotope Power System (BIPS) Flight System (FS), and Ground Demonstration System (GDS)

International Nuclear Information System (INIS)

1976-01-01

The system design specification for ground demonstration, development, and flight qualification of a Brayton Isotope Power System (BIPS) is presented. The requirements for both a BIPS conceptual Flight System (FS) and a Ground Demonstration System (GDS) are defined

Tracking Control for Switched Cascade Nonlinear Systems

Directory of Open Access Journals (Sweden)

Xiaoxiao Dong

2015-01-01

Full Text Available The issue of H∞ output tracking for switched cascade nonlinear systems is discussed in this paper, where not all the linear parts of subsystems are stabilizable. The conditions of the solvability for the issue are given by virtue of the structural characteristics of the systems and the average dwell time method, in which the total activation time for stabilizable subsystems is longer than that for the unstabilizable subsystems. At last, a simulation example is used to demonstrate the validity and advantages of the proposed approach.

Optimal placement of switching equipment in reconfigurable distribution systems

Directory of Open Access Journals (Sweden)

Mijailović Vladica

2011-01-01

Full Text Available This paper presents a comparative analysis of some measures that can improve the reliability of medium-voltage (MV distribution feeder. Strictly speaking, the impact of certain types of switching equipment installed on the feeder and possibilities of backup supply from the adjacent feeders were analyzed. For each analyzed case, equations for the calculation of System Average Interruption Duration Index and energy not delivered to the customers are given. The effects of certain measures are calculated for one real MV-feeder for radial supply to customers and in cases of possible backup supply to the customers. Installation locations of certain types of switching equipment for the given concept of energy supply are determined according to the criterion of minimum value of System Average Interruption Duration Index and according to the criterion of minimum value of energy not delivered to the customers.

Isotope Specific Remediation Media and Systems - 13614

Energy Technology Data Exchange (ETDEWEB)

Denton, Mark S.; Mertz, Joshua L. [Kurion, Inc. Oak Ridge, Tennessee 37831 (United States); Morita, Keisuke [Japan Atomic Energy Agency, Tokai Research and Development Center, Fukushima Project Team, Tokai-mura, Ibaraki-ken, 319-1195 (Japan)

2013-07-01

On March 11, 2011, now two years ago, the magnitude 9.0 Great East Japan earthquake, Tohoku, hit off the Fukushima coast of Japan. While, of course, most of the outcome of this unprecedented natural and manmade disaster was a negative, both in Japan and worldwide, there have been some extremely invaluable lessons learned and new emergency recovery technologies and systems developed. As always, the mother of invention is necessity. Among these developments has been the development and full-scale implementation of proven isotope specific media (ISMs) with the intent of surgically removing specific hazardous isotopes for the purpose of minimizing dose to workers and the environment. The first such ISMs to be deployed at the Fukushima site were those removing cesium (Cs-137) and iodine (I-129). Since deployment on June 17, 2011, along with treated cooling water recycle, some 70% of the curies in the building liquid wastes have been removed by the Kurion system alone. The current levels of cesium are now only 2% of the original levels. Such an unprecedented, 'external cooling system' not only allowed the eventual cold shut down of the reactors in mid-December, 2011, but has allowed workers to concentrate on the cleanup of other areas of the site. Water treatment will continue for quite some time due to continued leakage into the buildings and the eventual goal of cleaning up the reactors and fuel pools themselves. With the cesium removal now in routine operation, other isotopes of concern are likely to become priorities. One such isotope is that of strontium, and yttrium (Sr-90 and Y-90), which is still at original levels causing further dose issues as well as impediments to discharge of the treated waste waters. For over a year now, a new synthetic strontium specific media has been under development and testing both in our licensed facility in Oak Ridge, Tennessee, but also in confirmatory tests by the Japan Atomic Energy Agency (JAEA) in Japan for Tokyo

A fuzzy expert system for predicting the performance of switched reluctance motor

International Nuclear Information System (INIS)

Mirzaeian, B.; Moallem, M.; Lucas, Caro

2001-01-01

In this paper a fuzzy expert system for predicting the performance of a switched reluctance motor has been developed. The design vector consists of design parameters, and output performance variables are efficiency and torque ripple. An accurate analysis program based on Improved Magnetic Equivalent Circuit method has been used to generate the input-output data. These input-output data is used to produce the initial fuzzy rules for predicting the performance of Switched Reluctance Motor. The initial set of fuzzy rules with triangular membership functions has been devised using a table look-up scheme. The initial fuzzy rules have been optimized to a set of fuzzy rules with Gaussian membership functions using gradient descent training scheme. The performance prediction results for a 6/8, 4 kw, Switched Reluctance Motor shows good agreement with the results obtained from Improved Magnetic Equivalent Circuit method or Finite Element analysis. The developed fuzzy expert system can be used for fast prediction of motor performance in the optimal design process or on-line control schemes of Switched Reluctance motor

Output Tracking Control of Switched Hybrid Systems: A Fliess Functional Expansion Approach

Directory of Open Access Journals (Sweden)

Fenghua He

2013-01-01

Full Text Available The output tracking problem is investigated for a nonlinear affine system with multiple modes of continuous control inputs. We convert the family of nonlinear affine systems under consideration into a switched hybrid system by introducing a multiple-valued logic variable. The Fliess functional expansion is adopted to express the input and output relationship of the switched hybrid system. The optimal switching control is determined for a multiple-step output tracking performance index. The proposed approach is applied to a multitarget tracking problem for a flight vehicle aiming for one real target with several decoys flying around it in the terminal guidance course. These decoys appear as apparent targets and have to be distinguished with the approaching of the flight vehicle. The guidance problem of one flight vehicle versus multiple apparent targets should be considered if no large miss distance might be caused due to the limitation of the flight vehicle maneuverability. The target orientation at each time interval is determined. Simulation results show the effectiveness of the proposed method.

Guaranteed Cost H∞ Controller Synthesis for Switched Systems Defined on Semi-algebraic Sets

DEFF Research Database (Denmark)

Ahmadi, Mohamadreza; Mojallali, Hamed; Wisniewski, Rafael

2014-01-01

of Filippov solutions which subsumes solutions with infinite switching in finite time and sliding modes. Firstly, conditions assuring asymptotic stability of Filippov solutions pertained to a switched system defined on semi-algebraic sets are formulated. Accordingly, we derive a set of sum of squares...

Novel flat datacenter network architecture based on scalable and flow-controlled optical switch system.

Science.gov (United States)

Miao, Wang; Luo, Jun; Di Lucente, Stefano; Dorren, Harm; Calabretta, Nicola

2014-02-10

We propose and demonstrate an optical flat datacenter network based on scalable optical switch system with optical flow control. Modular structure with distributed control results in port-count independent optical switch reconfiguration time. RF tone in-band labeling technique allowing parallel processing of the label bits ensures the low latency operation regardless of the switch port-count. Hardware flow control is conducted at optical level by re-using the label wavelength without occupying extra bandwidth, space, and network resources which further improves the performance of latency within a simple structure. Dynamic switching including multicasting operation is validated for a 4 x 4 system. Error free operation of 40 Gb/s data packets has been achieved with only 1 dB penalty. The system could handle an input load up to 0.5 providing a packet loss lower that 10(-5) and an average latency less that 500 ns when a buffer size of 16 packets is employed. Investigation on scalability also indicates that the proposed system could potentially scale up to large port count with limited power penalty.

Diagnosis and Tolerant Strategy of an Open-Switch Fault for T-type Three-Level Inverter Systems

DEFF Research Database (Denmark)

Choi, Uimin; Lee, Kyo Beum; Blaabjerg, Frede

2014-01-01

This paper proposes a new diagnosis method of an open-switch fault and fault-tolerant control strategy for T-type three-level inverter systems. The location of faulty switch can be identified by the average of normalized phase current and the change of the neutral-point voltage. The proposed fault......-tolerant strategy is explained by dividing into two cases: the faulty condition of half-bridge switches and the neutral-point switches. The performance of the T-type inverter system improves considerably by the proposed fault tolerant algorithm when a switch fails. The roposed method does not require additional...... components and complex calculations. Simulation and experimental results verify the feasibility of the proposed fault diagnosis and fault-tolerant control strategy....

System and method for high precision isotope ratio destructive analysis

Science.gov (United States)

Bushaw, Bruce A; Anheier, Norman C; Phillips, Jon R

2013-07-02

A system and process are disclosed that provide high accuracy and high precision destructive analysis measurements for isotope ratio determination of relative isotope abundance distributions in liquids, solids, and particulate samples. The invention utilizes a collinear probe beam to interrogate a laser ablated plume. This invention provides enhanced single-shot detection sensitivity approaching the femtogram range, and isotope ratios that can be determined at approximately 1% or better precision and accuracy (relative standard deviation).

VME Switch for CERN's PS Analog Video System

CERN Document Server

Acebes, I; Heinze, W; Lewis, J; Serrano, J

2003-01-01

Analog video signal switching is used in CERN's Proton Synchrotron (PS) complex to route the video signals coming from Beam Diagnostics systems to the Meyrin Control Room (MCR). Traditionally, this has been done with custom electromechanical relay-based cards controlled serially via CAMAC crates. In order to improve the robustness and maintainability of the system, while keeping it analog to preserve the low latency, a VME card based on Analog Devices' AD8116 analog matrix chip has been developed. Video signals go into the front panel and exit the switch through the P2 connector of the VME backplane. The module is a 16 input, 32 output matrix. Larger matrices can be built using more modules and bussing their outputs together, thanks to the high impedance feature of the AD8116. Another VME module takes the selected signals from the P2 connector and performs automatic gain to send them at nominal output level through its front panel. This paper discusses both designs and presents experimental test results.

Optical computer switching network

Science.gov (United States)

Clymer, B.; Collins, S. A., Jr.

1985-01-01

The design for an optical switching system for minicomputers that uses an optical spatial light modulator such as a Hughes liquid crystal light valve is presented. The switching system is designed to connect 80 minicomputers coupled to the switching system by optical fibers. The system has two major parts: the connection system that connects the data lines by which the computers communicate via a two-dimensional optical matrix array and the control system that controls which computers are connected. The basic system, the matrix-based connecting system, and some of the optical components to be used are described. Finally, the details of the control system are given and illustrated with a discussion of timing.

Early inner solar system origin for anomalous sulfur isotopes in differentiated protoplanets.

Science.gov (United States)

Antonelli, Michael A; Kim, Sang-Tae; Peters, Marc; Labidi, Jabrane; Cartigny, Pierre; Walker, Richard J; Lyons, James R; Hoek, Joost; Farquhar, James

2014-12-16

Achondrite meteorites have anomalous enrichments in (33)S, relative to chondrites, which have been attributed to photochemistry in the solar nebula. However, the putative photochemical reactions remain elusive, and predicted accompanying (33)S depletions have not previously been found, which could indicate an erroneous assumption regarding the origins of the (33)S anomalies, or of the bulk solar system S-isotope composition. Here, we report well-resolved anomalous (33)S depletions in IIIF iron meteorites (solar system (solar system S-isotope composition was chondritic (consistent with IAB iron meteorites, Earth, Moon, and Mars). The range of mass-independent sulfur isotope compositions may reflect spatial or temporal changes influenced by photochemical processes. A tentative correlation between S isotopes and Hf-W core segregation ages suggests that the two systems may be influenced by common factors, such as nebular location and volatile content.

Mo isotope fractionation during hydrothermal evolution of porphyry Cu systems

Science.gov (United States)

Shafiei, Behnam; Shamanian, GholamHossein; Mathur, Ryan; Mirnejad, Hassan

2015-03-01

We present Mo isotope compositions of molybdenite types from three successive stages of ore deposition in several porphyry copper deposits of the Kerman region, Iran. The data provide new insights into controlling processes on Mo isotope fractionation during the hydrothermal evolution of porphyry systems. The Mo isotope compositions of 27 molybdenite samples show wide variations in δ97Mo ranging from -0.37 to +0.92 ‰. The data reveal that molybdenites in the early and transitional stages of mineralization (preferentially 2H polytypes; δ97Mo mean = 0.35 ‰) have higher δ97Mo values than late stage (mainly 3R polytypes; δ97Mo mean = 0.02 ‰) molybdenites. This trend suggests that fractionation of Mo isotopes occurred in high-temperature stages of mineralization and that hydrothermal systems generally evolve towards precipitation of molybdenite with lower δ97Mo values. Taking into account the genetic models proposed for porphyry Cu deposits along with the temperature-dependent fractionation of Mo isotope ratios, it is proposed that large variations of Mo isotopes in the early and the transitional stages of ore deposition could be controlled by the separation of the immiscible ore-forming fluid phases with different density, pH, and ƒO2 properties (i.e., brine and vapor). The fractionation of Mo isotopes during fluid boiling and Rayleigh distillation processes likely dominates the Mo isotope budget of the remaining ore-forming fluids for the late stage of mineralization. The lower δ97Mo values in the late stage of mineralization can be explained by depletion of the late ore-forming hydrothermal solutions in 97Mo, as these fluids have moved to considerable distance from the source. Finally, the relationship observed between MoS2 polytypes (2H and 3R) and their Mo isotopic compositions can be explained by the molecular vibration theory, in which heavier isotopes are preferentially partitioned into denser primary 2H MoS2 crystals.

System for illuminating a region for isotopically selective photoexcitation

International Nuclear Information System (INIS)

Debaryshe, P.G.; Janes, G.S.; Levy, R.H.; Lindenmeier, C.W.

1979-01-01

A method is described to improve laser beam utilization in isotope separation techniques (using laser induced isotopically selective photoexcitation) by increasing the probability of photon absorption without extreme beam propagation lengths. For this purpose an optical reflection system has been designed for illuminating substantially all of three-dimensional space of a transversely flowing vapor with multiple traversals of a beam of radiation. (UK)

An Improved SF6 System for the FXR Induction Linac Blumlein Switches

International Nuclear Information System (INIS)

DeHope, W; Kihara, R; Griffin, K L; Ong, M; Ross, T

2007-01-01

The now-mature FXR (Flash X-Ray) radiographic facility at Lawrence Livermore National Laboratory will be briefly described with emphasis on its pulsed power system. The heart of each accelerating cell's pulse forming Blumlein is it's sulfur hexafluoride-based triggered closing switch. FXR's recent upgrade to a recirculating SF 6 gas reclamation system will be described and the resulting accelerator performance and reliability improvements documented. This was accompanied by a detailed switch breakdown study on FXR's Test Stand and the recent analysis of the resulting statistics will be shown

Synchronized femtosecond laser pulse switching system based nano-patterning technology

Science.gov (United States)

Sohn, Ik-Bu; Choi, Hun-Kook; Yoo, Dongyoon; Noh, Young-Chul; Sung, Jae-Hee; Lee, Seong-Ku; Ahsan, Md. Shamim; Lee, Ho

2017-07-01

This paper demonstrates the design and development of a synchronized femtosecond laser pulse switching system and its applications in nano-patterning of transparent materials. Due to synchronization, we are able to control the location of each irradiated laser pulse in any kind of substrate. The control over the scanning speed and scanning step of the laser beam enables us to pattern periodic micro/nano-metric holes, voids, and/or lines in various materials. Using the synchronized laser system, we pattern synchronized nano-holes on the surface of and inside various transparent materials including fused silica glass and polymethyl methacrylate to replicate any image or pattern on the surface of or inside (transparent) materials. We also investigate the application areas of the proposed synchronized femtosecond laser pulse switching system in a diverse field of science and technology, especially in optical memory, color marking, and synchronized micro/nano-scale patterning of materials.

Isotopes in global change science: from isotope analytics to Earth system research

International Nuclear Information System (INIS)

Oeschger, H.

1998-01-01

The aim of this paper is to emphasize some of the studies of Jean Charles Fontes and his role in our scientific community. Isotopes represent a powerful tool for the understanding of the Earth's past environment and defining the envelope of natural environmental variability within which we can assess anthropogenic impact on the Earth's biosphere, geosphere and atmosphere. The reconstruction impacts of past climatic change on the Earth's system are a basis to validate models of the possible impacts of future climate change. Oceanic sediments, polar ice caps, continental sedimentary sequences and groundwater are archives of past climate. Their quantitative study is developed within the IGBP (International Geosphere-Biosphere Program) - Pages project, which strongly emphasizes an optimum use of isotope tools. (author)

Energy storage, compression, and switching. Vol. 2

International Nuclear Information System (INIS)

Nardi, V.; Bostick, W.H.; Sahlin, H.

1983-01-01

This book is a compilation of papers presented at the Second International Conference on Energy Storage, Compression, and Switching, which was held in order to assemble active researchers with a major interest in plasma physics, electron beams, electric and magnetic energy storage systems, high voltage and high current switches, free-electron lasers, and pellet implosion plasma focus. Topics covered include: Slow systems: 50-60 Hz machinery, homopolar generators, slow capacitors, inductors, and solid state switches; Intermediate systems: fast capacitor banks; superconducting storage and switching; gas, vacuum, and dielectric switching; nonlinear (magnetic) switching; imploding liners capacitors; explosive generators; and fuses; and Fast systems: Marx, Blumlein, oil, water, and pressurized water dielectrics; switches; magnetic insulation; electron beams; and plasmas

Brayton Isotope Power System (BIPS) facility specification

International Nuclear Information System (INIS)

1976-01-01

General requirements for the Brayton Isotope Power System (BIPS)/Ground Demonstration System (GDS) assembly and test facility are defined. The facility will include provisions for a complete test laboratory for GDS checkout, performance, and endurance testing, and a contamination-controlled area for assembly, fabrication, storage, and storage preparation of GDS components. Specifications, schedules, and drawings are included

Brayton Isotope Power System (BIPS) facility specification

Energy Technology Data Exchange (ETDEWEB)

1976-05-31

General requirements for the Brayton Isotope Power System (BIPS)/Ground Demonstration System (GDS) assembly and test facility are defined. The facility will include provisions for a complete test laboratory for GDS checkout, performance, and endurance testing, and a contamination-controlled area for assembly, fabrication, storage, and storage preparation of GDS components. Specifications, schedules, and drawings are included.

EDITORIAL: Molecular switches at surfaces Molecular switches at surfaces

Science.gov (United States)

Weinelt, Martin; von Oppen, Felix

2012-10-01

In nature, molecules exploit interaction with their environment to realize complex functionalities on the nanometer length scale. Physical, chemical and/or biological specificity is frequently achieved by the switching of molecules between microscopically different states. Paradigmatic examples are the energy production in proton pumps of bacteria or the signal conversion in human vision, which rely on switching molecules between different configurations or conformations by external stimuli. The remarkable reproducibility and unparalleled fatigue resistance of these natural processes makes it highly desirable to emulate nature and develop artificial systems with molecular functionalities. A promising avenue towards this goal is to anchor the molecular switches at surfaces, offering new pathways to control their functional properties, to apply electrical contacts, or to integrate switches into larger systems. Anchoring at surfaces allows one to access the full range from individual molecular switches to self-assembled monolayers of well-defined geometry and to customize the coupling between molecules and substrate or between adsorbed molecules. Progress in this field requires both synthesis and preparation of appropriate molecular systems and control over suitable external stimuli, such as light, heat, or electrical currents. To optimize switching and generate function, it is essential to unravel the geometric structure, the electronic properties and the dynamic interactions of the molecular switches on surfaces. This special section, Molecular Switches at Surfaces, collects 17 contributions describing different aspects of this research field. They analyze elementary processes, both in single molecules and in ensembles of molecules, which involve molecular switching and concomitant changes of optical, electronic, or magnetic properties. Two topical reviews summarize the current status, including both challenges and achievements in the field of molecular switches on

Switching Fuzzy Guaranteed Cost Control for Nonlinear Networked Control Systems

Directory of Open Access Journals (Sweden)

Linqin Cai

2014-01-01

Full Text Available This paper deals with the problem of guaranteed cost control for a class of nonlinear networked control systems (NCSs with time-varying delay. A guaranteed cost controller design method is proposed to achieve the desired control performance based on the switched T-S fuzzy model. The switching mechanism is introduced to handle the uncertainties of NCSs. Based on Lyapunov functional approach, some sufficient conditions for the existence of state feedback robust guaranteed cost controller are presented. Simulation results show that the proposed method is effective to guarantee system’s global asymptotic stability and quality of service (QoS.

Dwell time-based stabilisation of switched delay systems using free-weighting matrices

Science.gov (United States)

Koru, Ahmet Taha; Delibaşı, Akın; Özbay, Hitay

2018-01-01

In this paper, we present a quasi-convex optimisation method to minimise an upper bound of the dwell time for stability of switched delay systems. Piecewise Lyapunov-Krasovskii functionals are introduced and the upper bound for the derivative of Lyapunov functionals is estimated by free-weighting matrices method to investigate non-switching stability of each candidate subsystems. Then, a sufficient condition for the dwell time is derived to guarantee the asymptotic stability of the switched delay system. Once these conditions are represented by a set of linear matrix inequalities , dwell time optimisation problem can be formulated as a standard quasi-convex optimisation problem. Numerical examples are given to illustrate the improvements over previously obtained dwell time bounds. Using the results obtained in the stability case, we present a nonlinear minimisation algorithm to synthesise the dwell time minimiser controllers. The algorithm solves the problem with successive linearisation of nonlinear conditions.

Fuzzy combination of fuzzy and switching state-feedback controllers for nonlinear systems subject to parameter uncertainties.

Science.gov (United States)

Lam, H K; Leung, Frank H F

2005-04-01

This paper presents a fuzzy controller, which involves a fuzzy combination of local fuzzy and global switching state-feedback controllers, for nonlinear systems subject to parameter uncertainties with known bounds. The nonlinear system is represented by a fuzzy combined Takagi-Sugeno-Kang model, which is a fuzzy combination of the global and local fuzzy plant models. By combining the local fuzzy and global switching state-feedback controllers using fuzzy logic techniques, the advantages of both controllers can be retained and the undesirable chattering effect introduced by the global switching state-feedback controller can be eliminated. The steady-state error introduced by the global switching state-feedback controller when a saturation function is used can also be removed. Stability conditions, which are related to the system matrices of the local and global closed-loop systems, are derived to guarantee the closed-loop system stability. An application example will be given to demonstrate the merits of the proposed approach.

Loads Bias Genetic and Signaling Switches in Synthetic and Natural Systems

Science.gov (United States)

Medford, June; Prasad, Ashok

2014-01-01

Biological protein interactions networks such as signal transduction or gene transcription networks are often treated as modular, allowing motifs to be analyzed in isolation from the rest of the network. Modularity is also a key assumption in synthetic biology, where it is similarly expected that when network motifs are combined together, they do not lose their essential characteristics. However, the interactions that a network module has with downstream elements change the dynamical equations describing the upstream module and thus may change the dynamic and static properties of the upstream circuit even without explicit feedback. In this work we analyze the behavior of a ubiquitous motif in gene transcription and signal transduction circuits: the switch. We show that adding an additional downstream component to the simple genetic toggle switch changes its dynamical properties by changing the underlying potential energy landscape, and skewing it in favor of the unloaded side, and in some situations adding loads to the genetic switch can also abrogate bistable behavior. We find that an additional positive feedback motif found in naturally occurring toggle switches could tune the potential energy landscape in a desirable manner. We also analyze autocatalytic signal transduction switches and show that a ubiquitous positive feedback switch can lose its switch-like properties when connected to a downstream load. Our analysis underscores the necessity of incorporating the effects of downstream components when understanding the physics of biochemical network motifs, and raises the question as to how these effects are managed in real biological systems. This analysis is particularly important when scaling synthetic networks to more complex organisms. PMID:24676102

FreeSWITCH Cookbook

CERN Document Server

Minessale, Anthony

2012-01-01

This is a problem-solution approach to take your FreeSWITCH skills to the next level, where everything is explained in a practical way. If you are a system administrator, hobbyist, or someone who uses FreeSWITCH on a regular basis, this book is for you. Whether you are a FreeSWITCH expert or just getting started, this book will take your skills to the next level.

Novel flat datacenter network architecture based on scalable and flow-controlled optical switch system

NARCIS (Netherlands)

Miao, W.; Luo, J.; Di Lucente, S.; Dorren, H.J.S.; Calabretta, N.

2013-01-01

We propose and demonstrate an optical flat datacenter network based on scalable optical switch system with optical flow control. 4×4 dynamic switch operation at 40 Gb/s reported 300ns minimum end-to-end latency (including 25m transmission link) and

Modelling and properties of a nonlinear autonomous switching system in fed-batch culture of glycerol

Science.gov (United States)

Wang, Juan; Sun, Qingying; Feng, Enmin

2012-11-01

A nonlinear autonomous switching system is proposed to describe the coupled fed-batch fermentation with the pH as the feedback parameter. We prove the non-Zeno behaviors of the switching system and some basic properties of its solution, including the existence, uniqueness, boundedness and regularity. Numerical simulation is also carried out, which reveals that the proposed system can describe the factual fermentation process properly.

Measurement system analysis (MSA) of the isotopic ratio for uranium isotope enrichment process control

Energy Technology Data Exchange (ETDEWEB)

Medeiros, Josue C. de; Barbosa, Rodrigo A.; Carnaval, Joao Paulo R., E-mail: josue@inb.gov.br, E-mail: rodrigobarbosa@inb.gov.br, E-mail: joaocarnaval@inb.gov.br [Industrias Nucleares do Brasil (INB), Rezende, RJ (Brazil)

2013-07-01

Currently, one of the stages in nuclear fuel cycle development is the process of uranium isotope enrichment, which will provide the amount of low enriched uranium for the nuclear fuel production to supply 100% Angra 1 and 20% Angra 2 demands. Determination of isotopic ration n({sup 235}U)/n({sup 238}U) in uranium hexafluoride (UF{sub 6} - used as process gas) is essential in order to control of enrichment process of isotopic separation by gaseous centrifugation cascades. The uranium hexafluoride process is performed by gas continuous feeding in separation unit which uses the centrifuge force principle, establishing a density gradient in a gas containing components of different molecular weights. The elemental separation effect occurs in a single ultracentrifuge that results in a partial separation of the feed in two fractions: an enriched on (product) and another depleted (waste) in the desired isotope ({sup 235}UF{sub 6}). Industrias Nucleares do Brasil (INB) has used quadrupole mass spectrometry (QMS) by electron impact (EI) to perform isotopic ratio n({sup 235}U)/n({sup 238}U) analysis in the process. The decision of adjustments and change te input variables are based on the results presented in these analysis. A study of stability, bias and linearity determination has been performed in order to evaluate the applied method, variations and systematic errors in the measurement system. The software used to analyze the techniques above was the Minitab 15. (author)

A β-Ta system for current induced magnetic switching in the absence of external magnetic field

Science.gov (United States)

Chen, Wenzhe; Qian, Lijuan; Xiao, Gang

2018-05-01

Magnetic switching via Giant Spin Hall Effect (GSHE) has received great interest for its role in developing future spintronics logic or memory devices. In this work, a new material system (i.e. a transition metal sandwiched between two ferromagnetic layers) with interlayer exchange coupling is introduced to realize the deterministic field-free perpendicular magnetic switching. This system uses β-Ta, as the GSHE agent to generate a spin current and as the interlayer exchange coupling medium to generate an internal field. The critical switching current density at zero field is on the order of 106 A/cm2 due to the large spin Hall angle of β-Ta. The internal field, along with switching efficiency, depends strongly on the orthogonal magnetization states of two ferromagnetic coupling layers in this system.

A Novel Single Phase Hybrid Switched Reluctance Motor Drive System

DEFF Research Database (Denmark)

Liang, Jianing; Xu, Guoqing; Jian, Linni

2011-01-01

In this paper, a novel single phase hybrid switched reluctance motor(SRM) drive system is proposed. It integrated a single phase hybrid SRM and a novel single phase boost converter. This motor can reduce the number of phase switch. And the permanent magnet which is used in the motor can improve...... the performance and efficiency of SR motor. However, the inherent characteristic of this motor is that the negative torque is very sensitive with the excitation current near the turn-on angle. The slow excitation current limits the torque generation region and reduces the average torque. Therefore, a novel single...... phase boost converter is applied to improve the performance of this motor. It is easy to generate a double dclink voltage and dc-link voltage and switch both of them. The voltage of boost capacitor is self balance, so the protective circuit is not need to consider. The fast excitation mode helps hybrid...

Weighted H∞ Filtering for a Class of Switched Linear Systems with Additive Time-Varying Delays

Directory of Open Access Journals (Sweden)

Li-li Li

2015-01-01

Full Text Available This paper is concerned with the problem of weighted H∞ filtering for a class of switched linear systems with two additive time-varying delays, which represent a general class of switched time-delay systems with strong practical background. Combining average dwell time (ADT technique with piecewise Lyapunov functionals, sufficient conditions are established to guarantee the exponential stability and weighted H∞ performance for the filtering error systems. The parameters of the designed switched filters are obtained by solving linear matrix inequalities (LMIs. A modification of Jensen integral inequality is exploited to derive results with less theoretical conservatism and computational complexity. Finally, two examples are given to demonstrate the effectiveness of the proposed method.

Design of Measurement and Control System of Composite Fast Transfer Switch Based on PLC

Directory of Open Access Journals (Sweden)

ZHANG Hong-yi

2017-06-01

Full Text Available The fast transfer switch gets more extensive application in the power supply system along with the raising of power supply requirement for continuity and reliability in the sensitivity loads such as in airport，military place，hospital and large scale industrial production line． Therefore it is important that how to make fast transfer switch run safely and reliably． The paper expatiated the structure and principle of a fast transfer switch based on mechanical and electronic compound technology，and，according to the basic requirement and the characteristic of the fast transfer switch，a PLC mastered measuring and controlling system has been designed to raise the operation reliability of the fast transfer switch．

Application of enriched stable isotopes as tracers in biological systems

DEFF Research Database (Denmark)

Stürup, Stefan; Hansen, Helle Rüsz; Gammelgaard, Bente

2008-01-01

The application of enriched stable isotopes of minerals and trace elements as tracers in biological systems is a rapidly growing research field that benefits from the many new developments in inorganic mass spectrometric instrumentation, primarily within inductively coupled plasma mass spectrometry...... (ICP-MS) instrumentation, such as reaction/collision cell ICP-MS and multicollector ICP-MS with improved isotope ratio measurement and interference removal capabilities. Adaptation and refinement of radioisotope tracer experiment methodologies for enriched stable isotope experiments......, and the development of new methodologies coupled with more advanced compartmental and mathematical models for the distribution of elements in living organisms has enabled a broader use of enriched stable isotope experiments in the biological sciences. This review discusses the current and future uses of enriched...

Homogeneous Stabilizer by State Feedback for Switched Nonlinear Systems Using Multiple Lyapunov Functions’ Approach

Directory of Open Access Journals (Sweden)

Hui Ye

2017-01-01

Full Text Available This paper investigates the problem of global stabilization for a class of switched nonlinear systems using multiple Lyapunov functions (MLFs. The restrictions on nonlinearities are neither linear growth condition nor Lipschitz condition with respect to system states. Based on adding a power integrator technique, we design homogeneous state feedback controllers of all subsystems and a switching law to guarantee that the closed-loop system is globally asymptotically stable. Finally, an example is given to illustrate the validity of the proposed control scheme.

Open-Switch Fault Detection Method of a Back-to-Back Converter Using NPC Topology for Wind Turbine Systems

DEFF Research Database (Denmark)

Lee, June-Seok; Lee, Kyo_Beum; Blaabjerg, Frede

2015-01-01

system can break down in the worst case scenario. To improve the reliability of WTG systems, an open-switch fault detection method for back-to-back converters using the NPC topology is required. This study analyzes effects of inner and outer open-switch faults of the NPC rectifier and inverter......In wind turbine generation (WTG) systems, a back-to-back converter with a neutral-point-clamped (NPC) topology is widely used because this topology has more advantages than a conventional two-level topology, particularly when operating at high power. There are 12 switches in the NPC topology....... An open-switch fault in the NPC rectifier of the back-to-back converter leads to the distortion of the input current and torque vibration in the system. Additionally, an open-switch fault in the NPC inverter of the back-to-back converter causes the distortion of the output current. Furthermore, the WTG...

Open-switch fault detection method of an NPC converter for wind turbine systems

DEFF Research Database (Denmark)

Lee, June-Seok; Lee, Kyo-Beum; Blaabjerg, Frede

2013-01-01

In wind turbine generation (WTG) systems, the neutral-point-clamped (NPC) topology is widely used as the part of a back-to-back converter since the three-level NPC topology has more advantages than the conventional two-level inverter especially for high power. There are twelve switches in the NPC......-switch detection method of the NPC converter is different from that of the NPC inverter due to the different current paths of the NPC converter. This paper proposes the open-switch fault detection method of the NPC converter connected the permanent-magnet synchronous generator (PMSG). Moreover, the open...

Design study of fuel circulating system using Pd alloy membrane isotope separation method

International Nuclear Information System (INIS)

Naito, T.; Yamada, T.; Aizawa, T.; Kasahara, T.; Yamanaka, T.

1981-01-01

It is expected that the method of permeating through Pd-alloy membrances is effective for isotope separation and the refining of fuel gas. In this paper, the design study of the Fuel Circulating System (FCS) using Pb-alloy membranes is described. The study is mainly focused on the main vacuum, fuel gas refining, isotope separating, and tritium containment systems. In the fuel gas refining system, impurities are effectively removed by using Pd-alloy membranes. For the isotope separation system, the diffusion method through Pd-alloy membranes was adopted. From the standpoint of the safety and economy, a three-stage tritium containment system was adopted to control tritium release to the environment as low as possible. The principal conclusion drawn from the design study was as follows. In the FCS, while cryogenic distillation method appears to be practicable, Pd-alloy membrane method is attractive for isotope separation and the refining of fuel gas. For a large amount of tritium inventory, handling and control technologies should be completed by the experimental evaluation and development of the components and materials used for the FCS. A three-stage containment system was adopted to control tritium release to environment as low as possible. Consideration to prevent tritium escape will be necessary for fuel gas refiners and isotope separators. (Kato, T.)

Preliminary Failure Modes, Effects and Criticality Analysis (FMECA) of the conceptual Brayton Isotope Power System (BIPS) Flight System

International Nuclear Information System (INIS)

Miller, L.G.

1976-01-01

A failure modes, effects and criticality analysis (FMECA) was made of the Brayton Isotope Power System Flight System (BIPS-FS) as presently conceived. The components analyzed include: Mini-BRU; Heat Source Assembly (HSA); Mini-Brayton Recuperator (MBR); Space Radiator; Ducts and Bellows, Insulation System; Controls; and Isotope Heat Source (IHS)

Comparison of switching control algorithms effective in restricting the switching in the neighborhood of the origin

International Nuclear Information System (INIS)

Joung, JinWook; Chung, Lan; Smyth, Andrew W

2010-01-01

The active interaction control (AIC) system consisting of a primary structure, an auxiliary structure and an interaction element was proposed to protect the primary structure against earthquakes and winds. The objective of the AIC system in reducing the responses of the primary structure is fulfilled by activating or deactivating the switching between the engagement and the disengagement of the primary and auxiliary structures through the interaction element. The status of the interaction element is controlled by switching control algorithms. The previously developed switching control algorithms require an excessive amount of switching, which is inefficient. In this paper, the excessive amount of switching is restricted by imposing an appropriately designed switching boundary region, where switching is prohibited, on pre-designed engagement–disengagement conditions. Two different approaches are used in designing the newly proposed AID-off and AID-off 2 algorithms. The AID-off 2 algorithm is designed to affect deactivated switching regions explicitly, unlike the AID-off algorithm, which follows the same procedure of designing the engagement–disengagement conditions of the previously developed algorithms, by using the current status of the AIC system. Both algorithms are shown to be effective in reducing the amount of switching times triggered from the previously developed AID algorithm under an appropriately selected control sampling period for different earthquakes, but the AID-off 2 algorithm outperforms the AID-off algorithm in reducing the number of switching times

Control and switching synchronization of fractional order chaotic systems using active control technique

KAUST Repository

Radwan, A.G.; Moaddy, K.; Salama, Khaled N.; Momani, S.; Hashim, I.

2013-01-01

This paper discusses the continuous effect of the fractional order parameter of the Lü system where the system response starts stable, passing by chaotic behavior then reaching periodic response as the fractional-order increases. In addition, this paper presents the concept of synchronization of different fractional order chaotic systems using active control technique. Four different synchronization cases are introduced based on the switching parameters. Also, the static and dynamic synchronizations can be obtained when the switching parameters are functions of time. The nonstandard finite difference method is used for the numerical solution of the fractional order master and slave systems. Many numeric simulations are presented to validate the concept for different fractional order parameters.

Control and switching synchronization of fractional order chaotic systems using active control technique

KAUST Repository

Radwan, A.G.

2013-03-13

This paper discusses the continuous effect of the fractional order parameter of the Lü system where the system response starts stable, passing by chaotic behavior then reaching periodic response as the fractional-order increases. In addition, this paper presents the concept of synchronization of different fractional order chaotic systems using active control technique. Four different synchronization cases are introduced based on the switching parameters. Also, the static and dynamic synchronizations can be obtained when the switching parameters are functions of time. The nonstandard finite difference method is used for the numerical solution of the fractional order master and slave systems. Many numeric simulations are presented to validate the concept for different fractional order parameters.

Theoretical test of Jarzynski's equality for reversible volume-switching processes of an ideal gas system.

Science.gov (United States)

Sung, Jaeyoung

2007-07-01

We present an exact theoretical test of Jarzynski's equality (JE) for reversible volume-switching processes of an ideal gas system. The exact analysis shows that the prediction of JE for the free energy difference is the same as the work done on the gas system during the reversible process that is dependent on the shape of path of the reversible volume-switching process.

Isotope and hydrogeochemical studies of southern Jiangxi geothermal systems, China

International Nuclear Information System (INIS)

Zhou Wenbin; Li Xueli; Shi Weijun; Sun Zhanxue

1999-01-01

Southern Jiangxi is a geothermally active region, especially in Hengjing area. According to the work plan of IAEA Regional Collaboration in the Development of Geothermal Energy Resources and Environment Management through Isotope Techniques in East Asia and the Pacific (RAS-8-075), field investigation was carried out in Hengjing, southern Jiangxi Province, to demonstrate the use of isotope and geochemical techniques in low to medium temperature geothermal system. During the field investigation, 19 samples were taken from cold springs, hot springs and surface water in the area to determine their hydrochemical and gas compositions, hydrogen, oxygen, carbon and helium isotopes. The results of the study have shown that the geothermal waters in the studying region are of the same characteristics with the local meteoric water in oxygen and hydrogen isotope composition, indicating the geothermal waters are mainly derived from the local precipitation, while the gas composition and carbon and helium isotopes reveal that some gases in the geothermal waters have mantle origin. (author)

Kilowatt isotope power system phase II plan. Volume II: flight System Conceptual Design (FSCD)

International Nuclear Information System (INIS)

1978-03-01

The Kilowatt Isotope Power System (KIPS) Flight System Conceptual Design (FSCD) is described. Included are a background, a description of the flight system conceptual design, configuration of components, flight system performance, Ground Demonstration System test results, and advanced development tests

Multiuser switched diversity scheduling systems with per-user threshold

KAUST Repository

Nam, Haewoon

2010-05-01

A multiuser switched diversity scheduling scheme with per-user feedback threshold is proposed and analyzed in this paper. The conventional multiuser switched diversity scheduling scheme uses a single feedback threshold for every user, where the threshold is a function of the average signal-to-noise ratios (SNRs) of the users as well as the number of users involved in the scheduling process. The proposed scheme, however, constructs a sequence of feedback thresholds instead of a single feedback threshold such that each user compares its channel quality with the corresponding feedback threshold in the sequence. Numerical and simulation results show that thanks to the flexibility of threshold selection, where a potentially different threshold can be used for each user, the proposed scheme provides a higher system capacity than that for the conventional scheme. © 2006 IEEE.

Finite-time stabilisation of a class of switched nonlinear systems with state constraints

Science.gov (United States)

Huang, Shipei; Xiang, Zhengrong

2018-06-01

This paper investigates the finite-time stabilisation for a class of switched nonlinear systems with state constraints. Some power orders of the system are allowed to be ratios of positive even integers over odd integers. A Barrier Lyapunov function is introduced to guarantee that the state constraint is not violated at any time. Using the convex combination method and a recursive design approach, a state-dependent switching law and state feedback controllers of individual subsystems are constructed such that the closed-loop system is finite-time stable without violation of the state constraint. Two examples are provided to show the effectiveness of the proposed method.

Optimal Control of Switching Linear Systems

Directory of Open Access Journals (Sweden)

Ali Benmerzouga

2004-06-01

Full Text Available A solution to the control of switching linear systems with input constraints was given in Benmerzouga (1997 for both the conventional enumeration approach and the new approach. The solution given there turned out to be not unique. The main objective in this work is to determine the optimal control sequences {Ui(k ,  i = 1,..., M ;  k = 0, 1, ...,  N -1} which transfer the system from a given initial state  X0  to a specific target state  XT  (or to be as close as possible by using the same discrete time solution obtained in Benmerzouga (1997 and minimizing a running cost-to-go function. By using the dynamic programming technique, the optimal solution is found for both approaches given in Benmerzouga (1997. The computational complexity of the modified algorithm is also given.

Switched Control Strategies of Aggregated Commercial HVAC Systems for Demand Response in Smart Grids

Directory of Open Access Journals (Sweden)

Kai Ma

2017-07-01

Full Text Available This work proposes three switched control strategies for aggregated heating, ventilation, and air conditioning (HVAC systems in commercial buildings to track the automatic generation control (AGC signal in smart grid. The existing control strategies include the direct load control strategy and the setpoint regulation strategy. The direct load control strategy cannot track the AGC signal when the state of charge (SOC of the aggregated thermostatically controlled loads (TCLs exceeds their regulation capacity, while the setpoint regulation strategy provides flexible regulation capacity, but causes larger tracking errors. To improve the tracking performance, we took the advantages of the two control modes and developed three switched control strategies. The control strategies switch between the direct load control mode and the setpoint regulation mode according to different switching indices. Specifically, we design a discrete-time controller and optimize the controller parameter for the setpoint regulation strategy using the Fibonacci optimization algorithm, enabling us to propose two switched control strategies across multiple time steps. Furthermore, we extend the switched control strategies by introducing a two-stage regulation in a single time step. Simulation results demonstrate that the proposed switched control strategies can reduce the tracking errors for frequency regulation.

Stable isotope geochemistry of the Tongonan geothermal system, Leyte, Philippines

International Nuclear Information System (INIS)

Hulston, J.R.; Stewart, M.K.

1982-01-01

Stable isotope and geochemical data on samples from natural features, shallow wells and deep wells collected over a number of years from the Tongonan area of Leyte have been evaluated. The variations in the isotopic compositions of the thermal waters are used to describe natural processes occurring within the system. The effect of the ''excess enthalpy'' of the deep wells on the isotope data is formulated. Water from the deep Tongonan wells shows an oxygen-18 shift of 5 per mille, which is larger than at Wairakei and Broadlands, probably in part because of the high temperatures at Tongonan. Recent measurements indicate that the deuterium shift is very much smaller than previously thought. Isotopic measurements of methane in the gases suggests differing flows from the Eastern and Central Philippine faults

PLANETARY-SCALE STRONTIUM ISOTOPIC HETEROGENEITY AND THE AGE OF VOLATILE DEPLETION OF EARLY SOLAR SYSTEM MATERIALS

Energy Technology Data Exchange (ETDEWEB)

Moynier, Frederic; Podosek, Frank A. [Department of Earth and Planetary Science and McDonnell Center for Space Sciences, Washington University, St. Louis, MO 63130 (United States); Day, James M. D. [Geosciences Research Division, Scripps Institution of Oceanography, La Jolla, CA 92093-0244 (United States); Okui, Wataru; Yokoyama, Tetsuya [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo 152-8551 (Japan); Bouvier, Audrey [Department of Earth Sciences, University of Minnesota, Minneapolis, MN 55455-0231 (United States); Walker, Richard J., E-mail: moynier@levee.wustl.edu, E-mail: fap@levee.wustl.edu, E-mail: jmdday@ucsd.edu, E-mail: rjwalker@umd.edu, E-mail: okui.w.aa@m.titech.ac.jp, E-mail: tetsuya.yoko@geo.titech.ac.jp, E-mail: abouvier@umn.edu [Department of Geology, University of Maryland, College Park, MD 20742 (United States)

2012-10-10

Isotopic anomalies in planetary materials reflect both early solar nebular heterogeneity inherited from presolar stellar sources and processes that generated non-mass-dependent isotopic fractionations. The characterization of isotopic variations in heavy elements among early solar system materials yields important insight into the stellar environment and formation of the solar system, and about initial isotopic ratios relevant to long-term chronological applications. One such heavy element, strontium, is a central element in the geosciences due to wide application of the long-lived {sup 87}Rb-{sup 87}Sr radioactive as a chronometer. We show that the stable isotopes of Sr were heterogeneously distributed at both the mineral scale and the planetary scale in the early solar system, and also that the Sr isotopic heterogeneities correlate with mass-independent oxygen isotope variations, with only CI chondrites plotting outside of this correlation. The correlation implies that most solar system material formed by mixing of at least two isotopically distinct components: a CV-chondrite-like component and an O-chondrite-like component, and possibly a distinct CI-chondrite-like component. The heterogeneous distribution of Sr isotopes may indicate that variations in initial {sup 87}Sr/{sup 86}Sr of early solar system materials reflect isotopic heterogeneity instead of having chronological significance, as interpreted previously. For example, given the differences in {sup 84}Sr/{sup 86}Sr between calcium aluminum inclusions and eucrites ({epsilon}{sup 84}Sr > 2), the difference in age between these materials would be {approx}6 Ma shorter than previously interpreted, placing the Sr chronology in agreement with other long- and short-lived isotope systems, such as U-Pb and Mn-Cr.

Electronic logic to enhance switch reliability in detecting openings and closures of redundant switches

Science.gov (United States)

Cooper, James A.

1986-01-01

A logic circuit is used to enhance redundant switch reliability. Two or more switches are monitored for logical high or low output. The output for the logic circuit produces a redundant and failsafe representation of the switch outputs. When both switch outputs are high, the output is high. Similarly, when both switch outputs are low, the logic circuit's output is low. When the output states of the two switches do not agree, the circuit resolves the conflict by memorizing the last output state which both switches were simultaneously in and produces the logical complement of this output state. Thus, the logic circuit of the present invention allows the redundant switches to be treated as if they were in parallel when the switches are open and as if they were in series when the switches are closed. A failsafe system having maximum reliability is thereby produced.

Multiuser switched scheduling systems with per-user threshold and post-user selection

KAUST Repository

Nam, Haewoon

2010-06-01

A multiuser switched diversity scheduling scheme with per-user feedback threshold is proposed in this paper. Unlike the conventional multiuser switched diversity scheduling scheme where a single threshold is used by all the users in order to determine whether to transmit a feedback, the proposed scheme deploys per-user threshold, where each user uses a potentially different threshold than other users thresholds. This paper first provides a generic analytical framework for the optimal feedback thresholds in a closed form. Then we investigates the impact of user sequence strategies and post selection strategies on the performance of the multiuser switched scheduling scheme with per-user threshold. Numerical and simulation results show that the proposed scheme provides a higher system capacity compared to the conventional scheme. © 2010 IEEE.

Multiuser switched scheduling systems with per-user threshold and post-user selection

KAUST Repository

Nam, Haewoon; Alouini, Mohamed-Slim

2010-01-01

A multiuser switched diversity scheduling scheme with per-user feedback threshold is proposed in this paper. Unlike the conventional multiuser switched diversity scheduling scheme where a single threshold is used by all the users in order to determine whether to transmit a feedback, the proposed scheme deploys per-user threshold, where each user uses a potentially different threshold than other users thresholds. This paper first provides a generic analytical framework for the optimal feedback thresholds in a closed form. Then we investigates the impact of user sequence strategies and post selection strategies on the performance of the multiuser switched scheduling scheme with per-user threshold. Numerical and simulation results show that the proposed scheme provides a higher system capacity compared to the conventional scheme. © 2010 IEEE.

Intentional preparation of auditory attention-switches: Explicit cueing and sequential switch-predictability.

Science.gov (United States)

Seibold, Julia C; Nolden, Sophie; Oberem, Josefa; Fels, Janina; Koch, Iring

2018-06-01

In an auditory attention-switching paradigm, participants heard two simultaneously spoken number-words, each presented to one ear, and decided whether the target number was smaller or larger than 5 by pressing a left or right key. An instructional cue in each trial indicated which feature had to be used to identify the target number (e.g., female voice). Auditory attention-switch costs were found when this feature changed compared to when it repeated in two consecutive trials. Earlier studies employing this paradigm showed mixed results when they examined whether such cued auditory attention-switches can be prepared actively during the cue-stimulus interval. This study systematically assessed which preconditions are necessary for the advance preparation of auditory attention-switches. Three experiments were conducted that controlled for cue-repetition benefits, modality switches between cue and stimuli, as well as for predictability of the switch-sequence. Only in the third experiment, in which predictability for an attention-switch was maximal due to a pre-instructed switch-sequence and predictable stimulus onsets, active switch-specific preparation was found. These results suggest that the cognitive system can prepare auditory attention-switches, and this preparation seems to be triggered primarily by the memorised switching-sequence and valid expectations about the time of target onset.

Superconductivity, energy storage and switching

International Nuclear Information System (INIS)

Laquer, H.L.

1974-01-01

The phenomenon of superconductivity can contribute to the technology of energy storage and switching in two distinct ways. On one hand the zero resistivity of the superconductor can produce essentially infinite time constants so that an inductive storage system can be charged from very low power sources. On the other hand, the recovery of finite resistivity in a normal-going superconducting switch can take place in extremely short times, so that a system can be made to deliver energy at a very high power level. Topics reviewed include: physics of superconductivity, limits to switching speed of superconductors, physical and engineering properties of superconducting materials and assemblies, switching methods, load impedance considerations, refrigeration economics, limitations imposed by present day and near term technology, performance of existing and planned energy storage systems, and a comparison with some alternative methods of storing and switching energy. (U.S.)

Energy-Efficient Distributed Filtering in Sensor Networks: A Unified Switched System Approach.

Science.gov (United States)

Zhang, Dan; Shi, Peng; Zhang, Wen-An; Yu, Li

2016-04-21

This paper is concerned with the energy-efficient distributed filtering in sensor networks, and a unified switched system approach is proposed to achieve this goal. For the system under study, the measurement is first sampled under nonuniform sampling periods, then the local measurement elements are selected and quantized for transmission. Then, the transmission rate is further reduced to save constrained power in sensors. Based on the switched system approach, a unified model is presented to capture the nonuniform sampling, the measurement size reduction, the transmission rate reduction, the signal quantization, and the measurement missing phenomena. Sufficient conditions are obtained such that the filtering error system is exponentially stable in the mean-square sense with a prescribed H∞ performance level. Both simulation and experiment studies are given to show the effectiveness of the proposed new design technique.

Implications of Sepedi/English code switching for ASR systems

CSIR Research Space (South Africa)

Modipa, TI

2013-12-01

Full Text Available . We also perform an initial acoustic analysis to determine the impact of such code switching on speech recognition performance. We nd that the frequency of code switching is unexpectedly high, and that the continuum of code switching (from unmodi ed...

Switching Phenomena

Science.gov (United States)

Stanley, H. E.; Buldyrev, S. V.; Franzese, G.; Havlin, S.; Mallamace, F.; Mazza, M. G.; Kumar, P.; Plerou, V.; Preis, T.; Stokely, K.; Xu, L.

One challenge of biology, medicine, and economics is that the systems treated by these serious scientific disciplines can suddenly "switch" from one behavior to another, even though they possess no perfect metronome in time. As if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time. The past century has, philosophically, been concerned with placing aside the human tendency to see the universe as a fine-tuned machine. Here we will address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at some of the many temporal patterns in physics, economics, and medicine and even begin to characterize the switching phenomena that enable a system to pass from one state to another. We discuss some applications of correlated randomness to understanding switching phenomena in various fields. Specifically, we present evidence from experiments and from computer simulations supporting the hypothesis that water's anomalies are related to a switching point (which is not unlike the "tipping point" immortalized by Malcolm Gladwell), and that the bubbles in economic phenomena that occur on all scales are not "outliers" (another Gladwell immortalization).

Switched modified function projective synchronization of hyperchaotic Qi system with uncertain parameters

Science.gov (United States)

Sebastian Sudheer, K.; Sabir, M.

2010-12-01

This work is involved with switched modified function projective synchronization of two identical Qi hyperchaotic systems using adaptive control method. Switched synchronization of chaotic systems in which a state variable of the drive system synchronize with a different state variable of the response system is a promising type of synchronization as it provides greater security in secure communication. Modified function projective synchronization with the unpredictability of scaling functions can enhance security. Recently formulated hyperchaotic Qi system in the hyperchaotic mode has an extremely broad frequency bandwidth of high magnitudes, verifying its unusual random nature and indicating its great potential for some relevant engineering applications such as secure communications. By Lyapunove stability theory, the adaptive control law and the parameter update law are derived to make the state of two chaotic systems modified function projective synchronized. Synchronization under the effect of noise is also considered. Numerical simulations are presented to demonstrate the effectiveness of the proposed adaptive controllers.

Dynamic Isotope Power System: technology verification phase, program plan, 1 October 1978

International Nuclear Information System (INIS)

1979-01-01

The technology verification phase program plan of the Dynamic Isotope Power System (DIPS) project is presented. DIPS is a project to develop a 0.5 to 2.0 kW power system for spacecraft using an isotope heat source and a closed-cycle Rankine power-system with an organic working fluid. The technology verification phase's purposes are to increase the system efficiency to over 18%, to demonstrate system reliability, and to provide an estimate for flight test scheduling. Progress toward these goals is reported

Magnetically switched power supply system for lasers

Science.gov (United States)

Pacala, Thomas J. (Inventor)

1987-01-01

A laser power supply system is described in which separate pulses are utilized to avalanche ionize the gas within the laser and then produce a sustained discharge to cause the gas to emit light energy. A pulsed voltage source is used to charge a storage device such as a distributed capacitance. A transmission line or other suitable electrical conductor connects the storage device to the laser. A saturable inductor switch is coupled in the transmission line for containing the energy within the storage device until the voltage level across the storage device reaches a predetermined level, which level is less than that required to avalanche ionize the gas. An avalanche ionization pulse generating circuit is coupled to the laser for generating a high voltage pulse of sufficient amplitude to avalanche ionize the laser gas. Once the laser gas is avalanche ionized, the energy within the storage device is discharged through the saturable inductor switch into the laser to provide the sustained discharge. The avalanche ionization generating circuit may include a separate voltage source which is connected across the laser or may be in the form of a voltage multiplier circuit connected between the storage device and the laser.

3-5 modulation and switching devices for optical systems applications

Science.gov (United States)

Singh, Jasprit; Bhattacharya, Pallab

1995-04-01

The thrust for this three year program has been to develop novel devices and systems applications for multiple quantum well based devices. We have investigated architectures based upon the quantum confined Stark effect (QCSE), a means by which excitonic resonances in a quantum well are electric field tuned to shift the peaked absorption spectrum of the material. The devices based upon this concept have been used, in the past, to realize switching structures employing the characteristic negative differential resistance available in PIN-MQW diodes under illumination. We have focuses, primarily on three schemes based upon the QCSE, to extend the utility of quantum well based devices. Firstly, we have developed, tested and optimized a novel tunable optical filter for wavelength selective applications. Secondly, we have demonstrated an MQW based scheme for optical pattern recognition which we have applied towards header recognition in a packet switching network environment. Thirdly, we have extended previous MQW based switching schemes to implement an optical read only memory (ROM) which can store two bits of information on a single sight, read by two different probe wavelengths of light.

Loop containment (joint integrity) assessment Brayton Isotope Power System flight system

International Nuclear Information System (INIS)

1976-01-01

The Brayton Isotope Power System (BIPS) contains a large number of joints. Since the failure of a joint would result in loss of the working fluid and consequential failure of the BIPS, the integrity of the joints is of paramount importance. The reliability of the ERDA BIPS loop containment (joint integrity) is evaluated. The conceptual flight system as presently configured is depicted. A brief description of the flight system is given

Adaptive Backstepping-Based Neural Tracking Control for MIMO Nonlinear Switched Systems Subject to Input Delays.

Science.gov (United States)

Niu, Ben; Li, Lu

2018-06-01

This brief proposes a new neural-network (NN)-based adaptive output tracking control scheme for a class of disturbed multiple-input multiple-output uncertain nonlinear switched systems with input delays. By combining the universal approximation ability of radial basis function NNs and adaptive backstepping recursive design with an improved multiple Lyapunov function (MLF) scheme, a novel adaptive neural output tracking controller design method is presented for the switched system. The feature of the developed design is that different coordinate transformations are adopted to overcome the conservativeness caused by adopting a common coordinate transformation for all subsystems. It is shown that all the variables of the resulting closed-loop system are semiglobally uniformly ultimately bounded under a class of switching signals in the presence of MLF and that the system output can follow the desired reference signal. To demonstrate the practicability of the obtained result, an adaptive neural output tracking controller is designed for a mass-spring-damper system.

High-performance flat data center network architecture based on scalable and flow-controlled optical switching system

Science.gov (United States)

Calabretta, Nicola; Miao, Wang; Dorren, Harm

2016-03-01

Traffic in data centers networks (DCNs) is steadily growing to support various applications and virtualization technologies. Multi-tenancy enabling efficient resource utilization is considered as a key requirement for the next generation DCs resulting from the growing demands for services and applications. Virtualization mechanisms and technologies can leverage statistical multiplexing and fast switch reconfiguration to further extend the DC efficiency and agility. We present a novel high performance flat DCN employing bufferless and distributed fast (sub-microsecond) optical switches with wavelength, space, and time switching operation. The fast optical switches can enhance the performance of the DCNs by providing large-capacity switching capability and efficiently sharing the data plane resources by exploiting statistical multiplexing. Benefiting from the Software-Defined Networking (SDN) control of the optical switches, virtual DCNs can be flexibly created and reconfigured by the DCN provider. Numerical and experimental investigations of the DCN based on the fast optical switches show the successful setup of virtual network slices for intra-data center interconnections. Experimental results to assess the DCN performance in terms of latency and packet loss show less than 10^-5 packet loss and 640ns end-to-end latency with 0.4 load and 16- packet size buffer. Numerical investigation on the performance of the systems when the port number of the optical switch is scaled to 32x32 system indicate that more than 1000 ToRs each with Terabit/s interface can be interconnected providing a Petabit/s capacity. The roadmap to photonic integration of large port optical switches will be also presented.

A case study on the application of isotope ratio mass spectrometry (IRMS) in determining the provenance of a rock used in an alleged nickel switching incident.

Science.gov (United States)

Roelofse, F; Horstmann, U E

2008-01-15

The application of isotope ratio mass spectrometry (IRMS) in forensic science to establish the provenance of a range of questioned substances including soils, drugs, explosives, currency, ivory and rhino horn has been widely documented. The present study wishes to highlight the applicability of IRMS and specifically stable carbon IRMS in determining the provenance of a carbonate rock that was switched for nickel metal exported from South Africa to Israel. The technique employed effectively argued against a South African origin for the rock whilst simultaneously supporting an Israeli origin, enabling investigators to focus their attention accordingly. The study represents the first documented instance known to the authors where IRMS has been employed in the forensic geo-location of a rock.

Theoretical and Experimental Studies of a Switched Inertance Hydraulic System in a Four-Port High-Speed Switching Valve Configuration

Directory of Open Access Journals (Sweden)

Min Pan

2017-06-01

Full Text Available The switched inertance hydraulic system (SIHS is a novel high-bandwidth and energy-efficient digital device which can adjust or control flow and pressure by a means that does not rely on throttling the flow and dissipation of power. An SIHS can provide an efficient step-up or step-down of pressure or flow rate by using a digital control signal. In this article, analytical models of an SIHS in a four-port high-speed switching valve configuration are proposed, and the system dynamics and performance are investigated theoretically and experimentally. The flow responses, system characteristics, and power consumption can be predicted effectively and accurately by using the proposed models, which were validated by comparing with experiments and with numerical simulation. The four-port configuration is compared with the three-port configuration, and it is concluded that the former one is less efficient for valves of the same size, but provides a bi-direction control capability. As bi-direction control is a common requirement, this constitutes an important contribution to the development of efficient digital hydraulics.

Electrically tunable spatially variable switching in ferroelectric liquid crystal/water system

Science.gov (United States)

Choudhary, A.; Coondoo, I.; Prakash, J.; Sreenivas, K.; Biradar, A. M.

2009-04-01

An unusual switching phenomenon in the region outside conducting patterned area in ferroelectric liquid crystal (FLC) containing about 1-2 wt % of water has been observed. The presence of water in the studied heterogeneous system was confirmed by Fourier transform infrared spectroscopy. The observed optical studies have been emphasized on the "spatially variable switching" phenomenon of the molecules in the nonconducting region of the cell. The observed phenomenon is due to diffusion of water between the smectic layers of the FLC and the interaction of the curved electric field lines with the FLC molecules in the nonconducting region.

Analytical and computational study of magnetization switching in kinetic Ising systems with demagnetizing fields

DEFF Research Database (Denmark)

Richards, H.L.; Rikvold, P.A.

1996-01-01

particularly promising as materials for high-density magnetic recording media. In this paper we use analytic arguments and Monte Carlo simulations to quantitatively study the effects of the demagnetizing field on the dynamics of magnetization switching in two-dimensional, single-domain, kinetic Ising systems....... For systems in the weak-field ''stochastic region,'' where magnetization switching is on average effected by the nucleation and growth of a single droplet, the simulation results can be explained by a simple model in which the free energy is a function only of magnetization. In the intermediate......-field ''multidroplet region,'' a generalization of Avrami's law involving a magnetization-dependent effective magnetic field gives good agreement with the simulations. The effects of the demagnetizing field do not qualitatively change the droplet-theoretical picture of magnetization switching in highly anisotropic...

Identification of fractional-order systems via a switching differential evolution subject to noise perturbations

Energy Technology Data Exchange (ETDEWEB)

Zhu, Wu, E-mail: dtzhuwu@gmail.com [College of Information Science and Technology, Donghua University, Shanghai 201620 (China); Fang, Jian-an [College of Information Science and Technology, Donghua University, Shanghai 201620 (China); Tang, Yang, E-mail: yang.tang@pik-potsdam.de [Institute of Physics, Humboldt University, Berlin 12489 (Germany); Potsdam Institute for Climate Impact Research, Potsdam 14415 (Germany); Research Institute for Intelligent Control and System, Harbin Institute of Technology, Harbin 150006 (China); Zhang, Wenbing [Institute of Textiles and Clothing, The Hong Kong Polytechnic University, Hong Kong (China); Xu, Yulong [College of Information Science and Technology, Donghua University, Shanghai 201620 (China)

2012-10-01

In this Letter, a differential evolution variant, called switching DE (SDE), has been employed to estimate the orders and parameters in incommensurate fractional-order chaotic systems. The proposed algorithm includes a switching population utilization strategy, where the population size is adjusted dynamically based on the solution-searching status. Thus, this adaptive control method realizes the identification of fractional-order Lorenz, Lü and Chen systems in both deterministic and stochastic environments, respectively. Numerical simulations are provided, where comparisons are made with five other State-of-the-Art evolutionary algorithms (EAs) to verify the effectiveness of the proposed method. -- Highlights: ► Switching population utilization strategy is applied for differential evolution. ► The parameters are estimated in both deterministic and stochastic environments. ► Comparisons with five other EAs verify the effectiveness of the proposed method.

Identification of fractional-order systems via a switching differential evolution subject to noise perturbations

International Nuclear Information System (INIS)

Zhu, Wu; Fang, Jian-an; Tang, Yang; Zhang, Wenbing; Xu, Yulong

2012-01-01

In this Letter, a differential evolution variant, called switching DE (SDE), has been employed to estimate the orders and parameters in incommensurate fractional-order chaotic systems. The proposed algorithm includes a switching population utilization strategy, where the population size is adjusted dynamically based on the solution-searching status. Thus, this adaptive control method realizes the identification of fractional-order Lorenz, Lü and Chen systems in both deterministic and stochastic environments, respectively. Numerical simulations are provided, where comparisons are made with five other State-of-the-Art evolutionary algorithms (EAs) to verify the effectiveness of the proposed method. -- Highlights: ► Switching population utilization strategy is applied for differential evolution. ► The parameters are estimated in both deterministic and stochastic environments. ► Comparisons with five other EAs verify the effectiveness of the proposed method.

Switch-connected HyperX network

Science.gov (United States)

Chen, Dong; Heidelberger, Philip

2018-02-13

A network system includes a plurality of sub-network planes and global switches. The sub-network planes have a same network topology as each other. Each of the sub-network planes includes edge switches. Each of the edge switches has N ports. Each of the global switches is configured to connect a group of edge switches at a same location in the sub-network planes. In each of the sub-network planes, some of the N ports of each of the edge switches are connected to end nodes, and others of the N ports are connected to other edge switches in the same sub-network plane, other of the N ports are connected to at least one of the global switches.

Switched diversity strategies for dual-hop relaying systems

KAUST Repository

Gaaloul, Fakhreddine

2011-04-29

This paper investigates the effect of different switched diversity configurations on the implementation complexity and achieved performance of dual-hop amplify-and-forward (AF) relaying networks. A low-complexity model of the relay station is adopted, wherein single-input single-output antenna configuration is employed. Each of the transmitter and the receiver however employs multiple antennas to improve the overall link performance. Single-phase and two-phase based receive switching strategies are investigated assuming optimum first hop signal-to-noise ratio (SNR). Moreover, the simple scheme in which the switched diversity is applied independently over the two hops is studied using tight upper bounds. Thorough performance comparisons and switching thresholds optimization for the aforementioned strategies are presented. Simulation results are also provided to validate the mathematical development and to verify the numerical computations.

MINLP solution for an optimal isotope separation system

International Nuclear Information System (INIS)

Boisset-Baticle, L.; Latge, C.; Joulia, X.

1994-01-01

This paper deals with designing of cryogenic distillation systems for the separation of hydrogen isotopes in a thermonuclear fusion process. The design must minimize the tritium inventory in the distillation columns and satisfy the separation requirements. This induces the optimization of both the structure and the operating conditions of the columns. Such a problem is solved by use of a Mixed-Integer NonLinear Programming (MINLP) tool coupled to a process simulator. The MINLP procedure is based on the iterative and alternative treatment of two subproblems: a NLP problem which is solved by a reduced-gradient method, and a MILP problem, solved with a Branch and Bound method coupled to a simplexe. The formulation of the problem and the choice of an appropriate superstructure are here detailed, and results are finally presented, concerning the optimal design of a specific isotope separation system. (author)

Stochastic Switching Dynamics

DEFF Research Database (Denmark)

Simonsen, Maria

This thesis treats stochastic systems with switching dynamics. Models with these characteristics are studied from several perspectives. Initially in a simple framework given in the form of stochastic differential equations and, later, in an extended form which fits into the framework of sliding...... mode control. It is investigated how to understand and interpret solutions to models of switched systems, which are exposed to discontinuous dynamics and uncertainties (primarily) in the form of white noise. The goal is to gain knowledge about the performance of the system by interpreting the solution...

A polynomial approach for generating a monoparametric family of chaotic attractors via switched linear systems

International Nuclear Information System (INIS)

Aguirre-Hernández, B.; Campos-Cantón, E.; López-Renteria, J.A.; Díaz González, E.C.

2015-01-01

In this paper, we consider characteristic polynomials of n-dimensional systems that determine a segment of polynomials. One parameter is used to characterize this segment of polynomials in order to determine the maximal interval of dissipativity and unstability. Then we apply this result to the generation of a family of attractors based on a class of unstable dissipative systems (UDS) of type affine linear systems. This class of systems is comprised of switched linear systems yielding strange attractors. A family of these chaotic switched systems is determined by the maximal interval of perturbation of the matrix that governs the dynamics for still having scroll attractors

Brayton Isotope Power System. Phase I. (Ground demonstration system) Configuration Control Document (CCD)

International Nuclear Information System (INIS)

1976-01-01

The configuration control document (CCD) defines the BIPS-GDS configuration. The GDS configuration is similar to a conceptual flight system design, referred to as the BIPS-FS, which is discussed in App. I. The BIPS is being developed by ERDA as a 500 to 2000 W(e), 7-y life, space power system utilizing a closed Brayton cycle gas turbine engine to convert thermal energy (from an isotope heat source) to electrical energy at a net efficiency exceeding 25 percent. The CCD relates to Phase I of an ERDA Program to qualify a dynamic system for launch in the early 1980's. Phase I is a 35-month effort to provide an FS conceptual design and GDS design, fabrication, and test. The baseline is a 7-year life, 450-pound, 4800 W(t), 1300 W(e) system which will use two multihundred watt (MHW) isotope heat sources being developed

Investigating the Effect of Voltage-Switching on Low-Energy Task Scheduling in Hard Real-Time Systems

Science.gov (United States)

2005-01-01

We investigate the effect of voltage-switching on task execution times and energy consumption for dual-speed hard real - time systems , and present a...scheduling algorithm and apply it to two real-life task sets. Our results show that energy can be conserved in embedded real - time systems using energy...aware task scheduling. We also show that switching times have a significant effect on the energy consumed in hard real - time systems .

Distributed SCI-based data acquisition systems constructed from SCI bridges and SCI switches

International Nuclear Information System (INIS)

Wu Bin; Kristiansen, E.; Skaali, B.; Bogaerts, A.; Divia, R.; ); Perea, E.

1994-01-01

The IEEE standard 1596-1992, Scalable Coherent Interface (SCI) provides novel possibilities to build data acquisition systems for large and very high rate experiments in high energy physics. The RD24 project at CERN started two years ago to investigate applications of SCI to data acquisition at the Large Hadron Collider (LHC). As part of the RD24 project, simulation of large SCI-based data acquisition systems is performed by a simulator written in the object-oriented language MODSIM II. The goal of this paper is to investigate the difference between SCI switch- and SCI-based systems, and to study some of the design criteria for the SCI switch element to form the interconnection of large scale SCI-based data acquisition systems. 15 refs., 14 figs., 2 tabs

Fault detection for discrete-time switched systems with sensor stuck faults and servo inputs.

Science.gov (United States)

Zhong, Guang-Xin; Yang, Guang-Hong

2015-09-01

This paper addresses the fault detection problem of switched systems with servo inputs and sensor stuck faults. The attention is focused on designing a switching law and its associated fault detection filters (FDFs). The proposed switching law uses only the current states of FDFs, which guarantees the residuals are sensitive to the servo inputs with known frequency ranges in faulty cases and robust against them in fault-free case. Thus, the arbitrarily small sensor stuck faults, including outage faults can be detected in finite-frequency domain. The levels of sensitivity and robustness are measured in terms of the finite-frequency H- index and l2-gain. Finally, the switching law and FDFs are obtained by the solution of a convex optimization problem. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Small Stirling dynamic isotope power system for multihundred-watt robotic missions

International Nuclear Information System (INIS)

Bents, D.J.

1991-01-01

Free Piston Stirling Engine (FPSE) and linear alternator (LA) technology is combined with radioisotope heat sources to produce a compact dynamic isotope power system (DIPS) suitable for multihundred watt space application which appears competitive with advance radioisotope thermoelectric generators (RTGs). The small Stirling DIPS is scalable to multihundred watt power levels or lower. The FPSE/LA is a high efficiency convertor in sizes ranging from tens of kilowatts down to only a few watts. At multihundred watt unit size, the FPSE can be directly integrated with the General Purpose Heat Source (GPHS) via radiative coupling; the resulting dynamic isotope power system has a size and weight that compares favorably with the advanced modular (Mod) RTG, but requires less than a third the amount of isotope fuel. Thus the FPSE extends the high efficiency advantage of dynamic systems into a power range never previously considered competitive for DIPS. This results in lower fuel cost and reduced radiological hazard per delivered electrical watt. 33 refs

Organic Rankine Kilowatt Isotope Power System. Final phase I report

International Nuclear Information System (INIS)

1978-01-01

On 1 August 1975 under Department of Energy Contract EN-77-C-02-4299, Sundstrand Energy Systems commenced development of a Kilowatt Isotope Power System (KIPS) directed toward satisfying the higher power requirements of satellites of the 1980s and beyond. The KIPS is a 238 PuO 2 fueled organic Rankine cycle turbine power system which will provide design output power in the range of 500 to 2000 W/sub (e)/ with a minimum of system changes. The principal objectives of the Phase 1 development effort were to: conceptually design a flight system; design a Ground Demonstration System (GDS) that is prototypic of the flight system in order to prove the feasibility of the flight system design; fabricate and assemble the GDS; and performance and endurance test the GDS using electric heaters in lieu of the isotope heat source. Results of the work performed under the Phase 1 contract to 1 July 1978 are presented

CODE SWITCHING AND THE DEVELOPMENT OF LINGUISTIC SYSTEM OF SIMULTANEOUS BILINGUAL CHILDREN

Directory of Open Access Journals (Sweden)

Leni Amelia Suek

2017-11-01

Full Text Available Code switching and code mixing are the phenomena commonly seen done by a bilingual. This behavior is influenced by several aspects such as the linguistic system, sociolinguistics, pragmatics, and language competence of the bilingual. If children are able to distinguish two different languages since early age, they will be considered simultaneous bilinguals. They show that they develop multiple, rather than single, linguistic systems. However, it was understood that code switching and code mixing were due to the failure in using proper words, language features, and sociolinguistic competence. Yet, recent studies have shown that bilingual children are able to use both languages proficiently with no signs of confusion or failure in language use. This ability also does not hinder their cognitive development.

Switch Reluctance Motor Control Based on Fuzzy Logic System

Directory of Open Access Journals (Sweden)

S. V. Aleksandrovsky

2012-01-01

Full Text Available Due to its intrinsic simplicity and reliability, the switched reluctance motor (SRM has now become a promising candidate for variable-speed drive applications as an alternative induction motor in various industrial application. However, the SRM has the disadvantage of nonlinear characteristic and control. It is suggested to use controller based on fuzzy logic system. Design of FLS controller and simulation model presented.

A switched capacitor array based system for high-speed calorimetry

International Nuclear Information System (INIS)

Levi, M.; Bebek, C.; Ely, R.; Jared, R.; Kipnis, I.; Kirsten, F.; Kleinfelder, S.; Merrick, T.; Milgrome, O.

1991-12-01

A sixteen channel analog transient recorder with 256 cells per channel has been fabricated as an integrated circuit. The circuit uses switched capacitor array technology to achieve simultaneous read/write capability and twelve bit dynamic range. Combined with highly parallel analog-to-digital converter and readout control circuitry being developed this system should satisfy the demanding electronics requirements for calorimeter detectors at the SSC. The system design and test results are presented

Exponential stability of switched linear systems with time-varying delay

Directory of Open Access Journals (Sweden)

Satiracoo Pairote

2007-11-01

Full Text Available We use a Lyapunov-Krasovskii functional approach to establish the exponential stability of linear systems with time-varying delay. Our delay-dependent condition allows to compute simultaneously the two bounds that characterize the exponential stability rate of the solution. A simple procedure for constructing switching rule is also presented.

A System for English Vocabulary Acquisition Based on Code-Switching

Science.gov (United States)

Mazur, Michal; Karolczak, Krzysztof; Rzepka, Rafal; Araki, Kenji

2016-01-01

Vocabulary plays an important part in second language learning and there are many existing techniques to facilitate word acquisition. One of these methods is code-switching, or mixing the vocabulary of two languages in one sentence. In this paper the authors propose an experimental system for computer-assisted English vocabulary learning in…

Average contraction and synchronization of complex switched networks

International Nuclear Information System (INIS)

Wang Lei; Wang Qingguo

2012-01-01

This paper introduces an average contraction analysis for nonlinear switched systems and applies it to investigating the synchronization of complex networks of coupled systems with switching topology. For a general nonlinear system with a time-dependent switching law, a basic convergence result is presented according to average contraction analysis, and a special case where trajectories of a distributed switched system converge to a linear subspace is then investigated. Synchronization is viewed as the special case with all trajectories approaching the synchronization manifold, and is thus studied for complex networks of coupled oscillators with switching topology. It is shown that the synchronization of a complex switched network can be evaluated by the dynamics of an isolated node, the coupling strength and the time average of the smallest eigenvalue associated with the Laplacians of switching topology and the coupling fashion. Finally, numerical simulations illustrate the effectiveness of the proposed methods. (paper)

Brayton dynamic isotope power systems update

International Nuclear Information System (INIS)

Davis, K.A.; Pietsch, A.; Casagrande, R.D.

1986-01-01

Brayton dynamic power systems are uniquely suited for space applications. They are compact and highly efficient, offer inherent reliability due to only one moving part, and utilize a single phase and inert working fluid. Additional features include gas bearings, constant speed, and operation at essentially constant temperature. The design, utilizing an inert gas working fluid and gas bearing, is unaffected by zero gravity and can be easily started and restarted in space at low temperatures. This paper describes the salient features of the BIPS as a Dynamic Isotope Power System (DIPS), summarizes the development work to date, establishes the maturity of the design, provides an update on materials technology, and reviews systems integration considerations

Photonics in switching: Architectures, systems and enabling technologies

DEFF Research Database (Denmark)

Raffaelli, C.; Vlachos, K.; Andriolli, N.

2008-01-01

This paper describes recent research activities and results in the area of photonic switching carried out within the Virtual Department on Switching (VDS) of the European e-Photon/ONe Network of Excellence. Contributions from outstanding European research groups in this field are collected to offer...

Numerical analysis of intrinsic bistability and chromatic switching in Tm3+ single-doped systems under photon avalanche pumping scheme

International Nuclear Information System (INIS)

Li Li; Zhang Xinlu; Chen Lixue

2008-01-01

In this paper, we predict and numerically demonstrate the intrinsic intensity bistability, spectra bistability and chromatic switching of visible-infrared emission in Tm 3+ single-doped systems that are pumped by the photon avalanche scheme at 648 nm. Based on the coupled rate equation theory, the evolutions of the populations at various Tm 3+ energy levels, emission spectra and fluorescence intensity versus pump excitation are numerically investigated in detail. The results show that intrinsic optical bistability (IOB) associated with emission spectra and luminescence intensity takes place in the vicinity of the avalanche threshold (∼10 kW cm -2 ). When the pump excitation rises above the switching threshold (∼17.5 kW cm -2 ), the chromatic switching between the infrared (1716 nm) and the visible blue (452/469 nm) spectra can be performed. Moreover, the influences of system parameters on IOB and the origin of chromatic switching are discussed. These unique characteristics of Tm 3+ -doped systems would lead to the new possibility of the development of pump-controlled all-solid-state luminescence switches and optical bistability switches.

Identifying apparent local stable isotope equilibrium in a complex non-equilibrium system.

Science.gov (United States)

He, Yuyang; Cao, Xiaobin; Wang, Jianwei; Bao, Huiming

2018-02-28

Although being out of equilibrium, biomolecules in organisms have the potential to approach isotope equilibrium locally because enzymatic reactions are intrinsically reversible. A rigorous approach that can describe isotope distribution among biomolecules and their apparent deviation from equilibrium state is lacking, however. Applying the concept of distance matrix in graph theory, we propose that apparent local isotope equilibrium among a subset of biomolecules can be assessed using an apparent fractionation difference (|Δα|) matrix, in which the differences between the observed isotope composition (δ') and the calculated equilibrium fractionation factor (1000lnβ) can be more rigorously evaluated than by using a previous approach for multiple biomolecules. We tested our |Δα| matrix approach by re-analyzing published data of different amino acids (AAs) in potato and in green alga. Our re-analysis shows that biosynthesis pathways could be the reason for an apparently close-to-equilibrium relationship inside AA families in potato leaves. Different biosynthesis/degradation pathways in tubers may have led to the observed isotope distribution difference between potato leaves and tubers. The analysis of data from green algae does not support the conclusion that AAs are further from equilibrium in glucose-cultured green algae than in the autotrophic ones. Application of the |Δα| matrix can help us to locate potential reversible reactions or reaction networks in a complex system such as a metabolic system. The same approach can be broadly applied to all complex systems that have multiple components, e.g. geochemical or atmospheric systems of early Earth or other planets. Copyright © 2017 John Wiley & Sons, Ltd.

A switched energy saving position controller for variable-pressure electro-hydraulic servo systems.

Science.gov (United States)

Tivay, Ali; Zareinejad, Mohammad; Rezaei, S Mehdi; Baghestan, Keivan

2014-07-01

The electro-hydraulic servo system (EHSS) demonstrates a relatively low level of efficiency compared to other available actuation methods. The objective of this paper is to increase this efficiency by introducing a variable supply pressure into the system and controlling this pressure during the task of position tracking. For this purpose, an EHSS structure with controllable supply pressure is proposed and its dynamic model is derived from the basic laws of physics. A switching control structure is then proposed to control both the supply pressure and the cylinder position at the same time, in a way that reduces the overall energy consumption of the system. The stability of the proposed switching control system is guaranteed by proof, and its performance is verified by experimental testing. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Anomalous isotope effects in the U(IV)-U(VI) exchange system

International Nuclear Information System (INIS)

Fujii, Yasuhiko; Nomura, Masao; Okamoto, Makoto; Onitsuka, Hatsuki; Nakanishi, Takashi.

1992-01-01

In previous papers, the enrichment of 236 U in the U(IV) - U(VI) chemical exchange system was found to be significantly smaller than the value estimated by the normal mass dependence enrichment of 235 U. Further experiments have been carried out in the present work to confirm the strange phenomenon of the isotopic anomaly in uranium enrichment. The results have indicated that the separation coefficient of 236 U is the same value as one previously reported. To confirm the anomaly of uranium isotope separation, α-ray spectrometry was implemented to check the enrichment behavior of 234 U. Although no theoretical explanation is given for the isotopic anomaly, this is favorable phenomenon for the re-enrichment of recycled uranium which contains isotopes 232 U and 236 U. (author)

Switch evaluation test system for the National Ignition Facility

International Nuclear Information System (INIS)

Savage, M.E.; Simpson, W.W.; Reynolds, F.D.

1997-01-01

Flashlamp pumped lasers use pulsed power switches to commute energy stored in capacitor banks to the flashlamps. The particular application in which the authors are interested is the National Ignition Facility (NIF), being designed by Lawrence Livermore National Laboratory, Los Alamos National Laboratory, and Sandia National Laboratories (SNL). To lower the total cost of these switches, SNL has a research program to evaluate large closing switches. The target value of the energy switched by a single device is 1.6 MJ, from a 6 mF, 24kV capacitor bank. The peak current is 500 kA. The lifetime of the NIF facility is 24,000 shots. There is no switch today proven at these parameters. Several short-lived switches (100's of shots) exist that can handle the voltage and current, but would require maintenance during the facility life. Other type devices, notably ignitrons, have published lifetimes in excess of 20,000 shots, but at lower currents and shorter pulse widths. The goal of the experiments at SNL is to test switches with the full NIF wave shape, and at the correct voltage. The SNL facility can provide over 500 kA at 24 kV charge voltage. the facility has 6.4 mF total capacitance, arranged in 25 sub-modules. the modular design makes the facility more flexible (for possible testing at lower current) and safer. For pulse shaping (the NIF wave shape is critically damped) there is an inductor and resistor for each of the 25 modules. Rather than one large inductor and resistor, this lowers the current in the pulse shaping components, and raises their value to those more easily attained with lumped inductors and resistors. The authors show the design of the facility, and show results from testing conducted thus far. They also show details of the testing plan for high current switches

Electromechanical magnetization switching

Energy Technology Data Exchange (ETDEWEB)

Chudnovsky, Eugene M. [Department of Physics and Astronomy, Lehman College and Graduate School, The City University of New York, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Jaafar, Reem [Department of Mathematics, Engineering and Computer Science, LaGuardia Community College, The City University of New York, 31-10 Thomson Avenue, Long Island City, New York 11101 (United States)

2015-03-14

We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained.

Electromechanical magnetization switching

International Nuclear Information System (INIS)

Chudnovsky, Eugene M.; Jaafar, Reem

2015-01-01

We show that the magnetization of a torsional oscillator that, in addition to the magnetic moment also possesses an electrical polarization, can be switched by the electric field that ignites mechanical oscillations at the frequency comparable to the frequency of the ferromagnetic resonance. The 180° switching arises from the spin-rotation coupling and is not prohibited by the different symmetry of the magnetic moment and the electric field as in the case of a stationary magnet. Analytical equations describing the system have been derived and investigated numerically. Phase diagrams showing the range of parameters required for the switching have been obtained

Design and implementation of microcontroller-based automatic sequence counting and switching system

Directory of Open Access Journals (Sweden)

Joshua ABOLARINWA

2015-05-01

Full Text Available Technological advancement and its influence on human being have been on the increase in recent time. Major areas of such influence, include monitoring and control activities. In order to keep track of human movement in and out of a particular building, there is the need for an automatic counting system. Therefore, in this paper, we present the design and implementation of a microcontroller-based automatic sequence counting and switching system. This system was designed and developed to save cost, time, energy, and to achieve seamless control in the event of switching on or off of electrical appliances within a building. Top-down modular design approach was used in conjunction with the versatility of microcontroller. The system is able to monitor, sequentially count the number of entry and exit of people through an entrance, afterwards, automatically control any electrical device connected to it. From various tests and measurements obtained, there are comparative benefits derived from the deployment of this system in terms of simplicity and accuracy over similar system that is not microcontroller-based. Therefore, this system can be deployed at commercial quantity with wide range of applications in homes, offices and other public places.

Direct switching control of DC-DC power electronic converters using hybrid system theory

Energy Technology Data Exchange (ETDEWEB)

Zhao, J.; Lin, F. [Wayne State Univ., Detroit, MI (United States). Dept. of Electrical and Computer Engineering; Wang, C. [Wayne State Univ., Detroit, MI (United States). Dept. of Electrical and Computer Engineering; Wayne State Univ., Detroit, MI (United States). Div. of Engineering Technology

2010-07-01

A direct switching control (DSC) scheme for power electronics converters was described. The system was designed for use in both traditional and renewable energy applications as well as in electric drive vehicles. The proposed control scheme was based on a detailed hybrid system converter model that used model predictive control (MPC), piecewise affine (PWA) approximations and constrained optimal control methods. A DC-DC converter was modelled as a hybrid machine. Switching among different modes of the DC-DC converter were modelled as discrete events controlled by the hybrid controller. The modelling scheme was applied to a Buck converter. The DSC was used to control the switch of the power converter based on a hybrid machine model. Results of the study showed that the method can be used to regulate output voltage and inductor currents. The method also provides fast transient responses and effectively regulates both currents and voltage. The controller can be used to provide immediate responses to dynamic disturbances and output voltage fluctuations. 23 refs., 7 figs.

Isotope reversals in hydrocarbon gases of natural shale systems and well head production data

Energy Technology Data Exchange (ETDEWEB)

Berner, U.; Schloemer, S.; Stiller, E. [Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR), Hannover (Germany); Marquardt, D. [Rijksuniversiteit Utrecht (Netherlands)

2013-08-01

Relationships between gas geochemical signatures and the thermal maturity of source rocks containing aquatic organic matter are based on on pyrolysis experiments and have been successfully used in conventional hydrocarbon exploration since long. We demonstrate how these models can be applied to the evaluation of unconventional shale resources. For this purpose hydrocarbon gases have been extracted from low and high mature source rocks (type II kerogens) using laboratory desorption techniques. We determined the molecular composition of the gases as well as the carbon isotope ratios of methane to propane. In the extracted gases we observe an increase of {sup 13}C content in methane with increasing dry gas ratio (C1/{Sigma}C1-6). The carbon isotope ratios of ethane and propane initially increase with increasing dryness but start to become isotopically lighter above a dry gas ratio of 0.8. We show that oil-to-gas cracking explains the observed gas geochemical data, and that mixing between gases from different processes is a key factor to describe natural hydrocarbon systems of shales. However, data from published case studies using well head gases which show 'isotope roll-over' effects indicate that the isotopic reversal observed in well head samples deviate from those observed in natural shale systems in a fundamental way. We show that isotope reversals related to well head gases are best explained by an additional isotope fractionation effect induced through hydraulic fracturing and gas migration from the shale to the well head. Although, this induced isotope fractionation is an artifact which obscures isotopic information of natural systems to a large extend, we suggest a simple classification scheme which allows distinguishing between hot and cool spot areas using well head or mud line gas data. (orig.)

Automatic control of the NMB level in general anaesthesia with a switching total system mass control strategy.

Science.gov (United States)

Teixeira, Miguel; Mendonça, Teresa; Rocha, Paula; Rabiço, Rui

2014-12-01

This paper presents a model based switching control strategy to drive the neuromuscular blockade (NMB) level of patients undergoing general anesthesia to a predefined reference. A single-input single-output Wiener system with only two parameters is used to model the effect of two different muscle relaxants, atracurium and rocuronium, and a switching controller is designed based on a bank of total system mass control laws. Each of such laws is tuned for an individual model from a bank chosen to represent the behavior of the whole population. The control law to be applied at each instant corresponds to the model whose NMB response is closer to the patient's response. Moreover a scheme to improve the reference tracking quality based on the analysis of the patient's response, as well as, a comparison between the switching strategy and the Extended Kalman Kilter (EKF) technique are presented. The results are illustrated by means of several simulations, where switching shows to provide good results, both in theory and in practice, with a desirable reference tracking. The reference tracking improvement technique is able to produce a better reference tracking. Also, this technique showed a better performance than the (EKF). Based on these results, the switching control strategy with a bank of total system mass control laws proved to be robust enough to be used as an automatic control system for the NMB level.

Development and Testing of a Variable Conductance Thermal Acquisition, Transport, and Switching System

Science.gov (United States)

Bugby, David C.; Farmer, Jeffery T.; Stouffer, Charles J.

2013-01-01

This paper describes the development and testing of a scalable thermal management architecture for instruments, subsystems, or systems that must operate in severe space environments with wide variations in sink temperature. The architecture involves a serial linkage of one or more hot-side variable conductance heat pipes (VCHPs) to one or more cold-side loop heat pipes (LHPs). The VCHPs provide wide area heat acquisition, limited distance thermal transport, modest against gravity pumping, concentrated LHP startup heating, and high switching ratio variable conductance operation. The LHPs provide localized heat acquisition, long distance thermal transport, significant against gravity pumping, and high switching ratio variable conductance operation. The single-VCHP, single-LHP system described herein was developed to maintain thermal control of a small robotic lunar lander throughout the lunar day-night thermal cycle. It is also applicable to other variable heat rejection space missions in severe environments. Operationally, despite a 60-70% gas blocked VCHP condenser during ON testing, the system was still able to provide 2-4 W/K ON conductance, 0.01 W/K OFF conductance, and an end-to-end switching ratio of 200-400. The paper provides a detailed analysis of VCHP condenser performance, which quantified the gas blockage situation. Future multi-VCHP/multi-LHP thermal management system concepts that provide power/transport length scalability are also discussed.

System-Level Demonstration of a Dynamically Reconfigured Burst-Mode Link Using a Nanosecond Si-Photonic Switch

DEFF Research Database (Denmark)

Forencich, Alex; Kamchevska, Valerija; Dupuis, Nicolas

2018-01-01

Using a novel FPGA-based network emulator, microsecond-scale packets with 12.5-20-Gb/s data are generated, routed through a nanosecond Si-photonic switch, and received in a fast-locking burst-mode receiver. Error-free links with <382-ns system-level switching are shown....

Studies of isotopic effects in the excited electronic states of molecular systems

International Nuclear Information System (INIS)

1982-01-01

Rare gas halogen (RGH) lasers serve as convenient tools for a range of photophysical processes which exhibit isotope effects. This document summarizes progress in the production of molecular systems in their electronic excited states with the aid of RGH lasers, and the various isotopic effects one can study under these conditions. We conclude that the basic physical mechanisms involved in the isotopically sensitive characteristics of excited molecular electronic states are sufficiently selective to be useful in both the detection and separation of many atomic materials

Model predictive control of an air suspension system with damping multi-mode switching damper based on hybrid model

Science.gov (United States)

Sun, Xiaoqiang; Yuan, Chaochun; Cai, Yingfeng; Wang, Shaohua; Chen, Long

2017-09-01

This paper presents the hybrid modeling and the model predictive control of an air suspension system with damping multi-mode switching damper. Unlike traditional damper with continuously adjustable damping, in this study, a new damper with four discrete damping modes is applied to vehicle semi-active air suspension. The new damper can achieve different damping modes by just controlling the on-off statuses of two solenoid valves, which makes its damping adjustment more efficient and more reliable. However, since the damping mode switching induces different modes of operation, the air suspension system with the new damper poses challenging hybrid control problem. To model both the continuous/discrete dynamics and the switching between different damping modes, the framework of mixed logical dynamical (MLD) systems is used to establish the system hybrid model. Based on the resulting hybrid dynamical model, the system control problem is recast as a model predictive control (MPC) problem, which allows us to optimize the switching sequences of the damping modes by taking into account the suspension performance requirements. Numerical simulations results demonstrate the efficacy of the proposed control method finally.

Application of heavy stable isotopes in forensic isotope geochemistry: A review

International Nuclear Information System (INIS)

Aggarwal, Jugdeep; Habicht-Mauche, Judith; Juarez, Chelsey

2008-01-01

Light stable isotopes have been used for many years to characterize the source and transport of materials. More recently heavy isotope systems such as Sr, Nd and Pb have been added to this list in order to aid source identification. With the advent of multiple collector ICP-MS, the range of isotopic tools now available has increased considerably, however, until the isotope systematics of these new non-traditional isotope systems have become better understood, they will not be as useful in characterizing material source and transportation. Applications using heavy metal stable isotopes (mostly traditional heavy isotopes) have reached most avenues in science, including earth sciences, archaeology, anthropology, animal physiology, ecology and toxicology. This field will continue to grow as new applications are developed and techniques become simpler and quicker. This paper provides a review of how this field has grown and presents two new applications using Pb and Sr isotopes in glazes to determine the source of ore used in glazes, and using Sr isotopes to determine the origin of undocumented deceased Mexican border crossers

Application of heavy stable isotopes in forensic isotope geochemistry: A review

Energy Technology Data Exchange (ETDEWEB)

Aggarwal, Jugdeep [W.M. Keck Isotope Laboratory, Department of Earth Sciences, University of California, Santa Cruz, CA 95064 (United States)], E-mail: jaggarwal@pmc.ucsc.edu; Habicht-Mauche, Judith; Juarez, Chelsey [Department of Anthropology, University of California, Santa Cruz, CA 95064 (United States)

2008-09-15

Light stable isotopes have been used for many years to characterize the source and transport of materials. More recently heavy isotope systems such as Sr, Nd and Pb have been added to this list in order to aid source identification. With the advent of multiple collector ICP-MS, the range of isotopic tools now available has increased considerably, however, until the isotope systematics of these new non-traditional isotope systems have become better understood, they will not be as useful in characterizing material source and transportation. Applications using heavy metal stable isotopes (mostly traditional heavy isotopes) have reached most avenues in science, including earth sciences, archaeology, anthropology, animal physiology, ecology and toxicology. This field will continue to grow as new applications are developed and techniques become simpler and quicker. This paper provides a review of how this field has grown and presents two new applications using Pb and Sr isotopes in glazes to determine the source of ore used in glazes, and using Sr isotopes to determine the origin of undocumented deceased Mexican border crossers.

Automated spike preparation system for Isotope Dilution Mass Spectrometry (IDMS)

International Nuclear Information System (INIS)

Maxwell, S.L. III; Clark, J.P.

1990-01-01

Isotope Dilution Mass Spectrometry (IDMS) is a method frequently employed to measure dissolved, irradiated nuclear materials. A known quantity of a unique isotope of the element to be measured (referred to as the ''spike'') is added to the solution containing the analyte. The resulting solution is chemically purified then analyzed by mass spectrometry. By measuring the magnitude of the response for each isotope and the response for the ''unique spike'' then relating this to the known quantity of the ''spike'', the quantity of the nuclear material can be determined. An automated spike preparation system was developed at the Savannah River Site (SRS) to dispense spikes for use in IDMS analytical methods. Prior to this development, technicians weighed each individual spike manually to achieve the accuracy required. This procedure was time-consuming and subjected the master stock solution to evaporation. The new system employs a high precision SMI Model 300 Unipump dispenser interfaced with an electronic balance and a portable Epson HX-20 notebook computer to automate spike preparation

Golan Heights Groundwater Systems: Separation By REE+Y And Stable Isotopes

Science.gov (United States)

Siebert, C.; Geyer, S.; Knoeller, K.; Roediger, T.; Weise, S.; Dulski, P.; Moeller, P.; Guttman, J.

2008-12-01

In a semi-arid to arid country like Israel, all freshwater resources are under (over-) utilization. Particularly, the Golan Heights rank as one of the most important extraction areas of groundwater of good quality and quantity. Additionally the mountain range feed to a high degree the most important freshwater reservoir of Israel, the Sea of Galilee. Hence, knowing the sources and characters of the Golan Heights groundwater systems is an instantaneous demand regarding sustainable management and protection. Within the "German-Israeli-Jordanian-Palestinian Joint Research Program for the Sustainable Utilisation of Aquifer Systems", hundreds of water samples were taken from all over the Jordan-Dead Sea rift-system to understand groundwater flow-systems and salinisation. For that purpose, each sample was analysed for major and minor ions, rare earth elements including yttrium (REY) and stable isotopes of water (d18O, d2H). The REY distribution in groundwater is established during infiltration by the first water-rock interaction and consequently reflects the leachable components of sediments and rocks of the recharge area. In well- developed flow-systems, REY are adsorbed onto pore surfaces are in equilibrium with the percolating groundwater, even if the lithology changes (e.g. inter-aquifer flow). Thus, groundwater sampled from wells and springs still show the REY distribution pattern established in the recharge area. Since high temperatures do not occur in Golan Heights, d2H and d18O are less controlled by water-rock interaction than by climatic and geomorphological factors at the time of replenishment. Applying the REY signature as a grouping criterion of groundwaters, d18O vs. d2H plots yield a new dimension in interpreting isotope data. The combined use of hydrochemical and isotopic methods enabled us to contain the areas of replenishment and the flow-paths of all investigated groundwater in the Golan Heights. Despite location, salinity or temperature of spring or

The Application of High Temperature Superconducting Materials to Power Switches

CERN Document Server

March, S A; Ballarino, A

2009-01-01

Superconducting switches may find application in superconducting magnet systems that require energy extraction. Such superconducting switches could be bypass-switches that are operated in conjunction with a parallel resistor or dump-switches where all of the energy is dissipated in the switch itself. Bypass-switches are more suited to higher energy circuits as a portion of the energy can be dissipated in the external dump resistor. Dump- switches require less material and triggering energy as a lower switch resistance is needed to achieve the required total dump resistance. Both superconducting bypass-switches and superconducting dump-switches can be ther- mally activated. Switching times that are comparable to those obtained with mechanical bypass-switch systems can be achieved using a co-wound heater that is powered by a ca- pacitor discharge. Switches that have fast thermal diffusion times through the insulation can be modelled as a lumped system whereas those with slow thermal diffusion times were modelle...

An emergency call system for patients in locked-in state using an SSVEP-based brain switch.

Science.gov (United States)

Lim, Jeong-Hwan; Kim, Yong-Wook; Lee, Jun-Hak; An, Kwang-Ok; Hwang, Han-Jeong; Cha, Ho-Seung; Han, Chang-Hee; Im, Chang-Hwan

2017-11-01

Patients in a locked-in state (LIS) due to severe neurological disorders such as amyotrophic lateral sclerosis (ALS) require seamless emergency care by their caregivers or guardians. However, it is a difficult job for the guardians to continuously monitor the patients' state, especially when direct communication is not possible. In the present study, we developed an emergency call system for such patients using a steady-state visual evoked potential (SSVEP)-based brain switch. Although there have been previous studies to implement SSVEP-based brain switch system, they have not been applied to patients in LIS, and thus their clinical value has not been validated. In this study, we verified whether the SSVEP-based brain switch system can be practically used as an emergency call system for patients in LIS. The brain switch used for our system adopted a chromatic visual stimulus, which proved to be visually less stimulating than conventional checkerboard-type stimuli but could generate SSVEP responses strong enough to be used for brain-computer interface (BCI) applications. To verify the feasibility of our emergency call system, 14 healthy participants and 3 patients with severe ALS took part in online experiments. All three ALS patients successfully called their guardians to their bedsides in about 6.56 seconds. Furthermore, additional experiments with one of these patients demonstrated that our emergency call system maintains fairly good performance even up to 4 weeks after the first experiment without renewing initial calibration data. Our results suggest that our SSVEP-based emergency call system might be successfully used in practical scenarios. © 2017 Society for Psychophysiological Research.

A novel solid-state control system for the minimization of re-switching transient currents of induction motor

International Nuclear Information System (INIS)

Abro, M.R.; Larik, A.S.; Mahar, M.A.

2005-01-01

This work is an investigation into the minimizing re-closure transient currents of induction motors by activating NOVEL solid state control system switching at a matched condition. This emphasis is placed upon-circuit transition starting of cage motors, particularly star-delta switching. The initial study is carried out on single-phase induction motion. This system is capable of effective sensing re-closure of a switched off running single-phase induction motor. Further this scheme could be developed to give sequential delta closure of a switched off running three-phase induction motor during 1st cycles following the opening of the star mode. Consideration is also given to the possibility of using sensed re-closure to minimize transient whenever the supply to a running induction motor is briefly interrupted, irrespective of whether the interruption is by accident design. A brief study is made into the type of transient currents generated by opening the circuit of a running induction motor. The importance of the switching pattern for star-delta starting is explained and emphasized. (author)

Concentration effect on inter-mineral equilibrium isotope fractionation: insights from Mg and Ca isotopic systems

Science.gov (United States)

Huang, F.; Wang, W.; Zhou, C.; Kang, J.; Wu, Z.

2017-12-01

Many naturally occurring minerals, such as carbonate, garnet, pyroxene, and feldspar, are solid solutions with large variations in chemical compositions. Such variations may affect mineral structures and modify the chemical bonding environment around atoms, which further impacts the equilibrium isotope fractionation factors among minerals. Here we investigated the effects of Mg content on equilibrium Mg and Ca isotope fractionation among carbonates and Ca content on equilibrium Ca isotope fractionation between orthopyroxene (opx) and clinopyroxene (cpx) using first-principles calculations. Our results show that the average Mg-O bond length increases with decreasing Mg/(Mg+Ca) in calcite when it is greater than 1/48[1] and the average Ca-O bond length significantly decreases with decreasing Ca/(Ca+Mg+Fe) in opx when it ranges from 2/16 to 1/48[2]. Equilibrium isotope fractionation is mainly controlled by bond strengths, which could be measured by bond lengths. Thus, 103lnα26Mg/24Mg between dolomite and calcite dramatically increases with decreasing Mg/(Mg+Ca) in calcite [1] and it reaches a constant value when it is lower than 1/48. 103lnα44Ca/40Ca between opx and cpx significantly increases with decreasing Ca content in opx when Ca/(Ca+Mg+Fe) ranges from 2/16 to 1/48 [2]. If Ca/(Ca+Mg+Fe) is below 1/48, 103lnα44Ca/40Ca is not sensitive to Ca content. Based on our results, we conclude that the concentration effect on equilibrium isotope fractionation could be significant within a certain range of chemical composition of minerals, which should be a ubiquitous phenomenon in solid solution systems. [1] Wang, W., Qin, T., Zhou, C., Huang, S., Wu, Z., Huang, F., 2017. GCA 208, 185-197. [2] Feng, C., Qin, T., Huang, S., Wu, Z., Huang, F., 2014. GCA 143, 132-142.

Controlled Photon Switch Assisted by Coupled Quantum Dots

Science.gov (United States)

Luo, Ming-Xing; Ma, Song-Ya; Chen, Xiu-Bo; Wang, Xiaojun

2015-01-01

Quantum switch is a primitive element in quantum network communication. In contrast to previous switch schemes on one degree of freedom (DOF) of quantum systems, we consider controlled switches of photon system with two DOFs. These controlled photon switches are constructed by exploring the optical selection rules derived from the quantum-dot spins in one-sided optical microcavities. Several double controlled-NOT gate on different joint systems are greatly simplified with an auxiliary DOF of the controlling photon. The photon switches show that two DOFs of photons can be independently transmitted in quantum networks. This result reduces the quantum resources for quantum network communication. PMID:26095049

Seismic switch for strong motion measurement

Science.gov (United States)

Harben, P.E.; Rodgers, P.W.; Ewert, D.W.

1995-05-30

A seismic switching device is described that has an input signal from an existing microseismic station seismometer and a signal from a strong motion measuring instrument. The seismic switch monitors the signal level of the strong motion instrument and passes the seismometer signal to the station data telemetry and recording systems. When the strong motion instrument signal level exceeds a user set threshold level, the seismometer signal is switched out and the strong motion signal is passed to the telemetry system. The amount of time the strong motion signal is passed before switching back to the seismometer signal is user controlled between 1 and 15 seconds. If the threshold level is exceeded during a switch time period, the length of time is extended from that instant by one user set time period. 11 figs.

Multiuser switched diversity scheduling schemes

KAUST Repository

Shaqfeh, Mohammad; Alnuweiri, Hussein M.; Alouini, Mohamed-Slim

2012-01-01

Multiuser switched-diversity scheduling schemes were recently proposed in order to overcome the heavy feedback requirements of conventional opportunistic scheduling schemes by applying a threshold-based, distributed, and ordered scheduling mechanism. The main idea behind these schemes is that slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we characterize the achievable rate region of multiuser switched diversity systems and compare it with the rate region of full feedback multiuser diversity systems. We propose also a novel proportional fair multiuser switched-based scheduling scheme and we demonstrate that it can be optimized using a practical and distributed method to obtain the feedback thresholds. We finally demonstrate by numerical examples that switched-diversity scheduling schemes operate within 0.3 bits/sec/Hz from the ultimate network capacity of full feedback systems in Rayleigh fading conditions. © 2012 IEEE.

Multiuser switched diversity scheduling schemes

KAUST Repository

Shaqfeh, Mohammad

2012-09-01

Multiuser switched-diversity scheduling schemes were recently proposed in order to overcome the heavy feedback requirements of conventional opportunistic scheduling schemes by applying a threshold-based, distributed, and ordered scheduling mechanism. The main idea behind these schemes is that slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we characterize the achievable rate region of multiuser switched diversity systems and compare it with the rate region of full feedback multiuser diversity systems. We propose also a novel proportional fair multiuser switched-based scheduling scheme and we demonstrate that it can be optimized using a practical and distributed method to obtain the feedback thresholds. We finally demonstrate by numerical examples that switched-diversity scheduling schemes operate within 0.3 bits/sec/Hz from the ultimate network capacity of full feedback systems in Rayleigh fading conditions. © 2012 IEEE.

The Development of the Electrically Controlled High Power RF Switch and Its Application to Active RF Pulse Compression Systems

Energy Technology Data Exchange (ETDEWEB)

Guo, Jiquan [Stanford Univ., CA (United States)

2008-12-01

In the past decades, there has been increasing interest in pulsed high power RF sources for building high-gradient high-energy particle accelerators. Passive RF pulse compression systems have been used in many applications to match the available RF sources to the loads requiring higher RF power but a shorter pulse. Theoretically, an active RF pulse compression system has the advantage of higher efficiency and compactness over the passive system. However, the key component for such a system an element capable of switching hundreds of megawatts of RF power in a short time compared to the compressed pulse width is still an open problem. In this dissertation, we present a switch module composed of an active window based on the bulk effects in semiconductor, a circular waveguide three-port network and a movable short plane, with the capability to adjust the S-parameters before and after switching. The RF properties of the switch module were analyzed. We give the scaling laws of the multiple-element switch systems, which allow the expansion of the system to a higher power level. We present a novel overmoded design for the circular waveguide three-port network and the associated circular-to-rectangular mode-converter. We also detail the design and synthesis process of this novel mode-converter. We demonstrate an electrically controlled ultra-fast high power X-band RF active window built with PIN diodes on high resistivity silicon. The window is capable of handling multi-megawatt RF power and can switch in 2-300ns with a 1000A current driver. A low power active pulse compression experiment was carried out with the switch module and a 375ns resonant delay line, obtaining 8 times compression gain with a compression ratio of 20.

Fault Detection for Wireless Networked Control Systems with Stochastic Switching Topology and Time Delay

Directory of Open Access Journals (Sweden)

Pengfei Guo

2014-01-01

Full Text Available This paper deals with the fault detection problem for a class of discrete-time wireless networked control systems described by switching topology with uncertainties and disturbances. System states of each individual node are affected not only by its own measurements, but also by other nodes’ measurements according to a certain network topology. As the topology of system can be switched in a stochastic way, we aim to design H∞ fault detection observers for nodes in the dynamic time-delay systems. By using the Lyapunov method and stochastic analysis techniques, sufficient conditions are acquired to guarantee the existence of the filters satisfying the H∞ performance constraint, and observer gains are derived by solving linear matrix inequalities. Finally, an illustrated example is provided to verify the effectiveness of the theoretical results.

Design Method for the Coil-System and the Soft Switching Technology for High-Frequency and High-Efficiency Wireless Power Transfer Systems

Directory of Open Access Journals (Sweden)

Xu Liu

2017-12-01

Full Text Available Increasing the resonant frequency of a wireless power transfer (WPT system effectively improves the power transfer efficiency between the transmit and the receive coils but significantly limits the power transfer capacity with the same coils. Therefore, this paper proposes a coil design method for a series-series (SS compensated WPT system which can power up the same load with the same DC input voltage & current but with increased resonant frequency. For WPT systems with higher resonant frequencies, a new method of realizing soft-switching by tuning driving frequency is proposed which does not need to change any hardware in the WPT system and can effectively reduce switching losses generated in the inverter. Eighty-five kHz, 200 kHz and 500 kHz WPT systems are built up to validate the proposed methods. Experimental results show that all these three WPT systems can deliver around 3.3 kW power to the same load (15 Ω with 200 V input voltage and 20 A input current as expected and achieve more than 85% coil-system efficiency and 79% system overall efficiency. With the soft-switching technique, inverter efficiency can be improved from 81.91% to 98.60% in the 500 kHz WPT system.

Technology verification phase. Dynamic isotope power system. Final report

Energy Technology Data Exchange (ETDEWEB)

Halsey, D.G.

1982-03-10

The Phase I requirements of the Kilowatt Isotope Power System (KIPS) program were to make a detailed Flight System Conceptual Design (FSCD) for an isotope fueled organic Rankine cycle power system and to build and test a Ground Demonstration System (GDS) which simulated as closely as possible the operational characteristics of the FSCD. The activities and results of Phase II, the Technology Verification Phase, of the program are reported. The objectives of this phase were to increase system efficiency to 18.1% by component development, to demonstrate system reliability by a 5000 h endurance test and to update the flight system design. During Phase II, system performance was improved from 15.1% to 16.6%, an endurance test of 2000 h was performed while the flight design analysis was limited to a study of the General Purpose Heat Source, a study of the regenerator manufacturing technique and analysis of the hardness of the system to a laser threat. It was concluded from these tests that the GDS is basically prototypic of a flight design; all components necessary for satisfactory operation were demonstrated successfully at the system level; over 11,000 total h of operation without any component failure attested to the inherent reliability of this type of system; and some further development is required, specifically in the area of performance. (LCL)

Technology verification phase. Dynamic isotope power system. Final report

International Nuclear Information System (INIS)

Halsey, D.G.

1982-01-01

The Phase I requirements of the Kilowatt Isotope Power System (KIPS) program were to make a detailed Flight System Conceptual Design (FSCD) for an isotope fueled organic Rankine cycle power system and to build and test a Ground Demonstration System (GDS) which simulated as closely as possible the operational characteristics of the FSCD. The activities and results of Phase II, the Technology Verification Phase, of the program are reported. The objectives of this phase were to increase system efficiency to 18.1% by component development, to demonstrate system reliability by a 5000 h endurance test and to update the flight system design. During Phase II, system performance was improved from 15.1% to 16.6%, an endurance test of 2000 h was performed while the flight design analysis was limited to a study of the General Purpose Heat Source, a study of the regenerator manufacturing technique and analysis of the hardness of the system to a laser threat. It was concluded from these tests that the GDS is basically prototypic of a flight design; all components necessary for satisfactory operation were demonstrated successfully at the system level; over 11,000 total h of operation without any component failure attested to the inherent reliability of this type of system; and some further development is required, specifically in the area of performance

Model predictive control of a high speed switched reluctance generator system

NARCIS (Netherlands)

Marinkov, Sava; De Jager, Bram; Steinbuch, Maarten

2013-01-01

This paper presents a novel voltage control strategy for the high-speed operation of a Switched Reluctance Generator. It uses a linear Model Predictive Control law based on the average system model. The controller computes the DC-link current needed to achieve the tracking of a desired voltage

Chromium isotope variations

DEFF Research Database (Denmark)

D'Arcy, Joan Mary

the δ53Cr value of continental runoff into the ocean. The major findings were that river water is characterised by heavy δ53Cr values (+0.1‰ to +1.6‰), while soils are characterised by light δ53Cr values (-0.3‰), relative to the catchment bedrock (-0.17‰ to -0.21‰), indicating that Cr isotopes......, and the quantification the Cr isotope composition of major Cr fluxes into and out of ocean. This thesis adds to the current knowledge of the Cr isotope system and is divided into two studies. The focus of the first study was to determine what processes control the Cr isotopic compositionof river water and to quantify......Chromium (Cr) stable isotopes are a useful tracer of changes in redox conditions because changes in its oxidation state are accompanied by an isotopic fractionation. For this reason the Cr isotope system is being developed as a potential tool for paleo-redox reconstruction. Dissolved Cr in seawater...

Application Criteria for Nine-Switch Power Conversion Systems with Improved Thermal Performance

DEFF Research Database (Denmark)

Qin, Zian; Loh, Poh Chiang; Blaabjerg, Frede

2015-01-01

Nine-switch converter is a reduced-switch equivalence of the widely used twelve-switch back-to-back converter. Like other reduced-switch topologies, the nine-switch converter experiences operating constraints, which may limit its efficiency. This is however not universal, meaning losses of the nine...

Complete assignment of the methionyl carbonyl carbon resonance in switch variant anti-dansyl antibodies labeled with [1-13C]methionine

International Nuclear Information System (INIS)

Kato, Koichi; Matsunaga, C.; Igarashi, Takako; Kim, Hahyung; Odaka, Asano; Shimada, Ichio; Arata, Yoji

1991-01-01

A 13 C NMR study is reported of switch variant anti-dansyl antibodies developed by Dangl et al. who had used the fluorescence-activated cell sorter to select and clone these variants. These switch variant antibodies possess the identical V H , V L , and C L domains in conjunction with different heavy chain constant regions. In the present study, switch variant antibodies of IgG1, IgG2a, and IgG2b subclasses were used along with a short-chain IgG2a antibody, in which the entire C H 1 domain is deleted. The switch variant antibodies were specifically labeled with [1- 13 C]methionine by growing hybridoma cells in serum-free medium. Assignments of all the methionyl carbonyl carbon resonances have been completed by using the intact antibodies along with their fragments and recombined proteins in which either heavy or light chain is labeled. A double labeling method has played a crucial role in the process of the spectral assignments. The strategy used for the assignments has been described in detail. In incorporating 15 N-labeled amino acids into the antibodies for the double labeling, isotope dilution caused a serious problem except in the cases of [α- 15 N]lysine and [ 15 N]threonine, both of which cannot become the substrate of transaminases. It was found that β-chloro-L-alanine is most effective in suppressing the isotope scrambling. So far, spectral assignments by the double labeling method have been possible with 15 N-labeled Ala, His, Ile, Lys, Met, Ser, Thr, Tyr, and Val. On the basis of the results of the present 13 C study, possible use of the assigned carbonyl carbon resonances for the elucidation of the structure-function relationship in the antibody system has been briefly discussed

Noise-constrained switching times for heteroclinic computing

Science.gov (United States)

Neves, Fabio Schittler; Voit, Maximilian; Timme, Marc

2017-03-01

Heteroclinic computing offers a novel paradigm for universal computation by collective system dynamics. In such a paradigm, input signals are encoded as complex periodic orbits approaching specific sequences of saddle states. Without inputs, the relevant states together with the heteroclinic connections between them form a network of states—the heteroclinic network. Systems of pulse-coupled oscillators or spiking neurons naturally exhibit such heteroclinic networks of saddles, thereby providing a substrate for general analog computations. Several challenges need to be resolved before it becomes possible to effectively realize heteroclinic computing in hardware. The time scales on which computations are performed crucially depend on the switching times between saddles, which in turn are jointly controlled by the system's intrinsic dynamics and the level of external and measurement noise. The nonlinear dynamics of pulse-coupled systems often strongly deviate from that of time-continuously coupled (e.g., phase-coupled) systems. The factors impacting switching times in pulse-coupled systems are still not well understood. Here we systematically investigate switching times in dependence of the levels of noise and intrinsic dissipation in the system. We specifically reveal how local responses to pulses coact with external noise. Our findings confirm that, like in time-continuous phase-coupled systems, piecewise-continuous pulse-coupled systems exhibit switching times that transiently increase exponentially with the number of switches up to some order of magnitude set by the noise level. Complementarily, we show that switching times may constitute a good predictor for the computation reliability, indicating how often an input signal must be reiterated. By characterizing switching times between two saddles in conjunction with the reliability of a computation, our results provide a first step beyond the coding of input signal identities toward a complementary coding for

Computer-controlled detection system for high-precision isotope ratio measurements

International Nuclear Information System (INIS)

McCord, B.R.; Taylor, J.W.

1986-01-01

In this paper the authors describe a detection system for high-precision isotope ratio measurements. In this new system, the requirement for a ratioing digital voltmeter has been eliminated, and a standard digital voltmeter interfaced to a computer is employed. Instead of measuring the ratio of the two steadily increasing output voltages simultaneously, the digital voltmeter alternately samples the outputs at a precise rate over a certain period of time. The data are sent to the computer which calculates the rate of charge of each amplifier and divides the two rates to obtain the isotopic ratio. These results simulate a coincident measurement of the output of both integrators. The charge rate is calculated by using a linear regression method, and the standard error of the slope gives a measure of the stability of the system at the time the measurement was taken

Isotopic fractionation of tritium in biological systems.

Science.gov (United States)

Le Goff, Pierre; Fromm, Michel; Vichot, Laurent; Badot, Pierre-Marie; Guétat, Philippe

2014-04-01

Isotopic fractionation of tritium is a highly relevant issue in radiation protection and requires certain radioecological considerations. Sound evaluation of this factor is indeed necessary to determine whether environmental compartments are enriched/depleted in tritium or if tritium is, on the contrary, isotopically well-distributed in a given system. The ubiquity of tritium and the standard analytical methods used to assay it may induce biases in both the measurement and the signification that is accorded to the so-called fractionation: based on an exhaustive review of the literature, we show how, sometimes large deviations may appear. It is shown that when comparing the non-exchangeable fraction of organically bound tritium (neOBT) to another fraction of tritium (e.g. tritiated water) the preparation of samples and the measurement of neOBT reported frequently led to underestimation of the ratio of tritium to hydrogen (T/H) in the non-exchangeable compartment by a factor of 5% to 50%. In the present study, corrections are proposed for most of the biological matrices studied so far. Nevertheless, the values of isotopic fractionation reported in the literature remain difficult to compare with each other, especially since the physical quantities and units often vary between authors. Some improvements are proposed to better define what should encompass the concepts of exchangeable and non-exchangeable fractions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Results from a data acquisition system prototype project using a switch-based event builder

Energy Technology Data Exchange (ETDEWEB)

Black, D.; Andresen, J.; Barsotti, E.; Baumbaugh, A.; Esterline, D.; Knickerbocker, K.; Kwarciany, R.; Moore, G.; Patrick, J.; Swoboda, C.; Treptow, K.; Trevizo, O.; Urish, J.; VanConant, R.; Walsh, D. (Fermi National Accelerator Lab., Batavia, IL (United States)); Bowden, M.; Booth, A. (Superconducting Super Collider Lab., Dallas, TX (United States)); Cancelo, G. (La Plata Univ. Nacional (Argentina))

1991-11-01

A prototype of a high bandwidth parallel event builder has been designed and tested. The architecture is based on a simple switching network and is adaptable to a wide variety of data acquisition systems. An eight channel system with a peak throughput of 160 Megabytes per second has been implemented. It is modularly expandable to 64 channels (over one Gigabyte per second). The prototype uses a number of relatively recent commercial technologies, including very high speed fiber-optic data links, high integration crossbar switches and embedded RISC processors. It is based on an open architecture which permits the installation of new technologies with little redesign effort. 5 refs., 6 figs.

Results from a data acquisition system prototype project using a switch-based event builder

International Nuclear Information System (INIS)

Black, D.; Andresen, J.; Barsotti, E.; Baumbaugh, A.; Esterline, D.; Knickerbocker, K.; Kwarciany, R.; Moore, G.; Patrick, J.; Swoboda, C.; Treptow, K.; Trevizo, O.; Urish, J.; VanConant, R.; Walsh, D.; Bowden, M.; Booth, A.; Cancelo, G.

1991-11-01

A prototype of a high bandwidth parallel event builder has been designed and tested. The architecture is based on a simple switching network and is adaptable to a wide variety of data acquisition systems. An eight channel system with a peak throughput of 160 Megabytes per second has been implemented. It is modularly expandable to 64 channels (over one Gigabyte per second). The prototype uses a number of relatively recent commercial technologies, including very high speed fiber-optic data links, high integration crossbar switches and embedded RISC processors. It is based on an open architecture which permits the installation of new technologies with little redesign effort. 5 refs., 6 figs

Comprehensive theory of the Deans' switch as a variable flow splitter: fluid mechanics, mass balance, and system behavior.

Science.gov (United States)

Boeker, Peter; Leppert, Jan; Mysliwietz, Bodo; Lammers, Peter Schulze

2013-10-01

The Deans' switch is an effluent switching device based on controlling flows of carrier gas instead of mechanical valves in the analytical flow path. This technique offers high inertness and a wear-free operation. Recently new monolithic microfluidic devices have become available. In these devices the whole flow system is integrated into a small metal device with low thermal mass and leak-tight connections. In contrast to a mechanical valve-based system, a flow-controlled system is more difficult to calculate. Usually the Deans' switch is used to switch one inlet to one of two outlets, by means of two auxiliary flows. However, the Deans' switch can also be used to deliver the GC effluent with a specific split ratio to both outlets. The calculation of the split ratio of the inlet flow to the two outlets is challenging because of the asymmetries of the flow resistances. This is especially the case, if one of the outlets is a vacuum device, such as a mass spectrometer, and the other an atmospheric detector, e.g. a flame ionization detector (FID) or an olfactory (sniffing) port. The capillary flows in gas chromatography are calculated with the Hagen-Poiseuille equation of the laminar, isothermal and compressible flow in circular tubes. The flow resistances in the new microfluidic devices have to be calculated with the corresponding equation for rectangular cross-section microchannels. The Hagen-Poiseuille equation underestimates the flow to a vacuum outlet. A corrected equation originating from the theory of rarefied flows is presented. The calculation of pressures and flows of a Deans' switch based chromatographic system is done by the solution of mass balances. A specific challenge is the consideration of the antidiffusion resistor between the two auxiliary gas lines of the Deans' switch. A full solution for the calculation of the Deans' switch including this restrictor is presented. Results from validation measurements are in good accordance with the developed

Test results of a new detector system for gamma ray isotopic measurements

International Nuclear Information System (INIS)

Malcom, J.E.; Bonner, C.A.; Hurd, J.R.; Fleissner,

1993-01-01

A new type of gamma-ray detector system for isotopic measurements has been developed. This new system, a ''Duo detector'' array, consists of two intrinsic germanium detectors, a planar followed by a coaxial mounted on the same axis within a single cryostat assembly. This configuration allows the isotopic analysis system to take advantage of spectral data results that are collected simultaneously from different gamma-ray energy regimes. Princeton Gamma Tech (PGT) produced several prototypes of this Duo detector array which were then tested by Rocky Flats personnel until the design was optimized. An application for this detector design is in automated, roboticized NDA systems such as those being developed at the Los Alamos TA-55 Plutonium Facility. The Duo detector design reduces the space necessary for the isotopic instrument by a factor of two (only one liquid nitrogen dewar is needed), and also reduces the complexity of the mechanical systems and controlling software. Data will be presented on measurements of nuclear material with a Duo detector for a wide variety of matrices. Results indicate that the maximum count rate can be increased up to 100,000 counts per second yet maintaining excellent resolution and energy rate product

High voltage fast switches for nuclear applications

International Nuclear Information System (INIS)

Chatroux, D.; Lausenaz, Y.; Villard, J.F.; Lafore, D.

1999-01-01

SILVA process consists in a selective ionization of the 235 uranium isotope, using laser beams generated by dye lasers pumped by copper vapour laser (C.V.L.). SILVA involves power electronic for 3 power supplies: - copper vapour laser power supply, - extraction power supply to generate the electric field in the vapour, and - electron beam power supply for vapour generation. This article reviews the main switches that are proposed on the market or are on development and that could be used in SILVA power supplies. The SILVA technical requirements are: high power, high voltage and very short pulses (200 ns width). (A.C.)

Ultra High-Speed Radio Frequency Switch Based on Photonics.

Science.gov (United States)

Ge, Jia; Fok, Mable P

2015-11-26

Microwave switches, or Radio Frequency (RF) switches have been intensively used in microwave systems for signal routing. Compared with the fast development of microwave and wireless systems, RF switches have been underdeveloped particularly in terms of switching speed and operating bandwidth. In this paper, we propose a photonics based RF switch that is capable of switching at tens of picoseconds speed, which is hundreds of times faster than any existing RF switch technologies. The high-speed switching property is achieved with the use of a rapidly tunable microwave photonic filter with tens of gigahertz frequency tuning speed, where the tuning mechanism is based on the ultra-fast electro-optics Pockels effect. The RF switch has a wide operation bandwidth of 12 GHz and can go up to 40 GHz, depending on the bandwidth of the modulator used in the scheme. The proposed RF switch can either work as an ON/OFF switch or a two-channel switch, tens of picoseconds switching speed is experimentally observed for both type of switches.

Switched diversity strategies for dual-hop amplify-and-forward relaying systems

KAUST Repository

Gaaloul, Fakhreddine

2012-01-01

This study investigates different receive single-branch switch-based diversity schemes for dual-hop amplify-and-forward relaying networks. Specifically, three receive processing algorithms are adopted, in which the receive branch is selected using the arbitrary selection algorithm, the switching algorithm, or the switching algorithm with post-examining best branch selection. The identification of the receive branch is carried out for two different system models. For the first model, a single-antenna relaying station is used in conjunction with a multiple-antenna transceiver, where the processing is performed independently of the first hop-fading conditions. The second model suggests the use of parallel deployment of single-antenna relays to transfer information from a multiple-antenna transmitter to a single-antenna receiver, where the active relaying station is determined based on the pre-combining end-to-end fading conditions. Performance comparisons for various transmission scenarios on the first hop are presented using new formulations for the statistics of the combined signal-to-noise ratio. Simulation results are also provided to validate the mathematical development and to verify the numerical computations. © 2012 The Institution of Engineering and Technology.

A Wireless Implantable Switched-Capacitor Based Optogenetic Stimulating System

Science.gov (United States)

Lee, Hyung-Min; Kwon, Ki-Yong; Li, Wen

2015-01-01

This paper presents a power-efficient implantable optogenetic interface using a wireless switched-capacitor based stimulating (SCS) system. The SCS efficiently charges storage capacitors directly from an inductive link and periodically discharges them into an array of micro-LEDs, providing high instantaneous power without affecting wireless link and system supply voltage. A custom-designed computer interface in LabVIEW environment wirelessly controls stimulation parameters through the inductive link, and an optrode array enables simultaneous neural recording along with optical stimulation. The 4-channel SCS system prototype has been implemented in a 0.35-μm CMOS process and combined with the optrode array. In vivo experiments involving light-induced local field potentials verified the efficacy of the SCS system. An implantable version of the SCS system with flexible hermetic sealing is under development for chronic experiments. PMID:25570099

Complete assignment of the methionyl carbonyl carbon resonance in switch variant anti-dansyl antibodies labeled with (1- sup 13 C)methionine

Energy Technology Data Exchange (ETDEWEB)

Kato, Koichi; Matsunaga, C.; Igarashi, Takako; Kim, Hahyung; Odaka, Asano; Shimada, Ichio; Arata, Yoji (Univ. of Tokyo, Hongo (Japan))

1991-01-01

A {sup 13}C NMR study is reported of switch variant anti-dansyl antibodies developed by Dangl et al. who had used the fluorescence-activated cell sorter to select and clone these variants. These switch variant antibodies possess the identical V{sub H}, V{sub L}, and C{sub L} domains in conjunction with different heavy chain constant regions. In the present study, switch variant antibodies of IgG1, IgG2a, and IgG2b subclasses were used along with a short-chain IgG2a antibody, in which the entire C{sub H}1 domain is deleted. The switch variant antibodies were specifically labeled with (1-{sup 13}C)methionine by growing hybridoma cells in serum-free medium. Assignments of all the methionyl carbonyl carbon resonances have been completed by using the intact antibodies along with their fragments and recombined proteins in which either heavy or light chain is labeled. A double labeling method has played a crucial role in the process of the spectral assignments. The strategy used for the assignments has been described in detail. In incorporating {sup 15}N-labeled amino acids into the antibodies for the double labeling, isotope dilution caused a serious problem except in the cases of ({alpha}-{sup 15}N)lysine and ({sup 15}N)threonine, both of which cannot become the substrate of transaminases. It was found that {beta}-chloro-L-alanine is most effective in suppressing the isotope scrambling. So far, spectral assignments by the double labeling method have been possible with {sup 15}N-labeled Ala, His, Ile, Lys, Met, Ser, Thr, Tyr, and Val. On the basis of the results of the present {sup 13}C study, possible use of the assigned carbonyl carbon resonances for the elucidation of the structure-function relationship in the antibody system has been briefly discussed.

Study of magnetization switching in coupled magnetic nanostructured systems

Science.gov (United States)

Radu, Cosmin

A study of magnetization dynamics experiments in nanostructured materials using the rf susceptibility tunnel diode oscillator (TDO) method is presented along with a extensive theoretical analysis. An original, computer controlled experimental setup that measures the change in susceptibility with the variation in external magnetic field and sample temperature was constructed. The TDO-based experiment design and construction is explained in detail, showing all the elements of originality. This experimental technique has proven reliable for characterizing samples with uncoupled magnetic structure and various magnetic anisotropies like: CrO2, FeCo/IrMn and Co/SiO2 thin films. The TDO was subsequently used to explore the magnetization switching in coupled magnetic systems, like synthetic antiferromagnet (SAF) structures. Magnetoresistive random access memory (MRAM) is an important example of devices where the use of SAF structure is essential. To support the understanding of the SAF magnetic behavior, its configuration and application are reviewed and more details are provided in an appendix. Current problems in increasing the scalability and decreasing the error rate of MRAM devices are closely connected to the switching properties of the SAF structures. Several theoretical studies that were devoted to the understanding of the concepts of SAF critical curve are reviewed. As one can notice, there was no experimental determination of SAF critical curve, due to the difficulties in characterizing a magnetic coupled structure. Depending of the coupling strength between the two ferromagnetic layers, on the SAF critical curve one distinguishes several new features, inexistent in the case of uncoupled systems. Knowing the configuration of the SAF critical curve is of great importance in order to control its switching characteristics. For the first time a method of experimentally recording the critical curve for SAF is proposed in this work. In order to overcome technological

Switching Device Dead Time Optimization of Resonant Double-Sided LCC Wireless Charging System for Electric Vehicles

Directory of Open Access Journals (Sweden)

Xi Zhang

2017-11-01

Full Text Available Aiming at the reduction of the influence of the dead time setting on power level and efficiency of the inverter of double-sided LCC resonant wireless power transfer (WPT system, a dead time soft switching optimization method for metal–oxide–semiconductor field-effect transistor (MOSFET is proposed. At first, the mathematic description of double-sided LCC resonant wireless charging system is established, and the operating mode is analyzed as well, deducing the quantitative characteristic that the secondary side compensation capacitor C2 can be adjusted to ensure that the circuit is inductive. A dead time optimization design method is proposed, contributing to achieving zero-voltage switching (ZVS of the inverter, which is closely related to the performance of the WPT system. In the end, a prototype is built. The experimental results verify that dead time calculated by this optimized method can ensure the soft switching of the inverter MOSFET and promote the power and efficiency of the WPT.

The Laboratory for Laser Energetics’ Hydrogen Isotope Separation System

Energy Technology Data Exchange (ETDEWEB)

Shmayda, W.T., E-mail: wshm@lle.rochester.edu; Wittman, M.D.; Earley, R.F.; Reid, J.L.; Redden, N.P.

2016-11-01

The University of Rochester’s Laboratory for Laser Energetics has commissioned a hydrogen Isotope Separation System (ISS). The ISS uses two columns—palladium on kieselguhr and molecular sieve—that act in a complementary manner to separate the hydrogen species by mass. The 4-sL per day throughput system is compact and has no moving parts. The columns and the attendant gas storage and handling subsystems are housed in a 0.8 -m{sup 3} glovebox. The glovebox uses a helium cover gas that is continuously processed to extract oxygen and water vapor that permeates through the glovebox gloves and any tritium that is released while attaching or detaching vessels to add feedstock to or drawing product from the system. The isotopic separation process is automated and does not require manual intervention. A total of 315 TBq of tritium was extracted from 23.6 sL of hydrogen with tritium purities reaching 99.5%. Deuterium was the sole residual component in the processed gas. Raffinate contained 0.2 TBq of activity was captured for reprocessing. The total emission from the system to the environment was 0.4 GBq over three weeks.

Development of laser marking system with electro-optic Q-switch

Energy Technology Data Exchange (ETDEWEB)

Kim, Cheol Jung; Kim, Jeong Moog; Kim, Kwang Suk; Park, Seung Kyu; Baik, Sung Hoon

1995-11-01

We developed a high repetition electro-optic Q switch Nd:YAG laser and scan system for laser marking. We localized the scan mirrors and their mounts. We made the database for the optical properties of commercial flat-field lenses with our optics design software. We fabricated the detailed network between the galvanometer based beam scanning system and the laser generator. To accelerate the commercialization by the joint company, the training and transfer of technology were pursued in the joint participation by company researchers from the early stage. (author). 8 refs., 6 tabs., 27 figs.

Development of laser marking system with electro-optic Q-switch

International Nuclear Information System (INIS)

Kim, Cheol Jung; Kim, Jeong Moog; Kim, Kwang Suk; Park, Seung Kyu; Baik, Sung Hoon.

1995-11-01

We developed a high repetition electro-optic Q switch Nd:YAG laser and scan system for laser marking. We localized the scan mirrors and their mounts. We made the database for the optical properties of commercial flat-field lenses with our optics design software. We fabricated the detailed network between the galvanometer based beam scanning system and the laser generator. To accelerate the commercialization by the joint company, the training and transfer of technology were pursued in the joint participation by company researchers from the early stage. (author). 8 refs., 6 tabs., 27 figs

An extension of the Néel-Brown model for systems with multiple switching pathways

Energy Technology Data Exchange (ETDEWEB)

Roy, Arnab; Kumar, P.S. Anil, E-mail: anil@physics.iisc.ernet.in

2017-02-15

TheNéel-Brown model is the most widely accepted model for the description of magnetization reversal by thermal excitation. This model predicts a decreasing average switching field and an increasing width ΔH of switching field distribution as the temperature is increased, and has been found to hold good on several occasions. However, for a few classes of systems, the temperature dependence of ΔH shows the opposite trend, and so far no satisfactory explanation exists. We present here an experimental study of switching field statistics of permalloy (Ni{sub 80}Fe{sub 20}) thin films on Si(100) grown by pulsed laser ablation. It was seen that the sample deviates from the Neel-Brown behavior in the manner described above. We performed calculations based on a natural extension of the Néel-Brown model, which incorporated multiple reversal pathways characterized by a Gaussian distribution of coercive fields. Calculations based on this model for different values of the width parameter σ{sub HSW} show two distinct kinds of behavior. At low values of σ{sub HSW}, the total width ΔH is limited by thermal broadening according to the traditional Neel-Brown expression. This regime is characterized by an increasing ΔH with temperature. For high σ{sub HSW}, the broadening is dominated by σ{sub HSW}, which masks thermal broadening. In this regime, ΔH decreases with increasing temperature. Whereas the experimentally observed temperature dependence of the average switching field was found to be in good agreement with this model, qualitative agreement with regard to the temperature dependence of ΔH could be observed only for relaxation times lower than ~10{sup −40} s, which is much smaller than Néel-Brown relaxation times (10{sup −9}–10{sup −19} s) usually encountered in the literature. - Highlights: • The Néel-Brown model for magnetization reversal over an energy barrier due to thermal excitation is a widely accepted mechanism for magnetization reversal, and has

A Novel Silicon-based Wideband RF Nano Switch Matrix Cell and the Fabrication of RF Nano Switch Structures

Directory of Open Access Journals (Sweden)

Yi Xiu YANG

2011-12-01

Full Text Available This paper presents the concept of RF nano switch matrix cell and the fabrication of RF nano switch. The nano switch matrix cell can be implemented into complex switch matrix for signal routing. RF nano switch is the decision unit for the matrix cell; in this research, it is fabricated on a tri-layer high-resistivity-silicon substrate using surface micromachining approach. Electron beam lithography is introduced to define the pattern and IC compatible deposition process is used to construct the metal layers. Silicon-based nano switch fabricated by IC compatible process can lead to a high potential of system integration to perform a cost effective system-on-a-chip solution. In this paper, simulation results of the designed matrix cell are presented; followed by the details of the nano structure fabrication and fabrication challenges optimizations; finally, measurements of the fabricated nano structure along with analytical discussions are also discussed.

Application of environmental isotope techniques to selected hydrological systems in Pampean, Argentina

International Nuclear Information System (INIS)

Dapena, C.; Panarello, H.O.

2007-01-01

The isotopic composition of precipitation in Buenos Aires station is of great importance to understand the Pampean hydrological Systems. The rain isotope content ( 2 H, 18 O and 3 H) is being recorded since 1978 at Ciudad Universitaria Station, belonging to the Red Nacional de Colectores constitutes the main recharge factor for most of local and regional hydrologic system. The knowledge and characterization of their isotope content is of fundamental importance for a hydrological investigation, so we need a historical updated record. For this reason the International Atomic Energy Agency (IAEA) in co-operation with the World Meteorological Organization (WMO) developed an international network devoted to the measurement of isotope contents in precipitation named as GNIP (Global Network for Isotopes in Precipitation) which started in 1960. The main objective of the network is to evaluate on a global scale the spatial and temporal distribution of isotope contents in precipitation and their dependence to relevant meteorological parameters. In this framework, the 'Instituto de Geocronologia y Geologia Isotopica' (INGEIS) established a National Collector Network for Isotopes in Precipitation (RNC) which integrates with the GNIP. The operation of the network in Argentina began in November 1978 with one station located in Buenos Aires City. At present, INGEIS is operating 17 stations at different altitudes and latitudes, covering a wide range of temperatures and a large variety of climates. This information allows us to know the input functions (rain isotope content) at different regions of the country. Signatures of isotopes in precipitation are not static. They respond to both, synoptic and climatology and global climate change. Attracted by this issue, a new community, interested in palaeoclimate and atmospheric circulation modelling, started to use the GNIP data. However, it becomes apparent soon that the collected data were also useful in other water-related fields

Mass-Dependent and -Independent Fractionation of Mercury Isotopes in Aquatic Systems

Science.gov (United States)

Bergquist, B. A.; Joel, B. D.; Jude, D. J.

2008-12-01

Mercury is a globally distributed and highly toxic pollutant. Although Hg is a proven health risk, much of the natural cycle of Hg is not well understood and new approaches are needed to track Hg and the chemical transformations it undergoes in the environment. Recently, we demonstrated that Hg isotopes exhibit two types of isotope fractionation: (1) mass dependent fractionation (MDF) and (2) mass independent fractionation (MIF) of only the odd isotopes (Bergquist and Blum, 2007). The observation of large MIF of Hg isotopes (up to 5 permil) is exciting because only a few other isotopic systems have been documented to display large MIF, the most notable of which are oxygen and sulfur. In both cases, the application of MIF has proven very useful in a variety of fields including cosmochemistry, paleoclimatology, physical chemistry, atmospheric chemistry, and biogeochemistry. Both MDF and MIF isotopic signatures are observed in natural samples, and together they open the door to a new method for tracing Hg pollution and for investigating Hg behavior in the environment. For example, fish record MDF that appears to be related to size and age. Additionally, fish display MIF signatures that are consistent with the photo-reduction of methylmercury (Bergquist and Blum, 2007). If the MDF and MIF in ecosystems can be understood, the signatures in fish could inform us about the sources and processes transforming Hg and why there are differences in the bioaccumulation of Hg in differing ecosystems and populations of fish. This requires sampling of a variety of ecosystems, the sampling of many components of the ecosystems, and the use of other tracers such as carbon and nitrogen isotopes. We have expanded our studies of aquatic ecosystems to include several lakes in North America. Similar to other isotopic systems used to study food web dynamics and structure (i.e., C and N), the MDF of Hg in fish appears to be related to size and age. The MDF recorded in fish likely reflects

Switch-attention (aka switch-reference in South-American temporal clauses: facilitating oral transmission

Directory of Open Access Journals (Sweden)

Rik van Gijn

2012-01-01

Full Text Available Cultures without a written tradition depend entirely on the oral channel to transmit sometimes highly complex information. It is therefore not surprising that in the languages of such cultures linguistic devices evolve that enhance textual coherence, and thus comprehension. These devices should ideally also be economical in terms of morphosyntactic complexity in order to facilitate both production and comprehension. In this paper, I will argue that switch-attention (a term preferred over the traditional switch-reference systems in temporal clauses fulfill these requirements of cohesion and complexity reduction, making them particularly apt for orally transmitting texts. Moreover, switch-reference systems seem to diffuse relatively easily. These features taken together are suggested to be (partly responsible for the widely attested phenomenon in areas without a lengthy written tradition.

Analysis of Switched-Rigid Floating Oscillator

Directory of Open Access Journals (Sweden)

Prabhakar R. Marur

2009-01-01

Full Text Available In explicit finite element simulations, a technique called deformable-to-rigid (D2R switching is used routinely to reduce the computation time. Using the D2R option, the deformable parts in the model can be switched to rigid and reverted back to deformable when needed during the analysis. The time of activation of D2R however influences the overall dynamics of the system being analyzed. In this paper, a theoretical basis for the selection of time of rigid switching based on system energy is established. A floating oscillator problem is investigated for this purpose and closed-form analytical expressions are derived for different phases in rigid switching. The analytical expressions are validated by comparing the theoretical results with numerical computations.

Robust Fault Detection for Switched Fuzzy Systems With Unknown Input.

Science.gov (United States)

Han, Jian; Zhang, Huaguang; Wang, Yingchun; Sun, Xun

2017-10-03

This paper investigates the fault detection problem for a class of switched nonlinear systems in the T-S fuzzy framework. The unknown input is considered in the systems. A novel fault detection unknown input observer design method is proposed. Based on the proposed observer, the unknown input can be removed from the fault detection residual. The weighted H∞ performance level is considered to ensure the robustness. In addition, the weighted H₋ performance level is introduced, which can increase the sensibility of the proposed detection method. To verify the proposed scheme, a numerical simulation example and an electromechanical system simulation example are provided at the end of this paper.

Opioids Switching with Transdermal Systems in Chronic Cancer Pain

Directory of Open Access Journals (Sweden)

Barbarisi M

2009-05-01

Full Text Available Abstract Background Due to tolerance development and adverse side effects, chronic pain patients frequently need to be switched to alternative opioid therapy Objective To assess the efficacy and tolerability of an alternative transdermally applied (TDS opioid in patients with chronic cancer pain receiving insufficient analgesia using their present treatment. Methods A total of 32 patients received alternative opioid therapy, 16 were switched from buprenorphine to fentanyl and 16 were switched from fentanyl to buprenorphine. The dosage used was 50% of that indicated in equipotency conversion tables. Pain relief was assessed at weekly intervals for the next 3 weeks Results Pain relief as assessed by VAS, PPI, and PRI significantly improved (p Conclusion Opioid switching at 50% of the calculated equianalgesic dose produced a significant reduction in pain levels and rescue medication. The incidence of side effects decreased and no new side effects were noted. Further studies are required to provide individualized treatment for patients according to their different types of cancer.

The isotope record of short- and long-term dietary changes in sheep tooth enamel: Implications for quantitative reconstruction of paleodiets

Science.gov (United States)

Zazzo, A.; Balasse, M.; Passey, B. H.; Moloney, A. P.; Monahan, F. J.; Schmidt, O.

2010-06-01

Quantitative reconstruction of paleodiet by means of sequential sampling and carbon isotope analysis in hypsodont tooth enamel requires a precise knowledge of the isotopic enrichment between dietary carbon and carbon from enamel apatite ( ɛD-E), as well as of the timing and duration of the enamel mineralization process (amelogenesis). To better constrain these parameters, we performed a series of controlled feeding experiments on sheep ranging in age from 6 to 24 months-old. Twenty-eight lambs and 14 ewes were fed isotopically distinct diets for different periods of time, and then slaughtered, allowing the timing and rate of molar growth to be determined. High resolution sampling and stable carbon isotope analysis of breath CO 2 performed on six individuals following a diet-switch showed that 70-90% of dietary carbon had turned over in less than 24 h. Sequential sampling and carbon isotopic analysis was performed on the first (M 1) and second (M 2) lower molars of four lambs as well as on the third lower molar (M 3) of 11 ewes. The changes in diet were recorded in all molars. We found that the length of enamel matrix apposition is approximately one-quarter of the final tooth length during crown extension, and that enamel maturation spans slightly less than 3 months in M 1, and 4 months in M 2 and M 3. Portions of enamel in equilibrium with dietary carbon were used to calculate ɛD-E values. Animals on grass silage diets had values similar to previous observations, whereas animal switched to pelleted corn diets had values ca. 4‰ lower, a pattern consistent with lower methane production observed for animals fed concentrate diets. The tooth enamel forward model of Passey and Cerling (2002) closely predicted the amplitude of isotope changes recorded in tooth enamel, but slightly underestimated the rate of isotope change, suggesting that the rate of accumulation of carbonate during maturation may not be constant over time. Although stable isotope profiles in tooth

Power adaptation for joint switched diversity and adaptive modulation schemes in spectrum sharing systems

KAUST Repository

Bouida, Zied

2012-09-01

Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using transmit power adaptation, switched transmit diversity, and adaptive modulation in order to improve the performance of existing switching efficient schemes (SES) and bandwidth efficient schemes (BES). Taking advantage of the channel reciprocity principle, we assume that the channel state information (CSI) of the interference link is available to the secondary transmitter. This information is then used by the secondary transmitter to adapt its transmit power, modulation constellation size, and used transmit branch. The goal of this joint adaptation is to minimize the average number of switched branches and the average system delay given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. We analyze the proposed scheme in terms of the average number of branch switching, average delay, and we provide a closed-form expression of the average bit error rate (BER). We demonstrate through numerical examples that the proposed scheme provides a compromise between the SES and the BES schemes. © 2012 IEEE.

Power adaptation for joint switched diversity and adaptive modulation schemes in spectrum sharing systems

KAUST Repository

Bouida, Zied; Tourki, Kamel; Ghrayeb, Ali A.; Qaraqe, Khalid A.; Alouini, Mohamed-Slim

2012-01-01

Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using transmit power adaptation, switched transmit diversity, and adaptive modulation in order to improve the performance of existing switching efficient schemes (SES) and bandwidth efficient schemes (BES). Taking advantage of the channel reciprocity principle, we assume that the channel state information (CSI) of the interference link is available to the secondary transmitter. This information is then used by the secondary transmitter to adapt its transmit power, modulation constellation size, and used transmit branch. The goal of this joint adaptation is to minimize the average number of switched branches and the average system delay given the fading channel conditions, the required error rate performance, and a peak interference constraint to the primary receiver. We analyze the proposed scheme in terms of the average number of branch switching, average delay, and we provide a closed-form expression of the average bit error rate (BER). We demonstrate through numerical examples that the proposed scheme provides a compromise between the SES and the BES schemes. © 2012 IEEE.

An open-closed-loop iterative learning control approach for nonlinear switched systems with application to freeway traffic control

Science.gov (United States)

Sun, Shu-Ting; Li, Xiao-Dong; Zhong, Ren-Xin

2017-10-01

For nonlinear switched discrete-time systems with input constraints, this paper presents an open-closed-loop iterative learning control (ILC) approach, which includes a feedforward ILC part and a feedback control part. Under a given switching rule, the mathematical induction is used to prove the convergence of ILC tracking error in each subsystem. It is demonstrated that the convergence of ILC tracking error is dependent on the feedforward control gain, but the feedback control can speed up the convergence process of ILC by a suitable selection of feedback control gain. A switched freeway traffic system is used to illustrate the effectiveness of the proposed ILC law.

High-Voltage Power Supply System for Laser Isotope Separation

Energy Technology Data Exchange (ETDEWEB)

Ketaily, E.C.; Buckner, R.P.; Uhrik, R.L.

1979-06-26

This report presents several concepts for Laser High-Voltage Power Supply (HVPS) Systems for a Laser Isotope Separation facility. Selection of equipments and their arrangement into operational systems is based on proven designs and on application concepts now being developed. This report has identified a number of alternative system arrangements and has provided preliminary cost estimates for each. The report includes a recommendation for follow-on studies that will further define the optimum Laser HVPS Systems. Brief descriptions are given of Modulator/Regulator circuit trade-offs, system control interfaces, and their impact on costs.

High-Voltage Power Supply System for Laser Isotope Separation

International Nuclear Information System (INIS)

Ketaily, E.C.; Buckner, R.P.; Uhrik, R.L.

1979-01-01

This report presents several concepts for Laser High-Voltage Power Supply (HVPS) Systems for a Laser Isotope Separation facility. Selection of equipments and their arrangement into operational systems is based on proven designs and on application concepts now being developed. This report has identified a number of alternative system arrangements and has provided preliminary cost estimates for each. The report includes a recommendation for follow-on studies that will further define the optimum Laser HVPS Systems. Brief descriptions are given of Modulator/Regulator circuit trade-offs, system control interfaces, and their impact on costs

Isotope separation in crossed-jet systems

Energy Technology Data Exchange (ETDEWEB)

Gallagher, R.J.; Anderson, J.B.

1978-11-01

The separation of isotopes in crossed-jet systems was investigated with Monte Carlo calculations of the separation effects for jets of Ne/Ar and /sup 235/UF/sub 6///sup 238/UF/sub 6/ mixtures entering a hydrogen stream. For the ideal condition of uniform stream velocities at zero temperature, the separation factor ..cap alpha.. was found to be 16.0 for Ne/Ar and 1.17 for /sup 235/UF/sub 6///sup 238/UF/sub 6/. For less ideal but more practical conditions, Monte Carlo calculations of the complete crossed-jet systems gave separation factors as high as 3.3 for Ne/Ar and ..cap alpha.. = 1.046 - 1.078 for /sup 235/UF/sub 6///sup 238/UF/sub 6/.

Gas adsorption/absorption heat switch, phase 1

Science.gov (United States)

Chan, C. K.

1987-01-01

The service life and/or reliability of far-infrared sensors on surveillance satellites is presently limited by the cryocooler. The life and/or reliability, however, can be extended by using redundant cryocoolers. To reduce parasitic heat leak, each stage of the inactive redundant cryocooler must be thermally isolated from the optical system, while each stage of the active cryocooler must be thermally connected to the system. The thermal break or the thermal contact can be controlled by heat switches. Among different physical mechanisms for heat switching, mechanically activated heat switches tend to have low reliability and, furthermore, require a large contact force. Magnetoresistive heat switches are, except at very low temperatures, of very low efficiency. Heat switches operated by the heat pipe principle usually require a long response time. A sealed gas gap heat switch operated by an adsorption pump has no mechanical motion and should provide the reliability and long lifetime required in long-term space missions. Another potential application of a heat switch is the thermal isolation of the optical plane during decontamination.

Electron linac for medical isotope production with improved energy efficiency and isotope recovery

Science.gov (United States)

Noonan, John; Walters, Dean; Virgo, Matt; Lewellen, John

2015-09-08

A method and isotope linac system are provided for producing radio-isotopes and for recovering isotopes. The isotope linac is an energy recovery linac (ERL) with an electron beam being transmitted through an isotope-producing target. The electron beam energy is recollected and re-injected into an accelerating structure. The ERL provides improved efficiency with reduced power requirements and provides improved thermal management of an isotope target and an electron-to-x-ray converter.

Mass fractionation processes of transition metal isotopes

Science.gov (United States)

Zhu, X. K.; Guo, Y.; Williams, R. J. P.; O'Nions, R. K.; Matthews, A.; Belshaw, N. S.; Canters, G. W.; de Waal, E. C.; Weser, U.; Burgess, B. K.; Salvato, B.

2002-06-01

Recent advances in mass spectrometry make it possible to utilise isotope variations of transition metals to address some important issues in solar system and biological sciences. Realisation of the potential offered by these new isotope systems however requires an adequate understanding of the factors controlling their isotope fractionation. Here we show the results of a broadly based study on copper and iron isotope fractionation during various inorganic and biological processes. These results demonstrate that: (1) naturally occurring inorganic processes can fractionate Fe isotope to a detectable level even at temperature ˜1000°C, which challenges the previous view that Fe isotope variations in natural system are unique biosignatures; (2) multiple-step equilibrium processes at low temperatures may cause large mass fractionation of transition metal isotopes even when the fractionation per single step is small; (3) oxidation-reduction is an importation controlling factor of isotope fractionation of transition metal elements with multiple valences, which opens a wide range of applications of these new isotope systems, ranging from metal-silicate fractionation in the solar system to uptake pathways of these elements in biological systems; (4) organisms incorporate lighter isotopes of transition metals preferentially, and transition metal isotope fractionation occurs stepwise along their pathways within biological systems during their uptake.

Robust Hinf control of uncertain switched systems defined on polyhedral sets with Filippov solutions

DEFF Research Database (Denmark)

Ahmadi, Mohamadreza; Mojallali, Hamed; Wisniewski, Rafal

2012-01-01

This paper considers the control problem of a class of uncertain switched systems defined on polyhedral sets known as piecewise linear systems where, instead of the conventional Carathe ́odory solutions, Filippov solutions are studied. In other words, in contrast to the previous studies, solutions...

Evolution of the Campanian Ignimbrite Magmatic System II: Trace Element and Th Isotopic Evidence for Open-System Processes

Science.gov (United States)

Bohrson, W. A.; Spera, F. J.; Fowler, S.; Belkin, H.; de Vivo, B.

2005-12-01

The Campanian Ignimbrite, a large volume (~200 km3 DRE) trachytic to phonolitic ignimbrite was deposited at ~39.3 ka and represents the largest of a number of highly explosive volcanic events in the region near Naples, Italy. Thermodynamic modeling of the major element evolution using the MELTS algorithm (see companion contribution by Fowler et al.) provides detailed information about the identity of and changes in proportions of solids along the liquid line of descent during isobaric fractional crystallization. We have derived trace element mass balance equations that explicitly accommodate changing mineral-melt bulk distribution coefficients during crystallization and also simultaneously satisfy energy and major element mass conservation. Although major element patterns are reasonably modeled assuming closed system fractional crystallization, modeling of trace elements that represent a range of behaviors (e.g. Zr, Nb, Th, U, Rb, Sm, Sr) yields trends for closed system fractionation that are distinct from those observed. These results suggest open-system processes were also important in the evolution of the Campanian magmatic system. Th isotope data yield an apparent isochron that is ~20 kyr younger than the age of the deposit, and age-corrected Th isotope data indicate that the magma body was an open-system at the time of eruption. Because open-system processes can profoundly change isotopic characteristics of a magma body, these results illustrate that it is critical to understand the contribution that open-system processes make to silicic magma bodies prior to assigning relevance to age or timescale information derived from isotope systematics. Fluid-magma interaction has been proposed as a mechanism to change isotopic and elemental characteristics of magma bodies, but an evaluation of the mass and thermal constraints on such a process suggest large-scale fluid-melt interaction at liquidus temperatures is unlikely. In the case of the magma body associated with

Robust Stability and H∞ Control of Uncertain Piecewise Linear Switched Systems with Filippov Solutions

DEFF Research Database (Denmark)

Ahmadi, Mohamadreza; Mojallali, Hamed; Wisniewski, Rafal

2012-01-01

This paper addresses the robust stability and control problem of uncertain piecewise linear switched systems where, instead of the conventional Carathe ́odory solutions, we allow for Filippov solutions. In other words, in contrast to the previous studies, solutions with infinite switching in fini...... algorithm is proposed to surmount the aforementioned matrix inequality conditions....... time along the facets and on faces of arbitrary dimensions are also taken into account. Firstly, based on earlier results, the stability problem of piecewise linear systems with Filippov solutions is translated into a number of linear matrix inequality feasibility tests. Subsequently, a set of matrix...... inequalities are brought forward, which determines the asymptotic stability of the Filippov solutions of a given uncertain piecewise linear system. Afterwards, bilinear matrix inequality conditions for synthesizing a robust controller with a guaranteed H∞ per- formance are formulated. Finally, a V-K iteration...

Temperature Control of Gas Chromatograph Based on Switched Delayed System Techniques

Directory of Open Access Journals (Sweden)

Xiao-Liang Wang

2014-01-01

Full Text Available We address the temperature control problem of the gas chromatograph. We model the temperature control system of the gas chromatograph into a switched delayed system and analyze the stability by common Lyapunov functional technique. The PI controller parameters can be given based on the proposed linear matrix inequalities (LMIs condition and the designed controller can make the temperature of gas chromatograph track the reference signal asymptotically. An experiment is given to illustrate the effectiveness of the stability criterion.

Line Capacity Expansion and Transmission Switching in Power Systems With Large-Scale Wind Power

DEFF Research Database (Denmark)

Villumsen, Jonas Christoffer; Bronmo, Geir; Philpott, Andy B.

2013-01-01

In 2020 electricity production from wind power should constitute nearly 50% of electricity demand in Denmark. In this paper we look at optimal expansion of the transmission network in order to integrate 50% wind power in the system, while minimizing total fixed investment cost and expected cost...... of power generation. We allow for active switching of transmission elements to reduce congestion effects caused by Kirchhoff's voltage law. Results show that actively switching transmission lines may yield a better utilization of transmission networks with large-scale wind power and increase wind power...

Basic concepts and formulations for isotope geochemical modelling of groundwater systems

International Nuclear Information System (INIS)

Kalin, R.M.

1996-01-01

This chapter describes the basic chemical principles and methodologies for geochemical models and their use in the field of isotope hydrology. Examples of calculation procedures are given on actual field data. Summary information on available PC software for geochemical modeling is included. The specific software, NETPATH, which can be used for chemical speciation, mass balance and isotope balance along a flow path in groundwater systems, is discussed at some length with an illustrative example of its application to field data. (author). Refs, 14 figs, 15 tabs

Basic concepts and formulations for isotope geochemical modelling of groundwater systems

Energy Technology Data Exchange (ETDEWEB)

Kalin, R M [The Queen` s University, Belfast, Northern Ireland (United Kingdom). Dept. of Civil Engineering

1996-10-01

This chapter describes the basic chemical principles and methodologies for geochemical models and their use in the field of isotope hydrology. Examples of calculation procedures are given on actual field data. Summary information on available PC software for geochemical modeling is included. The specific software, NETPATH, which can be used for chemical speciation, mass balance and isotope balance along a flow path in groundwater systems, is discussed at some length with an illustrative example of its application to field data. (author). Refs, 14 figs, 15 tabs.

Mating-type switching by chromosomal inversion in methylotrophic yeasts suggests an origin for the three-locus Saccharomyces cerevisiae system.

Science.gov (United States)

Hanson, Sara J; Byrne, Kevin P; Wolfe, Kenneth H

2014-11-11

Saccharomyces cerevisiae has a complex system for switching the mating type of haploid cells, requiring the genome to have three mating-type (MAT)-like loci and a mechanism for silencing two of them. How this system originated is unknown, because the three-locus system is present throughout the family Saccharomycetaceae, whereas species in the sister Candida clade have only one locus and do not switch. Here we show that yeasts in a third clade, the methylotrophs, have a simpler two-locus switching system based on reversible inversion of a section of chromosome with MATa genes at one end and MATalpha genes at the other end. In Hansenula polymorpha the 19-kb invertible region lies beside a centromere so that, depending on the orientation, either MATa or MATalpha is silenced by centromeric chromatin. In Pichia pastoris, the orientation of a 138-kb invertible region puts either MATa or MATalpha beside a telomere and represses transcription of MATa2 or MATalpha2. Both species are homothallic, and inversion of their MAT regions can be induced by crossing two strains of the same mating type. The three-locus system of S. cerevisiae, which uses a nonconservative mechanism to replace DNA at MAT, likely evolved from a conservative two-locus system that swapped genes between expression and nonexpression sites by inversion. The increasing complexity of the switching apparatus, with three loci, donor bias, and cell lineage tracking, can be explained by continuous selection to increase sporulation ability in young colonies. Our results provide an evolutionary context for the diversity of switching and silencing mechanisms.

CONTROL OF BOUNCING IN RF MEMS SWITCHES USING DOUBLE ELECTRODE

KAUST Repository

Abdul Rahim, Farhan

2014-01-01

MEMS based mechanical switches are seen to be the likely replacements for CMOS based switches due to the several advantages that these mechanical switches have over CMOS switches. Mechanical switches can be used in systems under extreme conditions

An analytical system for the measurement of stable hydrogen isotopes in ambient volatile organic compounds

Science.gov (United States)

Meisehen, T.; Bühler, F.; Koppmann, R.; Krebsbach, M.

2015-10-01

Stable isotope measurements in atmospheric volatile organic compounds (VOCs) are an excellent tool to analyse chemical and dynamical processes in the atmosphere. While up to now isotope studies of VOCs in ambient air have mainly focussed on carbon isotopes, we herein present a new measurement system to investigate hydrogen isotope ratios in atmospheric VOCs. This system, consisting of a gas chromatography pyrolysis isotope ratio mass spectrometer (GC-P-IRMS) and a pre-concentration system, was thoroughly characterised using a VOC test mixture. A precision of better than 9 ‰ (in δ 2H) is achieved for n-pentane, 2-methyl-1,3-butadiene (isoprene), n-heptane, 4-methyl-pentane-2-one (4-methyl-2-pentanone), methylbenzene (toluene), n-octane, ethylbenzene, m/p-xylene and 1,2,4-trimethylbenzene. A comparison with independent measurements via elemental analysis shows an accuracy of better than 9 ‰ for n-pentane, n-heptane, 4-methyl-2-pentanone, toluene and n-octane. Above a minimum required pre-concentrated compound mass the obtained δ 2H values are constant within the standard deviations. In addition, a remarkable influence of the pyrolysis process on the isotope ratios is found and discussed. Reliable measurements are only possible if the ceramic tube used for the pyrolysis is sufficiently conditioned, i.e. the inner surface is covered with a carbon layer. It is essential to verify this conditioning regularly and to renew it if required. Furthermore, influences of a necessary H3+ correction and the pyrolysis temperature on the isotope ratios are discussed. Finally, the applicability to measure hydrogen isotope ratios in VOCs at ambient levels is demonstrated with measurements of outside air on 5 different days in February and March 2015. The measured hydrogen isotope ratios range from -136 to -105 ‰ forn-pentane, from -86 to -63 ‰ for toluene, from -39 to -15 ‰ for ethylbenzene, from -99 to -68 ‰ for m/p-xylene and from -45 to -34 ‰ for o-xylene.

A manual for a Laboratory Information Management System (LIMS) for light stable isotopes

Science.gov (United States)

Coplen, Tyler B.

1998-01-01

The reliability and accuracy of isotopic data can be improved by utilizing database software to (i) store information about samples, (ii) store the results of mass spectrometric isotope-ratio analyses of samples, (iii) calculate analytical results using standardized algorithms stored in a database, (iv) normalize stable isotopic data to international scales using isotopic reference materials, and (v) generate multi-sheet paper templates for convenient sample loading of automated mass-spectrometer sample preparation manifolds. Such a database program is presented herein. Major benefits of this system include (i) an increase in laboratory efficiency, (ii) reduction in the use of paper, (iii) reduction in workload due to the elimination or reduction of retyping of data by laboratory personnel, and (iv) decreased errors in data reported to sample submitters. Such a database provides a complete record of when and how often laboratory reference materials have been analyzed and provides a record of what correction factors have been used through time. It provides an audit trail for stable isotope laboratories. Since the original publication of the manual for LIMS for Light Stable Isotopes, the isotopes 3 H, 3 He, and 14 C, and the chlorofluorocarbons (CFCs), CFC-11, CFC-12, and CFC-113, have been added to this program.

Kilowatt isotope power system, Phase II Plan. Volume IV. Teledyne FSCD vs GDS

Energy Technology Data Exchange (ETDEWEB)

1978-03-15

This Volume contains Teledyne's input to the Kilowatt Isotope Power System Phase II Plan. Included is a description of the Flight System Heat Generation System, Flight System Radiator, Thermal Insulation Stability, GDS Heat Generation System and GDS Radiator.

Optically triggered high voltage switch network and method for switching a high voltage

Science.gov (United States)

El-Sharkawi, Mohamed A.; Andexler, George; Silberkleit, Lee I.

1993-01-19

An optically triggered solid state switch and method for switching a high voltage electrical current. A plurality of solid state switches (350) are connected in series for controlling electrical current flow between a compensation capacitor (112) and ground in a reactive power compensator (50, 50') that monitors the voltage and current flowing through each of three distribution lines (52a, 52b and 52c), which are supplying three-phase power to one or more inductive loads. An optical transmitter (100) controlled by the reactive power compensation system produces light pulses that are conveyed over optical fibers (102) to a switch driver (110') that includes a plurality of series connected optical triger circuits (288). Each of the optical trigger circuits controls a pair of the solid state switches and includes a plurality of series connected resistors (294, 326, 330, and 334) that equalize or balance the potential across the plurality of trigger circuits. The trigger circuits are connected to one of the distribution lines through a trigger capacitor (340). In each switch driver, the light signals activate a phototransistor (300) so that an electrical current flows from one of the energy reservoir capacitors through a pulse transformer (306) in the trigger circuit, producing gate signals that turn on the pair of serially connected solid state switches (350).

Optically triggered high voltage switch network and method for switching a high voltage

Energy Technology Data Exchange (ETDEWEB)

El-Sharkawi, Mohamed A. (Renton, WA); Andexler, George (Everett, WA); Silberkleit, Lee I. (Mountlake Terrace, WA)

1993-01-19

An optically triggered solid state switch and method for switching a high voltage electrical current. A plurality of solid state switches (350) are connected in series for controlling electrical current flow between a compensation capacitor (112) and ground in a reactive power compensator (50, 50') that monitors the voltage and current flowing through each of three distribution lines (52a, 52b and 52c), which are supplying three-phase power to one or more inductive loads. An optical transmitter (100) controlled by the reactive power compensation system produces light pulses that are conveyed over optical fibers (102) to a switch driver (110') that includes a plurality of series connected optical triger circuits (288). Each of the optical trigger circuits controls a pair of the solid state switches and includes a plurality of series connected resistors (294, 326, 330, and 334) that equalize or balance the potential across the plurality of trigger circuits. The trigger circuits are connected to one of the distribution lines through a trigger capacitor (340). In each switch driver, the light signals activate a phototransistor (300) so that an electrical current flows from one of the energy reservoir capacitors through a pulse transformer (306) in the trigger circuit, producing gate signals that turn on the pair of serially connected solid state switches (350).

A high-switching-frequency flyback converter in resonant mode

NARCIS (Netherlands)

Li, Jianting; van Horck, Frank B.M.; Daniel, Bobby J.; Bergveld, Henk Jan

2017-01-01

The demand of miniaturization of power systems has accelerated the research on high-switching-frequency power converters. A flyback converter in resonant mode that features low switching losses, less transformer losses, and low switching noise at high switching frequency is investigated in this

Measurement of organic carbon stable isotope composition of different soil types by EA-IRMS system

International Nuclear Information System (INIS)

Qi Biao; Ding Lingling; Cui Jiehua; Wang Yanhong

2009-01-01

Element analyzer-isotope ratio mass spectrometers (EA-IRMS) is a rapid and precise method for measuring stable carbon isotope. Pure CO 2 reference gas was calibrated via international standard-Urea, and the δ 13 C us PDB value of pure CO 2 is (-29.523 ± 0.0181)%. Stability and linearity of the EA-IRMS system, precision of δ 13 C measurement for samples were tested through experimental comparison. Moreover, determination method of organic carbon stable isotope in soil was based on the system. The EA-IRMS system had well linearity when ion intensity ranged from 1.0 to 7.0V, and it excelled the total linearity when the ion intensity was from 1.5 to 5.0V, and the accurate result of δ 13 C for sample analysis could be obtained with precision of 0.015%. If carbon content in sample is more than 5μg, the requirement for analyzing accurate result of δ 13 C could be achieved. The organic carbon stable isotope was measured in 18 different types soil samples, the average natural abundance of 13 C was 1.082%, and the organic carbon stable isotope composition was significantly different among different type soils. (authors)

Methane clumped isotopes: Progress and potential for a new isotopic tracer

Energy Technology Data Exchange (ETDEWEB)

Douglas, Peter M. J.; Stolper, Daniel A.; Eiler, John M.; Sessions, Alex L.; Lawson, Michael; Shuai, Yanhua; Bishop, Andrew; Podlaha, Olaf G.; Ferreira, Alexandre A.; Santos Neto, Eugenio V.; Niemann, Martin; Steen, Arne S.; Huang, Ling; Chimiak, Laura; Valentine, David L.; Fiebig, Jens; Luhmann, Andrew J.; Seyfried, William E.; Etiope, Giuseppe; Schoell, Martin; Inskeep, William P.; Moran, James J.; Kitchen, Nami

2017-11-01

The isotopic composition of methane is of longstanding geochemical interest, with important implications for understanding hydrocarbon systems, atmospheric greenhouse gas concentrations, the global carbon cycle, and life in extreme environments. Recent analytical developments focusing on multiply substituted isotopologues (‘clumped isotopes’) are opening a potentially valuable new window into methane geochemistry. When methane forms in internal isotopic equilibrium, clumped isotopes can provide a direct record of formation temperature, making this property particularly valuable for identifying different methane origins. However, it has also become clear that in certain settings methane clumped isotope measurements record kinetic rather than equilibrium isotope effects. Here we present a substantially expanded dataset of methane clumped isotope analyses, and provide a synthesis of the current interpretive framework for this parameter. We review different processes affecting methane clumped isotope compositions, describe the relationships between conventional isotope and clumped isotope data, and summarize the types of information that this measurement can provide in different Earth and planetary environments.

Improvement on Main/backup Controller Switching Device of the Nozzle Throat Area Control System for a Turbofan Aero Engine

Science.gov (United States)

Li, Jie; Duan, Minghu; Yan, Maode; Li, Gang; Li, Xiaohui

2014-06-01

A full authority digital electronic controller (FADEC) equipped with a full authority hydro-mechanical backup controller (FAHMBC) is adopted as the nozzle throat area control system (NTACS) of a turbofan aero engine. In order to ensure the switching reliability of the main/backup controller, the nozzle throat area control switching valve was improved from three-way convex desktop slide valve to six-way convex desktop slide valve. Simulation results show that, if malfunctions of FAEDC occur and abnormal signals are outputted from FADEC, NTACS will be seriously influenced by the main/backup controller switching in several working states, while NTACS will not be influenced by using the improved nozzle throat area control switching valve, thus the controller switching process will become safer and smoother and the working reliability of this turbofan aero engine is improved by the controller switching device improvement.

Changes in hydrogen isotope ratios in sequential plumage stages: an implication for the creation of isotope-base maps for tracking migratory birds.

Science.gov (United States)

Duxbury, J M; Holroyd, G L; Muehlenbachs, K

2003-09-01

Accurate reference maps are important in the use of stable-isotopes to track the movements of migratory birds. Reference maps created by the analysis of samples collected from young at the nest site are more accurate than simply referring to naturally occurring patterns of hydrogen isotope ratios created by precipitation cycles. Ratios of hydrogen isotopes in the nutrients incorporated early in the development of young birds can be derived from endogenous, maternal sources. Base-maps should be created with the analysis of tissue samples from hatchlings after local the isotopic signature of exogenous nutrients is dominant. Migratory species such as Peregrine Falcons are known to use endogenous sources in the creation of their eggs, therefore knowledge of what plumage stage best represents the local hydrogen ratios would assist in the planning of nest visits. We conducted diet manipulation experiments involving Japanese Quail and Peregrine Falcons to determine the plumage stage when hydrogen isotope ratios were indicative of a switch in their food source. The natal down of both the quail and falcons reflected the diet of breeding adult females. The hydrogen isotope ratios of a new food source were dominant in the juvenile down of the young falcons, although a further shift was detected in the final juvenile plumage. The juvenile plumage is grown during weeks 3-4 after hatch on Peregrine Falcons. Nest visits for the purpose of collecting feathers for isotope-base-map creation should be made around 4 weeks after the presumed hatch of the young falcons.

Expert system in power distribution lines switching; Sistema especialista em manobras de redes de distribuicao de energia eletrica

Energy Technology Data Exchange (ETDEWEB)

Cavellucci, Celso

1989-07-01

This work proposes an expert system integrated to procedures of numerical computation, denominated RD and projected to suggest alternatives of switching plans in the isolation and re-establishment of power distribution lines. The switching plans are based on the specialist's knowledge (network operator) and in evaluations of the electric conditions of the switching. Specialist's knowledge is represented in the form of triples (context, attribute, value) and production rules, that are evaluated conveniently by the machine of inference of the RD system. The electric power distribution is represented by a graph model, where the knots are load blocks and the arcs are key of the system. The evaluation of the electric requirements (voltage drop and physical capacity of the components of the power distribution lines) it is obtained through a maneuver simulator (numeric computation). The maneuver simulator bases on the Method of the Moments for the calculation of the voltage drop. With base in these ideas a prototype of the RD system was developed.

Expert system in power distribution lines switching; Sistema especialista em manobras de redes de distribuicao de energia eletrica

Energy Technology Data Exchange (ETDEWEB)

Cavellucci, Celso

1989-07-01

This work proposes an expert system integrated to procedures of numerical computation, denominated RD and projected to suggest alternatives of switching plans in the isolation and re-establishment of power distribution lines. The switching plans are based on the specialist's knowledge (network operator) and in evaluations of the electric conditions of the switching. Specialist's knowledge is represented in the form of triples (context, attribute, value) and production rules, that are evaluated conveniently by the machine of inference of the RD system. The electric power distribution is represented by a graph model, where the knots are load blocks and the arcs are key of the system. The evaluation of the electric requirements (voltage drop and physical capacity of the components of the power distribution lines) it is obtained through a maneuver simulator (numeric computation). The maneuver simulator bases on the Method of the Moments for the calculation of the voltage drop. With base in these ideas a prototype of the RD system was developed.

Isotopic anomalies and the early history of the solar system

International Nuclear Information System (INIS)

Begemann, F.

1981-01-01

Three elements are discussed in some detail. Inclusions from carbonaceous chondrites contain quite normal minerals where the oxygen is enriched by up to 5% in 16 O. The oxygen is neither in isotopic equilibrium with that of the bulk meteorites nor are the different minerals of a single inclusion isotopically homogenized. The xenon in acid-insoluble residues from carbonaceous chondrites contains at least two distinct anomalous components. One consists essentially of the middle-weight isotopes only; the abundance pattern is as expected for Xe produced in the s-process of nucleosynthesis. The second type is to some extent complementary to this s-xenon; it is characterized by an overabundance of the light and the heavy isotopes by up to 100%. Its origin is controversial. Direct production in a supernova has been suggested as well as a superposition of strongly mass-fractionated xenon, favouring the light isotopes, and fission xenon from the decay of (a) superheavy element (s), which in turn would presumably have to be produced in a supernova as well. Neon being more than 99% pure 22 Ne is most convincingly accounted for by in situ-decay of 2.6a 22 Na which implies a condensation of Na-bearing host phases within 10 years or so of the production of 22 Na. It is not clear at present whether this condensation took place in the expanding envelope of an exploding star or within the solar system, with the onset of the collapse of the pre-solar nebula being triggered by such an explosion. (orig./WL)

The double switch for atrioventricular discordance.

Science.gov (United States)

Brawn, William J

2005-01-01

Conventional surgery for atrioventricular discordance usually associated with ventricular arterial discordance leaves the morphologic right ventricle in the systemic circulation. Long-term follow-up results with this approach reveal a high incidence of right ventricular failure. The double switch procedure was introduced to restore the morphologic left ventricle to the systemic circulation. This operation is performed in two main ways: the atrial-arterial switch and the atrial switch plus Rastelli procedure. This double switch approach has been successful at least in the medium term in abolishing morphologic right ventricular failure and its associated tricuspid valve regurgitation. In the atrial-arterial switch group, there is an incidence of morphologic left ventricular dysfunction, sometimes associated with neoaortic valve regurgitation, and the minority of cases need aortic valve replacement. The long-term function of the morphologic left ventricle and the aortic valve need careful surveillance in the future. The atrial-Rastelli group of patients has not in the medium term shown evidence of ventricular dysfunction but will require change on a regular basis of their ventricular to pulmonary artery valved conduits.

Concave switching in single-hop and multihop networks

NARCIS (Netherlands)

Walton, N.

2015-01-01

Switched queueing networks model wireless networks, input-queued switches, and numerous other networked communications systems. We consider an (\\(\\alpha ,g\\))-switch policy; these policies provide a generalization of the MaxWeight policies of Tassiulas and Ephremides (IEEE Trans Autom Control

Consensus of Fractional-Order Multiagent Systems with Double Integrator under Switching Topologies

Directory of Open Access Journals (Sweden)

Shiyun Shen

2017-01-01

Full Text Available Due to the complexity of the practical environments, many systems can only be described with the fractional-order dynamics. In this paper, the consensus of fractional-order multiagent systems with double integrator under switching topologies is investigated. By applying Mittag-Leffler function, Laplace transform, and dwell time technique, a sufficient condition on consensus is obtained. Finally, a numerical simulation is presented to illustrate the effectiveness of the theoretical result.

Some characteristics of isotopic separation laser systems

International Nuclear Information System (INIS)

Pochon, E.

1988-01-01

The principle of Laser Isotope Separation (LIS) is simple and based on either selective electronic photoexcitation and photoionization of atomic vapor, or selective vibrational photoexcitation and photodissociation of molecules in the gas phase. These processes, respectively called SILVA (AVLIS) and SILMO (MLIS) in France, both use specific laser systems with wavelengths spanning from infrared to ultraviolet. This article describes briefly some of the characteristics of a SILVA laser system. Following a three-step process, a SILVA laser system is based on dye copper vapor lasers. The pulse dye lasers provide the tunable laser light and are optically pumped by copper vapor laser operating at high repetition rates. In order to meet plant laser system requirements, the main improvements under way relate to copper vapor laser devices the power capability, efficiency, reliability and lifetime of which have to be increased. 1 fig

Method for separating isotopes

International Nuclear Information System (INIS)

Jepson, B.E.

1976-01-01

The invention comprises a method for separating different isotopes of elements from each other by contacting a feed solution containing the different isotopes with a macrocyclic polyether to preferentially form a macrocyclic polyether complex with the lighter of the different isotopes. The macrocyclic polyether complex is then separated from the lighter isotope depleted feed solution. A chemical separation of isotopes is carried out in which a constant refluxing system permits a continuous countercurrent liquid-liquid extraction. (LL)

Non-fragile switched H∞ control for morphing aircraft with asynchronous switching

Directory of Open Access Journals (Sweden)

Haoyu CHENG

2017-06-01

Full Text Available This paper deals with the problem of non-fragile linear parameter-varying (LPV H∞ control for morphing aircraft with asynchronous switching. The switched LPV model of morphing aircraft is established by Jacobian linearization approach according to the nonlinear model. The data missing is taken into account in the link from sensors to controllers and the link from controllers to actuators, which satisfies Bernoulli distribution. The non-fragile switched LPV controllers are constructed with consideration of the uncertainties of controllers and asynchronous switching phenomenon. The parameter-dependent Lyapunov functional method and mode-dependent average dwell time (MDADT method are combined to guarantee the stability and prescribed performance of the system. The sufficient conditions on the solvability of the problem are derived in the form of linear matrix inequalities (LMI. In order to achieve higher efficiency of the designing process, an algorithm is applied to divide the whole set into subsets automatically. Simulation results are provided to verify the effectiveness and superiority of the method in the paper.

Magnesium isotope compositions of Solar System materials determined by double spiking

Science.gov (United States)

Hin, R.; Lai, Y. J.; Coath, C.; Elliott, T.

2015-12-01

As a major element, magnesium is of interest for investigating large scale processes governing the formation and evolution of rocky planetary bodies. Determining the Mg isotope composition of the Earth and other planetary bodies has hence been a topic of interest ever since mass-dependent fractionation of 'non-traditional' stable isotopes has been used to study high-temperature processes. Published results, however, suffer from disagreement on the Mg isotope compositions of the Earth and chondrites [1-5], which is attributed to residual matrix effects. Nonetheless, most recent studied have converged towards a homogeneous (chondritic) Mg isotope composition in the Solar System [2-5]. However, in several of the recent studies there is a hint of a systematic difference of about 0.02-0.06‰ in the 26Mg/24Mg isotope compositions of chondrites and Earth. Such difference, however, is only resolvable by taking standard errors, which assumes robust data for homogenous sample sets. The discrepancies between various studies unfortunately undermine the confidence in such robustness and homogeneity. The issues with matrix effects during isotopic analyses can be overcome by using a double spike approach. Such methodology generally requires three isotope ratios to solve for three unknowns, a requirement that cannot be met for Mg. However, using a newly developed approach, we present Mg isotope compositions obtained by critical mixture double spiking. This new approach should allow greater confidence in the robustness of the data and hence enable improvement of. Preliminary data indicate that chondrites have a resolvable ~0.04‰ lighter 26Mg/24Mg than (ultra)mafic rocks from Earth, Mars and the eucrite parent body, which appear indistinguishable from each other. It seems implausible that this difference is caused by magmatic process such as partial melting or crystallisation. More likely, Mg isotopes are fractionated by a non-magmatic process during the formation of planets, e

Mobile medium-voltage switching system. Temporary standby power supply in record time; Mobile Mittelspannungsschaltanlage. Vorlaeufige Wiederversorgung in Rekordzeit

Energy Technology Data Exchange (ETDEWEB)

Thiery, Matthias; Schwarz, Stefan [Siemens AG, Mannheim (Germany); Wingerter, Dieter [BASF SE, Ludwigshafen (Germany); Doering, Holger [B. Goebel und Sohn GmbH, Asschaffenburg (Germany). Fahrzeugbau

2011-02-28

BASF SE Ludwigshafen operates more than 100 medium-voltage switching stations for power supply to its plants. The complexity of the production plants and production method make it necessary to have immediate standby power supply in case of interruption of a medium-voltage switching station. For this purpose, a transportable emergency container was acquired that contains a medium-voltage switching system. Power can be supplied at very short notice, simply by plugging the necessary cable connections. No cranes or other tools are required for installation. The emergency container is designed for use at varying voltage levels and can be transported by road to other BASF sites in Europe. The switching station is a gas-insulated medium-voltage switching station 8DA10 by Siemens, designed for operating voltages of 6, 10, 20, and 35 kW.

A 15N-poor isotopic composition for the solar system as shown by Genesis solar wind samples.

Science.gov (United States)

Marty, B; Chaussidon, M; Wiens, R C; Jurewicz, A J G; Burnett, D S

2011-06-24

The Genesis mission sampled solar wind ions to document the elemental and isotopic compositions of the Sun and, by inference, of the protosolar nebula. Nitrogen was a key target element because the extent and origin of its isotopic variations in solar system materials remain unknown. Isotopic analysis of a Genesis Solar Wind Concentrator target material shows that implanted solar wind nitrogen has a (15)N/(14)N ratio of 2.18 ± 0.02 × 10(-3) (that is, ≈40% poorer in (15)N relative to terrestrial atmosphere). The (15)N/(14)N ratio of the protosolar nebula was 2.27 ± 0.03 × 10(-3), which is the lowest (15)N/(14)N ratio known for solar system objects. This result demonstrates the extreme nitrogen isotopic heterogeneity of the nascent solar system and accounts for the (15)N-depleted components observed in solar system reservoirs.

Radiation gradient isotope separator

International Nuclear Information System (INIS)

Hughes, J.L.

1980-01-01

A system is described for transporting, separating and storing charged particles, charged antiparticles and fully or partially ionized isotopes of any element comprising a laser beam generator, laser beam intensity profiler, a laser beam variable intensity attenuator, and means for injecting charged particles, charged antiparticles and ionized isotopes into the beam and extracting them from the system as required. The invention is particularly useful for channelling electrons and ions used for fuel pellet compression in inertial fusion systems, for separating the isotopes of elements and for the confinement of charged antiparticles and particle/antiparticle plasmas

a Method for Preview Vibration Control of Systems Having Forcing Inputs and Rapidly-Switched Dampers

Science.gov (United States)

ElBeheiry, E. M.

1998-07-01

In a variety of applications, especially in large scale dynamic systems, the mechanization of different vibration control elements in different locations would be decided by limitations placed on the modal vibration of the system and the inherent dynamic coupling between its modes. Also, the quality of vibration control to the economy of producing the whole system would be another trade-off leading to a mix of passive, active and semi-active vibration control elements in one system. This termactiveis limited to externally powered vibration control inputs and the termsemi-activeis limited to rapidly switched dampers. In this article, an optimal preview control method is developed for application to dynamic systems having active and semi-active vibration control elements mechanized at different locations in one system. The system is then a piecewise (bilinear) controller in which two independent sets of control inputs appear additively and multiplicatively. Calculus of variations along with the Hamiltonian approach are employed for the derivation of this method. In essence, it requires the active elements to be ideal force generators and the switched dampers to have the property of on-line variation of the damping characteristics to pre-determined limits. As the dampers switch during operation the whole system's structure differs, and then values of the active forcing inputs are adapted to match these rapid changes. Strictly speaking, each rapidly switched damper has pre-known upper and lower damping levels and it can take on any in-between value. This in-between value is to be determined by the method as long as the damper tracks a pre-known fully active control demand. In every damping state of each semi-active damper the method provides the optimal matching values of the active forcing inputs. The method is shown to have the feature of solving simple standard matrix equations to obtain closed form solutions. A comprehensive 9-DOF tractor semi-trailer model is used

A genetic bistable switch utilizing nonlinear protein degradation.

Science.gov (United States)

Huang, Daniel; Holtz, William J; Maharbiz, Michel M

2012-07-09

Bistability is a fundamental property in engineered and natural systems, conferring the ability to switch and retain states. Synthetic bistable switches in prokaryotes have mainly utilized transcriptional components in their construction. Using both transcriptional and enzymatic components, creating a hybrid system, allows for wider bistable parameter ranges in a circuit. In this paper, we demonstrate a tunable family of hybrid bistable switches in E. coli using both transcriptional components and an enzymatic component. The design contains two linked positive feedback loops. The first loop utilizes the lambda repressor, CI, and the second positive feedback loop incorporates the Lon protease found in Mesoplasma florum (mf-Lon). We experimentally tested for bistable behavior in exponential growth phase, and found that our hybrid bistable switch was able to retain its state in the absence of an input signal throughout 40 cycles of cell division. We also tested the transient behavior of our switch and found that switching speeds can be tuned by changing the expression rate of mf-Lon. To our knowledge, this work demonstrates the first use of dynamic expression of an orthogonal and heterologous protease to tune a nonlinear protein degradation circuit. The hybrid switch is potentially a more robust and tunable topology for use in prokaryotic systems.

Low-photon-number optical switch and AND/OR logic gates based on quantum dot-bimodal cavity coupling system.

Science.gov (United States)

Ma, Shen; Ye, Han; Yu, Zhong-Yuan; Zhang, Wen; Peng, Yi-Wei; Cheng, Xiang; Liu, Yu-Min

2016-01-11

We propose a new scheme based on quantum dot-bimodal cavity coupling system to realize all-optical switch and logic gates in low-photon-number regime. Suppression of mode transmission due to the destructive interference effect is theoretically demonstrated by driving the cavity with two orthogonally polarized pulsed lasers at certain pulse delay. The transmitted mode can be selected by designing laser pulse sequence. The optical switch with high on-off ratio emerges when considering one driving laser as the control. Moreover, the AND/OR logic gates based on photon polarization are achieved by cascading the coupling system. Both proposed optical switch and logic gates work well in ultra-low energy magnitude. Our work may enable various applications of all-optical computing and quantum information processing.

ICT: isotope correction toolbox.

Science.gov (United States)

Jungreuthmayer, Christian; Neubauer, Stefan; Mairinger, Teresa; Zanghellini, Jürgen; Hann, Stephan

2016-01-01

Isotope tracer experiments are an invaluable technique to analyze and study the metabolism of biological systems. However, isotope labeling experiments are often affected by naturally abundant isotopes especially in cases where mass spectrometric methods make use of derivatization. The correction of these additive interferences--in particular for complex isotopic systems--is numerically challenging and still an emerging field of research. When positional information is generated via collision-induced dissociation, even more complex calculations for isotopic interference correction are necessary. So far, no freely available tools can handle tandem mass spectrometry data. We present isotope correction toolbox, a program that corrects tandem mass isotopomer data from tandem mass spectrometry experiments. Isotope correction toolbox is written in the multi-platform programming language Perl and, therefore, can be used on all commonly available computer platforms. Source code and documentation can be freely obtained under the Artistic License or the GNU General Public License from: https://github.com/jungreuc/isotope_correction_toolbox/ {christian.jungreuthmayer@boku.ac.at,juergen.zanghellini@boku.ac.at} Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Biotin Switch Assays for Quantitation of Reversible Cysteine Oxidation.

Science.gov (United States)

Li, R; Kast, J

2017-01-01

Thiol groups in protein cysteine residues can be subjected to different oxidative modifications by reactive oxygen/nitrogen species. Reversible cysteine oxidation, including S-nitrosylation, S-sulfenylation, S-glutathionylation, and disulfide formation, modulate multiple biological functions, such as enzyme catalysis, antioxidant, and other signaling pathways. However, the biological relevance of reversible cysteine oxidation is typically underestimated, in part due to the low abundance and high reactivity of some of these modifications, and the lack of methods to enrich and quantify them. To facilitate future research efforts, this chapter describes detailed procedures to target the different modifications using mass spectrometry-based biotin switch assays. By switching the modification of interest to a biotin moiety, these assays leverage the high affinity between biotin and avidin to enrich the modification. The use of stable isotope labeling and a range of selective reducing agents facilitate the quantitation of individual as well as total reversible cysteine oxidation. The biotin switch assay has been widely applied to the quantitative analysis of S-nitrosylation in different disease models and is now also emerging as a valuable research tool for other oxidative cysteine modifications, highlighting its relevance as a versatile, robust strategy for carrying out in-depth studies in redox proteomics. © 2017 Elsevier Inc. All rights reserved.

Stable isotopes in mid-ocean ridge hydrothermal systems: Interactions between fluids, minerals, and organisms

Science.gov (United States)

Shanks, W. C., III; Böhlke, J. K.; Seal, R. R., II

Studies of abundance variations of light stable isotopes in nature have had a tremendous impact on all aspects of geochemistry since the development, in 1947, of a gas source isotope ratio mass spectrometer capable of measuring small variations in stable isotope ratios [Nier, 1947] Stable isotope geochemistry is now a mature field, as witnessed by the proliferation of commercially available mass spectrometers installed at virtually every major academic, government, and private-sector research geochemistry laboratory. A recent search of a literature database revealed over 3,000 articles that utilized stable isotope geochemistry over the last 20 years. Nonetheless, many exciting new technical developments are leading to exciting new discoveries and applications. In particular, micro analytical techniques involving new generations of laser- and ion-microprobes are revolutionizing the types of analyses that can be done on spot sizes as small as a few tens of micrometers [Shanks and Criss, 1989]. New generations of conventional gas source and thermal ionization mass spectrometers, with high levels of automation and increased sensitivity and precision, are allowing analyses of large numbers of samples, like those needed for stable isotope stratigraphy in marine sediments, and are enabling the development and application of new isotopic systems.

Toward a simple, repeatable, non-destructive approach to measuring stable-isotope ratios of water within tree stems

Science.gov (United States)

Raulerson, S.; Volkmann, T.; Pangle, L. A.

2017-12-01

Traditional methodologies for measuring ratios of stable isotopes within the xylem water of trees involve destructive coring of the stem. A recent approach involves permanently installed probes within the stem, and an on-site assembly of pumps, switching valves, gas lines, and climate-controlled structure for field deployment of a laser spectrometer. The former method limits the possible temporal resolution of sampling, and sample size, while the latter may not be feasible for many research groups. We present results from initial laboratory efforts towards developing a non-destructive, temporally-resolved technique for measuring stable isotope ratios within the xylem flow of trees. Researchers have used direct liquid-vapor equilibration as a method to measure isotope ratios of the water in soil pores. Typically, this is done by placing soil samples in a fixed container, and allowing the liquid water within the soil to come into isotopic equilibrium with the headspace of the container. Water can also be removed via cryogenic distillation or azeotropic distillation, with the resulting liquid tested for isotope ratios. Alternatively, the isotope ratios of the water vapor can be directly measured using a laser-based water vapor isotope analyzer. Well-established fractionation factors and the isotope ratios in the vapor phase are then used to calculate the isotope ratios in the liquid phase. We propose a setup which would install a single, removable chamber onto a tree, where vapor samples could non-destructively and repeatedly be taken. These vapor samples will be injected into a laser-based isotope analyzer by a recirculating gas conveyance system. A major part of what is presented here is in the procedure of taking vapor samples at 100% relative humidity, appropriately diluting them with completely dry N2 calibration gas, and injecting them into the gas conveyance system without inducing fractionation in the process. This methodology will be helpful in making

A high volume sampling system for isotope determination of volatile halocarbons and hydrocarbons

Directory of Open Access Journals (Sweden)

E. Bahlmann

2011-10-01

Full Text Available The isotopic composition of volatile organic compounds (VOCs can provide valuable information on their sources and fate not deducible from mixing ratios alone. In particular the reported carbon stable isotope ratios of chloromethane and bromomethane from different sources cover a δ¹³C-range of almost 100‰ making isotope ratios a very promising tool for studying the biogeochemistry of these compounds. So far, the determination of the isotopic composition of C₁ and C₂ halocarbons others than chloromethane is hampered by their low mixing ratios.

In order to determine the carbon isotopic composition of C₁ and C₂ halocarbons with mixing ratios as low as 1 pptv (i a field suitable cryogenic high volume sampling system and (ii a chromatographic set up for processing these samples have been developed and validated. The sampling system was tested at two different sampling sites, an urban and a coastal location in Northern Germany. The average δ¹³C-values for bromomethane at the urban site were −42.9 ± 1.1‰ and agreed well with previously published results. But at the coastal site bromomethane was substantially enriched in ¹³C by almost 10‰. Less pronounced differences were observed for chlorodifluoromethane, 1,1,1-trichloroethane and chloromethane. We suggest that these differences are related to the turnover of these compounds in ocean surface waters. Furthermore we report first carbon isotope ratios for iodomethane (−40.4‰ to −79.8‰, bromoform (−13.8‰ to 22.9‰, and other halocarbons.

Automatic measurement system for light element isotope analysis

International Nuclear Information System (INIS)

Satake, Hiroshi; Ikegami, Kouichi.

1990-01-01

The automatic measurement system for the light element isotope analysis was developed by installing the specially designed inlet system which was controlled by a computer. The microcomputer system contains specific interface boards for the inlet system and the mass spectrometer, Micromass 602 E. All the components of the inlet and the computer system installed are easily available in Japan. Ten samples can be automatically measured as a maximum of. About 160 minutes are required for 10 measurements of δ 18 O values of CO 2 . Thus four samples can be measured per an hour using this system, while usually three samples for an hour using the manual operation. The automatized analysis system clearly has an advantage over the conventional method. This paper describes the details of this automated system, such as apparatuses used, the control procedure and the correction for reliable measurement. (author)

Soft switching resonant converter with duty-cycle control in DC micro-grid system

Science.gov (United States)

Lin, Bor-Ren

2018-01-01

Resonant converter has been widely used for the benefits of low switching losses and high circuit efficiency. However, the wide frequency variation is the main drawback of resonant converter. This paper studies a new modular resonant converter with duty-cycle control to overcome this problem and realise the advantages of low switching losses, no reverse recovery current loss, balance input split voltages and constant frequency operation for medium voltage direct currentgrid or system network. Series full-bridge (FB) converters are used in the studied circuit in order to reduce the voltage stresses and power rating on power semiconductors. Flying capacitor is used between two FB converters to balance input split voltages. Two circuit modules are paralleled on the secondary side to lessen the current rating of rectifier diodes and the size of magnetic components. The resonant tank is operated at inductive load circuit to help power switches to be turned on at zero voltage with wide load range. The pulse-width modulation scheme is used to regulate output voltage. Experimental verifications are provided to show the performance of the proposed circuit.

Infrastructure for thulium-170 isotope power systems for autonomous underwater vehicle fleets

International Nuclear Information System (INIS)

Walter, C.E.

1991-07-01

The radioisotope thulium-170 is a safe and environmentally benign heat source for providing the high endurance and energy densities needed by advanced power systems for autonomous underwater vehicles (AUV). Thulium Isotope Power (TIP) systems have an endurance of ∼3000 h, and gravimetric and volumetric energy densities of 3 x 10 4 Wh/kg and 3 x 10 8 Wh/m 3 , respectively. These energy densities are more than 200 times higher than those currently provided by Ag-Zn battery technology. In order to capitalize on these performance levels with about one hundred AUVs in continuous use, it will be necessary to establish an infrastructure for isotope production and heat-source refurbishment. The infrastructure cost is not trivial, and studies are needed to determine its optimum configuration. The major component of the projected infrastructure is the nuclear reactor used to produce Tm- 170 by neutron absorption in Tm-169. The reactor design should ideally be optimized for TM-170 production. Using the byproduct ''waste'' heat beneficially would help defray the cost of isotope production. However, generating electric power with the reactor would compromise both the cost of electricity and the isotope production capacity. A coastal location for the reactor would be most convenient from end-use considerations, and the ''waste'' heat could be used to desalinate seawater in water-thirsty states. 13 refs., 6 figs., 2 tabs

The design of an isotope separation system for JET

International Nuclear Information System (INIS)

Sherman, R.H.

1987-10-01

Cryogenic distillation is planned as one of the processes to be used for isotope separation at JET. Three possible configurations of columns for this service are presented and discussed. The ability to easily control a system of columns must weigh heavily in the final selection of a process for construction. 5 refs., 6 figs., 6 tabs

Aspects regarding at 13C isotope separation column control using Petri nets system

International Nuclear Information System (INIS)

Boca, M L; Ciortea, M E

2015-01-01

This paper is intended to show that Petri nets can be also applicable in the chemical industry. It used linear programming, modeling underlying Petri nets, especially discrete event systems for isotopic separation, the purpose of considering and control events in real-time through graphical representations. In this paper it is simulate the control of 13 C Isotope Separation column using Petri nets. The major problem with 13 C comes from the difficulty of obtaining it and raising its natural fraction. Carbon isotopes can be obtained using many methods, one of them being the cryogenic distillation of carbon monoxide. Some few aspects regarding operating conditions and the construction of such cryogenic plants are known today, and even less information are available as far as the separation process modeling and control are concerned. In fact, the efficient control of the carbon monoxide distillation process represents a necessity for large-scale 13 C production. Referring to a classic distillation process, some models for carbon isotope separation have been proposed, some based on mass, component and energy balance equations, some on the nonlinear wave theory or the Cohen equations. For modeling the system it was used Petri nets because in this case it is deal with discrete event systems. In use of the non-timed and with auxiliary times Petri model, the transport stream was divided into sections and these sections will be analyzed successively. Because of the complexity of the system and the large amount of calculations required it was not possible to analyze the system as a unitary whole. A first attempt to model the system as a unitary whole led to the blocking of the model during simulation, because of the large processing times. (paper)

On-Chip Fluorescence Switching System for Constructing a Rewritable Random Access Data Storage Device.

Science.gov (United States)

Nguyen, Hoang Hiep; Park, Jeho; Hwang, Seungwoo; Kwon, Oh Seok; Lee, Chang-Soo; Shin, Yong-Beom; Ha, Tai Hwan; Kim, Moonil

2018-01-10

We report the development of on-chip fluorescence switching system based on DNA strand displacement and DNA hybridization for the construction of a rewritable and randomly accessible data storage device. In this study, the feasibility and potential effectiveness of our proposed system was evaluated with a series of wet experiments involving 40 bits (5 bytes) of data encoding a 5-charactered text (KRIBB). Also, a flexible data rewriting function was achieved by converting fluorescence signals between "ON" and "OFF" through DNA strand displacement and hybridization events. In addition, the proposed system was successfully validated on a microfluidic chip which could further facilitate the encoding and decoding process of data. To the best of our knowledge, this is the first report on the use of DNA hybridization and DNA strand displacement in the field of data storage devices. Taken together, our results demonstrated that DNA-based fluorescence switching could be applicable to construct a rewritable and randomly accessible data storage device through controllable DNA manipulations.

Isotopic hydrological studies carried out on the Karst water system

International Nuclear Information System (INIS)

Longinelli, A.

1988-03-01

The isotopic composition and temperature of many karst springs in the area of Trieste (Italy) have been measured for about three and a half years. During the same period the isotopic composition of precipitation has also been systematically studied. The isotopic composition of springs generally shows variations which are markedly shifted in time with respect to those of precipitation. In most of the springs the heavy isotope contents of winter samples are the highest of the whole year. On the contrary, summer samples normally show quite negative δ-values, the most negative of which often refer to the last summer months. The data obtained are explained in terms of variable mixing of waters from two main reservoirs. The less negative reservoir (in terms of δ) is recharged by ''local'' meteoric waters falling on the westernmost section of the karst area whose mean elevation is about 400 m a.s.l. The most negative reservoir is probably recharged by meteoric waters falling on the Slovenian section of the karst, whose mean elevation is about 800-900 m a.s.l. At least in the case of some of the northernmost karst springs, it is likely that a third water system, basically fed by the Isonzo river, flowing north of the karst area, could interfere with the previously mentioned reservoirs, partially controlling the outflow of some springs. 6 figs

Isotopic hydrodynamic of the aquifer systems Jaruco and Aguacate, Cuba

International Nuclear Information System (INIS)

Moleiro Leon, L.F.; Guerra Oliva, M.G.; Maloszewski, P.; Arellano Acosta, D.M.

2002-01-01

An isotopic dispersive model is applied to the Jaruco and Aguacate karstic groundwater basins of Western Cuba. The best fit of the model was validated with stable ( 18 O and 2 H ) and radioactive ( 3 H) isotopes. Modeling showed an aquifer stratification in two basic levels with turnover times of three month to upper level and close to 100 years to the lower level. The last one mainly supplies the base flow of the Ojo de agua and Bello springs and therefore, controls the dry season exploitation yields of the aqueducts of El Gato and Bello. Model results introduces an important constraint in the exploitation of groundwater resource of both aquifer systems

Electric Drive Discrete Control System with Automatic Switching-On Reserve for Autonomous Settlement

Directory of Open Access Journals (Sweden)

Tsytovich L.I.

2015-08-01

Full Text Available The paper aims at developing of control the water supply system’s electric drives for autonomous settlement. The system provides automatic switching to a reserve control channel at refusal of any of the functional elements of the working regulation channel. Usually, such systems have a test signal generator and analyzer to system response to their impact. This result to an increase in the structural redundancy of the system, increase its cost and increase the requirements for the staff qualification. A specific feature of the system is its ability to self-diagnosis of catastrophic malfunctions of scheme’s components and an automatic switching-on the reserve control channels, without applying any test signals to the whole complex of electrical equipment. Multi-zone integrating regulator with frequency-pulse-width modulation realizes this technical solution. Control system structure and signals timing diagrams are presented. The construction principle of adaptive interval-code synchronization device with improved noise stability to control the voltage regulators serving for smooth start-up of asynchronous motors of water pumps is considered as well. Such solution allowing increase noise stability and reliability work of the system in conditions of limited power electrical networks, which is characteristic for the autonomous settlements. The article may be of interest to specialists in the field of power electronics and information electronics, electric drives and process automation.

ICP-MS as the method of the determination of gallium, indium and thallium isotope ratios in the studies of isotope effects in the chromatography systems

International Nuclear Information System (INIS)

Herdzik, I.

2006-01-01

The procedure of the determination of gallium, indium and thallium isotope ratios and its application to the studies of the isotope effects in chromatography systems by the ICP-MS method (inductively coupled plasma-mass spectrometry) are presented. It was shown that it is possible to determine the isotope ratios of gallium ( 69/71 Ga), indium ( 113/115 In) and thallium ( 203/205 Tl) with the relative standard deviation 0.03-0.07%. Such precision appeared to be sufficient to calculate the unit separation factors in the column chromatographic processes. (author) [pl

Asynchronous anti-noise hyper chaotic secure communication system based on dynamic delay and state variables switching

Energy Technology Data Exchange (ETDEWEB)

Liu, Hongjun [Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China); Weifang Vocational College, Weifang 261041 (China); Wang, Xingyuan, E-mail: wangxy@dlut.edu.cn [Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China); Zhu, Quanlong [Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, Dalian 116024 (China)

2011-07-18

This Letter designs an asynchronous hyper chaotic secure communication system, which possesses high stability against noise, using dynamic delay and state variables switching to ensure the high security. The relationship between the bit error ratio (BER) and the signal-to-noise ratio (SNR) is analyzed by simulation tests, the results show that the BER can be ensured to reach zero by proportionally adjusting the amplitudes of the state variables and the noise figure. The modules of the transmitter and receiver are implemented, and numerical simulations demonstrate the effectiveness of the system. -- Highlights: → Asynchronous anti-noise hyper chaotic secure communication system. → Dynamic delay and state switching to ensure the high security. → BER can reach zero by adjusting the amplitudes of state variables and noise figure.

Design of a Command-Triggered Plasma Opening Switch for Terawatt Applications

International Nuclear Information System (INIS)

Savage, Mark E.; Mendel, C.W.; Seidel, David B.

1999-01-01

Inductive energy storage systems can have high energy density, lending to smaller, less expensive systems. The crucial element of an inductive energy storage system is the opening switch. This switch must conduct current while energy is stored in an inductor, then open quickly to transfer this energy to a load. Plasma can perform this function. The Plasma Opening Switch (POS) has been studied for more than two decades. Success with the conventional plasma opening switch has been limited. A system designed to significantly improve the performance of vacuum opening switches is described in this paper. The gap cleared of plasma is a rough figure-of-merit for vacuum opening switches. Typical opened gaps of 3 mm are reported for conventional switches. The goal for the system described in this paper is more than 3 cm. To achieve this, the command-triggered POS adds an active opening mechanism, which allows complete separation of conduction and opening. This separation is advantageous because of the widely different time scales of conduction and opening. The detrimental process of magnetic field penetration into the plasma during conduction is less important in this switch. The opening mechanism duration is much shorter than the conduction time, so penetration during opening is insignificant. Opening is accomplished with a fast magnetic field that pushes plasma out of the switch region. Plasma must be removed from the switch region to allow high voltage. This paper describes some processes important during conduction and opening, and show calculations on the trigger requirements. The design of the switch is shown. This system is designed to demonstrate both improved performance and nanosecond output jitter at levels greater than one terawatt. An amplification mechanism is described which reduces the trigger energy. Particle-in-cell simulations of the system are also shown

Development of SWITCH-Hawaii model: loads and renewable resources.

Science.gov (United States)

2016-08-01

This report summarizes work done to configure the SWITCH power system model using data for the Oahu power system. SWITCH is a planning model designed to choose optimal infrastructure investments for power systems over a multi-decade period. Investmen...

Pulsed laser triggered high speed microfluidic switch

Science.gov (United States)

Wu, Ting-Hsiang; Gao, Lanyu; Chen, Yue; Wei, Kenneth; Chiou, Pei-Yu

2008-10-01

We report a high-speed microfluidic switch capable of achieving a switching time of 10 μs. The switching mechanism is realized by exciting dynamic vapor bubbles with focused laser pulses in a microfluidic polydimethylsiloxane (PDMS) channel. The bubble expansion deforms the elastic PDMS channel wall and squeezes the adjacent sample channel to control its fluid and particle flows as captured by the time-resolved imaging system. A switching of polystyrene microspheres in a Y-shaped channel has also been demonstrated. This ultrafast laser triggered switching mechanism has the potential to advance the sorting speed of state-of-the-art microscale fluorescence activated cell sorting devices.

NATO Advanced Research Workshop on Optical Switching in Low-Dimensional Systems

CERN Document Server

Bányai, L

1989-01-01

This book contains all the papers presented at the NATO workshop on "Optical Switching in Low Dimensional Systems" held in Marbella, Spain from October 6th to 8th, 1988. Optical switching is a basic function for optical data processing, which is of technological interest because of its potential parallelism and its potential speed. Semiconductors which exhibit resonance enhanced optical nonlinearities in the frequency range close to the band edge are the most intensively studied materials for optical bistability and fast gate operation. Modern crystal growth techniques, particularly molecular beam epitaxy, allow the manufacture of semiconductor microstructures such as quantum wells, quantum wires and quantum dots in which the electrons are only free to move in two, one or zero dimensions, of the optically excited electron-hole pairs in these low respectively. The spatial confinement dimensional structures gives rise to an enhancement of the excitonic nonlinearities. Furthermore, the variations of the microstr...

Strategy evolution driven by switching probabilities in structured multi-agent systems

Science.gov (United States)

Zhang, Jianlei; Chen, Zengqiang; Li, Zhiqi

2017-10-01

Evolutionary mechanism driving the commonly seen cooperation among unrelated individuals is puzzling. Related models for evolutionary games on graphs traditionally assume that players imitate their successful neighbours with higher benefits. Notably, an implicit assumption here is that players are always able to acquire the required pay-off information. To relax this restrictive assumption, a contact-based model has been proposed, where switching probabilities between strategies drive the strategy evolution. However, the explicit and quantified relation between a player's switching probability for her strategies and the number of her neighbours remains unknown. This is especially a key point in heterogeneously structured system, where players may differ in the numbers of their neighbours. Focusing on this, here we present an augmented model by introducing an attenuation coefficient and evaluate its influence on the evolution dynamics. Results show that the individual influence on others is negatively correlated with the contact numbers specified by the network topologies. Results further provide the conditions under which the coexisting strategies can be calculated analytically.

Stable isotope studies of some low enthalpy geothermal systems in Kenya

Science.gov (United States)

Tole, Mwakio P.

Oxygen and hydrogen isotope compositions of some low enthalpy geothermal systems in Kenya have been determined. Plots on δ 18O versus δD diagrams show that the compositions do not deviate appreciably from local meteoric water values. This would indicate that local meteoric waters are heated at depth and rise to the surface without much interaction with the country rocks. This is interpreted to be the case for the geothermal systems at Majimoto and Narosura, which have salinities of less than 350 ppm TDS and calculated reservoir temperatures of less than 110°C. The geothermal systems at Kapedo and Homa mountain which have high salinities (> 2 000 ppm TDS) and relatively higher calculated reservoir temperatures (> 150° C) are interpreted to have been operating for long periods of time, such that the rocks through which the present day geothermal waters are circulating have attained isotopic equilibrium with local meteoric waters.

Trophic niche of squids: Insights from isotopic data in marine systems worldwide

Science.gov (United States)

Navarro, Joan; Coll, Marta; Somes, Christoper J.; Olson, Robert J.

2013-10-01

Cephalopods are an important prey resource for fishes, seabirds, and marine mammals, and are also voracious predators on crustaceans, fishes, squid and zooplankton. Because of their high feeding rates and abundance, squids have the potential to exert control on the recruitment of commercially important fishes. In this review, we synthesize the available information for two intrinsic markers (δ15N and δ13C isotopic values) in squids for all oceans and several types of ecosystems to obtain a global view of the trophic niches of squids in marine ecosystems. In particular, we aimed to examine whether the trophic positions and trophic widths of squid species vary among oceans and ecosystem types. To correctly compare across systems, we adjusted squid δ15N values for the isotopic variability of phytoplankton at the base of the food web provided by an ocean circulation-biogeochemistry-isotope model. Studies that focused on the trophic ecology of squids using isotopic techniques were few, and most of the information on squids was from studies on their predators. Our results showed that squids occupy a large range of trophic positions and exploit a large range of trophic resources, reflecting the versatility of their feeding behavior and confirming conclusions from food-web models. Clear differences in both trophic position and trophic width were found among oceans and ecosystem types. The study also reinforces the importance of considering the natural variation in isotopic values when comparing the isotopic values of consumers inhabiting different ecosystems.

Investigation of pump and pump switch failures in rainwater harvesting systems

Science.gov (United States)

Moglia, Magnus; Gan, Kein; Delbridge, Nathan; Sharma, Ashok K.; Tjandraatmadja, Grace

2016-07-01

Rainwater harvesting is an important technology in cities that can contribute to a number of functions, such as sustainable water management in the face of demand growth and drought as well as the detention of rainwater to increase flood protection and reduce damage to waterways. The objective of this article is to investigate the integrity of residential rainwater harvesting systems, drawing on the results of the field inspection of 417 rainwater systems across Melbourne that was combined with a survey of householders' situation, maintenance behaviour and attitudes. Specifically, the study moves beyond the assumption that rainwater systems are always operational and functional and draws on the collected data to explore the various reasons and rates of failure associated with pumps and pump switches, leaving for later further exploration of the failure in other components such as the collection area, gutters, tank, and overflows. To the best of the authors' knowledge, there is no data like this in academic literature or in the water sector. Straightforward Bayesian Network models were constructed in order to analyse the factors contributing to various types of failures, including system age, type of use, the reason for installation, installer, and maintenance behaviour. Results show that a number of issues commonly exist, such as failure of pumps (5% of systems), automatic pump switches that mediate between the tank and reticulated water (9% of systems), and systems with inadequate setups (i.e. no pump) limiting their use. In conclusion, there appears to be a lack of enforcement or quality controls in both installation practices by sometimes unskilled contractors and lack of ongoing maintenance checks. Mechanisms for quality control and asset management are required, but difficult to promote or enforce. Further work is needed into how privately owned assets that have public benefits could be better managed.

A free-air system for long-term stable carbon isotope labeling of adult forest trees

Science.gov (United States)

Stable carbon (C) isotopes, in particular employed in labeling experiments, are an ideal tool to broaden our understanding of C dynamics in trees and forest ecosystems. Here, we present a free-air exposure system, named isoFACE, designed for long-term stable C isotope labeling in...

Development and applications of new type isotope level-meters for cement factories

International Nuclear Information System (INIS)

Yang Shiqing; Min Hainian; Zhang Zhaoqing; Fu Heping; Dang Congjun; Wang Jingmin; Xia Junming

1998-01-01

According to the situation of current domestic switch isotope level-meters used for the level measurement and control in cement factories, a new type isotope level-meter is developed. The level-meter includes digit display circuit, count detection and control circuit and two ways control export, its response time is less than 1 second. The quenching circuit in the detector lengthens the using lifespan of G-M counter. The application in the factories indicates that the level-meter has the advantages of sensitive, strong anti-disturbance, reliable and adjustment simplicity. The use of the level-meter can make the better economy benefit and society benefit

Coupled qubits as a quantum heat switch

Science.gov (United States)

Karimi, B.; Pekola, J. P.; Campisi, M.; Fazio, R.

2017-12-01

We present a quantum heat switch based on coupled superconducting qubits, connected to two LC resonators that are terminated by resistors providing two heat baths. To describe the system, we use a standard second order master equation with respect to coupling to the baths. We find that this system can act as an efficient heat switch controlled by the applied magnetic flux. The flux influences the energy level separations of the system, and under some conditions, the finite coupling of the qubits enhances the transmitted power between the two baths, by an order of magnitude under realistic conditions. At the same time, the bandwidth at maximum power of the switch formed of the coupled qubits is narrowed.

System safety program plan for the Isotope Brayton Ground Demonstration System (phase I)

International Nuclear Information System (INIS)

1976-01-01

The safety engineering effort to be undertaken in achieving an acceptable level of safety in the Brayton Isotope Power System (BIPS) development program is discussed. The safety organizational relationships, the methods to be used, the tasks to be completed, and the documentation to be published are described. The plan will be updated periodically as the need arises

CAN GALACTIC CHEMICAL EVOLUTION EXPLAIN THE OXYGEN ISOTOPIC VARIATIONS IN THE SOLAR SYSTEM?

International Nuclear Information System (INIS)

Lugaro, Maria; Liffman, Kurt; Ireland, Trevor R.; Maddison, Sarah T.

2012-01-01

A number of objects in primitive meteorites have oxygen isotopic compositions that place them on a distinct, mass-independent fractionation line with a slope of one on a three-isotope plot. The most popular model for describing how this fractionation arose assumes that CO self-shielding produced 16 O-rich CO and 16 O-poor H 2 O, where the H 2 O subsequently combined with interstellar dust to form relatively 16 O-poor solids within the solar nebula. Another model for creating the different reservoirs of 16 O-rich gas and 16 O-poor solids suggests that these reservoirs were produced by Galactic chemical evolution (GCE) if the solar system dust component was somewhat younger than the gas component and both components were lying on the line of slope one in the O three-isotope plot. We argue that GCE is not the cause of mass-independent fractionation of the oxygen isotopes in the solar system. The GCE scenario is in contradiction with observations of the 18 O/ 17 O ratios in nearby molecular clouds and young stellar objects. It is very unlikely for GCE to produce a line of slope one when considering the effect of incomplete mixing of stellar ejecta in the interstellar medium. Furthermore, the assumption that the solar system dust was younger than the gas requires unusual timescales or the existence of an important stardust component that is not theoretically expected to occur nor has been identified to date.

Switching overvoltages in offshore wind power grids

DEFF Research Database (Denmark)

Arana Aristi, Ivan

and cables are presented. In Chapter 4 results from time domain measurements and simulations of switching operations in offshore wind power grids are described. Specifically, switching operations on a single wind turbine, the collection grid, the export system and the external grid measured in several real...... offshore wind farms are shown together with simulation results. Switching operations in offshore wind power grids can be simulated with different electromagnetic transient programs. Different programs were used in the project and compared results are included in Chapter 4. Also in Chapter 4 different......Switching transients in wind turbines, the collection grid, the export system and the external grid in offshore wind farms, during normal or abnormal operation, are the most important phenomena when conducting insulation coordination studies. However, the recommended models and methods from...

Measurement of infiltration rates in urban sewer systems by use of oxygen isotopes.

Science.gov (United States)

De Bénédittis, J; Bertrand-Krajewski, J L

2005-01-01

The paper presents the principle of a method to measure infiltration rates in sewer systems based on the use of oxygen isotopes and its application in Lyon (France). In the urban area of Lyon, significant differences in delta 18O that can reach 3 per thousand are observed between the oxygen isotopic compositions of groundwater originating from Rhone, Saone and from their associated alluvial aquifers. Drinking water supplying Lyon results mainly from pumping in the Rhone alluvial aquifer. Therefore, in some areas, the difference of isotopic composition between wastewater resulting from the consumption of drinking water and local groundwater can be used to measure infiltration in sewer systems. The application in the catchment of Ecully shows that the infiltration flow rate presents strong fluctuations at an hourly scale: it varies between 15 and 40 m3/h. This variability could be explained by non-constant discharges of pumping and by variations of the water level in the sewer.

Isotopic shifts in chemical exchange systems. 1. Large isotope effects in the complexation of Na+ isotopes by macrocyclic polyethers

International Nuclear Information System (INIS)

Knoechel, A.; Wilken, R.D.

1981-01-01

The complexation of 24 Na + and 22 Na + by 18 of the most widely used macrocyclic polyethers (crown ethers and monocyclic and bicyclic aminopolyethers) has been investigated in view of possible equilibrium isotope shifts. Solvated salts and polyether complexes were distributed differently into two phases and isotope ratios determined in both phases. Chloroform/water systems were shown to be particularly suitable to the investigations allowing favorable distribution for Na + and 13 of the 18 polyethers employed. With crown ethers 24 Na + enrichment varied from nonsignficant values (for large crown ethers) up to 3.1 +- 0.4% (18-crown-6). In the case of bicyclic aminopolyethers, ligands with cages of optimum size to accommodate Na + showed 24 Na + enrichment between O (nonsignificant) (2.2/sub B/2./sub B/) and 5.2 +- 1.8% (2.2.1). In contrast, for 2.2.2. and its derivatives, being too large for Na + , 22 Na + enrichment varying from O (nonsignificant) (2.2.2.p) up to 5.4 +- 0.5% (2.2.2.) has been observed. These values are remarkably high. They are explained by different bonding in solvate structure and polyether complex by using the theoretical approach of Bigeleisen

Sources and Contributions of Oxygen During Microbial Pyrite Oxidation: the Triple Oxygen Isotopes of Sulfate

Science.gov (United States)

Ziegler, K.; Coleman, M. L.; Mielke, R. E.; Young, E. D.

2008-12-01

The triple isotopes of oxygen (Δ17O' = δ17O'-0.528 × δ18O' using logarithmic deltas) can trace the oxygen sources of sulfate produced during sulfide oxidation, an important biogeochemical process on Earth's surface and possibly also on Mars [1]. δ18OSO4 compositions are determined by the isotopic selectivity of the mechanism(s) responsible for their changes, and the δ18O value of the reactants (O2 vs. H2O). The relative proportional importance and contribution of each of those sources and mechanisms, as well as their associated isotopic fractionations, are not well understood. We are investigating the use of Δ 17O as a quantitative and qualitative tracer for the different processes and oxygen sources involved in sulfate production. Δ17O signatures are distinct fingerprints of these reservoirs, independent of fractionation factors that can be ambiguous. We conducted controlled abiotic and biotic (Acidithiobacillus ferrooxidans, A.f.) laboratory experiments in which water was spiked with 18O, allowing us to quantify the sources of sulfate oxygen and therefore the processes attending sulfate formation. Results of this Δ17O tracer study show that A.f. microbes initiate pyrite S-oxidation within hours of exposure, and that sulfate is produced from ~90% atmospheric oxygen. This initial lag-phase (behavior in the initial lag-phase will aid in the understanding of the ecological conditions required for microbial populations to establish and survive. An exponential phase of growth, facilitated by microbial Fe2+-oxidation, follows. The source of sulfate rapidly switches to abiotic sulfide oxidation during exponential growth and the source of oxygen switches from atmospheric O2 to nearly ~100% water. Pending acquisition of complimentary chemistry data (in progress), we interpret our isotope data to indicate that the biotic fractionation factor ɛ18OSO4-O2 of at least ~ -25 to - 35‰ is augmented by microbially induced kinetic fractionation; it is larger than

Isotope hydrology of some hydrothermal systems of the Kurilo-Kamchatskay volcanic region

International Nuclear Information System (INIS)

Esikov, A.D.

1990-01-01

The hydrogen and oxygen isotope composition of underground and surface (thermal and cold) waters, as well as local precipitation waters from the geothermal fields of the Uzon caldera, the Mutnovsky volcano (Kamchatka), and the Baransky volcano (island of Iturup) have been analysed. As has been demonstrated, hydrothermal solutions were formed due to hypogene circulation of water originating from local precipitation. Observed variations in the isotope composition of the water are easily explained by underground boiling of hydrothermal solutions and their exchange with bedrock, and also by the processes of non-steady evaporation of water under differing surface conditions and the widely-spread mutual intermixing of waters of different origin. Data on the isotope composition of 50 samples from the region studied are to be found in the paper. The method of constructing diagrams in coordinates of δD vs δ 18 O is discussed in detail, reflecting a single-step separation of the thermal fluid. Data obtained during the analysis of the thermal fields estimates the processes forming the isotope composition of the world's geothermal sub-aerial systems as being unique. (author)

A compact seven switches topology and reduced DC-link capacitor size for single-phase stand-alone PV system with hybrid energy storages

DEFF Research Database (Denmark)

Liu, Xiong; Wang, Peng; Loh, Poh Chiang

2011-01-01

Single-phase stand-alone PV system is suitable for household applications in remote area. Hybrid battery/ultra-capacitor energy storage can reduce charge and discharge cycles and avoid deep discharges of battery. This paper proposes a compact seven switches structure for stand-alone PV system......, which otherwise needs nine switches configuration, inclusive of one switch for boost converter, four switches for single-phase inverter and four switches for two DC/DC converters of battery and ultra-capacitor. It is well-known that a bulky DC-link capacitor is always required to absorb second......-order harmonic current caused by single-phase inverter. In the proposed compact topology, a small size DC-link capacitor can achieve the same function through charging/discharging control of ultra-capacitor to mitigate second-order ripple current. Simulation results are provided to validate the effectiveness...

Indigenous technology development : seismic switch for nuclear reactors

International Nuclear Information System (INIS)

Varghese, Shiju; Shah, Jay; Limaye, P.K.; Soni, N.L; Patel, R.J.

2016-01-01

After Fukushima incident it has become a regulatory requirement to have automatic reactor trip on detection of earthquake beyond OBE level. Seismic Switches that meets the technical specifications required for nuclear reactor use were not available in the market. Hence, on Nuclear Power Corporation of India Ltd (NPCIL's) request, Refuelling Technology Division, BARC has developed Seismic Switches (electronic earthquake detectors) required for this application. Functionality of the system was successfully tested using a Shake Table. Two different designs of seismic switches have been developed. One is a microcontroller based system (digital) and the other is fully analogue electronics (analog) based. These switches are designed to meet the technical requirements of Class IA systems of nuclear reactors. It is also designed to meet other qualification tests such as EMI/EMC, climatic, vibration, and reliability requirements. In addition to nuclear industry seismic switches are having potential use in oil and gas, power plants, buildings and other industrial installations. These technologies are currently available for technology transfer and details are published in BARC website. This paper describes the requirements, principle of operation, and features and testing of the developed systems. (author)

Oxygen isotope fractionation in the CaCO3-DIC-H2O system

Science.gov (United States)

Devriendt, Laurent S.; Watkins, James M.; McGregor, Helen V.

2017-10-01

The oxygen isotope ratio (δ18O) of inorganic and biogenic carbonates is widely used to reconstruct past environments. However, the oxygen isotope exchange between CaCO3 and H2O rarely reaches equilibrium and kinetic isotope effects (KIE) commonly complicate paleoclimate reconstructions. We present a comprehensive model of kinetic and equilibrium oxygen isotope fractionation between CaCO3 and water (αc/w) that accounts for fractionation between both (a) CaCO3 and the CO32- pool (α c / CO32-) , and (b) CO32- and water (α CO32- / w) , as a function of temperature, pH, salinity, calcite saturation state (Ω), the residence time of the dissolved inorganic carbon (DIC) in solution, and the activity of the enzyme carbonic anhydrase. The model results suggest that: (1) The equilibrium αc/w is only approached in solutions with low Ω (i.e. close to 1) and low ionic strength such as in the cave system of Devils Hole, Nevada. (2) The sensitivity of αc/w to the solution pH and/or the mineral growth rate depends on the level of isotopic equilibration between the CO32- pool and water. When the CO32- pool approaches isotopic equilibrium with water, small negative pH and/or growth rate effects on αc/w of about 1-2‰ occur where these parameters covary with Ω. In contrast, isotopic disequilibrium between CO32- and water leads to strong (>2‰) positive or negative pH and growth rate effects on α CO32-/ w (and αc/w) due to the isotopic imprint of oxygen atoms derived from HCO3-, CO2, H2O and/or OH-. (3) The temperature sensitivity of αc/w originates from the negative effect of temperature on α CO32-/ w and is expected to deviate from the commonly accepted value (-0.22 ± 0.02‰/°C between 0 and 30 °C; Kim and O'Neil, 1997) when the CO32- pool is not in isotopic equilibrium with water. (4) The model suggests that the δ18O of planktic and benthic foraminifers reflects a quantitative precipitation of DIC in isotopic equilibrium with a high-pH calcifying fluid, leading

Synchronization of Switched Interval Networks and Applications to Chaotic Neural Networks

OpenAIRE

Cao, Jinde; Alofi, Abdulaziz; Al-Mazrooei, Abdullah; Elaiw, Ahmed

2013-01-01

This paper investigates synchronization problem of switched delay networks with interval parameters uncertainty, based on the theories of the switched systems and drive-response technique, a mathematical model of the switched interval drive-response error system is established. Without constructing Lyapunov-Krasovskii functions, introducing matrix measure method for the first time to switched time-varying delay networks, combining Halanay inequality technique, synchroniza...

Using Stable Isotopes to Detect Land Use Change and Nitrogen Sources in Aquatic Systems

Energy Technology Data Exchange (ETDEWEB)

Rogers, K. M. [National Isotope Center, GNS Science, Lower Hutt (New Zealand)

2013-05-15

Changing land use is one of the primary causes of increased sedimentation and nutrient levels in aquatic systems, resulting in contamination and reduction of biodiversity. Detecting and quantifying these inputs is the first step towards remediation, and enabling targeted reductions of transport processes into waterways from human impacted land surfaces. More recently, stable isotope analyses are being used as detection and quantification tools in aquatic environments. Carbon ({delta}{sup 13}C) and nitrogen ({delta}{sup 15}N) isotopes of sediments, as well as algae and invertebrates from aquatic systems can be used as proxies to record both short and long term environmental change. Excess nitrogen (or nitrogen-compounds) derived from urbanization, industry, forestry, farming and agriculture, increase the bioavailability of nitrogen to aquatic organisms, changing their natural {delta}15N isotopic signatures. Allochthonous (terrestrial) input from soil destabilization and human activity in surrounding catchments changes {delta}{sup 13}C isotopic compositions and increases the C:N ratio of sediments. Heavy metal and other organic pollutants can also be used to indicate urbanization and industrial contamination. The combined use of carbon and nitrogen isotopes, C:N ratios and heavy metals are powerful environmental monitoring tools, which are useful indicators of source and transport pathways of terrestrial derived material and anthropogenic pollutants into streams, rivers and estuaries. (author)

Research and development of a NYNEX switched multi-megabit data service prototype system

Science.gov (United States)

Maman, K. H.; Haines, Robert; Chatterjee, Samir

1991-02-01

Switched Multi-megabit Data Service (SMDS) is a proposed high-speed packet-switched service which will support broadband applications such as Local Area Network (LAN) interconnections across a metropolitan area and beyond. This service is designed to take advantage of evolving Metropolitan Area Network (MAN) standards and technology which will provide customers with 45-mbps and 1 . 5-mbps access to high-speed public data communications networks. This paper will briefly discuss SMDS and review its architecture including the Subscriber Network Interface (SNI) and the SMDS Interface Protocol (SIP). It will review the fundamental features of SMDS such as address screening addressing scheme and access classes. Then it will describe the SMDS prototype system developed in-house by NYNEX Science Technology.

A Sepic Type Switched Mode Power Supply System For Battery Charging In An Electric Tricycle Auto-Rickshaw

Directory of Open Access Journals (Sweden)

Kureve

2017-08-01

Full Text Available This paper analyzes the plug-in electric tricycle Auto rickshaw battery charging system using a non-isolated DC-DC SEPIC converter which operates as a switched mode power supply SMPS. The control of dc voltage output is by varying the gating pulses duty cycle of the switch in the dc-dc converter using PID controller based PWM technique. The 60 V 30 A DC-DC SEPIC converter is designed to provide non-inverting voltage buck from the rectified AC mains for charging deep cycle battery bank in an electric auto rickshaw. The charger system is implemented using MATLABSimulink.

Generation Method of Multipiecewise Linear Chaotic Systems Based on the Heteroclinic Shil’nikov Theorem and Switching Control

Directory of Open Access Journals (Sweden)

Chunyan Han

2015-01-01

Full Text Available Based on the heteroclinic Shil’nikov theorem and switching control, a kind of multipiecewise linear chaotic system is constructed in this paper. Firstly, two fundamental linear systems are constructed via linearization of a chaotic system at its two equilibrium points. Secondly, a two-piecewise linear chaotic system which satisfies the Shil’nikov theorem is generated by constructing heteroclinic loop between equilibrium points of the two fundamental systems by switching control. Finally, another multipiecewise linear chaotic system that also satisfies the Shil’nikov theorem is obtained via alternate translation of the two fundamental linear systems and heteroclinic loop construction of adjacent equilibria for the multipiecewise linear system. Some basic dynamical characteristics, including divergence, Lyapunov exponents, and bifurcation diagrams of the constructed systems, are analyzed. Meanwhile, computer simulation and circuit design are used for the proposed chaotic systems, and they are demonstrated to be effective for the method of chaos anticontrol.

A New Topology for UPQC Based on Reduced-Switch-Count Converter

OpenAIRE

Ajami, Ali; Mahmoudi, Mohsen; Seyfi, Ebrahim; Atashbahar, Farid

2014-01-01

Recently, reduced switch count converter switch numerous advantages such as low cost and weight, small size and high reliability have been introduced to be used in unified power quality conditioner (UPQC). In this paper a novel topologyfor UPQC based on back-to-backB4 converter and its control system are proposed. The conventional UPQC consists of twelve switches while the proposed topology for UPQC has 8 switches. By reducing the number of switches, the price of the whole system and losses a...

A New Topology for UPQC Based on Reduced-Switch-Count Converter

OpenAIRE

Ajami, Ali; Mahmoudi, Mohsen; Seyfi, Ebrahim; Atashbahar, Farid

2015-01-01

Recently, reduced switch count converter switch numerous advantages such as low cost and weight, small size and high reliability have been introduced to be used in unified power quality conditioner (UPQC). In this paper a novel topologyfor UPQC based on back-to-backB4 converter and its control system are proposed. The conventional UPQC consists of twelve switches while the proposed topology for UPQC has 8 switches. By reducing the number of switches, the price of the whole system and losses a...

A new fast-cycling system for AMS at ANU

Science.gov (United States)

De Cesare, M.; Fifield, L. K.; Weisser, D. C.; Tsifakis, D.; Cooper, A.; Lobanov, N. R.; Tunningley, T. B.; Tims, S. G.; Wallner, A.

2015-10-01

In order to perform higher precision measurements, an upgrade of the ANU accelerator is underway. Fast switching times on the low-energy side, with maximum settling times of 30 ms, are achieved by holding the injector magnet field constant while changing the energy of the different isotopes by changing the pre-acceleration voltage after the ion source. Because ions of the different isotopes then have different energies before injection, it is necessary to adjust the strength and steering of the electrostatic quadrupole lens that focusses the beam before entry into the accelerator. First tests of the low-energy system will be reported. At the high energy end, a larger vacuum box in the analyzing magnet has been designed, manufactured and installed to allow the transport of differences in mass as large as 10% at constant terminal voltage. For the cases where more than one isotope must be transported to the detector an additional refinement is necessary. If the accelerator voltage is to be kept constant, then the trajectories of the different isotopes around both the analyzing and switching magnets must be modified. This will be achieved using bounced electrostatic steerers before and after the magnets. Simulations have been performed with the ion optic code COSY Infinity to determine the optimal positions and sizes of these steerers.

Guaranteed Cost Finite-Time Control of Fractional-Order Positive Switched Systems

Directory of Open Access Journals (Sweden)

Leipo Liu

2017-01-01

Full Text Available The problem of guaranteed cost finite-time control of fractional-order positive switched systems (FOPSS is considered in this paper. Firstly, a new cost function is defined. Then, by constructing linear copositive Lyapunov functions and using the average dwell time (ADT approach, a state feedback controller and a static output feedback controller are constructed, respectively, and sufficient conditions are derived to guarantee that the corresponding closed-loop systems are guaranteed cost finite-time stable (GCFTS. Such conditions can be easily solved by linear programming. Finally, two examples are given to illustrate the effectiveness of the proposed method.

Design of Filter for a Class of Switched Linear Neutral Systems

Directory of Open Access Journals (Sweden)

Caiyun Wu

2013-01-01

Full Text Available This paper is concerned with the filtering problem for a class of switched linear neutral systems with time-varying delays. The time-varying delays appear not only in the state but also in the state derivatives. Based on the average dwell time approach and the piecewise Lyapunov functional technique, sufficient conditions are proposed for the exponential stability of the filtering error dynamic system. Then, the corresponding solvability condition for a desired filter satisfying a weighted performance is established. All the conditions obtained are delay-dependent. Finally, two numerical examples are given to illustrate the effectiveness of the proposed theory.

Robust passive control for Internet-based switching systems with time-delay

Energy Technology Data Exchange (ETDEWEB)

Guan Zhihong [Department of Control Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China); Zhang Hao [Department of Control Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei 430074 (China)], E-mail: ehao79@163.com; Yang Shuanghua [Department of Computer Science, Loughborough University, Loughborough LE11 3TU (United Kingdom)

2008-04-15

In this paper, based on remote control and local control strategy, a class of hybrid multi-rate control models with time-delay and switching controllers are formulated and the problem of robust passive control for this discrete system is investigated. By Lyapunov-Krasovskii function and applying it to a descriptor model transformation some new sufficient conditions in form of LMIs are derived. A numerical example is given to illustrate the effectiveness of the theoretical result.

Effects of doping concentration ratio on electrical characterization in pseudomorphic HEMT-based MMIC switches for ICT system

Science.gov (United States)

Mun, Jae-Kyoung; Oh, Jung-Hun; Sung, Ho-Kun; Wang, Cong

2015-12-01

The effects of the doping concentration ratios between upper and lower silicon planar-doping layers on the DC and RF characteristics of the double planar doped pseudomorphic high electron mobility transistors (pHEMTs) are investigated. From the device simulation, an increase of maximum extrinsic transconductance and a decrease of total on- and off-state capacitances are observed, as well as an increase of the upper to lower planar-doping concentration ratios (UTLPDR), which give rise to an enhancement of the switching speed and isolation characteristics. On the basis of simulation results, two types of pHEMTs are fabricated with two different UTLPDRs of 4:1 and 1:2. After applying these two types' pHEMTs, single-pole-double-throw (SPDT) transmitter/receiver monolithic microwave integrated circuit (MMIC) switches are also designed and fabricated. The SPDT MMIC switch with a 4:1 UTLPDR shows an insertion loss of 0.58 dB, isolation of 40.2 dB, and switching speed of 100 ns, respectively, which correspondingly indicate a 0.23 dB lower insertion loss, 2.90 dB higher isolation and 2.5 times faster switching speed than those of 1:2 UTLPDR at frequency range of 2-6 GHz. From the simulation results and comparative studies, we propose that the UTLPDR must be greater than 4:1 for the best switching performance. With the abovementioned excellent performances, the proposed switch would be quite promising in the application of information and communications technology system.

Theorical and experimental analysis of nitrogen-15 isotope enrichment by nitrogen monoxide and nitric acid system

International Nuclear Information System (INIS)

Ducatti, C.

1985-01-01

Nitrogen-15 isotope enrichment by chemical exchange in NO/HNO 3 system was studied using two different theories. The isotope fractionation factors obtained by the countercurrent theory was compared to those estimated by the isotope equipartition theory were confronted through a model. A column in countercurrent was built at laboratory scale and parameters such as: number of theoretical plates, height equivalent to a theoretical plate, type of packing, total height of column, production of H 15 NO 3 /week, obtained under isotope dynamic equilibrium conditions, were studied in comparison to those in the literature. (Author) [pt

High-power semiconductor RSD-based switch

Energy Technology Data Exchange (ETDEWEB)

Bezuglov, V G; Galakhov, I V; Grusin, I A [All-Russian Scientific Research Inst. of Experimental Physics, Sarov (Russian Federation); and others

1997-12-31

The operating principle and test results of a high-power semiconductor RSD-based switch with the following operating parameters is described: operating voltage 25 kV, peak operating current 200 kA, maximum transferred charge 70 C. The switch is intended for use by high-power capacitor banks of state-of-the-art research facilities. The switch was evaluated for applicability in commercial pulsed systems. The possibility of increasing the peak operating current to 500 kA is demonstrated. (author). 4 figs., 2 refs.

Helium isotopes in geothermal systems: Iceland, The Geysers, Raft River and Steamboat Springs

International Nuclear Information System (INIS)

Torgersen, T.

1982-01-01

Helium isotope ratios have been measured in geothermal fluids from Iceland, The Geysers, Raft River, Steamboat Springs and Hawaii. These ratios have been interpreted in terms of the processes which supply He in distinct isotopic ratios and in terms of the processes which can alter the isotopic ratio. Using this interpretational scheme, Iceland is found to be an area of hot-spot magmatic He implying an active volcanic source although the data are suggestive of high-temperature weathering release of crustal He incorporated in the geothermal fluids. By comparison to fumarolic gases from Hawaii and Juan De Fuca and Cayman Trench basaltic glass samples, The Geysers contains MOR type magmatic He again implying an active volcanic source possibly a 'leaky' transform related to the San Andreas Fault System. Raft River contains only crustal He indicating no active volcanic sources. Steamboat Springs He isotope ratios are distinctly less than typical plate margin volcanics but must still have a magmatic source. (author)

Cu Isotopic Composition in Surface Environments and in Biological Systems: A Critical Review.

Science.gov (United States)

Wang, Zhuhong; Chen, Jiubin; Zhang, Ting

2017-05-18

Copper (Cu) is a transition metal and an essential micronutrient for organisms, but also one of the most widespread toxic inorganic contaminants at very high content. The research on Cu isotopes has grown rapidly in the last decade. Hitherto, a large number of studies have been published on the theoretical fractionation mechanisms, experimental data and natural variations of Cu isotopes in variable environments and ecosystems. These studies reported a large variation of δ 65 Cu (-16.49 to +20.04‰) in terrestrial samples and showed that Cu isotopes could be fractionated by various biogeochemical processes to different extent. Several papers have previously reviewed the coupling of Cu and Zn isotope systematics, and we give here a tentative review of the recent publications only on Cu isotopesin variable surface repositories, animals and human beings, with a goal to attract much attention to research on Cu (and other metals) behaviors in the environment and biological systems.

Cu Isotopic Composition in Surface Environments and in Biological Systems: A Critical Review

Directory of Open Access Journals (Sweden)

Zhuhong Wang

2017-05-01

Full Text Available Copper (Cu is a transition metal and an essential micronutrient for organisms, but also one of the most widespread toxic inorganic contaminants at very high content. The research on Cu isotopes has grown rapidly in the last decade. Hitherto, a large number of studies have been published on the theoretical fractionation mechanisms, experimental data and natural variations of Cu isotopes in variable environments and ecosystems. These studies reported a large variation of δ65Cu (−16.49 to +20.04‰ in terrestrial samples and showed that Cu isotopes could be fractionated by various biogeochemical processes to different extent. Several papers have previously reviewed the coupling of Cu and Zn isotope systematics, and we give here a tentative review of the recent publications only on Cu isotopesin variable surface repositories, animals and human beings, with a goal to attract much attention to research on Cu (and other metals behaviors in the environment and biological systems.

Smooth invariant densities for random switching on the torus

Science.gov (United States)

Bakhtin, Yuri; Hurth, Tobias; Lawley, Sean D.; Mattingly, Jonathan C.

2018-04-01

We consider a random dynamical system obtained by switching between the flows generated by two smooth vector fields on the 2d-torus, with the random switchings happening according to a Poisson process. Assuming that the driving vector fields are transversal to each other at all points of the torus and that each of them allows for a smooth invariant density and no periodic orbits, we prove that the switched system also has a smooth invariant density, for every switching rate. Our approach is based on an integration by parts formula inspired by techniques from Malliavin calculus.

Switching the Fermilab Accelerator Control System to a relational database

International Nuclear Information System (INIS)

Shtirbu, S.

1993-01-01

The accelerator control system (open-quotes ACNETclose quotes) at Fermilab is using a made-in-house, Assembly language, database. The database holds device information, which is mostly used for finding out how to read/set devices and how to interpret alarms. This is a very efficient implementation, but it lacks the needed flexibility and forces applications to store data in private/shared files. This database is being replaced by an off-the-shelf relational database (Sybase 2 ). The major constraints on switching are the necessity to maintain/improve response time and to minimize changes to existing applications. Innovative methods are used to help achieve the required performance, and a layer seven gateway simulates the old database for existing programs. The new database is running on a DEC ALPHA/VMS platform, and provides better performance. The switch is also exposing problems with the data currently stored in the database, and is helping in cleaning up erroneous data. The flexibility of the new relational database is going to facilitate many new applications in the future (e.g. a 3D presentation of device location). The new database is expected to fully replace the old database during this summer's shutdown

The Robustness of Stochastic Switching Networks

OpenAIRE

Loh, Po-Ling; Zhou, Hongchao; Bruck, Jehoshua

2009-01-01

Many natural systems, including chemical and biological systems, can be modeled using stochastic switching circuits. These circuits consist of stochastic switches, called pswitches, which operate with a fixed probability of being open or closed. We study the effect caused by introducing an error of size ∈ to each pswitch in a stochastic circuit. We analyze two constructions – simple series-parallel and general series-parallel circuits – and prove that simple series-parallel circuits are robus...

Floating electrode microelectromechanical system capacitive switches: A different actuation mechanism

Science.gov (United States)

Papaioannou, G.; Giacomozzi, F.; Papandreou, E.; Margesin, B.

2011-08-01

The paper investigates the actuation mechanism in floating electrode microelectromechanical system capacitive switches. It is demonstrated that in the pull-in state, the device operation turns from voltage to current controlled actuation. The current arises from Poole-Frenkel mechanism in the dielectric film and Fowler-Nordheim in the bridge-floating electrode air gap. The pull-out voltage seems to arise from the abrupt decrease of Fowler-Nordheim electric field intensity. This mechanism seems to be responsible for the very small difference with respect to the pull-in voltage.

Photo-stimulated resistive switching of ZnO nanorods

International Nuclear Information System (INIS)

Park, Jinjoo; Lee, Seunghyup; Yong, Kijung

2012-01-01

Resistive switching memory devices are promising candidates for emerging memory technologies because they yield outstanding device performance. Storage mechanisms for achieving high-density memory applications have been developed; however, so far many of them exhibit typical resistive switching behavior from the limited controlling conditions. In this study, we introduce photons as an unconventional stimulus for activating resistive switching behaviors. First, we compare the resistive switching behavior in light and dark conditions to describe how resistive switching memories can benefit from photons. Second, we drive the switching of resistance not by the electrical stimulus but only by the modulation of photon. ZnO nanorods were employed as a model system to demonstrate photo-stimulated resistive switching in high-surface-area nanomaterials, in which photo-driven surface states strongly affect their photoconductivity and resistance states. (paper)

Isotope Exchange: a Potential Mechanism Regulating the Natural and Anthropogenic Pb Isotope Budget in Coastal Waters

Science.gov (United States)

Chen, M.; Boyle, E. A.; Zurbrick, C.; Carrasco, G. G.; Switzer, A.; Zhao, N.

2016-02-01

Two independent studies on anthropogenic Pb and Pb isotopes in coastal corals from the northern Arabian Gulf and the Singapore Straits have shown an isotopic excursion where the main Pb sources discharging to the water move to more crustal-like values, indicating that the Pb in coastal waters might exchange isotopically with crustal particulates without propotional change in concentration. To investigate this issue, Pb isotope exchange is assessed through a closed-system exchange experiment using estuarine waters collected at the Johor River mouth (discharging to the Singapore Straits). During the experiment, a known amount of NBS-981 (206Pb/207Pb=1.093) was spiked into the unfiltered Johor water (dissolved 206Pb/207Pb = 1.199) and the changing isotopic composition of the dissolved Pb was monitored. Shortly after the spike addition, dissolved Pb exhibited 206Pb/207Pb=1.178, reflecting the influence of the spike. Within the following few days, the 206Pb/207Pb in the water increased to >1.190 with limited changes of the dissolved Pb concentration. The observations in closed-system experiment agree with the isotope difference between Singapore aerosol and seawater in our 2-year-long field observations. The kinetics of isotope exchange were assessed using a simple model, which reproduced >70% of the observed Pb isotope variance. Both the close-system experiment and field measurements imply that isotope exchange can be an important mechanism for regulating the Pb and Pb isotopes in coastal waters. Investigations on the distribution of Pb and Pb isotope in estuaries and coastal waters should further assess the role of isotope exchange in ocean Pb chemistry.

Switching Markov chains for a holistic modeling of SIS unavailability

International Nuclear Information System (INIS)

Mechri, Walid; Simon, Christophe; BenOthman, Kamel

2015-01-01

This paper proposes a holistic approach to model the Safety Instrumented Systems (SIS). The model is based on Switching Markov Chain and integrates several parameters like Common Cause Failure, Imperfect Proof testing, partial proof testing, etc. The basic concepts of Switching Markov Chain applied to reliability analysis are introduced and a model to compute the unavailability for a case study is presented. The proposed Switching Markov Chain allows us to assess the effect of each parameter on the SIS performance. The proposed method ensures the relevance of the results. - Highlights: • A holistic approach to model the unavailability safety systems using Switching Markov chains. • The model integrates several parameters like probability of failure due to the test, the probability of not detecting a failure in a test. • The basic concepts of the Switching Markov Chains are introduced and applied to compute the unavailability for safety systems. • The proposed Switching Markov Chain allows assessing the effect of each parameter on the chemical reactor performance

A progress report of the switch-based data acquisition system prototype project and the application of switches from industry to high-energy physics event building

International Nuclear Information System (INIS)

Barsotti, E.; Booth, A.; Bowden, M.; Swoboda, C.

1990-01-01

A prototype of a data acquisition system based on a new scalable, highly-parallel, open-system architecture is being developed at Fermilab. The major component of the new architecture, the parallel event builder, is based on a telecommunications industry technique used in the implementation of switching systems, a barrel-shift switch. The architecture is scalable both in the expandability of the number of input channels and in the throughput of the system. Because of its scalability, the system is well suited for low to high-rate experiments, test beams and all SSC detectors. The architecture is open in that as new technologies are developed and made into commercial products (e.g., arrays of processors and workstations and standard data links), these new products can be easily integrated into the system with minimal system modifications and no modifications to the system's basic architecture. Scalability and openness should guarantee that the data acquisition system does not become obsolete during the lifetime of the experiment. The paper first gives a description of the architecture and the prototype project and then details both the prototype project's software and hardware status including details of some architecture simulation studies. Suggestions for future R and D work on the new data acquisition system architecture are then described. The paper concludes by examining interconnection networks from industry and their application to event building and to other areas of high-energy physics data acquisition systems

Advances in high voltage power switching with GTOs

International Nuclear Information System (INIS)

Podlesak, T.F.

1990-01-01

The control of high voltage at high power, particularly opening switches, has been difficult in the past. Using gate turnoff thyristors (GTOs) arranged in series enables large currents to be switched at high voltage. The authors report a high voltage opening switch has been successfully demonstrated. This switch uses GTOs in series and successfully operates at voltages higher than the rated voltage of the individual devices. It is believed that this is the first time this has been successfully demonstrated, in that GTOs have been operated in series before, but always in a manner as to not exceed the voltage capability of the individual devices. In short, the devices have not worked together, sharing the voltage, but one device has been operated using several backup devices. Of particular interest is how well the individual devices share the voltage applied to them. Equal voltage sharing between devices is absolutely essential, in order to not exceed the voltage rating of any of the devices in the series chain. This is accomplished at high (microsecond) switching speeds. Thus, the system is useful for high frequency applications as well as high power, making for a flexible circuit system element. This demonstration system is rated at 5 KV and uses 1 KV devices. A larger 24 KV system is under design and will use 4.5 KV devices. In order to design the 24 KV switch, the safe operating area of the large devices must be known thoroughly

Float level switch for a nuclear power plant containment vessel

International Nuclear Information System (INIS)

Powell, J.G.

1993-01-01

This invention is a float level switch used to sense rise or drop in water level in a containment vessel of a nuclear power plant during a loss of coolant accident. The essential components of the device are a guide tube, a reed switch inside the guide tube, a float containing a magnetic portion that activates a reed switch, and metal-sheathed, ceramic-insulated conductors connecting the reed switch to a monitoring system outside the containment vessel. Special materials and special sealing techniques prevent failure of components and allow the float level switch to be connected to a monitoring system outside the containment vessel. 1 figures

Float level switch for a nuclear power plant containment vessel

Science.gov (United States)

Powell, James G.

1993-01-01

This invention is a float level switch used to sense rise or drop in water level in a containment vessel of a nuclear power plant during a loss of coolant accident. The essential components of the device are a guide tube, a reed switch inside the guide tube, a float containing a magnetic portion that activates a reed switch, and metal-sheathed, ceramic-insulated conductors connecting the reed switch to a monitoring system outside the containment vessel. Special materials and special sealing techniques prevent failure of components and allow the float level switch to be connected to a monitoring system outside the containment vessel.

Medical isotope identification with large mobile detection systems

Science.gov (United States)

Mukhopadhyay, Sanjoy; Maurer, Richard

2012-10-01

The Remote Sensing laboratory (RSL) of National Security Technologies Inc. has built an array of large (5.08 - cm x 10.16 - cm x 40.6 - cm) thallium doped sodium iodide (NaI: Tl) scintillators to locate and screen gamma-ray emitting radioisotopes that are of interests to radiological emergency responders [1]. These vehicle mounted detectors provide the operators with rapid, simple, specific information for radiological threat assessment. Applications include large area inspection, customs inspection, border protection, emergency response, and monitoring of radiological facilities. These RSL mobile units are currently being upgraded to meet the Defense Threat Reduction Agency mission requirements for a next-generation system capable of detecting and identifying nuclear threat materials. One of the challenging problems faced by these gamma-ray detectors is the unambiguous identification of medical isotopes like 131I (364.49 keV [81.7%], 636.99 keV [7.17%]), 99Tcm (140.51 keV [89.1%]) and 67Ga (184.6 keV [19.7%], 300.2 [16.0%], 393.5 [4.5%] that are used in radionuclide therapy and often have overlapping gamma-ray energy regions of interest (ROI). The problem is made worse by short (about 5 seconds) acquisition time of the spectral data necessary for dynamic mobile detectors. This article describes attempts to identify medical isotopes from data collected from this mobile detection system in a short period of time (not exceeding 5 secs) and a large standoff distance (typically 10 meters) The mobile units offer identification capabilities that are based on hardware auto stabilization of the amplifier gain. The 1461 keV gamma-energy line from 40K is tracked. It uses gamma-ray energy windowing along with embedded mobile Gamma Detector Response and Analysis Software (GADRAS) [2] simultaneously to deconvolve any overlapping gamma-energy ROIs. These high sensitivity detectors are capable of resolving complex masking scenarios and exceed all ANSI N42.34 (2006) requirements

Joint switched transmit diversity and adaptive modulation in spectrum sharing systems

KAUST Repository

Qaraqe, Khalid A.; Bouida, Zied; Abdallah, Mohamed M.; Alouini, Mohamed-Slim

2011-01-01

Under the scenario of an underlay cognitive radio network, we propose in this paper an adaptive scheme using switched transmit diversity and adaptive modulation in order to minimize the average number of switched branches at the secondary

Switch: a planning tool for power systems with large shares of intermittent renewable energy.