WorldWideScience

Sample records for premature piston pin

  1. Experimental and theoretical studies of scuffing behavior in piston-pin/piston contacts

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A bench rig was built and used to study the scuffing mechanisms and the effects of sur-face roughness, clearance, and groove on scuffing in piston-pin/bore contacts for dynamic loadsand an oscillatory rotation. The experimental results show that the deterioration of the surfaceshear strength by fatigue cracks appears to contribute to the final scuffing, and the effects of thebore surface roughness and groove on the scuffing behavior are more significant than the clear-ance. A macro-micro approached scuffing model and a criterion for scuffing failure were developedappearing to be justifiable for the practical design and analysis of piston pin/bore bearings.

  2. Piston

    Energy Technology Data Exchange (ETDEWEB)

    Donahue, Richard J [Colgate, WI

    2009-03-24

    A number of embodiments of a piston may have a shape that provides enhanced piston guidance. In such embodiments, the piston shape may include an axial profile that is configured to provide certain thrust load characteristics.

  3. Piston

    Energy Technology Data Exchange (ETDEWEB)

    Donahue, Richard J [Colgate, WI

    2009-02-24

    A number of embodiments of a piston may have a shape that provides enhanced piston guidance. In such embodiments, the piston shape may include an axial profile that is configured to provide certain thrust load characteristics.

  4. Research on control method for machining non-cylinder pin hole of piston

    Institute of Scientific and Technical Information of China (English)

    WU Yi-jie; LENG Hong-bin; ZHAO Zhang-rong; CHEN Jun-hua

    2006-01-01

    The control method for machining non-cylinder pin hole of piston was studied systematically. A new method was presented by embedding giant magnetostrictive material (GMM) into the tool bar proper position. The model is established to characterize the relation between control current of coil and deformation of tool rod. A series of tests on deformation of giant magnetostrictive tool bar were done and the results validated the feasibility of the principle. The methods of measuring magnetostrictive coefficient of rare earth GMM were analyzed. The measuring device with the bias field and prestress was designed. A series of experiments were done to test magnetostrictive coefficient. Experimental results supplied accurate characteristic parameter for designing application device of GMM. The constitution of the developed control system made up of displacement detection and temperature detection for thermal deformation compensation was also introduced. The developed machine tool for boring the non-cylinder pin hole of piston has the micron order accuracy. This control method can be applied to other areas for machining precision or complex parts.

  5. Pistonics

    DEFF Research Database (Denmark)

    Perram, John W.; Præstgaard, Eigil; Smith, Edgar R.

    2011-01-01

    is proportional to its internal energy. We report molecular dynamics experiments with ideal gas particles and show that they can exchange energy with their container. We then construct a dynamical system modelling the motion of the piston and heat transfer to the surroundings when the piston is released...

  6. PISTON

    Energy Technology Data Exchange (ETDEWEB)

    Sewell, Christopher Meyer [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-01-08

    This presentation was a part of the guest lecture series for graduate classes at the University of Oregon on many-core visualization. It discussed a practical introduction to high-level data parallelism using thrust and PISTON; presented an overview of PISTON and PINION; provided tutorial examples; additional details on research results.

  7. Analysis of Piston Slap Motion

    Directory of Open Access Journals (Sweden)

    Narayan S.

    2015-05-01

    Full Text Available Piston slap is the major force contibuting towards noise levels in combustion engines.This type of noise depends upon a number of factors such as the piston-liner gap, type of lubricant used, number of piston pins as well as geometry of the piston. In this work the lateral and rotary motion of the piston in the gap between the cylinder liner and piston has been analyzed. A model that can predict the forces and response of the engine block due to slap has been dicussed. The parameters such as mass, spring and damping constant have been predicted using a vibrational mobility model.

  8. Analysis of Piston Slap Motion

    Science.gov (United States)

    Narayan, S.

    2015-05-01

    Piston slap is the major force contibuting towards noise levels in combustion engines.This type of noise depends upon a number of factors such as the piston-liner gap, type of lubricant used, number of piston pins as well as geometry of the piston. In this work the lateral and rotary motion of the piston in the gap between the cylinder liner and piston has been analyzed. A model that can predict the forces and response of the engine block due to slap has been dicussed. The parameters such as mass, spring and damping constant have been predicted using a vibrational mobility model.

  9. The influence oil film lubrication of the piston-cylinder dynamic

    Directory of Open Access Journals (Sweden)

    Adriana Tokar

    2008-10-01

    Full Text Available An analytical study of the dynamics of a piston in a reciprocating engine was conducted. The equation of Reynolds and moving of piston are derived. The analysis, which incorporates a hydrodynamic lubrication model, was applied to M501 diesel engine. The results of this study indicate that piston dynamics were found to be sensitive to piston-cylinder bore clearance, location of the wrist pin and lubricant viscosity, underscoring their importance in engine design.

  10. Theoretical Analysis of Noise of Piston Knocking Cylinder Wall in Automotive Engines

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Based on the loading conditions of engine, applying difference method to solve the hydrodynamic lubrication equation of piston skirt movement, the force acting on piston skirt and the moment on wrist pin were obtained. A computer program for simulating the piston second order motion was conducted to calculate the lateral motion of the upper part and the bottom part of piston skirts of the engine of automotive model CA1091. From the simulated result, the maximal impacting phase and the maximal impacting region of the piston were obtained. The result can be used for designing engine, diagnosing the noise of piston knocking cylinder wall and explaining many practical fault phenomena in theory.

  11. Entropic Damping of the Motion of a Piston

    Science.gov (United States)

    Mungan, Carl E.

    2017-03-01

    The concept of an "entropic force" can be introduced by considering a familiar setup, namely a horizontal cylinder enclosing an ideal monatomic gas by a piston of cross-sectional area A and mass m that can slide without friction. The surrounding atmospheric pressure Patm keeps the piston from flying out of the cylinder. The cylinder and piston have negligible heat capacity (compared to the gas), but the gas is not thermally insulated from the surroundings at room temperature TR. Ignore any viscosity or turbulence of the enclosed gas or surrounding air. Two specific and illustrative situations are analyzed here. In the first, the piston is massless, m = 0. The piston is temporarily held in place by a pin while the gas is quickly adjusted to initial pressure Pi = Patm and temperature slightly larger than that of the room, say Ti = 1.1TR, using a heater and regulator. The piston is then released from rest, vi = 0. In the second case, the piston has inertia, m > 0, and the gas is initially in both mechanical and thermal equilibrium with the surroundings so that Pi = Patm and Ti = TR. The piston is now given a quick inward push, vi < 0. In both situations, the aim is the same: Describe the subsequent evolution of the system.

  12. Stirling engine piston ring

    Science.gov (United States)

    Howarth, Roy B.

    1983-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  13. Premature Contractions

    Science.gov (United States)

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Premature Contractions - PACs and PVCs Updated:Dec 15,2016 ... You felt this more-forceful beat. Types of premature contractions Premature atrial contractions (PACs) start in the ...

  14. Pistons and engine testing

    CERN Document Server

    2016-01-01

    The ever-increasing demands placed on combustion engines are just as great when it comes to this centerpiece—the piston. Achieving less weight or friction, or even greater wear resistance, requires in-depth knowledge of the processes taking place inside the engine, suitable materials, and appropriate design and manufacturing processes for pistons, including the necessary testing measures. It is no longer possible for professionals in automotive engineering to manage without specific expertise of this kind, whether they work in the field of design, development, testing, or maintenance. This technical book answers these questions in detail and in a very clear and comprehensible way. In this second, revised edition, every chapter has been revised and expanded. The chapter on “Engine testing”, for example, now include extensive results in the area of friction power loss measurement and lube oil consumption measurement. Contents Piston function, requirements, and types Design guidelines Simulation of the ope...

  15. An Investigation on the Pin Bearings’ Optimization of a Hermetic Reciprocating Compressor

    Science.gov (United States)

    Ozdemir, A. R.; Hacioglu, B.; Kasapoglu, E.

    2015-08-01

    A hermetic reciprocating compressor is the most energy consuming component of the refrigerators. Therefore performance improvement studies of the compressor play an important role to reduce overall energy consumption of the refrigerators. Design of bearings is one of the major study areas influencing reciprocating compressor performance. In this study crank pin and piston pin bearings in hermetic compressor applications are investigated and optimized. The effect of operating conditions, bearing offset between crank pin and piston pin, bearing clearance and bearing location along the shaft on the friction loss were investigated and optimal bearing designs were developed. Efficiency measurements of the compressor showed that the improved crank pin and piston pin bearing designs provide up to 3.8% increase in the COP as a result of reduction in mechanical loss that is significantly influenced by the length of the bearings, bearing location along the shaft and operating conditions.

  16. Pistons and engine testing

    CERN Document Server

    GmbH, Mahle

    2012-01-01

    The ever-increasing demands placed on combustion engines are just as great when it comes to this centerpiece - the piston. Achieving less weight or friction, or even greater wear resistance, requires in-depth knowledge of the processes taking place inside the engine, suitable materials, and appropriate design and machining processes for pistons, including the necessary testing measures. It is no longer possible for professionals in automotive engineering to manage without specific know-how of this kind, whether they work in the field of design, development, testing, or maintenance. This techni

  17. Premature infant

    Science.gov (United States)

    There are many support groups for parents of premature babies. Ask the social worker in the neonatal intensive care unit. ... Prematurity used to be a major cause of infant deaths. Improved ... Prematurity can have long-term effects. Many premature infants ...

  18. The development and testing of ceramic components in piston engines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    McEntire, B.J. [Norton Co., Northboro, MA (United States). Advanced Ceramics Div.; Willis, R.W.; Southam, R.E. [TRW, Inc., Cleveland, OH (United States)

    1994-10-01

    Within the past 10--15 years, ceramic hardware has been fabricated and tested in a number of piston engine applications including valves, piston pins, roller followers, tappet shims, and other wear components. It has been shown that, with proper design and installation, ceramics improve performance, fuel economy, and wear and corrosion resistance. These results have been obtained using rig and road tests on both stock and race engines. Selected summaries of these tests are presented in this review paper.

  19. Internal combustion piston engines

    Energy Technology Data Exchange (ETDEWEB)

    Segaser, C.L.

    1977-07-01

    Current worldwide production of internal combustion piston engines includes many diversified types of designs and a very broad range of sizes. Engine sizes range from a few horsepower in small mobile units to over 40,000 brake horsepower in large stationary and marine units. The key characteristics of internal combustion piston engines considered appropriate for use as prime movers in Integrated Community Energy Systems (ICES) are evaluated. The categories of engines considered include spark-ignition gas engines, compression-ignition oil (diesel) engines, and dual-fuel engines. The engines are evaluated with respect to full-load and part-load performance characteristics, reliability, environmental concerns, estimated 1976 cost data, and current and future status of development. The largest internal combustion piston engines manufactured in the United States range up to 13,540 rated brake horsepower. Future development efforts are anticipated to result in a 20 to 25% increase in brake horsepower without increase in or loss of weight, economy, reliability, or life expectancy, predicated on a simple extension of current development trends.

  20. Happy Pinning

    DEFF Research Database (Denmark)

    Fausing, Bent

    2012-01-01

    This is about Pinterest, but with a different approach than usual to social networks. Pinterest is an image site par excellence. The images are as Windows that open outwards and also lets us look inwards and displays the soul and heart, the unintentional or pre-conscious desires. Happy Pinning!...

  1. Happy Pinning

    DEFF Research Database (Denmark)

    Fausing, Bent

    2012-01-01

    This is about Pinterest, but with a different approach than usual to social networks. Pinterest is an image site par excellence. The images are as Windows that open outwards and also lets us look inwards and displays the soul and heart, the unintentional or pre-conscious desires. Happy Pinning!...

  2. Premature ejaculation

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/001524.htm Premature ejaculation To use the sharing features on this page, please enable JavaScript. Premature ejaculation is when a man has an orgasm ...

  3. Your Premature Baby

    Science.gov (United States)

    ... birth defects, premature birth and infant mortality. Solving premature birth Featured articles Accomplishments and lessons learned since ... Complications & Loss > Preterm labor & premature birth > Premature babies Premature babies E-mail to a friend Please fill ...

  4. Carbon-Carbon Piston Architectures

    Science.gov (United States)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor); Schwind, Francis A. (Inventor)

    2000-01-01

    An improved structure for carbon-carbon composite piston architectures is disclosed. The improvement consists of replacing the knitted fiber, three-dimensional piston preform architecture described in U.S. Pat.No. 4,909,133 (Taylor et al.) with a two-dimensional lay-up or molding of carbon fiber fabric or tape. Initially, the carbon fabric of tape layers are prepregged with carbonaceous organic resins and/or pitches and are laid up or molded about a mandrel, to form a carbon-fiber reinforced organic-matrix composite part shaped like a "U" channel, a "T"-bar, or a combination of the two. The molded carbon-fiber reinforced organic-matrix composite part is then pyrolized in an inert atmosphere, to convert the organic matrix materials to carbon. At this point, cylindrical piston blanks are cored from the "U"-channel, "T"-bar, or combination part. These blanks are then densified by reimpregnation with resins or pitches which are subsequently carbonized. Densification is also accomplished by direct infiltration with carbon by vapor deposition processes. Once the desired density has been achieved, the piston billets are machined to final piston dimensions; coated with oxidation sealants; and/or coated with a catalyst. When compared to conventional steel or aluminum alloy pistons, the use of carbon-carbon composite pistons reduces the overall weight of the engine; allows for operation at higher temperatures without a loss of strength; allows for quieter operation; reduces the heat loss; and reduces the level of hydrocarbon emissions.

  5. Design of Piston Ring Friction Tester Apparatus

    DEFF Research Database (Denmark)

    Klit, Peder

    2006-01-01

    the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external load may be established by measuring the pressure distribution, i.e. the pressure drop in the piston ring package. Speed and temperature may also be established. The amount...... and forces on piston rod. Since the frictional forces are small compared to the rest of the acting forces the main design idea is to fix the piston, while the cylinder liner moves. This approach makes it simple to measure the parameters mentioned above by putting the instrumentation in the piston....

  6. Piston-assisted charge pumping

    CERN Document Server

    Kaur, D; Mourokh, L

    2015-01-01

    We examine charge transport through a system of three sites connected in series in the situation when an oscillating charged piston modulates the energy of the middle site. We show that with an appropriate set of parameters, charge can be transferred against an applied voltage. In this scenario, when the oscillating piston shifts away from the middle site, the energy of the site decreases and it is populated by a charge transferred from the lower energy site. On the other hand, when the piston returns to close proximity, the energy of the middle site increases and it is depopulated by the higher energy site. Thus through this process, the charge is pumped against the potential gradient. Our results can explain the process of proton pumping in one of the mitochondrial enzymes, Complex I. Moreover, this mechanism can be used for electron pumping in semiconductor nanostructures.

  7. 49 CFR 229.55 - Piston travel.

    Science.gov (United States)

    2010-10-01

    ..., DEPARTMENT OF TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Brake System § 229.55 Piston travel. (a) Brake cylinder piston travel shall be sufficient to provide brake shoe clearance...

  8. On the validity range of piston theory

    CSIR Research Space (South Africa)

    Meijer, M-C

    2015-06-01

    Full Text Available International Forum on Aeroelasticity and Structural Dynamics On the validity range of Piston Theory Marius-Corne Meijer, Laurent Dala Keywords: potential flow, local piston theory, perturbation, linearization, quasi-steady. Abstract: The basis...

  9. Two piston V-type Stirling engine

    Science.gov (United States)

    Corey, John A.

    1987-01-01

    A two piston Stirling engine which includes a heat exchanger arrangement placing the cooler and regenerator directly adjacent the compression space for minimal cold duct volume; a sealing arrangement which eliminates the need for piston seals, crossheads and piston rods; and a simplified power control system.

  10. Comparison of Nitinol Stapes Pistons with Conventional Stapes Pistons: A Cadaver Study

    Science.gov (United States)

    2011-01-01

    Comparison of Nitinol Stapes Pistons with Conventional Stapes Pistons: A Cadaver Study Samuel A. Spear1 and James V. Crawford2 1 48th Medical Group, ENT...cited. Objective. To visually compare the Nitinol “smart” stapes prosthesis to conventional manual crimping stapes pistons in temporal bone cadaver...answer questions about each stapes piston. The answers to the survey were then recorded for analysis. Results. 8 of 9 Nitinol pistons were described as

  11. Osteopenia - premature infants

    Science.gov (United States)

    Neonatal rickets; Brittle bones - premature infants; Weak bones - premature infants; Osteopenia of prematurity ... the baby. This helps the baby grow. A premature infant may not receive the proper amount of ...

  12. Investigation into Piston-Slap Force under Friction and Connecting Rod Effects of Diesel Engine

    Directory of Open Access Journals (Sweden)

    Fuadi Noor Balia

    2011-01-01

    Full Text Available In this paper, a dynamics analysis of diesel engine through investigation of the piston-slap force by considering the friction and connecting rod effects is presented. A single-cylinder of 500 cc Diesel Engine’s mechanism was examined. The position, velocity and acceleration of the pins and the center of mass for each linkage were calculated by using vector analysis principles. The governing equations of the forces and moments were derived based on the Cartesian coordinate principles, and solved by using Gauss elimination method. Hence, the piston-slap force onto the cylinder wall under friction and connecting rod effects were determined. Favourable comparison with previously published work was performed and excellent agreement between the results was obtained. The result shows that the friction and connecting rod effects significantly influence to the piston-slap force.

  13. Pediatric safety pin ingestion.

    Science.gov (United States)

    Sarihan, H; Kaklikkaya, I; Ozcan, F

    1998-08-01

    Fifteen consecutive children with ingested safety pins were evaluated retrospectively. Eight patients were males and seven were girls. The mean age of the patients was 5.4 years ranging from 7 months to 16 years. Two of 15 patients were mentally retarded Seven safety pins ingestion were noted by parents, three older children applied with safety pin swallowing. Three infants referred with hypersalivation and swallowing difficulty. One of two mentally retarded patients had recurrent aspiration pneumonia, the other had neck abscess. These patients' lesions were detected incidentally by thoracic X-ray. Nine safety pins were at the level of the cricopharyngeus, one at the level of the aortic arch and five at the esophagogastric junction. A right esophagoscopy was used for extraction of safety pins under general anesthesia and endotracheal intubation were used. Before esophagoscopy control plain X-ray was obtained for location of safety pin. Nine safety pins were extracted by esophagoscopy. Three safety pins spontaneously and three during anesthesia induction passed through the esophagus falling down the stomach. Five of these six safety pins were spontaneously extracted without complication. However one open safety pin lodged at the duodenum and laparotomy was required. In this article, etiology and management of safety pin ingestion in children are discussed.

  14. Premature delivery

    Directory of Open Access Journals (Sweden)

    Bernardita Donoso Bernales

    2012-09-01

    Full Text Available Preterm delivery is the single most important cause of perinatal morbidity and mortality. In Chile, preterm births have increased in the past decade, although neonatal morbidity and mortality attributable to it shows a downward trend, thanks to improvements in neonatal care of premature babies, rather than the success of obstetric preventive and therapeutic strategies. This article describes clinical entities, disease processes and conditions that constitute predisposing factors of preterm birth, as well as an outline for the prevention and clinical management of women at risk of preterm birth.

  15. New Universal Tribometer as Pin or Ball-on-Disc and Reciprocating Pin-on-Plate Types

    Directory of Open Access Journals (Sweden)

    H. Kaleli

    2016-06-01

    Full Text Available The present paper contains a description of a new Universal Tribometer design which enables simulation of different contact and test types such as pin-on-disc, ball-on-disc and linear reciprocating tests. There are many models of wear Tribometer in the world market. These devices are manufactured by various companies abroad and are imported to our country. Cost of this devices start from 50.000 euros and goes to hundreds of thousands of euros. One of the most commonly used of this device is Reciprocating Pin-on-Plate Tribo Test Machine. This wear tester is produced at a low limited cost within the KAP (Scientifical Research Project Coordinator of Yıldız Technical University. The test machine can work including three types of Tribotest rigs (Reciprocating Pin-on-Plate, Pin-on-Disc and Ball-on-Disc. It is designed to operate also at high temperatures up to 500 ˚C. The new piece of equipment allows instrumented tribological testing of piston ring and cylinder liner samples at low and high temperatures and boundary lubrication conditions of any typical gasoline or Diesel engines. Some friction results were shown in boundary lubricating conditions between piston ring and cylinder liner sliding pairs describing Tribotest machine is driven by AC servo motor which is more accurate than DC motor.

  16. Premature Ventricular Contractions (PVCs)

    Science.gov (United States)

    Diseases and Conditions Premature ventricular contractions (PVCs) By Mayo Clinic Staff Premature ventricular contractions (PVCs) are extra, abnormal heartbeats that begin in one of your heart's two ...

  17. Premature ejaculation

    Directory of Open Access Journals (Sweden)

    Chris G McMahon

    2007-01-01

    Full Text Available Premature ejaculation (PE is a common male sexual disorder. Recent normative data suggests that men with an intravaginal ejaculatory latency time (IELT of less than 1 minute have "definite" PE, while men with IELTs between 1 and 1.5 minutes have "probable" PE. Although there is insufficient empirical evidence to identify the etiology of PE, there is limited correlational evidence to suggest that men with PE have high levels of sexual anxiety and inherited altered sensitivity of central 5-HT (5-hydroxytryptamine, serotonin receptors. Pharmacological modulation of the ejaculatory threshold using off-label daily or on-demand selective serotonin re-uptake inhibitors is well tolerated and offers patients a high likelihood of achieving improved ejaculatory control within a few days of initiating treatment, consequential improvements in sexual desire and other sexual domains. Investigational drugs such as the ejaculo-selective serotonin transport inhibitor, dapoxetine represent a major development in sexual medicine. These drugs offer patients the convenience of on-demand dosing, significant improvements in IELT, ejaculatory control and sexual satisfaction with minimal adverse effects.

  18. Premature ejaculation.

    Science.gov (United States)

    McMahon, Chris G

    2007-04-01

    Premature ejaculation (PE) is a common male sexual disorder. Recent normative data suggests that men with an intravaginal ejaculatory latency time (IELT) of less than 1 minute have "definite" PE, while men with IELTs between 1 and 1.5 minutes have "probable" PE. Although there is insufficient empirical evidence to identify the etiology of PE, there is limited correlational evidence to suggest that men with PE have high levels of sexual anxiety and inherited altered sensitivity of central 5-HT (5-hydroxytryptamine, serotonin) receptors. Pharmacological modulation of the ejaculatory threshold using off-label daily or on-demand selective serotonin re-uptake inhibitors is well tolerated and offers patients a high likelihood of achieving improved ejaculatory control within a few days of initiating treatment, consequential improvements in sexual desire and other sexual domains. Investigational drugs such as the ejaculo-selective serotonin transport inhibitor, dapoxetine represent a major development in sexual medicine. These drugs offer patients the convenience of on-demand dosing, significant improvements in IELT, ejaculatory control and sexual satisfaction with minimal adverse effects.

  19. Fluid structure interaction in piston diaphragm pumps

    NARCIS (Netherlands)

    Van Rijswick, R.; Van Rhee, C.

    2013-01-01

    Piston diaphragm pumps are used world-wide for the transport of aggressive and/or abrasive fluids in the chemical, mining and mineral processing industries. Figure 1 shows a cross section of a piston diaphragm pump as is used in the mining and mineral processing industries for the transport of

  20. Double acting stirling engine piston ring

    Science.gov (United States)

    Howarth, Roy B.

    1986-01-01

    A piston ring design for a Stirling engine wherein the contact pressure between the piston and the cylinder is maintained at a uniform level, independent of engine conditions through a balancing of the pressure exerted upon the ring's surface and thereby allowing the contact pressure on the ring to be predetermined through the use of a preloaded expander ring.

  1. Fluid structure interaction in piston diaphragm pumps

    NARCIS (Netherlands)

    Van Rijswick, R.; Van Rhee, C.

    2013-01-01

    Piston diaphragm pumps are used world-wide for the transport of aggressive and/or abrasive fluids in the chemical, mining and mineral processing industries. Figure 1 shows a cross section of a piston diaphragm pump as is used in the mining and mineral processing industries for the transport of miner

  2. Casting of Motorcycle Piston from Aluminium Piston Scrap using Metallic Mould

    Directory of Open Access Journals (Sweden)

    Francis Uchenna OZIOKO

    2012-11-01

    Full Text Available The casting of motorcycle piston was carried out using metallic mould. The prepared piston sand core was positioned in the mould to provide casting with contours and cavities. The molten metal of required composition was poured into the metallic mould, allowed to solidify and take the desired shape of the cavity. Aluminium silicon piston scraps were used as the casting material. Melting of the aluminium piston scraps was achieved using local crucible furnace and finally pouring the molten metal into the metallic mould having the prepared piston sand core in place to obtain the piston. After fettling and cleaning, the casting was found to be good. The composition test revealed that the scrap piston was made from LM29 aluminium alloy. The cast piston was machined and subjected to performance rating test in a Jincheng AX100 motorcycle engine. The rating used was based on a scale from 1 to 10. The higher the rating, the better the evaluation of the piston in the specific area rated. Deposits are evaluated by appearance, ranging from 10 (clean - absence of deposits to 0.0 (maximum deposits. In spite of various production constraints the result of the performance test was good. The rating showed that the locally cast piston compared favourably with imported piston.

  3. Dynamics of crank-piston mechanisms

    CERN Document Server

    Davitashvili, Nodar

    2016-01-01

    This monograph focuses on the dynamical research work on crank-piston mechanisms considering basic and additional motions. In order to have full dynamical analyses of piston machines and their mechanisms, the book studies the crank-piston mechanisms with clearances in kinematic pairs. The tasks are carried out by focusing on friction, wear and impacts in mechanisms, as well as cracks formation in links and elasticity of details, with distributed and concentrated masses. Then, the reliability and durability of the mechanisms of piston machines is applied on oil and gas transportation. The monograph is meant for design specialists. It is also useful for specialists-manufacturers and designers of piston machines, scientists and lecturers, doctoral students.

  4. PINS Spectrum Identification Guide

    Energy Technology Data Exchange (ETDEWEB)

    A.J. Caffrey

    2012-03-01

    The Portable Isotopic Neutron Spectroscopy—PINS, for short—system identifies the chemicals inside munitions and containers without opening them, a decided safety advantage if the fill chemical is a hazardous substance like a chemical warfare agent or an explosive. The PINS Spectrum Identification Guide is intended as a reference for technical professionals responsible for the interpretation of PINS gamma-ray spectra. The guide is divided into two parts. The three chapters that constitute Part I cover the science and technology of PINS. Neutron activation analysis is the focus of Chapter 1. Chapter 2 explores PINS hardware, software, and related operational issues. Gamma-ray spectral analysis basics are introduced in Chapter 3. The six chapters of Part II cover the identification of PINS spectra in detail. Like the PINS decision tree logic, these chapters are organized by chemical element: phosphorus-based chemicals, chlorine-based chemicals, etc. These descriptions of hazardous, toxic, and/or explosive chemicals conclude with a chapter on the identification of the inert chemicals, e.g. sand, used to fill practice munitions.

  5. Effects of piston speed, compression ratio and cylinder geometry on system performance of a liquid piston

    Directory of Open Access Journals (Sweden)

    Mutlu Mustafa

    2016-01-01

    Full Text Available Energy storage systems are being more important to compensate irregularities of renewable energy sources and yields more profitable to invest. Compressed air energy storage (CAES systems provide sufficient of system usability, then large scale plants are found around the world. The compression process is the most critical part of these systems and different designs must be developed to improve efficiency such as liquid piston. In this study, a liquid piston is analyzed with CFD tools to look into the effect of piston speed, compression ratio and cylinder geometry on compression efficiency and required work. It is found that, increasing piston speeds do not affect the piston work but efficiency decreases. Piston work remains constant at higher than 0.05 m/s piston speeds but the efficiency decreases from 90.9 % to 74.6 %. Using variable piston speeds has not a significant improvement on the system performance. It is seen that, the effect of compression ratio is increasing with high piston speeds. The required power, when the compression ratio is 80, is 2.39 times greater than the power when the compression ratio is 5 at 0.01 m/s piston speed and 2.87 times greater at 0.15 m/s. Cylinder geometry is also very important because, efficiency, power and work alter by L/D, D and cylinder volume respectively.

  6. Adaptive FEM Analysis of the Temperature Field of Pistons in Diesel Engines and Their Thermal Stress and Deformation Calculation

    Institute of Scientific and Technical Information of China (English)

    覃文洁; 张儒华; 左正兴

    2004-01-01

    The adaptive FEM analysis of the temperature field of the piston in one diesel engine is given by using the ANSYS software. By making full use of the post results provided by the software, the posteriori error estimation and adaptive accuracy meshing algorithm is developed. So the blindness of the mesh design through experiences can be avoided, and the accuracy requirement is adapted to the relative temperature gradient distribution across the entire domain. Therefore the meshes and solutions can be obtained at the same time. Based on the temperature field analysis, the thermal stress and deformation fields are calculated as well. The results show that the stress concentrates on the edge of the piston pin boss and the inside surface of the first ring groove, and the deformation of the head of the piston is greatest. But the difference between the long and short axes of the bottom cross section is greatest.

  7. Flux pinning in superconductors

    CERN Document Server

    Matsushita, Teruo

    2014-01-01

    The book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, high-Tc and MgB2 superconductors. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed for artificial Nb pins in Nb-Ti, etc., are introduced for the pinning mechanism. Summation theories to derive the critical current density are discussed in detail. Irreversible magnetization and AC loss caused by the flux pinning are also discussed. The loss originally stems from the ohmic dissipation of normal electrons in the normal core driven by the electric field induced by the flux motion. The readers will learn why the resultant loss is of hysteresis type in spite of such mechanism. The influence of the flux pinning on the vortex phase diagram in high Tc superconductors is discussed, and the dependencies of the irreversibility field are also described on other quantities such as anisotropy of supercondu...

  8. Flux Pinning in Superconductors

    CERN Document Server

    Matsushita, Teruo

    2007-01-01

    The book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, high-Tc and MgB2 superconductors. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed for artificial Nb pins in Nb-Ti, etc., are introduced for the pinning mechanism. Summation theories to derive the critical current density are discussed in detail. Irreversible magnetization and AC loss caused by the flux pinning are also discussed. The loss originally stems from the ohmic dissipation of normal electrons in the normal core driven by the electric field induced by the flux motion. The readers will learn why the resultant loss is of hysteresis type in spite of such mechanism. The influence of the flux pinning on the vortex phase diagram in high Tc superconductors is discussed, and the dependencies of the irreversibility field are also described on other quantities such as anisotropy of supercondu...

  9. Numerical Simulation of Piston Ring Lubrication

    DEFF Research Database (Denmark)

    Felter, Christian Lotz

    2006-01-01

    This paper describes a numerical method that can be used to model the lubrication of piston rings. Classical lubrication theory is based on the Reynolds equation which is ap- plicable to confined geometries and open geometries where the flooding conditions are known. Lubrication of piston rings...... is extended to include also the oil film outside the piston rings. The numerical model consists of a 2D free surface code that solves the time dependent compressible Navier-Stokes equations. The equations are cast in Lagrangian form and discretized by a meshfree moving least squares method using the primitive......, however, fall outside this category of problems since the piston rings might suffer from starved running conditions. This means that the com- putational domain where Reynold equation is applicable (including a cavitation criteria) is unknown. In order to overcome this problem the computational domain...

  10. Electromagnetic Casimir piston in higher dimensional spacetimes

    CERN Document Server

    Teo, L P

    2011-01-01

    We consider the Casimir effect of the electromagnetic field in a higher dimensional spacetime of the form $M\\times \\mathcal{N}$, where $M$ is the 4-dimensional Minkowski spacetime and $\\mathcal{N}$ is an $n$-dimensional compact manifold. The Casimir force acting on a planar piston that can move freely inside a closed cylinder with the same cross section is investigated. Different combinations of perfectly conducting boundary conditions and infinitely permeable boundary conditions are imposed on the cylinder and the piston. It is verified that if the piston and the cylinder have the same boundary conditions, the piston is always going to be pulled towards the closer end of the cylinder. However, if the piston and the cylinder have different boundary conditions, the piston is always going to be pushed to the middle of the cylinder. By taking the limit where one end of the cylinder tends to infinity, one obtains the Casimir force acting between two parallel plates inside an infinitely long cylinder. The asymptot...

  11. Retinopathy of Prematurity (ROP)

    Science.gov (United States)

    ... of Prematurity (ROP) Facts About Retinopathy of Prematurity (ROP) This information was developed by the National Eye ... blind from ROP. Are there different stages of ROP? Yes. ROP is classified in five stages, ranging ...

  12. Pharmacotherapy for premature ejaculation

    NARCIS (Netherlands)

    Waldinger, Marcel D

    PURPOSE OF REVIEW: As there are various drugs and different treatment strategies to delay ejaculation, a review of the current drug treatments for premature ejaculation is relevant for daily clinical practice. RECENT FINDINGS: There are four premature ejaculation subtypes: lifelong premature

  13. Pharmacotherapy for premature ejaculation

    NARCIS (Netherlands)

    Waldinger, Marcel D

    2014-01-01

    PURPOSE OF REVIEW: As there are various drugs and different treatment strategies to delay ejaculation, a review of the current drug treatments for premature ejaculation is relevant for daily clinical practice. RECENT FINDINGS: There are four premature ejaculation subtypes: lifelong premature ejacula

  14. PINS-3X Operations

    Energy Technology Data Exchange (ETDEWEB)

    E.H. Seabury

    2013-09-01

    Idaho National Laboratory’s (INL’s) Portable Isotopic Neutron Spectroscopy System (PINS) non-intrusively identifies the chemical fill of munitions and sealed containers. The PINS-3X variant of the system is used to identify explosives and uses a deuterium-tritium (DT) electronic neutron generator (ENG) as the neutron source. Use of the system, including possession and use of the neutron generator and shipment of the system components requires compliance with a number of regulations. This report outlines some of these requirements as well as some of the requirements in using the system outside of INL.

  15. Diffusion inspires selection of pinning nodes in pinning control

    Science.gov (United States)

    Zhou, Ming-Yang; He, Xingsheng; Fu, Zhong-Qian; Liao, Hao; Cai, Shi-min; Zhuo, Zhao

    2016-03-01

    The outstanding problem of controlling a complex network via pinning is related to network dynamics and has the potential to master large-scale real-world systems as well. This paper addresses the heart issue about how to choose pinning nodes for pinning control, where pinning control aims to control a network to an identical state by injecting feedback control signals to a small fraction of nodes. We explore networks' controllability from not only mathematical analysis, but also the aspects of network topology and information diffusion. Then, the connection between pinning control and information diffusion is given, and pinning node selection is transferred into multi-spreader problem in information diffusion. Based on information diffusion, a heuristic method is proposed to select pinning nodes by optimizing the spreading ability of multiple spreaders. The proposed method greatly improves the controllability of large practical networks, and provides a new perspective to investigate pinning node selection.

  16. Health Issues of Premature Babies

    Science.gov (United States)

    ... Text Size Email Print Share Health Issues of Premature Babies Page Content Because premature babies are born before they are physically ready ... associated with prematurity. Because of these health concerns, premature babies are given extra medical attention and assistance ...

  17. Drive piston assembly for a valve actuator assembly

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Zongxuan (Troy, MI)

    2010-02-23

    A drive piston assembly is provided that is operable to selectively open a poppet valve. The drive piston assembly includes a cartridge defining a generally stepped bore. A drive piston is movable within the generally stepped bore and a boost sleeve is coaxially disposed with respect to the drive piston. A main fluid chamber is at least partially defined by the generally stepped bore, drive piston, and boost sleeve. First and second feedback chambers are at least partially defined by the drive piston and each are disposed at opposite ends of the drive piston. At least one of the drive piston and the boost sleeve is sufficiently configured to move within the generally stepped bore in response to fluid pressure within the main fluid chamber to selectively open the poppet valve. A valve actuator assembly and engine are also provided incorporating the disclosed drive piston assembly.

  18. Systematic parametric design/calculation of the piston rod unit

    Science.gov (United States)

    Kacani, V.

    2015-08-01

    In this article a modern and economic method for the strength calculation of the piston rod unit and its components under different operating conditions will be presented. Herefore the commercial FEA - Software will be linked with the company-owned calculation tools. The parametric user input will be followed by an automatic Pre- and Postprocessing. Afterwards the strength calculation is processed on all critical points of the piston rod connection, assisted by an extra module, based on general standards and special codes for reciprocating compressors. In this process most arrangements of the piston rod unit as well as the special geometries of the single-components (piston, piston rod and piston nut) can be considered easily. In this article the modeling of the notches, especially on the piston rod, piston as well as the piston nut will be covered in detail.

  19. The Experimental Study of Atmospheric Stirling Engines Using Pin-Fin Arrays' Heat Exchangers

    Science.gov (United States)

    Isshiki, Seita; Sato, Hidekazu; Konno, Shoji; Shiraishi, Hiroaki; Isshiki, Naotsugu; Fujii, Iwane; Mizui, Hiroyuki

    This paper reports experimental results on two kinds of atmospheric Stirling engines that were designed and manufactured using a pin-fin array heat exchanger for the heater and cooler (abbreviated to “pin-fin Stirling engine” hereafter). The first one is a large β type pin-fin Stirling engine with a 1.7-liter displacement volume and power piston volume. The heater consists of an aluminum circular disk with a diameter of 270mm and with large-scale pin-fin arrays carved into the surface. The maximum output reached 91W at a temperature difference of 330K, which is 36% of the scheduled value and 68% of the Kolin's cubic power law. The maximum thermal efficiency was estimated 4.2%. The second engine is an α type pin-fin Stirling engine. Glass syringes were used for the piston-cylinder system and the Ross-yoke mechanism was used for the crank mechanism. By changing temperature difference, the characteristic of output torque in the large range was measured with a precision torque detector.

  20. Pinning Down versus Density

    OpenAIRE

    2015-01-01

    The pinning down number $ {pd}(X)$ of a topological space $X$ is the smallest cardinal $\\kappa$ such that for any neighborhood assignment $U:X\\to \\tau_X$ there is a set $A\\in [X]^\\kappa$ with $A\\cap U(x)\

  1. Connecting rod for stroke piston internal combustion engines with asymmetrical shank cross-section. Pleuel fuer Hubkolben-Brennkraftmaschinen mit asymmetrischem Schaftquerschnitt

    Energy Technology Data Exchange (ETDEWEB)

    Petschick, S.

    1991-08-08

    The invention affects a connecting rod for stroke piston internal combustion engines with a connecting rod eye for incorporation of a piston pin; a connecting rod shank has two head sides which are thickened as compared to the central piece in between along its entire length, and a connecting rod head. The connecting rod is to permit a greater width of the crankshaft counterweight and thus enable the desired mass equilibrium. This becomes possible by having the connecting rod shank flattened on one side at the head side, giving it an assymetrical cross-section.

  2. Insulated Piston Heads for Diesel Engines

    Science.gov (United States)

    Tricoire, A.; Kjellman, B.; Wigren, J.; Vanvolsem, M.; Aixala, L.

    2009-06-01

    Widely studied in the 1980s, the insulation of pistons in engines aimed at reducing the heat losses and thus increasing the indicated efficiency. However, those studies stopped in the beginning of the 1990s because of NO x emission legislation and also because of lower oil prices. Currently, with the improvement of exhaust after treatment systems (diesel particulate filter, selective catalytic reduction, and diesel oxidation catalyst) and engine technologies (exhaust gas recirculation), there are more trade-offs for NO x reduction. In addition, the fast rise of the oil prices tends to lead back to insulation technologies in order to save fuel. A 1 mm thick plasma sprayed thermal barrier coating with a graded transition between the topcoat and the bondcoat was deposited on top of a serial piston for heavy-duty truck engines. The effects of the insulated pistons on the engine performance are also discussed, and the coating microstructure is analyzed after engine test.

  3. NEW METHOD TO MEASURE PISTON SKIRT DIMENSIONS

    Institute of Scientific and Technical Information of China (English)

    Qin Yuexia; Hu Dejin

    2004-01-01

    The measurement of the middle-convex and varying ellipse profile of a piston skirt is a key technology because of its complex profile and high precision. Generally, a piston is measured on special device after it is machined. High accuracy can be achieved through this off-line measurement, but the result diverges from the actual dimension. Therefore, a no-contact in-site measurement system is proposed. A laser displacement meter is used to measure the profile of the piston skirt. A computer connected to the meter is used to process the measured data. A regression analysis method is used to process the ellipse section data. The method of moving average is used to process the middle-convex curve data. By using the given system, high measurement accuracy can be gained, and the production requirement is met.

  4. Development of deep drawn aluminum piston tanks

    Energy Technology Data Exchange (ETDEWEB)

    Whitehead, J.C.; Bronder, R.L.; Kilgard, L.W.; Evans, M.C.; Ormsby, A.E.; Spears, H.R.; Wilson, J.D.

    1990-06-08

    An aluminum piston tank has been developed for applications requiring lightweight, low cost, low pressure, positive-expulsion liquid storage. The 3 liter (183 in{sup 3}) vessel is made primarily from aluminum sheet, using production forming and joining operations. The development process relied mainly on pressurizing prototype parts and assemblies to failure, as the primary source of decision making information for driving the tank design toward its optimum minimum-mass configuration. Critical issues addressed by development testing included piston operation, strength of thin-walled formed shells, alloy choice, and joining the end cap to the seamless deep drawn can. 9 refs., 8 figs.

  5. SIMULATE-4 pin power calculations

    Energy Technology Data Exchange (ETDEWEB)

    Bahadir, T. [Studsvik Scandpower, Inc., 1087 Beacon St., Newton, MA 02459 (United States); Lindahl, S. Oe [Studsvik Scandpower AB, Hantverkargatan 2A, SE-722 12 Vasteraas (Sweden)

    2006-07-01

    A new pin power reconstruction module has been implemented in Studsvik Scandpower's next generation nodal code, SIMULATE-4. Heterogeneous pin powers are calculated by modulating multi-group pin powers from the sub-mesh solver of SIMULATE-4 with pin form factors from single-assembly CASMO-5 lattice calculations. The multi-group pin power model captures instantaneous spectral effects, and actinide tracking on the assembly sub-mesh describes exposure-induced pin power variations. Model details and verification tests against high order multi-assembly transport methods are presented. The accuracy of the new methods is also demonstrated by comparing SIMULATE-4 calculations with measured critical experiment pin powers. (authors)

  6. LED Monitoring System of the Phenix Muon Piston Calorimeter

    Science.gov (United States)

    Motschwiller, Steven

    2010-11-01

    The Muon Piston Calorimeter in the PHENIX experiment at RHIC has a monitoring system consisting of LEDs and PIN diodes to calibrate out the time dependent changes to the detector. The LEDs track the temperature and radiation-damage changes to the response of the MPC, while the absolute calibration can be done using 0̂ decays. To execute this, LEDs flash light through the PbWO4 crystal to the Avalanche Photo Diodes The MPC is made up of 416 independent electromagnetic calorimeter towers. By using the LEDs we can correct for changes in the gains of each tower in the MPC, on a run by run basis. Because the LED value only gives a relative measurement of the gain over time, this method of calibration can only be used in conjunction with absolute calibrations provided by 0̂ decays or by minimum ionizing peaks . This work will be used to make a final measurement on Transverse energy at √sNN = 200 GV in Au+Au collisions.

  7. Staged combustion with piston engine and turbine engine supercharger

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Larry E [Los Gatos, CA; Anderson, Brian L [Lodi, CA; O' Brien, Kevin C [San Ramon, CA

    2011-11-01

    A combustion engine method and system provides increased fuel efficiency and reduces polluting exhaust emissions by burning fuel in a two-stage combustion system. Fuel is combusted in a piston engine in a first stage producing piston engine exhaust gases. Fuel contained in the piston engine exhaust gases is combusted in a second stage turbine engine. Turbine engine exhaust gases are used to supercharge the piston engine.

  8. Experimental Investigation of Piston Rings for Internal Combustion Engines

    DEFF Research Database (Denmark)

    Klit, Peder; Vølund, Anders

    2008-01-01

    One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. A very important condition for describing the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external l...

  9. How Hot Can a Fire Piston Get?

    Science.gov (United States)

    Scott-Brown, J. A.; Cunningham, O. A.; Goad, B. C.

    2010-01-01

    The fire piston is just a sealed syringe containing a small amount of tinder. When the plunger is forced downwards, the air inside is compressed and heats up, setting fire to the tinder. It has been used as a convenient and portable way of starting fires "over a wide area from northern Burma and Siam through the Malay Peninsula and the Malayan…

  10. Rotary-piston internal combustion engine. Rotationskolbenbrennkraftmaschine

    Energy Technology Data Exchange (ETDEWEB)

    Eiermann, D.

    1991-08-08

    Rotary-piston internal combustion engine in trochoidal design with a slide bearing piston which is controlled by a synchronous gear. The gear is covered by an insert unit which is screwed at the eccentric. The insert unit seals the synchronous gear from the remaining machine parts; it has a hollow cylinder which covers the hollow gear of the synchronous gear and is eccentric to the eccentric shaft; it is sealed with a sealing ring from a shoulder of the piston. A further hollow cylinder is coaxial to the eccentric shaft; it surrounds the mount part with a clearance for the pinion; it projects into the boring at the side of the shaft and it is sealed by a sealing ring from the boring. An annular space which is sealed from the remaining engine rooms is on the other side of the bearing. The oil which escapes from the bearing is led from this annular space through the cooling rooms of the piston to the synchronous gear. The oil is carried off into a drain channel through the space which is formed by the coaxial hollow cylinder in the sidewall.

  11. Piston rod seal for a Stirling engine

    Science.gov (United States)

    Shapiro, Wilbur

    1984-01-01

    In a piston rod seal for a Stirling engine, a hydrostatic bearing and differential pressure regulating valve are utilized to provide for a low pressure differential across a rubbing seal between the hydrogen and oil so as to reduce wear on the seal.

  12. 考虑内燃机系统耦合振动的活塞拍击研究%Piston slap reduction considering coupled vibration of an internal combustion engine

    Institute of Scientific and Technical Information of China (English)

    郑光泽

    2013-01-01

    为研究内燃机中主要机械噪声源-活塞拍击,考虑活塞、连杆、曲轴及缸体的耦合振动对活塞拍击影响,建立活塞拍击动力学分析模型,研究某型柴油机活塞拍击及缸体振动响应.探讨活塞裙部轮廓形状、偏置活塞销对活塞拍击及缸体辐射噪声影响,计算结果及实验数据表明,活塞轮廓形状对活塞拍击频率成分分布及噪声品质有重要影响,活塞销向主推力面适当偏置有助于降低活塞拍击及辐射噪声水平.%Piston slap is a major noise source of an internal combustion engine.Reducing piston slap is one of the most important measures to improve noise and vibration of an internal combustion engine.The influence of the coupled vibration of piston,connecting rod,crankshaft and engine block on piston slap was taken into consideration,and a dynamic analytsis model of piston slap was developed here.The piston slap and the vibration response of the engine block of a certain type of Diesel engine were investigated based on the proposed model.The effect of piston skirt profile and piston pin offset on piston slap and radiated noise of engine block was discussed.The calculation results and test data showed that the profile of piston skirt has a significant influence on higher frequency components of piston slap and engine noise quality,the piston pin offset toward major thrust side can decrease the maximum value of piston slap and sound pressure level of radiated noise.

  13. Experimental Investigation of Piston Rings for Internal Combustion Engines

    DEFF Research Database (Denmark)

    Christiansen, Jens; Klit, Peder; Vølund, Anders;

    2007-01-01

    One of the major prerequisites for calculating piston ring friction is a good description of the tribological situation. A very important condition for describing the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. For piston rings the external...... forces are small compared to the rest of the acting forces the main design idea is to fix the piston, while the cylinder liner moves. This approach makes it simple to measure the parameters mentioned above by putting the instrumentation in the piston. The aim of this paper is describe the tribological...

  14. Pinning, de-pinning and re-pinning of a slowly varying rivulet

    KAUST Repository

    Paterson, C.

    2013-09-01

    The solutions for the unidirectional flow of a thin rivulet with prescribed volume flux down an inclined planar substrate are used to describe the locally unidirectional flow of a rivulet with constant width (i.e. pinned contact lines) but slowly varying contact angle as well as the possible pinning and subsequent de-pinning of a rivulet with constant contact angle and the possible de-pinning and subsequent re-pinning of a rivulet with constant width as they flow in the azimuthal direction from the top to the bottom of a large horizontal cylinder. Despite being the same locally, the global behaviour of a rivulet with constant width can be very different from that of a rivulet with constant contact angle. In particular, while a rivulet with constant non-zero contact angle can always run from the top to the bottom of the cylinder, the behaviour of a rivulet with constant width depends on the value of the width. Specifically, while a narrow rivulet can run all the way from the top to the bottom of the cylinder, a wide rivulet can run from the top of the cylinder only to a critical azimuthal angle. The scenario in which the hitherto pinned contact lines of the rivulet de-pin at the critical azimuthal angle and the rivulet runs from the critical azimuthal angle to the bottom of the cylinder with zero contact angle but slowly varying width is discussed. The pinning and de-pinning of a rivulet with constant contact angle, and the corresponding situation involving the de-pinning and re-pinning of a rivulet with constant width at a non-zero contact angle which generalises the de-pinning at zero contact angle discussed earlier, are described. In the latter situation, the mass of fluid on the cylinder is found to be a monotonically increasing function of the constant width. © 2013 Elsevier Masson SAS. All rights reserved.

  15. Casimir pistons with general boundary conditions

    Directory of Open Access Journals (Sweden)

    Guglielmo Fucci

    2015-02-01

    Full Text Available In this work we analyze the Casimir energy and force for a scalar field endowed with general self-adjoint boundary conditions propagating in a higher dimensional piston configuration. The piston is constructed as a direct product I×N, with I=[0,L]⊂R and N a smooth, compact Riemannian manifold with or without boundary. The study of the Casimir energy and force for this configuration is performed by employing the spectral zeta function regularization technique. The obtained analytic results depend explicitly on the spectral zeta function associated with the manifold N and the parameters describing the general boundary conditions imposed. These results are then specialized to the case in which the manifold N is a d-dimensional sphere.

  16. Fuel pin cladding

    Science.gov (United States)

    Vaidyanathan, S.; Adamson, M.G.

    1986-01-28

    Disclosed is an improved fuel pin cladding, particularly adapted for use in breeder reactors, consisting of composite tubing with austenitic steel on the outer portion of the thickness of the tube wall and with nickel and/or ferritic material on the inner portion of the thickness of the tube wall. The nickel forms a sacrificial barrier as it reacts with certain fission products thereby reducing fission product activity at the austenitic steel interface. The ferritic material forms a preventive barrier for the austenitic steel as it is immune to liquid metal embrittlement. The improved cladding permits the use of high density fuel which in turn leads to a better breeding ratio in breeder reactors, and will increase the threshold at which failure occurs during temperature transients. 2 figs.

  17. Fuel pin cladding

    Science.gov (United States)

    Vaidyanathan, Swaminathan; Adamson, Martyn G.

    1986-01-01

    An improved fuel pin cladding, particularly adapted for use in breeder reactors, consisting of composite tubing with austenitic steel on the outer portion of the thickness of the tube wall and with nickel and/or ferritic material on the inner portion of the thickness of the tube wall. The nickel forms a sacrificial barrier as it reacts with certain fission products thereby reducing fission product activity at the austenitic steel interface. The ferritic material forms a preventive barrier for the austenitic steel as it is immune to liquid metal embrittlement. The improved cladding permits the use of high density fuel which in turn leads to a better breeding ratio in breeder reactors, and will increase the threshold at which failure occurs during temperature transients.

  18. Analysis of Variation of Piston Temperature with Piston Dimensions and Undercrown Cooling

    Science.gov (United States)

    Sanders, J C; Schramm, W B

    1948-01-01

    A theoretical analysis is presented that permits estimation of the changes in piston-temperature distribution induced by variations in the crown thickness, the ring-groove-pad thickness, and the undercrown surface heat-transfer coefficient. The analysis consists of the calculation of operating temperatures at various points in the piston body on the basis of the experimentally determined surface heat-transfer coefficients and boundary-region temperatures, as well as arbitrarily selected surface coefficients. Surface heat-transfer coefficients were estimated from the internal temperature gradients obtained by hardness surveys of aluminum pistons that had been operated under severe conditions in a liquid-cooled, single-cylinder, 5 1/2 by 6-inch test engine.

  19. Improving Free-Piston Stirling Engine Power Density

    Science.gov (United States)

    Briggs, Maxwell H.

    2016-01-01

    Analyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58% using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a maximum piston power increase of 14%. Analytical predictions are compared to experimental data showing close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.

  20. Improving Power Density of Free-Piston Stirling Engines

    Science.gov (United States)

    Briggs, Maxwell H.; Prahl, Joseph M.; Loparo, Kenneth A.

    2016-01-01

    Analyses and experiments demonstrate the potential benefits of optimizing piston and displacer motion in a free-piston Stirling Engine. Isothermal analysis shows the theoretical limits of power density improvement due to ideal motion in ideal Stirling engines. More realistic models based on nodal analysis show that ideal piston and displacer waveforms are not optimal, often producing less power than engines that use sinusoidal piston and displacer motion. Constrained optimization using nodal analysis predicts that Stirling engine power density can be increased by as much as 58 percent using optimized higher harmonic piston and displacer motion. An experiment is conducted in which an engine designed for sinusoidal motion is forced to operate with both second and third harmonics, resulting in a piston power increase of as much as 14 percent. Analytical predictions are compared to experimental data and show close agreement with indirect thermodynamic power calculations, but poor agreement with direct electrical power measurements.

  1. Improving Free-Piston Stirling Engine Specific Power

    Science.gov (United States)

    Briggs, Maxwell H.

    2015-01-01

    This work uses analytical methods to demonstrate the potential benefits of optimizing piston and/or displacer motion in a Stirling engine. Isothermal analysis was used to show the potential benefits of ideal motion in ideal Stirling engines. Nodal analysis is used to show that ideal piston and displacer waveforms are not optimal in real Stirling engines. Constrained optimization was used to identify piston and displacer waveforms that increase Stirling engine specific power.

  2. Internal position and limit sensor for free piston machines

    Science.gov (United States)

    Holliday, Ezekiel S. (Inventor); Wood, James Gary (Inventor)

    2012-01-01

    A sensor for sensing the position of a reciprocating free piston in a free piston Stirling machine. The sensor has a disk mounted to an end face of the power piston coaxially with its cylinder and reciprocating with the piston The disk includes a rim around its outer perimeter formed of an electrically conductive material A coil is wound coaxially with the cylinder, spaced outwardly from the outer perimeter of the disk and mounted in fixed position relative to the pressure vessel, preferably on the exterior of the pressure vessel wall.

  3. Micafungin in Premature and Non-premature Infants

    Science.gov (United States)

    Wu, Chunzhang; Tweddle, Lorraine; Roilides, Emmanuel

    2014-01-01

    Background: Invasive fungal infections cause excessive morbidity and mortality in premature neonates and severely ill infants. Methods: Safety and efficacy outcomes of micafungin were compared between prematurely and non-prematurely born infants premature [birth weight (BW) premature, received ≥1 dose of micafungin. Among premature patients, 14.5% were low BW (1500–2499 g), 36.4% very low BW (1000–1499 g) and 49.1% extremely low BW (premature)] died. Significantly more non-premature than premature patients discontinued treatment (P = 0.003). Treatment-related adverse events were recorded in 23% of patients with no difference between groups. More extremely low BW (n = 4, 15%) and very low BW (n = 8, 40%) infants experienced treatment-related adverse events than low BW (n = 0) and there was no relation to micafungin dose or duration. For a subgroup of 30 patients with invasive candidiasis, treatment success was achieved in 73% in both premature and non-premature groups. Prophylaxis was successful in 4/5 non-premature hematopoietic stem cell transplant patients. Conclusion: Micafungin has a safe profile in premature and non-premature infants with substantial efficacy. PMID:24892849

  4. DESIGN AND CONSTRUCTION OF A HYDRAULIC PISTON

    OpenAIRE

    Santos De La Cruz, Eulogio; Universidad Nacional Mayor de San Marcos; Rojas Lazo, Oswaldo; Universidad Nacional Mayor de San Marcos; Yenque Dedios, Julio; Universidad Nacional Mayor de San Marcos; Lavado Soto, Aurelio; Universidad Nacional Mayor de San Marcos

    2014-01-01

    A hydraulic system project includes the design, materials selection and construction of the hydraulic piston, hydraulic circuit and the joint with the pump and its accesories. This equiment will be driven by the force of moving fluid, whose application is in the devices of machines, tools, printing, perforation, packing and others. El proyecto de un sistema hidráulico, comprende el diseño, selección de materiales y construcción del pistón hidráulico, circuito hidráulico y el ensamble con l...

  5. Free Piston Double Diaphragm Shock Tube

    OpenAIRE

    OGURA, Eiji; FUNABIKI, Katsushi; SATO, Shunichi; Abe, Takashi; 小倉, 栄二; 船曳, 勝之; 佐藤, 俊逸; 安部, 隆士

    1997-01-01

    A free piston double diaphragm shock tube was newly developed for generation of high Mach number shock wave. Its characteristics was investigated for various operation parameters; such as a strength of the diaphragm at the end of the comparession tube, an initial pressure of low pressure tube, an initial pressure of medium pressure tube and the volume of compression tube. Under the restriction of fixed pressures for the driver high pressure tube (32×10^5Pa) and the low pressure tube (40Pa) in...

  6. Manually operated piston-driven shock tube

    OpenAIRE

    Reddy, KPJ; Sharath, N

    2013-01-01

    A simple hand-operated shock tube capable of producing Mach 2 shock waves is described. Performance of this miniature shock tube using compressed high pressure air created by a manually operated piston in the driver section of the shock tube as driver gas with air at 1 atm pressure as the test gas in the driven tube is presented. The performance of the shock tube is found to match well with the theoretically estimated values using normal shock relations. Applications of this shock tube named ...

  7. Stability analysis of free piston Stirling engines

    Science.gov (United States)

    Bégot, Sylvie; Layes, Guillaume; Lanzetta, François; Nika, Philippe

    2013-03-01

    This paper presents a stability analysis of a free piston Stirling engine. The model and the detailed calculation of pressures losses are exposed. Stability of the machine is studied by the observation of the eigenvalues of the model matrix. Model validation based on the comparison with NASA experimental results is described. The influence of operational and construction parameters on performance and stability issues is exposed. The results show that most parameters that are beneficial for machine power seem to induce irregular mechanical characteristics with load, suggesting that self-sustained oscillations could be difficult to maintain and control.

  8. Paddle-pin alinement test

    Science.gov (United States)

    Gilliam, D. M.; Foster, J. A.

    1977-01-01

    Segmented insulated test bar speeds up patch distributor paddle-pin test. Device eliminates need to disconnect cables or remove distributor. Printed circuit cable and connector reduces weight on bar, adding to tester portability.

  9. Pinning Mechanisms in YBCO Tapes

    CERN Document Server

    Spera, Marcello; Ballarino, Amalia

    2015-01-01

    In this thesis work, a study on flux pinning mechanisms of commercial YBCO tapes is presented. This study has been performed via critical current characterization using transport (via direct I-V curves) and magnetization (via a Vibrating Sample Magnetometer) measurements. The latter ones turned out to be better concerning the comprehension of the pinning landscape of the provided samples, as a wider range of magnetic fields and temperatures is available for those measurements in the setup I used. The comparison of the experimental data with existing theoretical models allowed me to draw a picture of the pinning mechanisms underlying in each sample, and they turned out to be quite different one another. Moreover, for high-performance research tapes, another interesting feature has been found: the counterplay between the self-field critical current and the in-field one. Very well engineered artificial pinning structures limit the self-field critical current density due to the hi...

  10. LINC-NIRVANA piston control elements

    Science.gov (United States)

    Brix, Mario; Pott, Jörg-Uwe; Bertram, Thomas; Rost, Steffen; Borelli, Jose Luis; Herbst, Thomas M.; Kuerster, Martin; Rohloff, Ralf-Rainer

    2010-07-01

    We review the status of hardware developments related to the Linc-Nirvana optical path difference (OPD) control. The status of our telescope vibration measurements is given. We present the design concept of a feed-forward loop to damp the impact of telescope mirror vibrations on the OPD seen by Linc-Nirvana. At the focus of the article is a description of the actuator of the OPD control loop. The weight and vibration optimized construction of this actuator (aka piston mirror) and its mount has a complex dynamical behavior, which prevents classical PI feedback control from delivering fast and precise motion of the mirror surface. Therefore, an H-; optimized control strategy will be applied, custom designed for the piston mirror. The effort of realizing a custom controller on a DSP to drive the piezo is balanced by the outlook of achieving more than 5x faster servo bandwidths. The laboratory set-up to identify the system, and verify the closed loop control performance is presented. Our goal is to achieve 30 Hz closed-loop control bandwidth at a precision of 30 nm.

  11. Experimental Piston Ring Tribology for Marine Diesel Engines

    DEFF Research Database (Denmark)

    Klit, Peder; Vølund, Anders

    2008-01-01

    A very important condition for describing the frictional behavior of a piston ring correctly is knowledge about the amount of lubricant present. It is often assumed that piston rings operate under fully flooded conditions, but this is not the case in real life operation. In large two-stroke engines...

  12. TRIBOLOGICAL PERFORMANCE OF PISTON RING IN MARINE DIESEL ENGINE

    DEFF Research Database (Denmark)

    Imran, Tajammal; Klit, Peder; Felter, Christian

    From a tribology point of view, it is the two dead centers that are the main area of interest for experimental study of piston rings in large marine diesel engines. Therefore, in this work the performance of piston rings is studied to mark the importance of the two dead centers. A test rig based...

  13. Fluid powered linear piston motor with harmonic coupling

    Energy Technology Data Exchange (ETDEWEB)

    Raymond, David W.

    2016-09-20

    A motor is disclosed that includes a module assembly including a piston that is axially cycled. The piston axial motion is coupled to torque couplers that convert the axial motion into rotary motion. The torque couplers are coupled to a rotor to rotate the rotor.

  14. Entropic Damping of the Motion of a Piston

    Science.gov (United States)

    Mungan, Carl E.

    2017-01-01

    The concept of an "entropic force" can be introduced by considering a familiar setup, namely a horizontal cylinder enclosing an ideal monatomic gas by a piston of cross-sectional area "A" and mass "m" that can slide without friction. The surrounding atmospheric pressure P[subscript atm] keeps the piston from flying…

  15. Experimental Thermal Analysis of Diesel Engine Piston and Cylinder Wall

    Directory of Open Access Journals (Sweden)

    Subodh Kumar Sharma

    2015-01-01

    Full Text Available Knowledge of piston and cylinder wall temperature is necessary to estimate the thermal stresses at different points; this gives an idea to the designer to take care of weaker cross section area. Along with that, this temperature also allows the calculation of heat losses through piston and cylinder wall. The proposed methodology has been successfully applied to a water-cooled four-stroke direct-injection diesel engine and it allows the estimation of the piston and cylinder wall temperature. The methodology described here combines numerical simulations based on FEM models and experimental procedures based on the use of thermocouples. Purposes of this investigation are to measure the distortion in the piston, temperature, and radial thermal stresses after thermal loading. To check the validity of the heat transfer model, measure the temperature through direct measurement using thermocouple wire at several points on the piston and cylinder wall. In order to prevent thermocouple wire entanglement, a suitable pathway was designed. Appropriate averaged thermal boundary conditions such as heat transfer coefficients were set on different surfaces for FE model. The study includes the effects of the thermal conductivity of the material of piston, piston rings, and combustion chamber wall. Results show variation of temperature, stresses, and deformation at various points on the piston.

  16. Reduction of HCCI combustion noise through piston crown design

    DEFF Research Database (Denmark)

    Pedersen, Troels Dyhr; Schramm, Jesper

    2010-01-01

    Seven shapes of piston crowns have been evaluated for their ability to reduce HCCI knock and transmission of combustion noise to the engine. The performance of each piston crown was evaluated with measurements of cylinder pressure, engine vibration and acoustic sound pressure measured one meter a...

  17. Computational Modelling of Piston Ring Dynamics in 3D

    Directory of Open Access Journals (Sweden)

    Dlugoš Jozef

    2014-12-01

    Full Text Available Advanced computational models of a piston assembly based on the level of virtual prototypes require a detailed description of piston ring behaviour. Considering these requirements, the piston rings operate in regimes that cannot, in general, be simplified into an axisymmetric model. The piston and the cylinder liner do not have a perfect round shape, mainly due to machining tolerances and external thermo-mechanical loads. If the ring cannot follow the liner deformations, a local loss of contact occurs resulting in blow-by and increased consumption of lubricant oil in the engine. Current computational models are unable to implement such effects. The paper focuses on the development of a flexible 3D piston ring model based on the Timoshenko beam theory using the multibody system (MBS. The MBS model is compared to the finite element method (FEM solution.

  18. Piston motion in the perfect-conductive magnetizable uncompressible fluid

    Energy Technology Data Exchange (ETDEWEB)

    Naletova, V.A.

    1977-01-01

    A solution is given for the movement of a perfect conductive solid horizontal piston at a constant velocity u, parallel to the plane of the piston, in a perfect conductive magnetizable uncompressible fluid in an applied magnetic field H/sub 0/. Either a shock wave, a centered wave, or a alvenian fracture, or a combination of an alvenian fracture and waves can be propagated in front of the piston under these conditions. In this case either the shock or centered wave is propagated at first, followed by the movement of the alvenian fracture. Either case is manifested at such velocities. When the piston moves along the boundary, the piston-medium can flow as a surface current which can be found from the solution to the problem. 3 references, 3 figures.

  19. Enhanced pinning in superconducting thin films with graded pinning landscapes

    Science.gov (United States)

    Motta, M.; Colauto, F.; Ortiz, W. A.; Fritzsche, J.; Cuppens, J.; Gillijns, W.; Moshchalkov, V. V.; Johansen, T. H.; Sanchez, A.; Silhanek, A. V.

    2013-05-01

    A graded distribution of antidots in superconducting a-Mo79Ge21 thin films has been investigated by magnetization and magneto-optical imaging measurements. The pinning landscape has maximum density at the sample border, decreasing linearly towards the center. Its overall performance is noticeably superior than that for a sample with uniformly distributed antidots: For high temperatures and low fields, the critical current is enhanced, whereas the region of thermomagnetic instabilities in the field-temperature diagram is significantly suppressed. These findings confirm the relevance of graded landscapes on the enhancement of pinning efficiency, as recently predicted by Misko and Nori [Phys. Rev. B 85, 184506 (2012)].

  20. Influence of surface treatments on fatigue life of a two-stroke free piston linear engine component using random loading

    Institute of Scientific and Technical Information of China (English)

    RAHMAN M.M.; ARIFFIN A.K.; JAMALUDIN N.; HARON C.H.C.

    2006-01-01

    This paper describes the finite element (FE) analysis technique to predict fatigue life using the narrow band frequency response approach. The life prediction results are useful for improving the component design methodology at the very early development stage. The approach is found to be suitable for a periodic loading but requires very large time records to accurately describe random loading processes. This paper is aimed at investigating the effects of surface treatments on the fatigue life of the free piston linear engine's components. Finite element modelling and frequency response analysis were conducted using computer aided design and finite element analysis commercial codes, respectively. In addition, the fatigue life prediction was carried out using finite element based fatigue analysis commercial code. Narrow band approach was specially applied to predict the fatigue life of the free piston linear engine cylinder block. Significant variation was observed between the surface treatments and untreated cylinder block of free piston engine. The obtained results indicated that nitrided treatment yielded the longest life. This approach can determine premature products failure phenomena, and therefore can reduce time to market, improve product reliability and customer confidence.

  1. Interface roughening and pinning

    Science.gov (United States)

    Roux, Stéphane; Hansen, Alex

    1994-04-01

    We study a simple model for thé pinning of an interface by impurities with random strengths, and thé depinning due to thé applied pressure, in a quasi-static propagation lirait. The model is very close to thé so called "Robin Hood" model introduced by Zaitsev. It is designed to describe e.g. thé invasion of a wetting fluid (imbibition) in a heterogeneous porous medium containing a second immiscible fluid. The relation between this model and other previously proposed approaches is discussed. The front of thé invaded domain is shown to develop a self-affine structure with an increase of thé roughness as a power-law of thé injected volume. The value of thé apparent roughness exponent can be favorably compared to some experimental measurements although we argue that thé true roughness exponent is out of reach of commonly used methods. We show that thé distribution f(d, Δ t) of distances d between discrete local invasions at a time interval Δ t can be described by a scaling law f(d, Δ t) = d^{-1}\\varphi(d/sqrt{Δ t}). This form can be obtained from thé identification of a hierarchical structure of "bursts" in thé pressure signal. Those "bursts" are quahtatively similar to those observed in quasistatic drainage, (i.e. invasion percolation), although characterized by différent scaling indices. Nous étudions un modèle simple pour analyser l'accrochage d'une interface sur des impuretés et le décrochage sous l'effet d'une pression appliquée, dans une limite quasi-statique. Ce modèle est très voisin du modèle "Robin Hood" introduit par Zaitsev. Il s'applique en particulier à l'invasion d'un fluide mouillant (imbibition) dans un milieu poreux hétérogène contenant un fluide immiscible. Nous discutons les relations entre ce modèle et d'autres approches proposées pour décrire ce phénomène. Le front d'invasion acquiert une structure auto-affine, avec un développement de la rugosité selon une loi de puissance du volume injecté. La valeur de l

  2. PinBus Interface Design

    Energy Technology Data Exchange (ETDEWEB)

    Hammerstrom, Donald J.; Adgerson, Jewel D.; Sastry, Chellury; Pratt, Richard M.; Pratt, Robert G.

    2009-12-30

    On behalf of the U.S. Department of Energy, PNNL has explored and expanded upon a simple control interface that might have merit for the inexpensive communication of smart grid operational objectives (demand response, for example) to small electric end-use devices and appliances. The approach relies on bi-directional communication via the electrical voltage states of from one to eight shared interconnection pins. The name PinBus has been suggested and adopted for the proposed interface protocol. The protocol is defined through the presentation of state diagrams and the pins’ functional definitions. Both simulations and laboratory demonstrations are being conducted to demonstrate the elegance and power of the suggested approach. PinBus supports a very high degree of interoperability across its interfaces, allowing innumerable pairings of devices and communication protocols and supporting the practice of practically any smart grid use case.

  3. Piston ring lubrication and hydrocarbon emissions from internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Froelund, K.

    1997-11-01

    Is it the intention with this project to improve the existing hydrocarbon emission model at the Institute by combining it with a model for predicting the piston ring lubrication. The piston ring lubrication model should be experimentally verified to ensure the validity of the model. The following items were the objectives of the current study: Develop a piston ring lubrication model. This implies the development of a ring-pack gas flow model; Examine the response of the piston ring lubrication model to changing engineer conditions. Especially, it would be interesting to look at the engine warm-up phase since this is the phase where the engine-out emissions are highest and where the commonly used three way catalyst is not capable of converting the engine-out emissions, thereby leading the engine-out emissions directly out in to the environment with the exhaust gases; In order to verify the piston ring lubrication model the lubricant distribution on the cylinder liner should be investigated experimentally. Here again it would be of great interesting to look at the engine warm-up phase; The piston ring lubrication model should be adjusted for application together with the new hydrocarbon emission model for SI-engines at the Institute in order to increase the accuracy of the latter; The piston ring lubrication model could be used for describing the transport of PAH`s in diesel engines. (EG)

  4. Composite ceramic/metal piston assembly and method of making

    Energy Technology Data Exchange (ETDEWEB)

    Hartsock, D.L.

    1987-03-17

    This patent describes an integrally cast composite assembly of a cylindrical cap attached to a piston having a higher thermal expansion characteristic than the cylindrical cap, the cap being adapted to receive a ceramic insert, comprising: (a) a piston body comprised substantially as a body of revolution about an axis and comprised of a material having a higher thermal expansion characteristic than the cylindrical cap. The piston body has a crown top and an annular crown side wall with an upper edge, and an annular undercut surface terminating the crown side wall. The undercut surface makes an angle with a plane extending perpendicular to the axis and passing through the upper edge of the crown side wall. The angle is substantially equal to the arc tangent of H/R where H is the median distance of the undercut surface from the plane and R is the median radius fo the undercut surface from the axis of the piston; and (b) a cylindrical cap disposed on the piston crown top and having a cap side wall depending about the crown side wall, the cap side wall having an annular lip extending radially inwardly from the cap side wall. The lip has surface mateable with the undercut surface of the piston body so that there exists a tightly stressed camming relationship between the mateable surfaces as a result of the shrinkage of the piston body upon solidification.

  5. Lifestyle influences on prematurity.

    Science.gov (United States)

    Creasy, R K

    1991-01-01

    It is apparent from this review that the lifestyle of an individual gravida can potentially lead to a premature delivery. Some of these adverse behavioral characteristics may be dealt with by education and motivation, and some with actual medical treatment. However, there also appears to be significant need for public policy reorientation if we are to make a significant impact on the problem of preterm delivery.

  6. Piston diameter in stapes surgery. Does it have a bearing?

    Directory of Open Access Journals (Sweden)

    Neha Gupta

    2014-01-01

    Full Text Available Aims and Objectives: This prospective randomized controlled trial was done to study the effect of piston diameter on hearing outcomes after stapedotomy. Materials and Methods: All the patients diagnosed to have otosclerosis were included in the study. A total of 52 patients were studied ranging in age from 18 to 50 years. The subjects were randomized into two groups, that is, 0.4 mm piston (group A and 0.6 mm piston (group B. The subjects were taken up for small fenestra stapedotomy using either a 0.4 or 0.6 mm piston. The main outcome measures were hearing improvement, air-bone gap closure, and overclosure of air-bone gap. Results: There was no statistical difference in hearing improvement in two different piston diameters, 0.4 and 0.6 mm at speech frequencies. In group A, the air-bone gap improvement in the third follow-up was not significant (P > 0.05, whereas group B showed a statistically significant improvement (P = 0.003. The mean overclosure of air-bone gap was better in patients with 0.4 mm piston at speech frequencies and also at 250 Hz. Significantly, overclosure of air-bone gap at higher frequencies (4 and 8 KHz was seen only with a smaller sized piston. (0.4 mm. Discussion: We analyzed the effect of piston diameter on the hearing results after small fenestra stapedotomy by using similar surgical procedure and similar prosthesis in all patients. Conclusion: There is evidence to suggest that 0.4 mm piston may be better suited for providing optimum hearing results.

  7. Synchronizability on complex networks via pinning control

    Indian Academy of Sciences (India)

    Yi Liang; Xingyuan Wang

    2013-04-01

    It is proved that the maximum eigenvalue sequence of the principal submatrices of coupling matrix is decreasing. The method of calculating the number of pinning nodes is given based on this theory. The findings reveal the relationship between the decreasing speed of maximum eigenvalue sequence of the principal submatrices for coupling matrix and the synchronizability on complex networks via pinning control. We discuss the synchronizability on some networks, such as scale-free networks and small-world networks. Numerical simulations show that different pinning strategies have different pinning synchronizability on the same complex network, and the synchronizability with pinning control is consistent with one without pinning control in various complex networks.

  8. Loss terms in free-piston Stirling engine models

    Science.gov (United States)

    Gordon, Lloyd B.

    1992-01-01

    Various models for free piston Stirling engines are reviewed. Initial models were developed primarily for design purposes and to predict operating parameters, especially efficiency. More recently, however, such models have been used to predict engine stability. Free piston Stirling engines have no kinematic constraints and stability may not only be sensitive to the load, but also to various nonlinear loss and spring constraints. The present understanding is reviewed of various loss mechanisms for free piston Stirling engines and how they have been incorporated into engine models is discussed.

  9. Role Of Computational Simulations In The Design Of Piston Rings

    Directory of Open Access Journals (Sweden)

    Novotný Pavel

    2015-06-01

    Full Text Available The paper presents computational approaches using modern strategies for a dynamic piston ring solution as a fluid structural problem. Computational model outputs can be used to understand design parameter influences on defined results of a primarily integral character. Piston ring dynamics incorporates mixed lubrication conditions, the influence of surface roughness on oil film lubrication, the influence of ring movement on gas dynamics, oil film formulation on a cylinder liner and other significant influences. The solution results are presented for several parameters of SI engine piston rings.

  10. Reversible compression of an optical piston through Kramers dynamics

    CERN Document Server

    Schnoering, Gabriel

    2015-01-01

    We study the reversible crossover between stable and bistable phases of an over-damped Brownian bead inside an optical piston. The interaction potentials are solved developing a method based on Kramers' theory that exploits the statistical properties of the stochastic motion of the bead. We evaluate precisely the energy balance of the crossover. We show that the deformation of the optical potentials induced by the compression of the piston is related to a production of heat which measures the non-adiabatic character of the crossover. This reveals how specific thermodynamic processes can be designed and controlled with a high level of precision by tailoring the optical landscapes of the piston.

  11. Improved pinning regime by energetic ions using reduction of pinning potential

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, Roy; Gandini, Alberto; Sawh, Ravi-Persad; Parks, Drew; Mayes, Bill

    2003-05-15

    When ion damage is used to create pinning centers, full columnar pinning centers provide the largest pinning potential, U{sub pin}, but not the greatest J{sub c} or pinned field, B{sub pin}. Some of the characteristics of columnar defects which limit J{sub c} and B{sub pin} are discussed, including reduction of percolation path, and the need for a larger number of columns of damage, for pinning, than are usually estimated. It is concluded that columnar pinning centers are limited to B{sub pin}<4 T, and also severely reduce J{sub c}. Evidence is reviewed that aligned damage, or broken-columnar pinning centers, described herein, can provide orders of magnitude higher J{sub c}, and higher pinned field, despite providing lower U{sub pin}. A pinning center morphology is discussed which utilizes multiple-in-line-damage (MILD). For, e.g., present day large grain HTS J{sub c}, obtainable by MILD pinning, is estimated to be of the order of 10{sup 6} A/cm{sup 2} at 77 K, even when crystal plane alignment and weak links are not improved. Pinned field is increased by over an order of magnitude. An experiment is proposed to confirm these observations, and to directly compare MILD to columnar pinning centers. It will also determine the optimum MILD structure. Other measurements of interest, made possible by the same data set, are described.

  12. 内燃机活塞拍击动力学模型研究%Research on dynamical model of piston slap of internal combustion engine

    Institute of Scientific and Technical Information of China (English)

    郑光泽

    2013-01-01

    文中基于运动机构的振动响应分析方法,考虑活塞与连杆、曲轴及内燃机缸体的耦合振动对活塞拍击的影响,构建了内燃机活塞拍击动力学分析模型.应用本模型分析某型3.5L柴油发动机的活塞拍击现象,通过对比研究空载、满载工况下缸体的振动响应证明了动力学模型的有效性.理论分析了空载工况下内燃机零部件耦合振动特性对活塞拍击冲击力、活塞回转角度、连杆重心加速度及活塞拍击对连杆运动、曲轴扭转振动响应、主轴承座反力的影响机理.%Based on an analytical method on vibratory response of elastic part in movement, by taking the influence of coupled vibration of piston, connecting rod, crankshaft and engine block on piston slap into consideration, the dynamical model of piston slap is developed. Some type of 3. 5 L diesel engine' s piston slap phenomenon is analyzed by using this method, the comparisons of vibration response of engine block in both no-load and full-load conditions show that the validity of the this model. Finally, the displacement of piston gravity, rotation angle around piston pin, impact force induced by piston slap with coupled vibration and without coupled vibration is discussed in detail. The influence of piston slap on acceleration of connecting-rod gravity, torsional vibration of crankshaft and reaction force acting on main bearing are invested inverse.

  13. Experimental Evaluation of the Free Piston Engine - Linear Alternator (FPLA)

    Energy Technology Data Exchange (ETDEWEB)

    Leick, Michael T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moses, Ronald W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    This report describes the experimental evaluation of a prototype free piston engine - linear alternator (FPLA) system developed at Sandia National Laboratories. The opposed piston design wa developed to investigate its potential for use in hybrid electric vehicles (HEVs). The system is mechanically simple with two - stroke uniflow scavenging for gas exchange and timed port fuel injection for fuel delivery, i.e. no complex valving. Electrical power is extracted from piston motion through linear alternators wh ich also provide a means for passive piston synchronization through electromagnetic coupling. In an HEV application, this electrical power would be used to charge the batteries. The engine - alternator system was designed, assembled and operated over a 2 - year period at Sandia National Laboratories in Livermore, CA. This report primarily contains a description of the as - built system, modifications to the system to enable better performance, and experimental results from start - up, motoring, and hydrogen combus tion tests.

  14. Multiple Scattering: Dispersion, Temperature Dependence, and Annular Pistons

    CERN Document Server

    Milton, Kimball A; Parashar, Prachi; Cavero-Pelaez, Ines; Brevik, Iver; Ellingsen, Simen A

    2010-01-01

    We review various applications of the multiple scattering approach to the calculation of Casimir forces between separate bodies, including dispersion, wedge geometries, annular pistons, and temperature dependence. Exact results are obtained in many cases.

  15. Experimental Evaluation of the Free Piston Engine - Linear Alternator (FPLA).

    Energy Technology Data Exchange (ETDEWEB)

    Leick, Michael T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Moses, Ronald W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    This report describes the experimental evaluation of a prototype free piston engine - linear alternator (FPLA) system developed at Sandia National Laboratories. The opposed piston design wa developed to investigate its potential for use in hybrid electric vehicles (HEVs). The system is mechanically simple with two - stroke uniflow scavenging for gas exchange and timed port fuel injection for fuel delivery, i.e. no complex valving. Electrical power is extracted from piston motion through linear alternators wh ich also provide a means for passive piston synchronization through electromagnetic coupling. In an HEV application, this electrical power would be used to charge the batteries. The engine - alternator system was designed, assembled and operated over a 2 - year period at Sandia National Laboratories in Livermore, CA. This report primarily contains a description of the as - built system, modifications to the system to enable better performance, and experimental results from start - up, motoring, and hydrogen combus tion tests.

  16. Dynamics of a massive piston in an ideal gas

    Energy Technology Data Exchange (ETDEWEB)

    Chernov, N I [University of Alabama at Birmingham, Birmingham, Alabama (United States); Lebowitz, J L [Rutgers, State University of New Jersey, New Brunswick, NJ (United States); Sinai, Yakov G [L.D. Landau Institute for Theoretical Physics, Russian Academy of Sciences, Moscow (Russian Federation)

    2002-12-31

    This survey is a study of a dynamical system consisting of a massive piston in a cubic container of large size L filled with an ideal gas. The piston has mass M{approx}L{sup 2} and undergoes elastic collisions with N{approx}L{sup 3} non-interacting gas particles of mass m=1. It is found that under suitable initial conditions there is a scaling regime with time and space scaled by L in which the motion of the piston and the one-particle distribution of the gas satisfy autonomous coupled equations (hydrodynamic equations) such that in the limit L{yields}{infinity} the mechanical trajectory of the piston converges in probability to the solution of the hydrodynamic equations for a certain period of time. There is also a heuristic discussion of the dynamics of the system on longer intervals of time.

  17. Structural design of Stirling engine with free pistons

    Science.gov (United States)

    Matusov, Jozef; Gavlas, Stanislav; Malcho, Milan

    2014-08-01

    Stirling engine is a device that converts thermal energy to mechanical work, which is mostly used to drive a generator of electricity. Advantage of Stirling engine is that it works with closed-cycle, where working medium is regularly cooled and heated, which acts on the working piston. This engine can be made in three modifications - alpha, beta, gamma. This paper discusses the design of the gamma Stirling engine with free pistons.

  18. Gas Vapor Injection on Refrigerant Cycle Using Piston Technology

    OpenAIRE

    Colmek, Sophie; Goderneaux, Laurent

    2012-01-01

    Gas vapor injection on refrigerant cycle is always used with Scroll, Rotary or others compressors technology to improve efficiency of the system at low and high ambient temperatures. Probably this kind of compressor is more adapted than the piston technology owing to their mechanical system. In this paper, we present the challenge of vapor injection realized on piston technology compressor range non for improving the cooling capacity of the system but to maintain the compressor temperature in...

  19. Pinning-controllability of complex networks

    OpenAIRE

    Sorrentino, Francesco; Di Bernardo, Mario; Garofalo, Franco; Chen, Guanrong

    2007-01-01

    We study the problem of controlling a general complex network towards an assigned synchronous evolution, by means of a pinning control strategy. We define the pinning-controllability of the network in terms of the spectral properties of an extended network topology. The roles of the control and coupling gains as well as of the number of pinned nodes are also discussed.

  20. Premature aging syndrome.

    Science.gov (United States)

    Coppedè, Fabio

    2012-01-01

    Hutchinson-Gilford progeria syndrome and Werner syndrome are two of the best characterized human progeroid diseases with clinical features mimicking physiological aging at an early age. Both disorders have been the focus of intense research in recent years since they might provide insights into the pathology of normal human aging. The chapter contains a detailed description of the clinical features of both disorders and then it focuses on the genetics, the resulting biochemical alterations at the protein level and the most recent findings and hypotheses concerning the molecular basis of the premature aging phenotypes. A description of available diagnostic and therapeutic approaches is included.

  1. The problems of piston skirt microgeometry in combustion engines

    Science.gov (United States)

    Iskra, A.; Babiak, M.; Wróblewski, E.

    2016-09-01

    Geometry of the slot between piston bearing surface and cylinder bore affects the friction losses of the IC engine to the far extent. It appears that these losses depend more on the area covered with oil than the thickness of oil layer separating collaborating parts. Barrel-shaped or stepwise piston bearing surface is the way to reduce the oil covered area. Turns out that the referred to friction losses contributes more to area covered by the oil film than the film thickness of the separation elements cooperating. The method to reduce the area covered by the oil film is a modification of the bearing surface of the piston by adjusting the profile. This paper presents the results of simulation leading to the reduction in friction losses and abrasive wear of piston bearing surface and cylinder bore. Covering the piston bearing surface with a thin layer of graphite one can get an extremely advantageous tribological properties of the piston assembly which means the expected parameters of oil film and in a case of film rupture-an ignorable abrasive wear of the graphite layer and/or cylinder bore.

  2. Three dimensional Casimir piston for massive scalar fields

    CERN Document Server

    Lim, S C

    2008-01-01

    We consider Casimir force acting on a three dimensional rectangular piston due to a massive scalar field subject to periodic, Dirichlet and Neumann boundary conditions. Exponential cut-off method is used to derive the Casimir energy in the interior region and the exterior region separated by the piston. It is shown that the divergent term of the Casimir force acting on the piston due to the interior region cancels with that due to the exterior region, thus render a finite well-defined Casimir force acting on the piston. Explicit expressions for the total Casimir force acting on the piston is derived, which show that the Casimir force is always attractive for all the different boundary conditions considered. As a function of a -- the distance from the piston to the opposite wall, it is found that the magnitude of the Casimir force behaves like $1/a^4$ when $a\\to 0^+$ and decays exponentially when $a\\to \\infty$. Moreover, the magnitude of the Casimir force is always a decreasing function of a. On the other hand...

  3. Electromagnetic liquid pistons for capillarity-based pumping.

    Science.gov (United States)

    Malouin, Bernard A; Vogel, Michael J; Olles, Joseph D; Cheng, Lili; Hirsa, Amir H

    2011-02-07

    The small scales associated with lab-on-a-chip technologies lend themselves well to capillarity-dominated phenomena. We demonstrate a new capillarity-dominated system where two adjoining ferrofluid droplets can behave as an electronically-controlled oscillator or switch by an appropriate balance of magnetic, capillary, and inertial forces. Their oscillatory motion can be exploited to displace a surrounding liquid (akin to an axial piston pump), forming electromagnetic "liquid pistons." Such ferrofluid pistons can pump a precise volume of liquid via finely tunable amplitudes (cf. pump stroke) or resonant frequencies (cf. pump speed) with no solid moving parts for long-term operation without wear in a small device. Furthermore, the rapid propagation of electromagnetic fields and the favorable scaling of capillary forces with size permit micron sized devices with very fast operating speeds (∼kHz). The pumping dynamics and performance of these liquid pistons is explored, with experimental measurements showing good agreement with a spherical cap model. While these liquid pistons may find numerous applications in micro- and mesoscale fluidic devices (e.g., remotely activated drug delivery), here we demonstrate the use of these liquid pistons in capillarity-dominated systems for chip-level, fast-acting adaptive liquid lenses with nearly perfect spherical interfaces.

  4. Self-shearing retentive pins: a laboratory evaluation of pin channel penetration before shearing.

    Science.gov (United States)

    Barkmeier, W W; Cooley, R L

    1979-09-01

    This laboratory study determined the depth reached by self-shearing pins in dentin pin channels. Pin channels were prepared with the self-limiting shoulder twist drill for each of the four systems tested. Mean channel depth reached for the various pin systems was: Stabilok (small), 2.31 mm; Stabilok (medium), 1.78 mm; Reten Pin, 1.40 mm; and TMS (Regular), 2.04 mm. A coparison was also made by calculating the mean percent of penetration in relation to the depth of prepared pin channel: Stabilok (small), 92.50%; Stabilok (medium), 63.62%; Reten Pin, 66.67%; and TMS (Regular) 81.75%.

  5. Fluid Dynamics in Rotary Piston Blood Pumps.

    Science.gov (United States)

    Wappenschmidt, Johannes; Sonntag, Simon J; Buesen, Martin; Gross-Hardt, Sascha; Kaufmann, Tim; Schmitz-Rode, Thomas; Autschbach, Ruediger; Goetzenich, Andreas

    2017-03-01

    Mechanical circulatory support can maintain a sufficient blood circulation if the native heart is failing. The first implantable devices were displacement pumps with membranes. They were able to provide a sufficient blood flow, yet, were limited because of size and low durability. Rotary pumps have resolved these technical drawbacks, enabled a growing number of mechanical circulatory support therapy and a safer application. However, clinical complications like gastrointestinal bleeding, aortic insufficiency, thromboembolic complications, and impaired renal function are observed with their application. This is traced back to their working principle with attenuated or non-pulsatile flow and high shear stress. Rotary piston pumps potentially merge the benefits of available pump types and seem to avoid their complications. However, a profound assessment and their development requires the knowledge of the flow characteristics. This study aimed at their investigation. A functional model was manufactured and investigated with particle image velocimetry. Furthermore, a fluid-structure interaction computational simulation was established to extend the laboratory capabilities. The numerical results precisely converged with the laboratory measurements. Thus, the in silico model enabled the investigation of relevant areas like gap flows that were hardly feasible with laboratory means. Moreover, an economic method for the investigation of design variations was established.

  6. Visceral-locomotory pistoning in crawling caterpillars.

    Science.gov (United States)

    Simon, Michael A; Woods, William A; Serebrenik, Yevgeniy V; Simon, Sharotka M; van Griethuijsen, Linnea I; Socha, John J; Lee, Wah-Keat; Trimmer, Barry A

    2010-08-24

    Animals with an open coelom do not fully constrain internal tissues, and changes in tissue or organ position during body movements cannot be readily discerned from outside of the body. This complicates modeling of soft-bodied locomotion, because it obscures potentially important changes in the center of mass as a result of internal tissue movements. We used phase-contrast synchrotron X-ray imaging and transmission light microscopy to directly visualize internal soft-tissue movements in freely crawling caterpillars. Here we report a novel visceral-locomotory piston in crawling Manduca sexta larvae, in which the gut slides forward in advance of surrounding tissues. The initiation of gut sliding is synchronous with the start of the terminal prolegs' swing phase, suggesting that the animal's center of mass advances forward during the midabdominal prolegs' stance phase and is therefore decoupled from visible translations of the body. Based on synchrotron X-ray data and transmission light microscopy results, we present evidence for a two-body mechanical system with a nonlinear elastic gut that changes size and translates between the anterior and posterior of the animal. The proposed two-body system--the container and the contained--is unlike any form of legged locomotion previously reported and represents a new feature in our emerging understanding of crawling.

  7. Tribological properties of IF-MoS2 nanoparticles as lubricant additive on cylinder liner and piston ring tribo-pair

    OpenAIRE

    Charoo, M.S.; Wani, Mohammad Farooq

    2016-01-01

    Friction and wear behaviors of different concentrations of IF-MoS2 nanoparticles in SAE 20W40 were studied. First of all tribological tests with SAE 20W40 + IF-MoS2 were carried out on a four ball wear test machine as per ASTM D 4172 standard to study its wear properties. Detailed friction and wear studies on cylinder liner and piston ring tribo-pair were conducted on pin-on-block universal tribometer under lubricated conditions of SAE 20W40+ IF-MoS2. These experimental studies were conducted...

  8. Pinning control of chimera states

    Science.gov (United States)

    Gambuzza, Lucia Valentina; Frasca, Mattia

    2016-08-01

    The position of the coherent and incoherent domain of a chimera state in a ring of nonlocally coupled oscillators is strongly influenced by the initial conditions, making nontrivial the problem of confining them in a specific region of the structure. In this paper we propose the use of spatial pinning to induce a chimera state where the nodes belonging to one domain, either the coherent or the incoherent, are fixed by the control action. We design two different techniques according to the dynamics to be forced in the region of pinned nodes, and validate them on FitzHugh-Nagumo and Kuramoto oscillators. Furthermore, we introduce a suitable strategy to deal with the effects of finite size in small structures.

  9. Be on Pins and Needles

    Institute of Scientific and Technical Information of China (English)

    周立

    2003-01-01

    英语对话:A:It seems you’re on pins and needles today.Anything troubling you?B:Yeah.I don’t know why bad things keep happening to me .You see,mycar was stolen and the warehouse had been broken into.I can’t keep myfinger on the causes of this damned thing.A:There must be someone who had planned that.Do you have a partieularperson in mind?

  10. Mobile hydraulic power supply. Liquid piston Stirling engine pump

    Energy Technology Data Exchange (ETDEWEB)

    Ven, James D. van de [100 Institute Road, Department of Mechanical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609 (United States)

    2009-11-15

    Conventional mobile hydraulic power supplies involve numerous kinematic connections and are limited by the efficiency, noise, and emissions of internal combustion engines. The Stirling cycle possesses numerous benefits such as the ability to operate from any heat source, quiet operation, and high theoretical efficiency. The Stirling engine has seen limited success due to poor heat transfer in the working chambers, difficulty sealing low-molecular weight gases at high pressure, and non-ideal piston displacement profiles. As a solution to these limitations, a liquid piston Stirling engine pump is proposed. The liquid pistons conform to irregular volumes, allowing increased heat transfer through geometry features on the interior of the working chambers. Creating near-isothermal operation eliminates the costly external heat exchangers and increases the engine efficiency through decreasing the engine dead space. The liquid pistons provide a positive gas seal and thermal transport to the working chambers. Controlling the flow of the liquid pistons with valves enables matching the ideal Stirling cycle and creates a direct hydraulic power supply. Using liquid hydrogen as a fuel source allows cooling the compression side of the engine before expanded the fuel into a gas and combusting it to heat the expansion side of the engine. Cooling the compression side not only increases the engine power, but also significantly increases the potential thermal efficiency of the engine. A high efficiency Stirling engine makes energy regeneration through reversing the Stirling cycle practical. When used for regeneration, the captured energy can be stored in thermal batteries, such as a molten salt. The liquid piston Stirling engine pump requires further research in numerous areas such as understanding the behavior of the liquid pistons, modeling and optimization of a full engine pump, and careful selection of materials for the extreme operating temperatures. Addressing these obtainable

  11. Design Analysis and Optimization of Internal Combustion Engine Piston using CAE tool ANSYS

    Directory of Open Access Journals (Sweden)

    Aditya Kumar Gupta

    2014-11-01

    Full Text Available In the internal combustion engine there are many reciprocating parts which are responsible for giving the motion to the engine. from them the piston is very important part of the internal combustion engine.. The working condition of the piston is so worst in comparison of other parts of the internal combustion engine. There is very high probability to failure of the piston due to high wear and tear. So there is necessary to inspection the working condition of piston. In before there is no availability of software packages. So there is difficult to check out the failure of the piston, it is also very time taken process. In now days the software packages are used to consume less time and give quality assurance. In this study work there are two steps of analysis of the piston they are Designing and Analysis. Firstly design the model of the piston in giving design specification on the modelling software like INVENTOR . Then giving it the constraints which are act on the working condition of the piston after import the model of the piston into the analysis software ANSYS in IGES format. Then the analysis become completed on the different parameters(temperature, stress, deformation and easily analysis the result. In this work the piston become optimized after the reducing the material of the piston. the mass and volume of the piston become reduced. The deformation also increased after the optimization which is responsible for the stress distribution on the piston head or piston crown.

  12. Premature ovarian failure.

    Science.gov (United States)

    Shelling, Andrew N

    2010-11-01

    Premature ovarian failure (POF) is a common cause of infertility in women, and is characterised by amenorrhoea, hypo-oestrogenism and elevated gonadotrophin levels in women under the age of 40. Known causes include iatrogenic agents that cause permanent damage to the ovaries, such as chemotherapy, radiation therapy and surgery, autoimmune conditions, X-chromosome abnormalities and autosomal genetic conditions. However, few genes have been identified that can explain a substantial proportion of cases of POF. Most women with POF are deeply upset by the diagnosis, partly due to the unexpected menopausal symptoms, but also due to infertility. Therefore, early detection would provide better opportunity for early intervention, and furthermore, the identification of specific gene defects will help to direct potential targets for future treatment.

  13. Apnea of prematurity

    Directory of Open Access Journals (Sweden)

    Piermichele Paolillo

    2013-06-01

    Full Text Available Apnea of prematurity (AOP is one of the most frequent pathologies in the Neonatal Intensive Care Unit, with an incidence inversely related to gestational age. Its etiology is often multi factorial and diagnosis of idiopathic forms requires exclusion of other underlying diseases. Despite being a self-limiting condition which regresses with the maturation of the newborn, possible long-term effects of recurring apneas and the degree of desaturation and bradycardia who may lead to abnormal neurological outcome are not yet clarified. Therefore AOP needs careful evaluation of its etiology and adequate therapy that can be both pharmacological and non-pharmacological. Proceedings of the 9th International Workshop on Neonatology · Cagliari (Italy · October 23rd-26th, 2013 · Learned lessons, changing practice and cutting-edge research

  14. Premature ejaculation: A review

    Directory of Open Access Journals (Sweden)

    Sukumar Reddy Gajjala

    2014-01-01

    Full Text Available Premature ejaculation (PE is a common male sexual disorder. It is defined by the Diagnostic and statistical manual of mental disorders as "ejaculation occurring, without control, on or shortly after penetration and before the person wishes it, causing marked distress or interpersonal difficulty. [1] Although the timing of intravaginal ejaculatory latency time (IELT (i.e., time from penetration to ejaculation is not included in this definition, an IELT of <2 min, or ejaculation occurring before penetration, has been considered consistent with PE. [2] Management involves both the patient and his partner. Therapeutic options should suit both partners and be appropriate to their habit in planning and frequency of intercourse. Follow-up at appropriate intervals to judge efficacy, titrate dosage of pharmacological treatments and ascertain side effects is mandatory.

  15. Intrauterine infection and prematurity.

    Science.gov (United States)

    Gonçalves, Luís F; Chaiworapongsa, Tinnakorn; Romero, Roberto

    2002-01-01

    Intrauterine infection is a major cause of premature labor with and without intact membranes. Intrauterine infection is present in approximately 25% of all preterm births and the earlier the gestational age at delivery, the higher the frequency of intra-amniotic infection. Microorganisms may also gain access to the fetus before delivery. A fetal inflammatory response syndrome elicited in response to microbial products is associated with the impending onset of preterm labor and also with multi-systemic organ involvement in the human fetus and a higher rate of perinatal morbidity. The most common microorganisms involved in intrauterine infections are Ureaplasma urealyticum, Fusobacterium species and Mycoplasma hominis. The role of Chlamydia trachomatis and viruses in preterm labor remain to be determined. Use of molecular microbiology techniques to diagnose intrauterine infection may uncover the role of fastidious microorganisms that have not yet been discovered. Antibiotic administration to patients with asymptomatic bacteriuria is associated with a significant reduction in the rate of preterm birth. However, such benefit has not been demonstrated for patients with bacterial vaginosis, or women who carry Streptococcus agalactia, Ureaplasma urealyticum or Trichomonas vaginalis. Antibiotic administration to patients with preterm premature rupture of membranes is associated with prolongation of pregnancy and a reduction in the rate of clinical chorioamnionitis and neonatal sepsis. The benefit has not been demonstrated in patients with preterm labor and intact membranes. Major efforts are required to determine why some women develop an ascending intrauterine infection and others do not and also what interventions may reduce the deleterious effect of systemic fetal inflammation. Copyright 2002 Wiley-Liss, Inc.

  16. Apnea of Prematurity (For Parents)

    Science.gov (United States)

    ... other babies. The apnea of prematurity does not cause brain damage. A healthy baby who is apnea free for a week will probably never have AOP again. Although sudden infant death syndrome (SIDS) does happen more often in premature infants, no relationship between AOP and SIDS has ...

  17. Investigation of the bulk pinning force in YBCO superconducting films with nano-engineered pinning centres

    Science.gov (United States)

    Crisan, A.; Dang, V. S.; Yearwood, G.; Mikheenko, P.; Huhtinen, H.; Paturi, P.

    2014-08-01

    For practical applications of superconducting materials in applied magnetic fields, artificial pinning centres in addition to natural ones are required to oppose the Lorentz force. These pinning centres are actually various types of defects in the superconductor matrix. The pinning centres can be categorised on their dimension (volume, surface, or point) and on their character (normal cores or Δκ cores). We have used the Dew Hughes approach to determine the types of pinning centres present in various samples, with various thicknesses, temperatures and nanostructured additions to the superconducting matrix. Results show that normal surface pinning centres are present throughout almost all the samples, as dominant pinning mechanism. Such 2D extended pinning centres are mainly due to dislocations, grain boundaries, nanorods. Strong normal point pinning centres were found to be common in BZO doped YBCO samples. Other types of pinning centres, in various (minor) concentrations were also found in some of the samples.

  18. Instantaneous heat flux flowing into piston top-land surface of D.I. diesel engine; DI diesel kikan no piston top land bu eno shunji netsuryusoku

    Energy Technology Data Exchange (ETDEWEB)

    Taguma, M. [Zexel Corp., Tokyo (Japan); Inui, M.; Enomoto, Y.; Hagihara, Y. [Musashi Institute of Technology, Tokyo (Japan); Koyama, T. [Mitsubishi Motors Co., Tokyo (Japan)

    1997-10-01

    The thermal loads of the piston top-land surface in D.I. diesel engine during actual operation is not cleared. The authors fixed thin film thermocouples in the top-land center of a standard piston, and measured the instantaneous heat fluxes in that place. As a result, the authors made clear the thermal loads of the piston top-land surface in a cycle, and confirmed presence of the flame inflow to the piston top-land center. In addition, the authors made clear the thermal loads of the piston top-land surface in EGR operation. 4 refs., 8 figs.

  19. Alignment Pins for Assembling and Disassembling Structures

    Science.gov (United States)

    Campbell, Oliver C.

    2008-01-01

    Simple, easy-to-use, highly effective tooling has been devised for maintaining alignment of bolt holes in mating structures during assembly and disassembly of the structures. The tooling was originally used during removal of a body flap from the space shuttle Atlantis, in which misalignments during removal of the last few bolts could cause the bolts to bind in their holes. By suitably modifying the dimensions of the tooling components, the basic design of the tooling can readily be adapted to other structures that must be maintained in alignment. The tooling includes tapered, internally threaded alignment pins designed to fit in the bolt holes in one of the mating structures, plus a draw bolt and a cup that are used to install or remove each alignment pin. In preparation for disassembly of two mating structures, external supports are provided to prevent unintended movement of the structures. During disassembly of the structures, as each bolt that joins the structures is removed, an alignment pin is installed in its place. Once all the bolts have been removed and replaced with pins, the pins maintain alignment as the structures are gently pushed or pulled apart on the supports. In assembling the two structures, one reverses the procedure described above: pins are installed in the bolt holes, the structures are pulled or pushed together on the supports, then the pins are removed and replaced with bolts. The figure depicts the tooling and its use. To install an alignment pin in a bolt hole in a structural panel, the tapered end of the pin is inserted from one side of the panel, the cup is placed over the pin on the opposite side of the panel, the draw bolt is inserted through the cup and threaded into the pin, the draw bolt is tightened to pull the pin until the pin is seated firmly in the hole, then the draw bolt and cup are removed, leaving the pin in place. To remove an alignment pin, the cup is placed over the pin on the first-mentioned side of the panel, the draw

  20. Three-dimensional Casimir piston for massive scalar fields

    Science.gov (United States)

    Lim, S. C.; Teo, L. P.

    2009-08-01

    We consider Casimir force acting on a three-dimensional rectangular piston due to a massive scalar field subject to periodic, Dirichlet and Neumann boundary conditions. Exponential cut-off method is used to derive the Casimir energy. It is shown that the divergent terms do not contribute to the Casimir force acting on the piston, thus render a finite well-defined Casimir force acting on the piston. Explicit expressions for the total Casimir force acting on the piston is derived, which show that the Casimir force is always attractive for all the different boundary conditions considered. As a function of a - the distance from the piston to the opposite wall, it is found that the magnitude of the Casimir force behaves like 1/a4 when a→0+ and decays exponentially when a→∞. Moreover, the magnitude of the Casimir force is always a decreasing function of a. On the other hand, passing from massless to massive, we find that the effect of the mass is insignificant when a is small, but the magnitude of the force is decreased for large a in the massive case.

  1. A CWT-based methodology for piston slap experimental characterization

    Science.gov (United States)

    Buzzoni, M.; Mucchi, E.; Dalpiaz, G.

    2017-03-01

    Noise and vibration control in mechanical systems has become ever more significant for automotive industry where the comfort of the passenger compartment represents a challenging issue for car manufacturers. The reduction of piston slap noise is pivotal for a good design of IC engines. In this scenario, a methodology has been developed for the vibro-acoustic assessment of IC diesel engines by means of design changes in piston to cylinder bore clearance. Vibration signals have been analysed by means of advanced signal processing techniques taking advantage of cyclostationarity theory. The procedure departs from the analysis of the Continuous Wavelet Transform (CWT) in order to identify a representative frequency band of piston slap phenomenon. Such a frequency band has been exploited as the input data in the further signal processing analysis that involves the envelope analysis of the second order cyclostationary component of the signal. The second order harmonic component has been used as the benchmark parameter of piston slap noise. An experimental procedure of vibrational benchmarking is proposed and verified at different operational conditions in real IC engines actually equipped on cars. This study clearly underlines the crucial role of the transducer positioning when differences among real piston-to-cylinder clearances are considered. In particular, the proposed methodology is effective for the sensors placed on the outer cylinder wall in all the tested conditions.

  2. Transtibial prosthetic suspension: Less pistoning versus easy donning and doffing

    Directory of Open Access Journals (Sweden)

    Hossein Gholizadeh, MEngSc

    2012-12-01

    Full Text Available Poor suspension increases slippage of the residual limb inside the socket during ambulation. The main purpose of this article is to evaluate the pistoning at the prosthetic liner-socket interface during gait and assess patients’ satisfaction with two different liners. Two prostheses with seal-in and locking liners were fabricated for each of the 10 subjects with transtibial amputation. The Vicon motion system was used to measure the pistoning during gait. The subjects were also asked to complete a Prosthesis Evaluation Questionnaire. The results revealed higher pistoning inside the socket during gait with the locking liner than with the seal-in liner (p < 0.05. The overall satisfaction with the locking liner was higher (p < 0.05 because of the relative ease with which the patients could don and doff the device. As such, pistoning may not be the main factor that determines patients’ overall satisfaction with the prosthesis and other factors may also contribute to comfort and satisfaction with prostheses. The article also verifies the feasibility of the Vicon motion system for measuring pistoning during gait.

  3. Spherical rotary piston machine as an artificial heart.

    Science.gov (United States)

    Wipf, S L

    1991-01-01

    A positive displacement pump with six rotary pistons was proposed as an artificial heart. The pump's design was characterized by high symmetry and compactness. Thus, a spherical volume of 4 1/4 inch diameter sufficed for a pump delivering 10 L/min at 120 pulses/min with the pistons turning at 30 rpm. The pistons and four connecting gears were the only moving parts. The pump functions in two separate halves as left and right ventricles, with two of the six pistons each having inlet and outlet passages, and one of them replacing mitral and pulmonary valves with the other, tricuspid and aortic valves. The function of the intraventricular septum was provided by the other four pistons whose interiors also accommodated driving motors each capable of 0.4 Nm torque for a combined power of 5 watts. There were no stagnant regions in the pumping volume, and at all internal surfaces in contact with blood, there was periodic shear stress not exceeding approximately 300 Pa.

  4. Magnetic Piston Propagation in a 100-ns Plasma Opening Switch

    Science.gov (United States)

    Weingarten, A.; Grabowski, C.; Chakrabarti, N.; Maron, Y.; Fruchtman, A.

    1998-11-01

    The propagation of a magnetic piston through the plasma of a 90-ns, 170-kA POS is observed by studying the electron density, magnetic field, and ion velocity evolution. For the prefilled plasma n_e=(2.2± 0.5)× 10^14 cm-3, and T_e=5.5± 1 eV. The plasma composition is studied from absolute line intensities and collisional-radiative calculations. Most of the plasma ions are protons (90% near the cathode) with the rest being mainly CIV. The Hall-MHD conditions are not fulfilled for our experiment and ion motion is significant. The 3D-resolved ne evolution during the current pulse is studied from the line intensities of ions doped in the plasma using laser evaporation, and the magnetic field from Zeeman splitting. A diagonal magnetic piston propagates from the generator towards the load at about half the proton Alfven velocity. The protons are specularly reflected by the piston, while the heavy ions cross the potential hill in the piston, acquiring a lower velocity. The proton reflection causes an increase of ne ahead of the piston, followed by a sharp (10-20 ns) and substantial drop in ne (to 10-50% from the initial value). The magnetic field distribution studied using chordal observation, and theoretical analysis of ne and the magnetic field evolution are presented.

  5. Spectroscopic amplifier for pin diode; Amplificador espectroscopico para diodo Pin

    Energy Technology Data Exchange (ETDEWEB)

    Alonso M, M. S.; Hernandez D, V. M.; Vega C, H. R., E-mail: bebe.luna_s@hotmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

    2014-10-15

    The photodiode remains the basic choice for the photo-detection and is widely used in optical communications, medical diagnostics and field of corpuscular radiation. In detecting radiation it has been used for monitoring radon and its progeny and inexpensive spectrometric systems. The development of a spectroscopic amplifier for Pin diode is presented which has the following characteristics: canceler Pole-Zero (P/Z) with a time constant of 8 μs; constant gain of 57, suitable for the acquisition system; 4th integrator Gaussian order to waveform change of exponential input to semi-Gaussian output and finally a stage of baseline restorer which prevents Dc signal contribution to the next stage. The operational amplifier used is the TLE2074 of BiFET technology of Texas Instruments with 10 MHz bandwidth, 25 V/μs of slew rate and a noise floor of 17 nv/(Hz)1/2. The integrated circuit has 4 operational amplifiers and in is contained the total of spectroscopic amplifier that is the goal of electronic design. The results show like the exponential input signal is converted to semi-Gaussian, modifying only the amplitude according to the specifications in the design. The total system is formed by the detector, which is the Pin diode, a sensitive preamplifier to the load, the spectroscopic amplifier that is what is presented and finally a pulse height analyzer (Mca) which is where the spectrum is shown. (Author)

  6. Numerical simulation of piston ring in the mixed lubrication

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Piston and piston ring lubrication is a factor that strongly affects the performance of thereciprocating internal combustion engine. When the oil film thickness becomes smaller than a cer-tain value, depending upon the roughness of the surfaces in contact, mixed lubrication has to beconsidered. This paper analyzes the lubrication of piston ring and predicts pressure distribution,lubricant film thickness and surface deformation. The work is based on a unified numerical ap-proach assuming that the pressure distribution obeys Reynolds equation in hydrodynamic lubrica-tion regions while in asperities contact regions, the contact pressure can be obtained through theso-called reduced Reynolds equation. The computation experience shows the unified equationsystem is stable and can deal with severe operating conditions.

  7. RE-1000 free-piston Stirling engine update

    Science.gov (United States)

    Schreiber, J.

    1985-01-01

    A free piston Stirling engine was tested. The tests performed over the past several years on the single cylinder engine were designed to investigate the dynamics of a free piston Stirling engine. The data are intended to be used primarily for computer code validation. The tests designed to investigate the sensitivity of the engine performance to variations in working space pressure, heater and cooler temperatures, regenerator porosity, power piston mass and displacer dynamics were completed. In addition, some data were recorded with alternate working fluids. A novel resonant balance system for the engine was also tested. Some preliminary test results of the tests performed are presented along with an outline of future tests to be run with the engine coupled to a hydraulic output unit. A description of the hydraulic output unit is given.

  8. P-REx: the piston drift reconstruction experiment

    Science.gov (United States)

    Pott, Jörg-Uwe; Fu, Qiang; Widmann, Felix; Peter, Diethard

    2016-08-01

    For sensitive infra-red long-baseline interferometry, it is crucial to control the differential piston between the apertures. Classically this is achieved with a fringe tracker which measures the movement of the interferometric fringes. In this paper, we describe a new method to reconstruct the piston variation introduced by atmospheric turbulence with real-time data from adaptive optics wave-front sensing. Concurrently, the dominant wind speed vector can also be retrieved. The method is analyzed in simulation for atmospheric turbulence of various strength, and wind vectors varying with layer altitude. The results from the simulations show that this method could help to reliably retrieve the piston variation and wind speed from wavefront sensor data. The method is related to concepts of predictive control AO algorithms and reconstruction of the point spread function.

  9. Lubrication and tribology in seawater hydraulic piston pump

    Institute of Scientific and Technical Information of China (English)

    WANG Dong; LI Zhuang-yun; ZHU Yu-quan

    2003-01-01

    Water hydraulic systems have provoked major interest because of the human friendly and environmental safety aspects. Piston pump is one of the most frequently used hydraulic units in recent engineering technique. In water hydraulic piston pump, poor lubrication is more likely to happen than in oil hydraulic one because of difference in properties between water and oil. So there are some key problems such as corrosive wear and erosion, which are investigated briefly. Many new materials have been developed, which give longer life expectancies with water without corrosion and erosion. A new type of seawater hydraulic piston pumps with better suction characteristics had been developed at HUST. Much of this research has concentrated on new materials, structure and experiments, which are also specially introduced.

  10. RE-1000 free-piston Stirling engine update

    Science.gov (United States)

    Schreiber, J.

    1985-01-01

    A free piston Stirling engine was tested. The tests performed over the past several years on the single cylinder engine were designed to investigate the dynamics of a free piston Stirling engine. The data are intended to be used primarily for computer code validation. The tests designed to investigate the sensitivity of the engine performance to variations in working space pressure, heater and cooler temperatures, regenerator porosity, power piston mass and displacer dynamics were completed. In addition, some data were recorded with alternate working fluids. A novel resonant balance system for the engine was also tested. Some preliminary test results of the tests performed are presented along with an outline of future tests to be run with the engine coupled to a hydraulic output unit. A description of the hydraulic output unit is given.

  11. Prenatal Stress, Prematurity, and Asthma.

    Science.gov (United States)

    Medsker, Brock; Forno, Erick; Simhan, Hyagriv; Celedón, Juan C

    2015-12-01

    Asthma is the most common chronic disease of childhood, affecting millions of children in the United States and worldwide. Prematurity is a risk factor for asthma, and certain ethnic or racial minorities such as Puerto Ricans and non-Hispanic blacks are disproportionately affected by both prematurity and asthma. In this review, we examine current evidence to support maternal psychosocial stress as a putative link between prematurity and asthma, while also focusing on disruption of the hypothalamic-pituitary-adrenal (HPA) axis and immune responses as potential underlying mechanisms for stress-induced "premature asthma." Prenatal stress may cause not only abnormalities in the HPA axis but also epigenetic changes in the fetal glucocorticoid receptor gene (NR3C1), leading to impaired glucocorticoid metabolism. Moreover, maternal stress can alter fetal cytokine balance, favoring TH2 (allergic) immune responses characteristic of atopic asthma: interleukin 6 (IL-6), which has been associated with premature labor, can promote TH2 responses by stimulating production of IL-4 and IL-13. Given a link among stress, prematurity, and asthma, future research should include birth cohorts aimed at confirming and better characterizing "premature asthma." If confirmed, clinical trials of prenatal maternal stress reduction would be warranted to reduce the burden of these common comorbidities. While awaiting the results of such studies, sound policies to prevent domestic and community violence (eg, from firearms) are justified, not only by public safety but also by growing evidence of detrimental effects of violence-induced stress on psychiatric and somatic health.

  12. Assembly for electrical conductivity measurements in the piston cylinder device

    Science.gov (United States)

    Watson, Heather Christine [Dublin, CA; Roberts, Jeffrey James [Livermore, CA

    2012-06-05

    An assembly apparatus for measurement of electrical conductivity or other properties of a sample in a piston cylinder device wherein pressure and heat are applied to the sample by the piston cylinder device. The assembly apparatus includes a body, a first electrode in the body, the first electrode operatively connected to the sample, a first electrical conductor connected to the first electrode, a washer constructed of a hard conducting material, the washer surrounding the first electrical conductor in the body, a second electrode in the body, the second electrode operatively connected to the sample, and a second electrical conductor connected to the second electrode.

  13. Experimental Study on the WavePiston Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Angelelli, E.

    This report presents the results of an experimental study of the power performance of the WavePiston wave energy converter. It focuses mainly on evaluating the power generating capabilities of the device and the effect of the following issues: Scaling ratios PTO loading Wave height and wave period...... dependency Oblique incoming waves Distance between plates During the study, the model supplied by the client, WavePiston, has been rigorously tested as all the anticipated tests have been done thoroughly and during all tests, good quality data has been obtained from all the sensors....

  14. A mechanical model of an axial piston machine

    OpenAIRE

    Löfstrand Grip, Rasmus

    2009-01-01

    A mechanical model of an axial piston-type machine with a so-called wobble plate and Z-shaft mechanism is presented. The overall aim is to design and construct an oil-free piston expander demonstrator as a first step to realizing an advanced and compact small-scale steam engine system. The benefits of a small steam engine are negligible NOx emissions (due to continuous, low-temperature combustion), no gearbox needed, fuel flexibility (e.g., can run on biofuel and solar), high part-load effici...

  15. Mathematical Model of Piston Ring Sealing in Combustion Engine

    Directory of Open Access Journals (Sweden)

    Koszałka Grzegorz

    2015-01-01

    Full Text Available This paper presents a mathematical model of piston-rings-cylinder sealing (TPC of a combustion engine. The developed model is an itegrated model of gas flow through gaps in TPC unit, displacements and twisting motions of piston rings in ring grooves as well as generation of oil film between ring face surfaces and cylinder liner. Thermal deformations and wear of TPC unit elements as well as heat exchange between flowing gas and surrounding walls, were taken into account in the model. The paper contains descriptions of: assumptions used for developing the model, the model itself, its numerical solution as well as its computer application for carrying out simulation tests.

  16. Mathematical Model of Piston Ring Sealing in Combustion Engine

    OpenAIRE

    Koszałka Grzegorz; Guzik Mirosław

    2015-01-01

    This paper presents a mathematical model of piston-rings-cylinder sealing (TPC) of a combustion engine. The developed model is an itegrated model of gas flow through gaps in TPC unit, displacements and twisting motions of piston rings in ring grooves as well as generation of oil film between ring face surfaces and cylinder liner. Thermal deformations and wear of TPC unit elements as well as heat exchange between flowing gas and surrounding walls, were taken into account in the model. The pape...

  17. Uncertainty of pin height measurement for the determination of wear in pin-on-plate test

    DEFF Research Database (Denmark)

    Drago, Nicola; De Chiffre, Leonardo; Poulios, Konstantinos

    2014-01-01

    machine (CMM), achieving an expanded measurement uncertainty (k = 2) better than 1 mm. A simple dedicated fixture adaptable to workshop environment was developed and its metrological capability investigated, estimating an average uncertainty of measurement in the order of 5 mm (k = 2). Fixture......The paper concerns measurement of pin height for the determination of wear in a pin-on-plate (POP) or pin-on-disc (POD) test, where a pin is mounted on a holder that can be fixed on the test rig and removed for measurements. The amount of wear is assessed as difference of pin height before...... and after the test, using the distance between holder plane and pin friction plane as measurand. A series of measurements were performed in connection with POP testing of different friction material pins mounted on an aluminium holder. Pin height measurements were carried out on a coordinate measuring...

  18. Improved shock-detection pin arrangement

    Energy Technology Data Exchange (ETDEWEB)

    Erskine, D.J.

    1995-08-01

    Shockwave speeds are often measured by comparing arrival times at the tips of electrical shorting pins in a hexagonal array over two elevations (called up and down). In the conventional arrangement, the center pin is solely responsible for measuring the curvature of the wavefront. Without this datum the shock speed cannot be precisely determined. In some experiments this pin fail frequently enough to be a problem. We report a simple rearrangement between up and down designated pins which eliminates the critical reliance on a single.

  19. PIN1 gene variants in Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Siedlecki Janusz

    2009-11-01

    Full Text Available Abstract Background Peptidyl-prolyl isomerase, NIMA-interacting 1 (PIN1 plays a significant role in the brain and is implicated in numerous cellular processes related to Alzheimer's disease (AD and other neurodegenerative conditions. There are confounding results concerning PIN1 activity in AD brains. Also PIN1 genetic variation was inconsistently associated with AD risk. Methods We performed analysis of coding and promoter regions of PIN1 in early- and late-onset AD and frontotemporal dementia (FTD patients in comparison with healthy controls. Results Analysis of eighteen PIN1 common polymorphisms and their haplotypes in EOAD, LOAD and FTD individuals in comparison with the control group did not reveal their contribution to disease risk. In six unrelated familial AD patients four novel PIN1 sequence variants were detected. c.58+64C>T substitution that was identified in three patients, was located in an alternative exon. In silico analysis suggested that this variant highly increases a potential affinity for a splicing factor and introduces two intronic splicing enhancers. In the peripheral leukocytes of one living patient carrying the variant, a 2.82 fold decrease in PIN1 expression was observed. Conclusion Our data does not support the role of PIN1 common polymorphisms as AD risk factor. However, we suggest that the identified rare sequence variants could be directly connected with AD pathology, influencing PIN1 splicing and/or expression.

  20. Tribological Properties of IF-MoS2 Nanoparticles as Lubricant Additive on Cylinder Liner and Piston Ring Tribo-pair

    Directory of Open Access Journals (Sweden)

    M.S. Charoo

    2016-06-01

    Full Text Available Friction and wear behaviors of different concentrations of IF-MoS2 nanoparticles in SAE 20W40 were studied. First of all tribological tests with SAE 20W40 + IF-MoS2 were carried out on a four ball wear test machine as per ASTM D 4172 standard to study its wear properties. Detailed friction and wear studies on cylinder liner and piston ring tribo-pair were conducted on pin-on-block universal tribometer under lubricated conditions of SAE 20W40+ IF-MoS2. These experimental studies were conducted at different operating parameters to ascertain the influence of nanoadditive on friction and wear of cylinder liner and piston ring tribo-pair. A minimum coefficient of friction of 0.0772 was observed for 0.5 wt% of IF-MoS2 at normal load of 100 N at sliding velocity of 0.03 m/sec. A substantial reduction of 65 % in the wear of cylinder liner and piston ring tribo-pair was also observed when lubricated with SAE 20W40 and 0.5 wt% of IF-MoS2. Scanning electron microscopy and energy dispersive spectrometry analysis of the worn out surfaces was also carried out to find the causes for observed friction and wear behavior.

  1. CAD/CAM/CAI Application for High-Precision Machining of Internal Combustion Engine Pistons

    Directory of Open Access Journals (Sweden)

    V. V. Postnov

    2014-07-01

    Full Text Available CAD/CAM/CAI application solutions for internal combustion engine pistons machining was analyzed. Low-volume technology of internal combustion engine pistons production was proposed. Fixture for CNC turning center was designed.

  2. Simulation of a Martini Displacer Free Piston Stirling Engine for Electric Power Generation

    National Research Council Canada - National Science Library

    Pascal Stouffs; Nasser Seraj Mehdizadeh

    2000-01-01

    .... A dynamic simulation of this engine has been developed using a decoupled analysis. The equation of motion of the free piston induces a strong coupling between the electrical load and the thermodynamics inside the free piston Stirling engine...

  3. 往复活塞压缩机的偏心活塞%Off-centre Piston in Reciprocator Piston Compressor

    Institute of Scientific and Technical Information of China (English)

    许大钊

    2011-01-01

    This article has given kinematical analytics and dynamical analytics for the off-centre piston in the crank link mechanism.According to the results of the theoretic analytics, the features and applications of the offcentre piston have been pointed out.%对偏心活塞的曲柄连杆机构进行运动分析和动力分析.根据理论分析的结果,提出了偏心活塞曲柄连杆机构的特点及其应用.

  4. Premature ovarian failure

    Directory of Open Access Journals (Sweden)

    Vujović Svetlana

    2012-01-01

    Full Text Available Premature ovarian failure (POF is the occurrence of hypergonadotropic hypoestrogenic amenorrhea in women under the age of forty years. It is idiopathic in 74-90% patients. Known cases can be divided into primary and secondary POF. In primary POF genetic aberrations can involve the X chromosome (monosomy, trisomy, translocations, deletions or autosomes. Genetic mechanisms include reduced gene dosage and non-specific chromosome effects impairing meiosis, decreasing the pool of primordial follicles and increasing atresia due to apoptosis or failure of follicle maturation. Autoimmune ovarian damage is caused by alteration of T-cell subsets and T-cell mediated injury, increase of autoantibody producing B-cells, a low number of effector/cytotoxic lymphocyte, which decreases the number and activity of natural killer cells. Bilateral oophorectomy, chemotherapy, radiotherapy and infections cause the secondary POF. Symptoms of POF include irritability, nervousness, loss of libido, depression, lack of concentration, hot flushes, weight gaining, dry skin, vaginal dryness, frequent infections etc. The diagnosis is confirmed by the level of FSH of over 40 IU/L and estradiol below 50 pmol/L in women aged below 40 years. Biochemical and other hormonal analysis (free thyroxin, TSH, prolactin, testosterone, karyotype (<30 years of age, ultrasound of the breasts and pelvis are advisable. Optimal therapy is combined estrogen progestagen therapy given in a sequential rhythm, after excluding absolute contraindications. Testosterone can be added to adnexectomized women and those with a low libido. Sequential estrogen progestagen replacement therapy is the first line therapy for ovulation induction in those looking for pregnancy and after that oocyte donation will be advised. Appropriate estro-progestagen therapy improves the quality of life and prevents complications such as cardiovascular diseases, osteoporosis, stroke etc.

  5. STUDY ON RECIPROCATING SEALS FOR A LARGER DIAMETER AXIAL PISTON

    Institute of Scientific and Technical Information of China (English)

    Yang Jian; Yang Huayong; Xu Bing

    2004-01-01

    Sealing performance of the reciprocating seals on a larger diameter (100 mm in diameter ) axial piston is theoretically investigated.Based on the characteristics of the clearance flow between the seal and the piston, reasonable boundary conditions for Navier-Stokes equations are determined and the equations are modified, so that the final equations can describe the real flow state of the clearance flow.Through combining the final equations with finite element method, the pressure distributions within the clearance field during the reciprocating motion of the piston and the leakage rate with the pressure are studied.The deflections of the seal which affect sealing performance are calculated as well.Sealing performance of piston seals using oil as the working liquid is compared with using water.It is concluded that the seal using water as the working liquid is under dry friction, which cannot be dealt with the theory of fluid mechanics.The seal structure is only acceptable using oil as the working liquid..

  6. Experiments on the WavePiston, Wave Energy Converter

    DEFF Research Database (Denmark)

    Angelelli, E.; Zanuttigh, B.; Kofoed, Jens Peter

    2011-01-01

    This paper analyses the performance of a new Wave Energy Converter (WEC) of the Oscillating Water Column type (OWC), named WavePiston. This near-shore floating device is composed of plates (i.e. energy collectors) sliding around a cylinder, that is placed perpendicular to the shore. Tests...

  7. Spatial impulse responses from a flexible baffled circular piston

    NARCIS (Netherlands)

    Aarts, R.M.; Janssen, A.J.E.M.

    2011-01-01

    The theory of orthogonal polynomial (Zernike) expansions of functions on a disk, as used in the diffraction theory of optical aberrations, is applied to obtain (semi-) analytical expressions for the spatial impulse responses arising from a non-uniformly moving, baffled, circular piston. These expres

  8. ІNVESTIGATION OF PECULIARITIES OF PISTON RINGS LASER BORATING

    Directory of Open Access Journals (Sweden)

    BOLSHAKOV V. I.

    2015-11-01

    Full Text Available Problem formulation. Piston rings are subject to wear while in operation. Insufficient wear resistance of materials limits the growth of machines productivity as well as the terms of their exploitation. The required complex of properties of piston rings made of cast iron cannot be always reached by applying traditional methods of heat treatment or chemical heat treatment processing. Thus, application of traditional borating methods associated with diffusion of boron into the solid phase leads to the formation of the working layer exhibiting high brittleness. Therefore, the problem of increasing the wear resistance of piston rings without embrittlement is challenging. The use oflaser heating during borating provides the formation of a new layer with special properties. However, the optimum properties can be achieved only after determining the relationship between the parameters of running a process and the depth of the borated layer. Goal of research. To determine the influence of laser heating parameters on the depth of the borated layer, as the properties of piston rings depend on the depth of the latter. Conclusions. Increase in the speed of displacing parts during laser heating reduces the depth of the borated layer, and increase of the spot diameter enhances the depth of the layer. The phases and structural components of the borated layer were interpreted by means of X-ray and metallographic methods. The results of investigations can be applied to other machine parts, which are subject to intensive wear.

  9. Closing the innovation cycle in lightweighting compressor pistons technolog

    NARCIS (Netherlands)

    Wentzel, C.; Eijk, A.; Groenewegen, G.; Bergsma, O.

    2016-01-01

    What started out as an exercise in exploring the weight reduction potential of those allegedly “heavy recip crossheads”, turned out to be a fast leap towards implementation of a new hybrid material concept for very lightweight pistons. This was enabled by a next phase in the EFRC R&D group research

  10. Development and Testing of a Novel Green Propellant Piston Tank

    Science.gov (United States)

    Diaz, C. E.; Cavender, D. P.; Higdon, K.; Abrams, J.; Duchek, M. E.; Mader, H.

    2017-01-01

    Analytical Mechanics Associates (AMA), in cooperation with NASA Marshall Space Flight Center's (MSFC's) Spacecraft Propulsion Systems Branch, developed and tested a novel propellant tank design that employs an internal piston pressurized with an inert gas to expel propellant to thrusters. During the course of this activity, AMA designed, oversaw fabrication, and delivered to MSFC for testing, a piston propellant tank sized for 3U or larger CubeSats. MSFC conducted liquid expulsion testing using ethylene glycol as a referee fluid to map the tank's performance at different pressures and piston positions. Following the expulsion test campaign, the tank is planned to be integrated into a propulsion system test bed for hot fire tests with a 100mN monopropellant thruster to evaluate the tank's influence on thruster performance when operated in a flight like manner. Described in this paper is a comprehensive summary of how the tanks were designed, built, and tested. The fundamental knowledge gained through the fabrication and testing of these tanks gives evidence that the piston tank design may be scalable to meet the requirements and constraints of other small satellites.

  11. Preterm labor and premature birth: Are you at risk?

    Science.gov (United States)

    ... labor and premature birth: Are you at risk? Preterm labor and premature birth: Are you at risk? ... for preterm labor and premature birth. What are preterm labor and premature birth? Preterm and premature mean ...

  12. The maize PIN gene family of auxin transporters

    Directory of Open Access Journals (Sweden)

    Cristian eForestan

    2012-02-01

    Full Text Available Auxin is a key regulator of plant development and its differential distribution in plant tissues, established by a polar cell-to-cell transport, can trigger a wide range of developmental processes. A few members of the two families of auxin efflux transport proteins, PIN-formed (PIN and P-glycoprotein (ABCB/PGP, have so far been characterized in maize. Nine new Zea mays auxin efflux carriers PIN family members and two maize PIN-like genes have now been identified. Four members of PIN1 (named ZmPIN1a–d cluster, one gene homologous to AtPIN2 (ZmPIN2, three orthologs of PIN5 (ZmPIN5a–c, one gene paired with AtPIN8 (ZmPIN8, and three monocot-specific PINs (ZmPIN9, ZmPIN10a and b were cloned and the phylogenetic relationships between early land plants, monocots and eudicots PIN proteins investigated, including the new maize PIN proteins. Tissue-specific expression patterns of the twelve maize PIN genes, two PIN-like genes and ZmABCB1, an ABCB auxin efflux carrier, were analyzed using semi-quantitative RT–PCR. ZmPIN gene transcripts have overlapping expression domains in the root apex, during male and female inflorescence differentiation and kernel development. However, some PIN family members have specific tissue localization: ZmPIN1d transcript marks the L1 layer of the SAM and IM during the flowering transition and the monocot-specific ZmPIN9 is expressed in the root endodermis and pericycle. The phylogenetic and gene structure analyses together with the expression pattern of the ZmPIN gene family indicate that subfunctionalization of some maize PINs can be associated to the differentiation and development of monocot-specific organs and tissues and might have occurred after the divergence between dicots and monocots.

  13. Pinning impulsive control algorithms for complex network.

    Science.gov (United States)

    Sun, Wen; Lü, Jinhu; Chen, Shihua; Yu, Xinghuo

    2014-03-01

    In this paper, we further investigate the synchronization of complex dynamical network via pinning control in which a selection of nodes are controlled at discrete times. Different from most existing work, the pinning control algorithms utilize only the impulsive signals at discrete time instants, which may greatly improve the communication channel efficiency and reduce control cost. Two classes of algorithms are designed, one for strongly connected complex network and another for non-strongly connected complex network. It is suggested that in the strongly connected network with suitable coupling strength, a single controller at any one of the network's nodes can always pin the network to its homogeneous solution. In the non-strongly connected case, the location and minimum number of nodes needed to pin the network are determined by the Frobenius normal form of the coupling matrix. In addition, the coupling matrix is not necessarily symmetric or irreducible. Illustrative examples are then given to validate the proposed pinning impulsive control algorithms.

  14. Nanoscale pinning effect evaluated from deformed nanobubbles

    Science.gov (United States)

    Teshima, Hideaki; Nishiyama, Takashi; Takahashi, Koji

    2017-01-01

    Classical thermodynamics theory predicts that nanosized bubbles should disappear in a few hundred microseconds. The surprisingly long lifetime and stability of nanobubbles are therefore interesting research subjects. It has been proposed that the stability of nanobubbles arises through pinning of the three-phase contact line, which results from intrinsic nanoscale geometrical and chemical heterogeneities of the substrate. However, a definitive explanation of nanobubble stability is still lacking. In this work, we examined the stability mechanism by introducing a "pinning force." We investigated nanobubbles at a highly ordered pyrolytic graphite/pure water interface by peak force quantitative nano-mechanical mapping and estimated the pinning force and determined its maximum value. We then observed the shape of shrinking nanobubbles. Because the diameter of the shrinking nanobubbles was pinned, the height decreased and the contact angle increased. This phenomenon implies that the stability results from the pinning force, which flattens the bubble through the pinned three-phase contact line and prevents the Laplace pressure from increasing. The pinning force can also explain the metastability of coalesced nanobubbles, which have two semispherical parts that are joined to form a dumbbell-like shape. The pinning force of the semispherical parts was stronger than that of the joint region. This result demonstrates that the contact line of the semispherical parts is pinned strongly to keep the dumbbell-like shape. Furthermore, we proposed a nanobubble generation mechanism for the solvent-exchange method and explained why the pinning force of large nanobubbles was not initially at its maximum value, as it was for small nanobubbles.

  15. Pattern Reconfigurable Patch Antenna menggunakan Edge Shorting Pin dan Symmetrical Control Pin

    Directory of Open Access Journals (Sweden)

    DWI ANDI NURMANTRIS

    2016-02-01

    Full Text Available Abstrak Metode baru dalam mendesain suatu pattern reconfigurable antenna telah diteliti. Penelitian ini fokus pada optimasi antena patch lingkaran single layer pencatuan probe koaksial dengan mengintegrasikan 24 switch/shorting pin pada sisi patch yang disebut edge shorting pin dan 8 shorting pin membentuk lingkaran dengan radius tertentu dan selanjutnya disebut symmetrical control pin yang fungsinya sebagai metode penyepadan impedansi. Algoritma Genetika yang dikombinasikan dengan Finite Element Software digunakan untuk mengoptimasi kombinasi  switch, radius lingkaran symmetrical control pin, dan radius patch untuk mendapatkan kemampuan pattern reconfigurability. Antena ini menghasilkan 8 kemungkinan arah radiasi azzimuth dengan resolusi 45o dan arah elevasi 30o pada frekuensi 2,4 Ghz. Optimasi, simulasi, fabrikasi, dan pengukuran dilakukan untuk memverifikasi hasil penelitian. Kata kunci: Patch Lingkaran, Edge Shorting Pin, Symmetrical Control Pin, Algoritma Genetika, Pattern Reconfigurable   Abstract New method for desaining pattern reconfigurable antenna was studied. This study focuses on the optimization of a single layer circular patch antenna with probe feed by integrating the 24 switch / shorting pin on the side of the patch that called Edge Shorting Pins and 8 shorting pins form circular line in such radius that called Symmetrical Control Pins as a impedance matching method. Genetic algorithm combined with the Finite Element Software is used to optimize the switch combination, the radius of circular line of symmetrical control pins, and the patch radius to obtain a pattern reconfigurability capabilities. This antenna produces 8 possible directions of azimuth radiation with a resolution of 45o and 30o elevation direction at a frequency of 2.4 GHz. Optimization, simulation, fabrication, and measurement was done to verify the results. Keywords: Circular Patch, Edge Shorting Pin, Symmetrical Control Pin, Genetic Algorithm, Pattern

  16. Effects of Auxins on PIN-FORMED2 (PIN2) Dynamics Are Not Mediated by Inhibiting PIN2 Endocytosis.

    Science.gov (United States)

    Jásik, Ján; Bokor, Boris; Stuchlík, Stanislav; Mičieta, Karol; Turňa, Ján; Schmelzer, Elmon

    2016-10-01

    By using the photoconvertible fluorescence protein Dendra2 as a tag we demonstrated that neither the naturally occurring auxins indole-3-acetic acid and indole-3-butyric acid, nor the synthetic auxin analogs 1-naphthaleneacetic acid and 2,4-dichlorophenoxyacetic acid nor compounds inhibiting polar auxin transport such as 2,3,5-triiodobenzoic acid and 1-N-naphthylphthalamic acid, were able to inhibit endocytosis of the putative auxin transporter PIN-FORMED2 (PIN2) in Arabidopsis (Arabidopsis thaliana) root epidermis cells. All compounds, except Indole-3-butyric acid, repressed the recovery of the PIN2-Dendra2 plasma membrane pool after photoconversion when they were used in high concentrations. The synthetic auxin analogs 1-naphthaleneacetic acid and 2,4-dichlorophenoxyacetic acid showed the strongest inhibition. Auxins and auxin transport inhibitors suppressed also the accumulation of both newly synthesized and endocytotic PIN2 pools in Brefeldin A compartments (BFACs). Furthermore, we demonstrated that all compounds are also interfering with BFAC formation. The synthetic auxin analogs caused the highest reduction in the number and size of BFACs. We concluded that auxins and inhibitors of auxin transport do affect PIN2 turnover in the cells, but it is through the synthetic rather than the endocytotic pathway. The study also confirmed inappropriateness of the BFA-based approach to study PIN2 endocytosis because the majority of PIN2 accumulating in BFACs is newly synthesized and not derived from the plasma membrane. © 2016 American Society of Plant Biologists. All Rights Reserved.

  17. Durability Assessment of Cylinder Block for Two Stroke Free Piston Linear Engine using Random Loading

    Directory of Open Access Journals (Sweden)

    M. M. Rahman

    2009-01-01

    Full Text Available This research presents the durability assessment of cylinder block for a two-stroke free piston engine using narrow band approach. The life prediction results are worthy for improving the component design at the very early developing stage. This approach is adequate for periodic loading, however, requires very large time records to accurately describe random loading processes. Fatigue damage in conventionally determined from time signals of the loading, frequently in the form of stress and strain. However, there are scenarios when a spectral form of loading is more appropriate. In this case the loading is defined in terms of its magnitude at different frequencies in the form of a Power Spectral Density (PSD plot. The vibration fatigue calculation can be utilized where the random loading and response are categorized using power spectral density functions and the dynamic structure is modeled as a linear transfer function. This research also investigates the effect of the mean stress on the fatigue life prediction using the random loading. The acquired results indicate that the Goodman mean stress correction method gives the most conservative results with the Gerber and no (zero mean stress method. It is observed that the compressive mean stresses are beneficial while the tensile mean stresses are detrimental to the fatigue life. The proposed technique is capable of determining premature products failure phenomena. Therefore, this technique is able to reduce cost, time to market, improve the product reliability and finally the user confidence.

  18. Pinning controllability of complex networks with community structure.

    Science.gov (United States)

    Miao, Qingying; Tang, Yang; Kurths, Jürgen; Fang, Jian-an; Wong, W K

    2013-09-01

    In this paper, we study the controllability of networks with different numbers of communities and various strengths of community structure. By means of simulations, we show that the degree descending pinning scheme performs best among several considered pinning schemes under a small number of pinned nodes, while the degree ascending pinning scheme is becoming more powerful by increasing the number of pinned nodes. It is found that increasing the number of communities or reducing the strength of community structure is beneficial for the enhancement of the controllability. Moreover, it is revealed that the pinning scheme with evenly distributed pinned nodes among communities outperforms other kinds of considered pinning schemes.

  19. Simulation of Thermal-Mechanical Strength for Marine Engine Piston Using FEA

    Directory of Open Access Journals (Sweden)

    Jiang Guo He

    2014-03-01

    Full Text Available Simulation of Thermal-Mechanical Strength for Marine Engine Piston Using FEA Abstract: This paper involves simulation of a 2-stroke 6S35ME marine diesel engine piston to determine its temperature field, thermal, mechanical and coupled thermal-mechanical stress. The distribution and magnitudes of the afore-mentioned strength parameters are useful in design, failure analysis and optimization of the engine piston. The piston model was developed in solid-works and imported into ANSYS for preprocessing, loading and post processing. Material model chosen was 10-node tetrahedral thermal solid 87. The simulation parameters used in this paper were piston material, combustion pressure, inertial effects and temperature. The highest calculated stress was the thermal-mechanical coupled stress and was below the yield stress of the piston material (580Mpa at elevated temperatures hence the piston would withstand the induced stresses during work cycles.

  20. NUMERICAL ANALYSIS OF STRIKE OF PISTON TO CYLINDER UNDER SUPERCHARGE CONDITIONS

    Institute of Scientific and Technical Information of China (English)

    余志壮; 宋正华; 董光能; 谢友柏

    2004-01-01

    Objective To investigate the changes to the strike extent of piston to cylinder after engine supercharge design. Methods The lubrication model between the skirt of piston and liner is established by means of piston dynamics, combined with the hydrodynamic lubrication equation. Optimized numerical analysis method is employed in solving the dynamics and lubrication equations. The analyses about piston strike under two combustion gas pressures are performed. Results The peak values of maximum eccentricity under supercharge condition are much greater than under non-supercharge condition, which means a stronger impulsion of piston to cylinder wall and a greater possibility of scuffing. The horizontal velocities of piston in supercharge condition are larger, which illuminate the more unstable motion state. Conclusion The analysis gives a new conclusion. Combustion gas pressure plays an important role in the piston strike motion. Influences of supercharge should be taken into account so that the traditional product test items can be improved.

  1. Liner surface improvements for low friction piston ring packs

    Science.gov (United States)

    Anderberg, C.; Dimkovski, Z.; Rosén, B.-G.

    2014-01-01

    The development of engine components in the automotive industry is governed by several constraints such as environmental legislation and customer expectations. About a half of the frictional losses in an internal combustion engine come from the interactions between the piston assembly and cylinder liner surface. The tribological considerations in the contact between the piston ring and cylinder liner have attracted much attention over the past few decades. Many non-conventional cylinder liner finishes have been, and are being, developed with the aim to reduce friction losses and oil consumption, but the effects of the surface finish on piston ring pack performance is not well understood. One way of reducing friction in the cylinder system is to reduce the tangential load from the piston ring pack, focusing on the oil control ring. However, the side-effect of this is a disappointingly increased oil consumption. In this study a number of different cylinder liner surface specifications were developed and implemented in test engines with the aim of maintaining the level for oil consumption when decreasing the tangential load for the piston ring pack. To improve our understanding of the result, the same surfaces were evaluated in elastic and elasto-plastic rough contact and hydrodynamic flow simulation models. It is shown that oil consumption is strongly related to surface texture on the cylinder liners and at lower speeds (900-1200 rpm), a ‘rougher surface’ with a high core (e.g. Sk) and valley roughness (e.g. Svk) results in higher oil consumption. At the medium speed range (1200-3600 rpm), oil consumption continues to dominate for the ‘rough’ surfaces but with a visible influence of a lower oil consumption for a decreased roughness within the ‘rough’ surface group. ‘Smooth’ surfaces with a ‘smooth’ core (Sk), irrespective of the valley component (Svk), show similar oil consumption. For engine speeds above 3600 rpms, an increase in plateau

  2. A Research on the Effects of Dynamic Characteristics of Connecting Rod on the Piston Slap of Engine%发动机连杆动力学特性对活塞拍击的影响分析

    Institute of Scientific and Technical Information of China (English)

    郑光泽; 袁林

    2012-01-01

    传统的发动机活塞拍击动力学研究,通常仅关注活塞与缸套之间的耦合振动,以活塞销附加质量近似模拟连杆往复运动惯性力对活塞运动的影响,且忽略来自发动机其他机件的动力学特性的影响.本文中基于运动机件的振动响应分析法,建立了考虑活塞、连杆、曲轴和缸体的运动与振动特性的发动机耦合振动模型.运用该模型分析了某型3.5L柴油机的活塞拍击力的产生机理,重点探讨连杆惯性力的不同假设和连杆的弹性振动特性对活塞拍击力的影响.发动机缸体振动响应的分析结果和实验数据的对比表明,连杆动力学特性对活塞拍击和发动机缸体振动响应有显著影响.%The conventional researches on the piston slap dynamics of engine are often limited to the coupled vibration between piston and cylinder liner, and the effects of inertial force due to the reciprocating movement of connecting rod on the movement of piston is simply simulated by the additional mass of piston pin with the effects of dynamic characteristics of other components ignored. In this paper, based on the vibration response analysis of moving components, a coupled vibration model for engine is developed with consideration of the motion and vibration characteristics of piston, connecting rod, crankshaft and cylinder block, with which the generation mechanism of piston slap force in a 3. 5 L diesel engine is analyzed, with the effects of different inertial force assumptions and the elastic vibration characteristics of connecting rod on piston slap force emphatically investigated. The comparison between analysis results and test data of the vibration response of engine cylinder block show that the dynamics characteristics of connecting rod have significant effects on piston slap and the vibration response of cylinder block.

  3. Externally heated valve engine a new approach to piston engines

    CERN Document Server

    Kazimierski, Zbyszko

    2016-01-01

    This book reports on a novel approach for generating mechanical energy from different, external heat sources using the body of a typical piston engine with valves. By presenting simple yet effective numerical models, the authors show how this new approach, which combines existing internal combustion technology with a lubrication system, is able to offer an economic solution to the problem of mechanical energy generation in piston engines. Their results also show that a stable heat generation process can be guaranteed outside of the engine. The book offers a detailed report on physical and numerical models of 4-stroke and 2-stroke versions of the EHVE together with different models of heat exchange, valves and results of their simulations. It also delivers the test results of an engine prototype run in laboratory conditions. By presenting a novel theoretical framework and providing readers with extensive knowledge of both the advantages and challenges of the method, this book is expected to inspire academic re...

  4. Palm Power Free-Piston Stirling Engine Control Electronics

    Science.gov (United States)

    Keiter, Douglas E.; Holliday, Ezekiel

    2007-01-01

    A prototype 35We, JP-8 fueled, soldier-wearable power system for the DARPA Palm Power program has been developed and tested by Sunpower. A hermetically-sealed 42We Sunpower Free-Piston Stirling Engine (FPSE) with integral linear alternator is the prime mover for this system. To maximize system efficiency over a broad range of output power, a non-dissipative, highly efficient electronic control system which modulates engine output power by varying piston stroke and converts the AC output voltage of the FPSE into 28Vdc for the Palm Power end user, has been designed and demonstrated as an integral component of the Palm Power system. This paper reviews the current status and progress made in developing the control electronics for the Palm Power system, in addition to describing the operation and demonstrated performance of the engine controller in the context of the current JP-8 fueled Palm Power system.

  5. An Approximate Solution for Spherical and Cylindrical Piston Problem

    Indian Academy of Sciences (India)

    S K Singh; V P Singh

    2000-02-01

    A new theory of shock dynamics (NTSD) has been derived in the form of a finite number of compatibility conditions along shock rays. It has been used to study the growth and decay of shock strengths for spherical and cylindrical pistons starting from a non-zero velocity. Further a weak shock theory has been derived using a simple perturbation method which admits an exact solution and also agrees with the classical decay laws for weak spherical and cylindrical shocks.

  6. Free piston variable-stroke linear-alternator generator

    Science.gov (United States)

    Haaland, Carsten M.

    1998-01-01

    A free-piston variable stroke linear-alternator AC power generator for a combustion engine. An alternator mechanism and oscillator system generates AC current. The oscillation system includes two oscillation devices each having a combustion cylinder and a flying turnbuckle. The flying turnbuckle moves in accordance with the oscillation device. The alternator system is a linear alternator coupled between the two oscillation devices by a slotted connecting rod.

  7. The problem of the open safety pin.

    Science.gov (United States)

    Marsh, B R

    1975-01-01

    The open safety pin lodged in the stomach or esophagus presents a challenge to surgical judgment and technical skill. Most foreign bodies causing trouble lodge in the esophagus. Once in the stomach, uneventful passage can be expected in 80 to 90% of cases. Active intervention is reserved for those where intestinal performation is likely or where there is failure to progress. We have used the fiberesophagoscope to remove three open safety pins from the stomachs of two patients whose symptoms and threat of perforation required intervention. The microbiopsy forceps was used successfully to retrieve the open pins, but a newly developed grasping forceps for use with the fiberesophagoscope now provides a more secure hold on such foreign bodies. Rigid instruments retain their value for selected cases, but the flexible equipment now provides an important advance in the management of the open safety pin in the stomach.

  8. Pinning Synchronization of Switched Complex Dynamical Networks

    Directory of Open Access Journals (Sweden)

    Liming Du

    2015-01-01

    Full Text Available Network topology and node dynamics play a key role in forming synchronization of complex networks. Unfortunately there is no effective synchronization criterion for pinning synchronization of complex dynamical networks with switching topology. In this paper, pinning synchronization of complex dynamical networks with switching topology is studied. Two basic problems are considered: one is pinning synchronization of switched complex networks under arbitrary switching; the other is pinning synchronization of switched complex networks by design of switching when synchronization cannot achieved by using any individual connection topology alone. For the two problems, common Lyapunov function method and single Lyapunov function method are used respectively, some global synchronization criteria are proposed and the designed switching law is given. Finally, simulation results verify the validity of the results.

  9. Aluminium matrix heterophase composites for air compressor pistons

    Directory of Open Access Journals (Sweden)

    M.Dyzia

    2011-04-01

    Full Text Available The article presents the results of surface test of composite shaped in the permanent mould casting process. As part of the research anddevelopment project realized in the Department of Materials Technology at the Silesian University of Technology, a pilot plant scale stand was built to manufacture of more than 50 kg suspensions in a single technological cycle. Made in industrial conditions castings to form in the five inner core mould mounted in GM110 permanent mould casting machine confirmed the possibility of the shaping the composite pistons. Castings made from composite suspension AlSi7Mg/SiC and AlSi7Mg/SiC + Cg according to the technology procedure were classified as correct and devoted to the proper machining forming working surfaces of the piston to the air compressor. Comparative tests were performed for the casting of unreinforced AlSi7Mg alloy and composite castings. To assess the ability to fill the mold cavity and the accuracy of mapping used in contour shape FRT analysis of the distance between the grooves on the surface of the piston skirt. Studies have confirmed the differences in the fluidity of alloy matrix and composites suspensions. The difference in the accuracy of the dimensional mapping mould does not disqualify of composite materials, all castings are classified as correct and used for machining.

  10. Maximum Work of Free-Piston Stirling Engine Generators

    Science.gov (United States)

    Kojima, Shinji

    2017-04-01

    Using the method of adjoint equations described in Ref. [1], we have calculated the maximum thermal efficiencies that are theoretically attainable by free-piston Stirling and Carnot engine generators by considering the work loss due to friction and Joule heat. The net work done by the Carnot cycle is negative even when the duration of heat addition is optimized to give the maximum amount of heat addition, which is the same situation for the Brayton cycle described in our previous paper. For the Stirling cycle, the net work done is positive, and the thermal efficiency is greater than that of the Otto cycle described in our previous paper by a factor of about 2.7-1.4 for compression ratios of 5-30. The Stirling cycle is much better than the Otto, Brayton, and Carnot cycles. We have found that the optimized piston trajectories of the isothermal, isobaric, and adiabatic processes are the same when the compression ratio and the maximum volume of the same working fluid of the three processes are the same, which has facilitated the present analysis because the optimized piston trajectories of the Carnot and Stirling cycles are the same as those of the Brayton and Otto cycles, respectively.

  11. Flux pinning in superconductors. 2. ed.

    Energy Technology Data Exchange (ETDEWEB)

    Matsushita, Teruo [Kyushu Institute of Technology, Iizuka, Fukuoka (Japan). Dept. of Computer Science and Electronics

    2014-04-01

    Ideal for graduate students studying superconductivity and experts alike. Written by a researcher with more than 30 years experience in the field. All chapters are completely revised. The book covers the flux pinning mechanisms and properties and the electromagnetic phenomena caused by the flux pinning common for metallic, high-Tc and MgB2 superconductors. The condensation energy interaction known for normal precipitates or grain boundaries and the kinetic energy interaction proposed for artificial Nb pins in Nb-Ti, etc., are introduced for the pinning mechanism. Summation theories to derive the critical current density are discussed in detail. Irreversible magnetization and AC loss caused by the flux pinning are also discussed. The loss originally stems from the ohmic dissipation of normal electrons in the normal core driven by the electric field induced by the flux motion. The readers will learn why the resultant loss is of hysteresis type in spite of such mechanism. The influence of the flux pinning on the vortex phase diagram in high Tc superconductors is discussed, and the dependencies of the irreversibility field are also described on other quantities such as anisotropy of superconductor, specimen size and electric field strength. Recent developments of critical current properties in various high-Tc superconductors and MgB2 are introduced. Other topics are: singularity in the case of transport current in a parallel magnetic field such as deviation from the Josephson relation, reversible flux motion inside pinning potentials which causes deviation from the critical state model prediction, the concept of the minimization of energy dissipation in the flux pinning phenomena which gives the basis for the critical state model, etc. Significant reduction in the AC loss in AC wires with very fine filaments originates from the reversible flux motion which is dominant in the two-dimensional pinning. The concept of minimum energy dissipation explains also the behavior

  12. Your Premature Baby: Low Birthweight

    Science.gov (United States)

    ... many low-birthweight babies are born prematurely, many risk factors for having a low-birthweight baby are the same for preterm labor and ... risk for having a low-birthweight baby. Medical risk factors for having a low-birthweight baby Preterm labor . This is labor that starts ...

  13. Music Therapy with Premature Infants

    Science.gov (United States)

    Standley, Jayne

    2003-01-01

    Over 20 years of research and clinical practice in music therapy with premature infants has been compiled into this text designed for Board Certified Music Therapists specializing in Neonatal Intensive Care clinical services, for NICU medical staff incorporating research-based music therapy into developmental care plans, and for parents of…

  14. Music Therapy with Premature Infants

    Science.gov (United States)

    Standley, Jayne

    2003-01-01

    Over 20 years of research and clinical practice in music therapy with premature infants has been compiled into this text designed for Board Certified Music Therapists specializing in Neonatal Intensive Care clinical services, for NICU medical staff incorporating research-based music therapy into developmental care plans, and for parents of…

  15. Anisotropic flux pinning in high Tc superconductors

    Science.gov (United States)

    Koleśnik, S.; Igalson, J.; Skośkiewicz, T.; Szymczak, R.; Baran, M.; Pytel, K.; Pytel, B.

    1995-02-01

    In this paper we present a comparison of the results of FC magnetization measurements on several PbSr(Y,Ca)CuO crystals representing various levels of flux pinning. The pinning centers in our crystals have been set up during the crystal growth process or introduced by neutron irradiation. Some possible explanations of the observed effects, including surface barrier, flux-center distribution and sample-shape effects, are discussed.

  16. Open safety pin in the nasal cavity.

    Science.gov (United States)

    Sen, I; Sikder, B; Sinha, R; Paul, R

    2004-04-01

    Foreign bodies in the nasal cavity are common-day occurrences in Otolaryngologic practice. But an open safety pin in nose with it' s sharp end directed towards roof is a rare incidence, and available literature is silent about this presentation; it is probably, the first of it' s kind being reported. Two cases of safety pins inside the nasal cavity, one open and the other closed, have been presented here with a brief review of literature.

  17. Open safety pin in the nasal cavity

    OpenAIRE

    Sen, I; Sikder, B.; R. Sinha; Paul, R

    2004-01-01

    Foreign bodies in the nasal cavity are common-day occurrences in Otolaryngologic practice. But an open safety pin in nose with it’ s sharp end directed towards roof is a rare incidence, and available literature is silent about this presentation; it is probably, the first of it’ s kind being reported. Two cases of safety pins inside the nasal cavity, one open and the other closed, have been presented here with a brief review of literature.

  18. IMp: The customizable LEGO® Pinned Insect Manipulator

    Directory of Open Access Journals (Sweden)

    Steen Dupont

    2015-02-01

    Full Text Available We present a pinned insect manipulator (IMp constructed of LEGO® building bricks with two axes of movement and two axes of rotation. In addition we present three variants of the IMp to emphasise the modular design, which facilitates resizing to meet the full range of pinned insect specimens, is fully customizable, collapsible, affordable and does not require specialist tools or knowledge to assemble.

  19. Memory-only selection of dictionary PINs

    OpenAIRE

    Stanek, Martin

    2014-01-01

    We estimate the security of dictionary-based PINs (Personal Identification Numbers) that a user selects from his/her memory without any additional aids. The estimates take into account the distribution of words in source language. We use established security metrics, such as entropy, guesswork, marginal guesswork and marginal success rate. The metrics are evaluated for various scenarios -- aimed at improving the security of the produced PINs. In general, plain and straightforward construction...

  20. The pinning effect in quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Monisha, P. J., E-mail: pjmonisha@gmail.com [School of Physics, University of Hyderabad, Hyderabad-500046 (India); Mukhopadhyay, Soma [Department of Physics, D V R College of Engineering and Technology, Hyderabad-502285 (India)

    2014-04-24

    The pinning effect is studied in a Gaussian quantum dot using the improved Wigner-Brillouin perturbation theory (IWBPT) in the presence of electron-phonon interaction. The electron ground state plus one phonon state is degenerate with the electron in the first excited state. The electron-phonon interaction lifts the degeneracy and the first excited states get pinned to the ground state plus one phonon state as we increase the confinement frequency.

  1. Study on contact pressure at pin connection detail; Pin setsugobu no sesshokuatsu ni taisuru kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Miki, C.; Anami, K. [Tokyo Institute of Technology, Tokyo (Japan); Suzuki, M. [Ministry of Construction, Tokyo (Japan); Ohashi, H. [Honshu-Shikoku Bridge Authority, Tokyo (Japan)

    1997-07-21

    Contact pressure between pin and pin plate is discussed by FEM and UT from the point of view of the connection detail of hanger lope of long span suspension bridge. Application of the UT to the 25S surface specimen (and smoother surface) is effective. The results of UT and FEM distribution of contact pressure near the center of plate almost agree with the Hertz law. However near the surface of pin plate the contact pressure and plate width of large contact pressure region increase larger than those near contact pressure and plate width of large contact pressure region increase larger than those near center of pin plate. 12 refs., 17 figs.

  2. Improved pinning by multiple in-line damage

    Energy Technology Data Exchange (ETDEWEB)

    Weinstein, Roy [Beam Particle Dynamics Laboratories, University of Houston, Houston, TX 77204-5005 (United States); Sawh, Ravi-Persad [Beam Particle Dynamics Laboratories, University of Houston, Houston, TX 77204-5005 (United States); Gandini, Alberto [Beam Particle Dynamics Laboratories, University of Houston, Houston, TX 77204-5005 (United States); Parks, Drew [Beam Particle Dynamics Laboratories, University of Houston, Houston, TX 77204-5005 (United States)

    2005-02-01

    Columnar pinning centres provide the largest pinning potential, U{sub pin}, but not the greatest J{sub c} or pinnable field, B{sub pin}. Characteristics of ion-generated columnar defects which limit J{sub c} and B{sub pin} are discussed, including reduction of the percolation path, and the need for a larger number of columns of damage, for pinning, than are usually estimated. It is concluded that columnar pinning centres limit B{sub pin} to less than 4 T, and also severely reduce J{sub c}. The goal of maximizing U{sub pin}, via columnar centres, appears to have obscured a more rewarding approach and resulted in neglect of a large regime of ion interactions. Evidence is reviewed that multiple in-line damage (MILD), described herein, can provide orders of magnitude higher J{sub c} and B{sub pin}, despite providing lower U{sub pin}. The MILD pinning centre morphology is discussed, and it is estimated that for present-day large grain high T{sub c} superconductors, a J{sub c} value of {approx}10{sup 6}Acm{sup -2} is obtainable at 77 K, even when crystal plane alignment and weak links are not improved. In addition, the pinned field is increased by over an order of magnitude. An experiment is proposed to confirm these calculations, directly compare MILD pinning to continuous columnar pinning, and determine the optimum MILD structure. Applications of MILD pinning are discussed.

  3. MODERN PRODUCTS FOR FEEDING PREMATURE BABIES

    National Research Council Canada - National Science Library

    A. V. Surzhik

    2012-01-01

    .... Adequate feeding is one of the fundamental factors of premature babies nursing. To ensure a premature baby with all necessary components for power saving in breast milk intake, breast milk fortifiers...

  4. Piston surface heat transfer during combustion in large marine diesel engines

    DEFF Research Database (Denmark)

    Jensen, Michael Vincent; Walther, Jens Honore

    2010-01-01

    In the design process of large marine diesel engines information on the maximum heat load on the piston surface experienced during the engine cycle is an important parameter. The peak heat load occurs during combustion when hot combustion products impinge on the piston surface. Although the maximum...... with burning off piston surface material. In this work the peak heat load on the piston surface of large marine diesel engines during combustion was investigated. Measurements of the instantaneous surface temperature and surface heat flux on pistons in large marine engines are difficult due to expensive...... was calculated under different conditions in the numerical setup in order to obtain information of the actual peak heat flux experienced at the piston in large marine diesel engines during combustion. The variation of physical parameters influencing the heat transfer during combustion included a variation...

  5. Development of a Collins-type cryocooler floating piston control algorithm

    Science.gov (United States)

    Hogan, Jake; Hannon, Charles L.; Brisson, John

    2012-06-01

    The Collins-type cryocooler uses a floating piston design for the working fluid expansion. The piston floats between a cold volume, where the working fluid is expanded, and a warm volume. The piston is shuttled between opposite ends of the closed cylinder by opening and closing valves connecting several reservoirs at various pressures to the warm volume. Ideally, these pressures should be distributed between the high and low system pressure to gain good control of the piston motion. In this work, a numerical quasi-steady thermodynamic model is developed for the piston cycle. The model determines the steady state pressure distribution of the reservoirs for a given control algorithm. The results are then extended to show how valve timing modifications can be used to overcome helium leakage past the piston during operation.

  6. a Simple Model to Estimate the Impact Force Induced by Piston Slap

    Science.gov (United States)

    CHO, S.-H.; AHN, S.-T.; KIM, Y.-H.

    2002-08-01

    The dynamics of piston's secondary motion (lateral and rotational motion) across the clearance between piston and cylinder inner wall of reciprocating machines are analyzed. This paper presents an analytical model, which can predict the impact forces and vibratory response of engine block surface induced by the piston slap of an internal combustion engine. A piston is modelled on a three-degree-of-freedom system to represent its planar motion. When slap occurs, the impact point between piston skirt and cylinder inner wall is modelled on a two-degree-of-freedom vibratory system. The equivalent parameters such as mass, spring constant, and damping constant of piston and cylinder inner wall are estimated by using measured (driving) point mobility. Those parameters are used to calculate the impact force and for estimating the vibration level of engine block surfaces. The predicted results are compared with experimental results to verify the model.

  7. Outcomes for Extremely Premature Infants

    Science.gov (United States)

    Glass, Hannah C.; Costarino, Andrew T.; Stayer, Stephen A.; Brett, Claire; Cladis, Franklyn; Davis, Peter J.

    2015-01-01

    Premature birth is a significant cause of infant and child morbidity and mortality. In the United States, the premature birth rate, which had steadily increased during the 1990s and early 2000s, has decreased annually for four years and is now approximately 11.5%. Human viability, defined as gestational age at which the chance of survival is 50%, is currently approximately 23–24 weeks in developed countries. Infant girls, on average, have better outcomes than infant boys. A relatively uncomplicated course in the intensive care nursery for an extremely premature infant results in a discharge date close to the prenatal EDC. Despite technological advances and efforts of child health experts during the last generation, the extremely premature infant (less than 28 weeks gestation) and extremely low birth weight infant (ELBW) (premature labor improved neonatal mortality and morbidity in the late 1990s. The recognition that chronic postnatal administration of steroids to infants should be avoided may have improved outcomes in the early 2000s. Evidence from recent trials attempting to define the appropriate target for oxygen saturation in preterm infants suggests arterial oxygen saturation between 91–95% (compared to 85–89%) avoids excess mortality. However, final analyses of data from these trials have not been published, so definitive recommendations are still pending The development of neonatal neurocognitive care visits may improve neurocognitive outcomes in this high-risk group. Long-term follow up to detect and address developmental, learning, behavioral, and social problems is critical for children born at these early gestational ages. The striking similarities in response to extreme prematurity in the lung and brain imply that agents and techniques that benefit one organ are likely to also benefit the other. Finally, since therapy and supportive care continue to change, the outcomes of ELBW infants are ever evolving. Efforts to minimize injury, preserve

  8. Outcomes for extremely premature infants.

    Science.gov (United States)

    Glass, Hannah C; Costarino, Andrew T; Stayer, Stephen A; Brett, Claire M; Cladis, Franklyn; Davis, Peter J

    2015-06-01

    Premature birth is a significant cause of infant and child morbidity and mortality. In the United States, the premature birth rate, which had steadily increased during the 1990s and early 2000s, has decreased annually for 7 years and is now approximately 11.39%. Human viability, defined as gestational age at which the chance of survival is 50%, is currently approximately 23 to 24 weeks in developed countries. Infant girls, on average, have better outcomes than infant boys. A relatively uncomplicated course in the intensive care nursery for an extremely premature infant results in a discharge date close to the prenatal estimated date of confinement. Despite technological advances and efforts of child health experts during the last generation, the extremely premature infant (less than 28 weeks gestation) and extremely low birth weight infant (death and disability with 30% to 50% mortality and, in survivors, at least 20% to 50% risk of morbidity. The introduction of continuous positive airway pressure, mechanical ventilation, and exogenous surfactant increased survival and spurred the development of neonatal intensive care in the 1970s through the early 1990s. Routine administration of antenatal steroids during premature labor improved neonatal mortality and morbidity in the late 1990s. The recognition that chronic postnatal administration of steroids to infants should be avoided may have improved outcomes in the early 2000s. Evidence from recent trials attempting to define the appropriate target for oxygen saturation in preterm infants suggests arterial oxygen saturation between 91% and 95% (compared with 85%-89%) avoids excess mortality; however, final analyses of data from these trials have not been published, so definitive recommendations are still pending. The development of neonatal neurocritical intensive care units may improve neurocognitive outcomes in this high-risk group. Long-term follow-up to detect and address developmental, learning, behavioral, and

  9. Mixed Lubrication Analysis and Experiment Validation of Internal Combustion Piston Skirt

    Institute of Scientific and Technical Information of China (English)

    杨俊伟; 于旭东; 王成焘; 谢友柏

    2004-01-01

    A mixed lubrication model was established for piston skirt lubrication. The mathematical model developed in this paper incorporates governing equations of motion with average Reynolds equation. This model considers the surfaceroughness and profile. The corresponding computer program can be used to calculate oscillatory motion of piston during the entire trajectory, which has the excellent convergence.In addition, a set of equipment, which adopt the laser induced fluorescent method, was developed to measure the oil film thickness between the piston and the bore.

  10. Performance comparison of pin fin in-duct flow arrays with various pin cross-sections

    Energy Technology Data Exchange (ETDEWEB)

    Sahiti, N. [LSTM-Erlangen, Institute of Fluid Mechanics, Friedrich-Alexander-University, Erlangen-Nuremberg, Cauerstr. 4, D-91058 Erlangen (Germany)]. E-mail: sahiti@lstm.uni-erlangen.de; Lemouedda, A. [Department of Process Engineering, Georg-Simon-Ohm University of Applied Sciences, Wassertorstr. 10, D-90489 Nuremberg (Germany); Stojkovic, D. [LSTM-Erlangen, Institute of Fluid Mechanics, Friedrich-Alexander-University, Erlangen-Nuremberg, Cauerstr. 4, D-91058 Erlangen (Germany); Durst, F. [LSTM-Erlangen, Institute of Fluid Mechanics, Friedrich-Alexander-University, Erlangen-Nuremberg, Cauerstr. 4, D-91058 Erlangen (Germany); Franz, E. [Department of Process Engineering, Georg-Simon-Ohm University of Applied Sciences, Wassertorstr. 10, D-90489 Nuremberg (Germany)

    2006-08-15

    Pin fin arrays are frequently used for cooling of high thermal loaded electronic components. Whereas the pin fin accomplishment regarding heat transfer is always higher than that of other fin configurations, the high pressure drop accompanying pins seriously reduces their overall performance. In order to check how the form of pin cross-section influences the pressure drop and heat transfer capabilities, six forms of pin cross-section were numerically investigated. By employing the conjugate heat transfer boundary conditions, numerical simulations close to realistic working conditions were performed. Two geometric comparison criteria were applied so that the conclusions derived from numerical computations were valid for various possible geometric parameters and working conditions. Both staggered and inline pin arrangements were investigated as these are common in practical applications. The heat transfer and pressure drop characteristics are presented in terms of appropriate dimensionless variables. The final judgment of the performance of the pin fin cross-section was performed based on the heat exchanger performance plot. Such a plot allows the assessment of the pin performance including their heat transfer and the pressure drop.

  11. Design of a terahertz CW photomixer based on PIN and superlattice PIN devices

    DEFF Research Database (Denmark)

    Krozer, Viktor; Eichhorn, Finn

    2006-01-01

    We present the design of a photomixer LO based on standard and superlattice PIN diodes, operating at 1 THz. The design is based on a direct integration of a double slot antenna with the PIN device and a suitable matching circuit. The antenna has been designed together with a dielectric lens using...

  12. Thermal Stress Analysis of a Speculative IC Engine Piston using CAE Tools

    Directory of Open Access Journals (Sweden)

    Hitesh pandey

    2014-11-01

    Full Text Available This paper deals with the pressure due to expanding combustion gases in the combustion chamber space at the top of the cylinder which generate thermal stresses due to presence of heat involved on the reciprocating masses. The present work deals with the use of different materials for IC engine piston and a comparative study is made to achieve the best possible result. Piston parameters are taken using the conventional formulas and are constant throughout the analysis. Moreover the boundary conditions are chosen such that the piston does not moves sideways except in the direction of line of action of the piston itself.

  13. Assessment of 25 kW free-piston Stirling technology alternatives for solar applications

    Science.gov (United States)

    Erbeznik, Raymond M.; White, Maurice A.; Penswick, L. B.; Neely, Ronald E.; Ritter, Darren C.; Wallace, David A.

    The final design, construction, and testing of a 25-kW free-piston advanced Stirling conversion system (ASCS) are examined. The final design of the free-piston hydraulic ASCS consists of five subsystems: heat transport subsystem (solar receiver and pool boiler), free-piston hydraulic Stirling engine, hydraulic subsystem, cooling subsystem, and electrical and control subsystem. Advantages and disadvantages are identified for each technology alternative. Technology alternatives considered are gas bearings vs flexure bearings, stationary magnet linear alternator vs moving magnetic linear alternator, and seven different control options. Component designs are generated using available in-house procedures to meet the requirements of the free-piston Stirling convertor configurations.

  14. MODERN PRODUCTS FOR FEEDING PREMATURE BABIES

    Directory of Open Access Journals (Sweden)

    A. V. Surzhik

    2012-01-01

    Full Text Available In recent decades there has been substantial progress in the technology of premature infants nursing, especially with extremely low birth weight. Adequate feeding is one of the fundamental factors of premature babies nursing. To ensure a premature baby with all necessary components for power saving in breast milk intake, breast milk fortifiers — specifically developed additives that adjust the composition of food for premature babies, are used for more than 20 years (for premature babies receiving breast milk. On the one hand, to preserve all benefits of breastfeeding, on the other — to prevent the deficit development of necessary elements for adequate growth and development of nutrients.

  15. Dynamics and Stability of Pinned-Clamped and Clamped-Pinned Cylindrical Shells Conveying Fluid

    Science.gov (United States)

    Misra, A. K.; Wong, S. S. T.; Païdoussis, M. P.

    2001-11-01

    The paper examines the dynamics and stability of fluid-conveying cylindrical shells having pinned-clamped or clamped-pinned boundary conditions, where ``pinned'' is an abbreviation for ``simply supported''. Flügge's equations are used to describe the shell motion, while the fluid-dynamic perturbation pressure is obtained utilizing the linearized potential flow theory. The solution is obtained using two methods - the travelling wave method and the Fourier-transform approach. The results obtained by both methods suggest that the negative damping of the clamped-pinned systems and positive damping of the pinned-clamped systems, observed by previous investigators for any arbitrarily small flow velocity, are simply numerical artefacts; this is reinforced by energy considerations, in which the work done by the fluid on the shell is shown to be zero. Hence, it is concluded that both systems are conservative.

  16. [Forensic importance of premature craniosynostosis].

    Science.gov (United States)

    Fehlow, P

    1991-01-01

    In agreement with Canabis craniosynostosis as a little known organic partial factor of sociopathy is demonstrated. A psychic syndrome of the frontal lobe with increased susceptibility in environmental damages is assumed to be basic disorder. In the criminals of the material sexual offenders were preponderating. Associated craniofacial dysplasias are a risk for psychic maldevelopment. The importance of premature craniosynostocis as a biological risk factor, incidence, diagnostic, indication for an operation, also in the meaning of a neurosurgical "Konflikttherapie" (cosmetical indication) are discussed.

  17. Potential of pin-by-pin SPN calculations as an industrial reference

    Energy Technology Data Exchange (ETDEWEB)

    Fliscounakis, M.; Girardi, E.; Courau, T.; Couyras, D. [EDF R and D/Sinetics, 1 av du General de Gaulle, F92141 Clamart Cedex (France)

    2012-07-01

    This paper aims at analysing the potential of pin-by-pin SP{sub n} calculations to compute the neutronic flux in PWR cores as an alternative to the diffusion approximation. As far as pin-by-pin calculations are concerned, a SPH equivalence is used to preserve the reactions rates. The use of SPH equivalence is a common practice in core diffusion calculations. In this paper, a methodology to generalize the equivalence procedure in the SP{sub n} equations context is presented. In order to verify and validate the equivalence procedure, SP{sub n} calculations are compared to 2D transport reference results obtained with the APOLL02 code. The validation cases consist in 3x3 analytical assembly color sets involving burn-up heterogeneities, UOX/MOX interfaces, and control rods. Considering various energy discretizations (up to 26 groups) and flux development orders (up to 7) for the SP{sub n} equations, results show that 26-group SP{sub 3} calculations are very close to the transport reference (with pin production rates discrepancies < 1%). This proves the high interest of pin-by-pin SP{sub n} calculations as an industrial reference when relying on 26 energy groups combined with SP{sub 3} flux development order. Additionally, the SP{sub n} results are compared to diffusion pin-by-pin calculations, in order to evaluate the potential benefit of using a SP{sub n} solver as an alternative to diffusion. Discrepancies on pin-production rates are less than 1.6% for 6-group SP{sub 3} calculations against 3.2% for 2-group diffusion calculations. This shows that SP{sub n} solvers may be considered as an alternative to multigroup diffusion. (authors)

  18. A double tuned rail damper—increased damping at the two first pinned-pinned frequencies

    Science.gov (United States)

    Maes, J.; Sol, H.

    2003-10-01

    Railway-induced vibrations are a growing matter of environmental concern. The rapid development of transportation, the increase of vehicle speeds and vehicle weights have resulted in higher vibration levels. In the meantime vibrations that were tolerated in the past are now considered to be a nuisance. Numerous solutions have been proposed to remedy these problems. The majority only acts on a specific part of the dynamic behaviour of the track. This paper presents a possible solution to reduce the noise generated by the 'pinned-pinned' frequencies. Pinned-pinned frequencies correspond with standing waves whose nodes are positioned exactly at the sleeper supports. The two first pinned-pinned frequencies are situated approximately at 950 and 2200 Hz (UIC60-rail and sleeper spacing of 0.60 m). To attenuate these vibrations, the Department of MEMC at the VUB has developed a dynamic vibration absorber called the Double Tuned Rail Damper (DTRD). The DTRD is mounted between two sleepers on the rail and is powered by the motion of the rail. The DTRD consists of two major parts: a steel plate which is connected to the rail with an interface of an elastic layer, and a rubber mass. The two first resonance frequencies of the steel plate coincide with the targeted pinned-pinned frequencies of the rail. The rubber mass acts as a motion controller and energy absorber. Measurements at a test track of the French railway company (SNCF) have shown considerable attenuation of the envisaged pinned-pinned frequencies. The attenuation rate surpasses 5 dB/m at certain frequency bands.

  19. Statistics of dislocation pinning at localized obstacles

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, A. [S. N. Bose National Centre for Basic Sciences, Salt Lake, Kolkata 700098 (India); Bhattacharya, M., E-mail: mishreyee@vecc.gov.in; Barat, P. [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata 700064 (India)

    2014-10-14

    Pinning of dislocations at nanosized obstacles like precipitates, voids, and bubbles is a crucial mechanism in the context of phenomena like hardening and creep. The interaction between such an obstacle and a dislocation is often studied at fundamental level by means of analytical tools, atomistic simulations, and finite element methods. Nevertheless, the information extracted from such studies cannot be utilized to its maximum extent on account of insufficient information about the underlying statistics of this process comprising a large number of dislocations and obstacles in a system. Here, we propose a new statistical approach, where the statistics of pinning of dislocations by idealized spherical obstacles is explored by taking into account the generalized size-distribution of the obstacles along with the dislocation density within a three-dimensional framework. Starting with a minimal set of material parameters, the framework employs the method of geometrical statistics with a few simple assumptions compatible with the real physical scenario. The application of this approach, in combination with the knowledge of fundamental dislocation-obstacle interactions, has successfully been demonstrated for dislocation pinning at nanovoids in neutron irradiated type 316-stainless steel in regard to the non-conservative motion of dislocations. An interesting phenomenon of transition from rare pinning to multiple pinning regimes with increasing irradiation temperature is revealed.

  20. Radon measurements with a PIN photodiode

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Martin, A. [Laboratorio de Investigacion en Baja Radiactividad (LIBRA), Edificio I-D, Campus Miguel Delibes, Universidad de Valladolid, Valladolid 47011 (Spain) and Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, Valladolid 47011 (Spain)]. E-mail: alonsomm@libra.uva.es; Gutierrez-Villanueva, J.L. [Laboratorio de Investigacion en Baja Radiactividad (LIBRA), Edificio I-D, Campus Miguel Delibes, Universidad de Valladolid, Valladolid 47011 (Spain); Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, Valladolid 47011 (Spain); Munoz, J.M. [Departamento de Electricidad y Electronica, Universidad de Valladolid, Valladolid 47011 (Spain); Garcia-Talavera, M. [Laboratorio de Investigacion en Baja Radiactividad (LIBRA), Edificio I-D, Campus Miguel Delibes, Universidad de Valladolid, Valladolid 47011 (Spain); Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, Valladolid 47011 (Spain); Adamiec, G. [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, Valladolid 47011 (Spain); Iniguez, M.P. [Departamento de Fisica Teorica, Atomica y Optica, Universidad de Valladolid, Valladolid 47011 (Spain)

    2006-10-15

    Silicon photodiodes are well suited to detect alphas coming from different sources as neutron reactions or radon daughters. In this work a radon in air detecting device, using an 18x18 mm silicon PIN photodiode is studied. The ionized airborne decay products formed during radon diffusion were focused by an accelerating high voltage to the PIN surface. Several conducting rings were disposed inside a cylindrical PVC vessel in such a way that they reproduced the electric field created by a punctual charge located behind PIN position. Alpha spectra coming from the neutral and ionized species deposited on the PIN surface, dominated by {sup 218}Po and {sup 214}Po progeny peaks, were recorded for varying conditions. Those include radon concentration from a Pylon source, high voltage (thousands of volts) and PIN inverse bias voltage. Different parameters such as temperature and humidity were also registered during data acquisition. The increase in the particle collection efficiency with respect to zero electric field was compared with the corresponding to a parallel plates configuration. A discussion is made in terms of the most appropriate voltages for different radon concentrations.

  1. Vacuum stress and closed paths in rectangles, pistons and pistols

    Science.gov (United States)

    Fulling, S. A.; Kaplan, L.; Kirsten, K.; Liu, Z. H.; Milton, K. A.

    2009-04-01

    Rectangular cavities are solvable models that nevertheless touch on many of the controversial or mysterious aspects of the vacuum energy of quantum fields. This paper is a thorough study of the two-dimensional scalar field in a rectangle by the method of images, or closed classical (or optical) paths, which is exact in this case. For each point r and each specularly reflecting path beginning and ending at r, we provide formulae for all components of the stress tensor Tμν(r), for all values of the curvature coupling constant ξ and all values of an ultraviolet cutoff parameter. Arbitrary combinations of Dirichlet and Neumann conditions on the four sides can be treated. The total energy is also investigated, path by path. These results are used in an attempt to clarify the physical reality of the repulsive (outward) force on the sides of the box predicted by calculations that neglect both boundary divergences and the exterior of the box. Previous authors have studied 'piston' geometries that avoid these problems and have found the force to be attractive. We consider a 'pistol' geometry that comes closer to the original problem of a box with a movable lid. We find again an attractive force, although its origin and detailed behavior are somewhat different from the piston case. However, the pistol (and the piston) model can be criticized for extending idealized boundary conditions into short distances where they are physically implausible. Therefore, it is of interest to see whether leaving the ultraviolet cutoff finite yields results that are more plausible. We then find that the force depends strongly on a geometrical parameter; it can be made repulsive, but only by forcing that parameter into the regime where the model is least convincing physically.

  2. The effect of temperature on pinning mechanisms in HTS composites

    Science.gov (United States)

    Sotnikova, A. P.; Rudnev, I. A.

    2016-09-01

    Pinning mechanism in samples of second generation tapes (2G) of high-temperature superconductors (HTS) was studied The critical current and the pinning force were calculated from the magnetization curves measured in the temperature range of 4.2 - 77 K in magnetic fields up to 14 Tesla using vibration sample magnetometer. To determine the pinning mechanism the dependences of pinning force on magnetic field were constructed according to the Dew-Hughes model and Kramer's rule. The obtained dependences revealed a significant influence of the temperature on effectiveness of different types of pinning. At low temperatures the 2G HTS tapes of different manufacturers demonstrated an equal efficiency of the pinning centers but with temperature increase the differences in pinning mechanisms as well as in properties and effectiveness of the pinning centers become obvious. The influence of the pinning mechanism on the energy losses in HTS tapes was shown.

  3. Modeling and Simulation of Aerial Dispersion on Piston Dispersal Mechanism%Modeling and Simulation of Aerial Dispersion on Piston Dispersal Mechanism

    Institute of Scientific and Technical Information of China (English)

    陶如意; 王浩; 黄蓓

    2011-01-01

    For the aerial dispersing interior ballistic process and submunition exterior ballistic initial conditions of cluster munition with piston maximum travel limit, a novel model is established, and the numerical simulation is performed. The piston maximum travel limit and the effect of reaction force on carrier body are researched using the internal ballistic model. Guide tube, cluster munition rotating and submunition assembly are analyzed using the submunition initial external ballistic model. The computational results are consistent with the practical process and the experimental data, and prove the rationality of this model. The theoretical methods are presented for the construction design and dispersion analysis of piston dispersal mechanism.

  4. Free-Piston Stirling Machine for Extreme Temperatures

    Science.gov (United States)

    Wood, James Gary (Inventor)

    2013-01-01

    A free piston Stirling machine including a thermal buffer tube extending from the machine's expansion space and surrounded by its heat rejector and its regenerator, a displacer cylinder extending from the thermal buffer tube to the compression space and surrounded by the heat rejecting heat exchanger, and a displacer that reciprocates within an excursion limit that extends into the regenerator by no more than 20% of the length of the regenerator during normal operation and preferably within excursion limits that are substantially the length of the heat rejector.

  5. Piston cylinder cell for high pressure ultrasonic pulse echo measurements

    Science.gov (United States)

    Kepa, M. W.; Ridley, C. J.; Kamenev, K. V.; Huxley, A. D.

    2016-08-01

    Ultrasonic techniques such as pulse echo, vibrating reed, or resonant ultrasound spectroscopy are powerful probes not only for studying elasticity but also for investigating electronic and magnetic properties. Here, we report on the design of a high pressure ultrasonic pulse echo apparatus, based on a piston cylinder cell, with a simplified electronic setup that operates with a single coaxial cable and requires sample lengths of mm only. The design allows simultaneous measurements of ultrasonic velocities and attenuation coefficients up to a pressure of 1.5 GPa. We illustrate the performance of the cell by probing the phase diagram of a single crystal of the ferromagnetic superconductor UGe2.

  6. Prediction for Outlet Noise of Rolling Piston Comperssor

    Directory of Open Access Journals (Sweden)

    Zhang Tieshan

    2015-01-01

    Full Text Available An acoustic wave equation with considering small perturbation is presented first by use of the fluidic mechanics and aerodynamics, then a theoretical model for predicting the outlet noise of rolling piston compressors is investigated, and the sound pressure and sound power of the outlet noise are formulated based on the acoustic wave equation. The experimental data and simulation results for the outlet noise with different rotation velocities have been compared with the discrepancy less than 2.6%, which verifies the approach presented in this paper.

  7. β Style Free-Piston Stirling Engine Control System Research

    Directory of Open Access Journals (Sweden)

    Xu Jian

    2016-01-01

    Full Text Available For the Free-Piston Stirling Engines (FPSE control system, a three -phase bridge circuit is reused as the system output about rectifier and start inverter. When FPSE system is in the power stage, the double closed loop control strategy and optimization algorithm of PI control parameters is adopted to ensure the highest system transmission efficiency under the requirements of the system output power and guarantee the stability of the running system. The simulation results prove the effectiveness of the above research content.

  8. Termination of pinned spirals by local stimuli

    Science.gov (United States)

    Chen, Jiang-Xing; Guo, Ming-Ming; Ma, Jun

    2016-02-01

    The termination of pinned spirals on a defect by means of local stimuli is studied. On a completely unexcitable defect, the elimination process is discussed and its corresponding mechanism is presented. Especially, the mechanism of unpinning spirals on a partially unexcitable defect, which has not been investigated so far, is explored. With fixed pacing frequency ω L , there exists a maximal radius R max above which the pinned spiral cannot be removed. It is found that the value of R max does not increase as ω L in a dynamical regime, forming a platform in the R\\textit{max}\\text-ωL curves. Based on analyzing the dispersion relation on the spiral tip around the obstacle, the underlying mechanism is clarified. Also, it is found that when multiple spirals are pinned, the value of R max decreases on a partially unexcitable defect while the change is very slight on a completely unexcitable one.

  9. Pin solar cells made of amorphous silicon

    Science.gov (United States)

    Plaettner, R. D.; Kruehler, W. W.

    Investigations leading to solar cells with a structure SnO2-pin and an efficiency up to 9.8% are reviewed. The production of large-surface metal/pin/transparent conductive oxide (TCO)-solar cells is discussed. A two-chamber reactor, grid structure and tinning of cells, and an a-Si-module are described. The production of glass/TCO/pin/metal-solar cells and a-SiGe:H-compounds is outlined. Measurements on solar cells and diodes including the efficiency of a-Si:H-solar cells, spectral sensitivity, diffusion lengths, field effect measurements, and modifications of solar cells (space-charge limited currents, reduction of solar cells aging) are treated.

  10. Effective pinning energy landscape perturbations for propagating magnetic domain walls

    Science.gov (United States)

    Burn, D. M.; Atkinson, D.

    2016-01-01

    The interaction between a magnetic domain wall and a pinning site is explored in a planar nanowire using micromagnetics to reveal perturbations of the pinning energetics for propagating domain walls. Numerical simulations in the high damping ’quasi-static’ and low damping ’dynamic’ regimes are compared and show clear differences in de-pinning fields, indicating that dynamical micromagnetic models, which incorporate precessionally limited magnetization processes, are needed to understand domain wall pinning. Differences in the micromagnetic domain wall structure strongly influence the pinning and show periodic behaviour with increasing applied field associated with Walker breakdown. In the propagating regime pinning is complicated. PMID:27694953

  11. Broken safety pin in bronchus - Anaesthetic considerations

    Directory of Open Access Journals (Sweden)

    Roona Shad

    2012-01-01

    Full Text Available Safety pins are not commonly aspirated objects in infants and form only a small fraction of all the metallic foreign body (FB which accounts for 4.4% of all foreign bodies found in tracheobronchial tree. Bronchoscopy procedure has various complications, in addition to failure to remove FB due to its impaction, especially with metallic pointed objects ending up in open surgical removal. Infant with inhaled foreign body are always a challenge to anaesthetist. We had one such case of broken safety pin impacted in the wall of right bronchus of an infant with failure to remove on repeated attempts at rigid bronchoscopy.

  12. Broken safety pin in bronchus - Anaesthetic considerations.

    Science.gov (United States)

    Shad, Roona; Agarwal, Aditya

    2012-11-01

    Safety pins are not commonly aspirated objects in infants and form only a small fraction of all the metallic foreign body (FB) which accounts for 4.4% of all foreign bodies found in tracheobronchial tree. Bronchoscopy procedure has various complications, in addition to failure to remove FB due to its impaction, especially with metallic pointed objects ending up in open surgical removal. Infant with inhaled foreign body are always a challenge to anaesthetist. We had one such case of broken safety pin impacted in the wall of right bronchus of an infant with failure to remove on repeated attempts at rigid bronchoscopy.

  13. Self-Pinning on a Liquid Surface.

    Science.gov (United States)

    Antoine, C; Irvoas, J; Schwarzenberger, K; Eckert, K; Wodlei, F; Pimienta, V

    2016-02-04

    We report on the first experimental evidence of a self-pinning liquid drop on a liquid surface. This particular regime is observed for a miscible heavier oil drop (dichloromethane) deposited on an aqueous solution laden by an ionic surfactant (hexadecyltrimethylammonium bromide). Experimental characterization of the drop shape evolution coupled to particle image velocimetry points to the correlation between the drop profile and the accompanying flow field. A simple model shows that the observed pinned stage is the result of a subtle competition between oil dissolution and surfactant adsorption.

  14. New types of high field pinning centers and pinning centers for the peak effect

    Science.gov (United States)

    Gajda, Daniel; Zaleski, Andrzej; Morawski, Andrzej; Hossain, Md Shahriar A.

    2017-08-01

    In this article, we report the results of a study that shows the existence of pinning centers inside grains and between grains in NbTi wires. We accurately show the ranges of magnetic fields in which the individual pinning centers operate. The pinning centers inside grains are activated in high magnetic fields above 6 T. We show the range of magnetic fields in which individual defects, dislocations, precipitates inside grains and substitutions in the crystal lattice can operate. We show the existence of a new kind of high field pinning center, which operates in high magnetic fields from 8 to ˜9.5 T. We indicate that dislocations create pinning centers in the range of magnetic fields from 6 to 8 T. In addition, our measurements suggest that the peak effect (increased critical current density (J c) near the upper critical field (B c2)) could be attributed to martensitic (needle-shaped) α‧-Ti inclusions inside grains. These centers are very important because they work very effectively in magnetic fields above 9.5-10 T. We also show that the α-Ti precipitates (between grains) with a thickness similar to the coherence length create pinning centers which work very effectively in magnetic fields from 3 to 6 T. In magnetic fields below 3 T, they act very efficiently in grain boundaries. The measurements indicate that the pinning centers created by dislocations only can be tested by transport measurements. This indicates that dislocations do not increase the magnetic critical current density (J cm). Cold drawing improves pinning centers at grain boundaries and increases the dislocation density, and cold-drawing pinning centers are responsible for the peak effect.

  15. Effect of the number of pins and inter-pin distance on somatosensory evoked magnetic fields following mechanical tactile stimulation.

    Science.gov (United States)

    Onishi, Hideaki; Sugawara, Kazuhiro; Yamashiro, Koya; Sato, Daisuke; Suzuki, Makoto; Kirimoto, Hikari; Tamaki, Hiroyuki; Murakami, Hiroatsu; Kameyama, Shigeki

    2013-10-16

    Magnetoencephalography (MEG) recordings were collected to investigate the effect of the number of mechanical pins and inter-pin distance on somatosensory evoked magnetic fields (SEFs) following mechanical stimulation (MS). We used a 306-ch whole-head MEG system. SEFs were elicited through tactile stimuli with 1-, 2-, 3-, 4- and 8-pins using healthy participants. Tactile stimuli were applied to the tip of the right index finger. SEF following electrical stimulation of the index finger was recorded in order to compare the activity in the primary somatosensory cortex (S1) following MS. Prominent SEFs were recorded from the contralateral hemisphere approximately 54 ms (P50m) and 125 ms (P100m) after MS regardless of the number of pins. Equivalent current dipoles were located in the S1. The source activities for P50m and P100m significantly increased in tandem with the number of pins for MS. However, the increased ratios for the source activities according to the increase in the number of pins were significantly smaller than that induced by electrical stimulation, and when the number of the pins doubled from 1-pin to 2-pins, from 2-pins to 4-pins, and from 4-pins to 8-pins, S1 activities increased by only 130%. Additionally, source activities significantly increased when the inter-pin distance increased from 2.4 to 7.2 mm. The number of stimulated receptors was considered to have increased with an increase in the inter-pin distance as well as an increase in the number of pins. These findings clarified the effect of the number of pins and inter-pin distance for MS on SEFs.

  16. A free-piston Stirling cryocooler using metal diaphragms

    Science.gov (United States)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-12-01

    A novel concept for a free-piston Stirling cryocooler has been proposed. The concept uses a pair of metal diaphragms to seal and suspend the displacer of a free-piston Stirling cryocooler. The diaphragms allow the displacer to move without rubbing or moving seals, potentially resulting in a long-life mechanism. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicates the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. Sage predicted the macroscopic behaviour of the prototype well but did not provide sufficient insights to improve performance significantly. This paper presents details of the development, modelling and testing of the proof-of-concept prototype and a second, improved prototype.

  17. The low-cost and precise piston gas pressure regulator

    Science.gov (United States)

    Kudasik, Mateusz; Skoczylas, Norbert

    2016-03-01

    The present paper discusses the concept and functioning of an innovative instrument for precise stabilization of gas pressure. The piston gas pressure regulator was constructed at the Strata Mechanics Research Institute of the Polish Academy of Sciences. The tests to which the instrument was subjected involved observing the values of stabilized pressure at the level of 10 bar and 3 bar, for various gas flow rates at the outlet of the instrument. The piston gas pressure regulator operates within the range of 0-10 bar and the gas flow range of 0-240 cm3 min-1. The precision of the process of stabilizing the initial pressure is  ±0.005 bar, regardless of the gas pressure value and the flow rate observed at the outlet of the instrument. Although the pressure transducer’s accuracy is 0.25% of the full range, the conducted tests of the regulator demonstrated that the obtained changeability of the stabilized pressure is at least two times lower. Unlike some other gas pressure regulators available on the market, the instrument constructed by the authors of the present paper is highly precise when it comes to the process of stabilization, and inexpensive to build.

  18. Real-time estimation of differential piston at the LBT

    Science.gov (United States)

    Böhm, Michael; Pott, Jörg-Uwe; Sawodny, Oliver; Herbst, Tom; Kürster, Martin

    2014-07-01

    In this paper, we present and compare different strategies to minimize the effects of telescope vibrations to the differential piston (OPD) for LINC/NIRVANA at the LBT using an accelerometer feedforward compensation approach. We summarize why this technology is of importance for LINC/NIRVANA, but also for future telescopes and instruments. We outline the estimation problem in general and its specifics at the LBT. Model based estimation and broadband filtering techniques can be used to solve the estimation task, each having its own advantages and disadvantages, which will be discussed. Simulation results and measurements at the LBT are shown to motivate and support our choice of the estimation algorithm for the instrument LINC/NIRVANA. We explain our laboratory setup aimed at imitating the vibration behaviour at the LBT in general, and the M2 as main contributor in particular, and we demonstrate the controller's ability to suppress vibrations in the frequency range of 8 Hz to 60 Hz. In this range, telescope vibrations are the most dominant disturbance to the optical path. For our measurements, we introduce a disturbance time series which has a frequency spectrum comparable to what can be measured at the LBT on a typical night. We show promising experimental results, indicating the ability to suppress differential piston induced by telescope vibrations by a factor of about 5 (RMS), which is significantly better than any currently commissioned system.

  19. Method Evaluating the Durability of Aircraft Piston Engines

    Directory of Open Access Journals (Sweden)

    Luca PIANCASTELLI

    2012-12-01

    Full Text Available A significant issue in aircraft engines is quantifying residual life to overhaul. The algorithm described in this paper calculates with a good level of reliability the residual life of a petrol piston engine. The method was tested on small, latest-generation, naturally-aspirated aircraft and racing piston engines, and has been effective in several experiments. This method is implemented directly on the electronic control system of the engine with very few lines of C-code. The method can also be used in many industrial engines. This innovative method assumes that only two main factors (power level and wear affect engine durability or time between overhauls. These two factors are considered as separate and combined with worst case criteria. The wear is assumed to follow a logarithmic law and a formula similar to the Miner’s law for material fatigue is used, making it possible to calculate the power-level curve with knowledge of only two points. The wear-curve is also related to elapsed engine cycles. The algorithm is very simple and can be implemented with just a few lines of software code accessing data collected from existing sensors. The system is currently used to evaluate actual residual life of racing engines.

  20. Advanced Controller Developed for the Free-Piston Stirling Convertor

    Science.gov (United States)

    Gerber, Scott S.

    2005-01-01

    A free-piston Stirling power convertor is being considered as an advanced power-conversion technology for future NASA deep-space missions requiring long-life radioisotope power systems. The NASA Glenn Research Center has identified key areas where advanced technologies can enhance the capability of Stirling energy-conversion systems. One of these is power electronic controls. Current power-conversion technology for Glenn-tested Stirling systems consists of an engine-driven linear alternator generating an alternating-current voltage controlled by a tuning-capacitor-based alternating-current peak voltage load controller. The tuning capacitor keeps the internal alternator electromotive force (EMF) in phase with its respective current (i.e., passive power factor correction). The alternator EMF is related to the piston velocity, which must be kept in phase with the alternator current in order to achieve stable operation. This tuning capacitor, which adds volume and mass to the overall Stirling convertor, can be eliminated if the controller can actively drive the magnitude and phase of the alternator current.

  1. New 5 Kilowatt Free-piston Stirling Space Convertor Developments

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Chapman, Peter A., Jr.

    2007-01-01

    The NASA Vision for Exploration of the moon may someday require a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kW. In the 1990s, Mechanical Technology Inc. s Stirling Engine Systems Division (some of whose Stirling personnel are now at Foster-Miller, Inc.) developed a 25 kW free piston Stirling Space Power Demonstrator Engine under the SP-100 program. This system consisted of two 12.5 kW engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA and DoE have been developing dual 55 W and 80 W Stirling convertor systems for potential use with radioisotope heat sources. Total test times of all convertors in this effort exceed 120,000 hours. Recently, NASA began a new project with Auburn University to develop a 5 kW, single convertor for potential use in a lunar surface reactor power system. Goals of this development program include a specific power in excess of 140 W/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Auburn University awarded a subcontract to Foster-Miller, Inc. to undertake development of the 5 kW Stirling Convertor Assembly. The characteristics of the design along with progress in developing the system will be described.

  2. Focused, phased-array plane piston and spherically-shaped concave piston transducers: comparison for the same aperture and focal point.

    Science.gov (United States)

    Warriner, Renée K; Cobbold, Richard S C

    2012-04-01

    It has sometimes been assumed that the phased-array plane piston transducer and the spherically-shaped concave piston transducer are equivalent structures when both have the same aperture and focal point. This assumption has not been previously examined, nor has an expression for the on-axis impulse response of the focused, phased-array plane piston transducer been derived. It is shown in this paper how such an expression can be obtained. Comparisons of the impulse response for both structures show similarities, as well as some differences that could be significant as the observation point approaches the focal point. Comparisons are also performed for wide-band pulses close to the focus as well as for sinusoidal excitation. A physical explanation for the cause of the impulse response discrepancy is shown to be due to the nature of the piston focusing delay and its effect on the Rayleigh integral.

  3. Premature birth and diseases in premature infants: common genetic background?

    Science.gov (United States)

    Hallman, Mikko

    2012-04-01

    It has been proposed that during human evolution, development of obligate bipedalism, narrow birth canal cross-sectional area and the large brain have forced an adjustment in duration of pregnancy (scaling of gestational age; Plunkett 2011). Children compared to other mammals are born with proportionally small brains (compared to adult brains), suggesting shortening of pregnancy duration during recent evolution. Prevalence of both obstructed delivery and premature birth is still exceptionally high. In near term infants, functional maturity and viability is high, and gene variants predisposing to respiratory distress syndrome (RDS) are rare. Advanced antenatal and neonatal treatment practices during the new era of medicine allowed survival of also very preterm infants (gestation premature birth. Specific genes associating with diseases in preterm infants may also contribute to the susceptibility to preterm birth. Understanding and applying the knowledge of genetic interactions in normal and abnormal perinatal-neonatal development requires large, well-structured population cohorts, studies involving the whole genome and international interdisciplinary collaboration.

  4. Directionality of sperm whale sonar clicks and its relation to piston radiation theory

    DEFF Research Database (Denmark)

    Beedholm, K.; Møhl, Bertel

    2006-01-01

    with the spatial impulse response of a piston. The angle of a recorded click can be estimated as the angle producing the spatial impulse response that gives the best match with the observation when convolved with the on-axis wave form. It is concluded that piston theory applies to sperm whale sonar click emission....

  5. Novel Tribotester for Cylinder Liner/Piston Ring Contacts of Two Stroke Marine Diesel Engines

    DEFF Research Database (Denmark)

    Pedersen, Michael Torben; Imran, Tajammal; Klit, Peder

    2009-01-01

    A good tribological description for the cylinder liner and piston ring materials is always desired in order to achieve an improved combination of the materials. The piston ring package in a two-stroke-diesel engine operates in three lubrication regimes and the materials must be characterized in r...

  6. Scavenge flow analysis of opposed-piston two-stroke engine based on dynamic characteristics

    Directory of Open Access Journals (Sweden)

    Fu-kang Ma

    2015-04-01

    Full Text Available Opposed-piston two-stroke engine has been proposed by Beijing Institute of Technology to improve power density and complete machine balance relative to conventional engines. In order to study opposed-piston two-stroke engine scavenging flow, a scavenging system was configured using a three-dimensional computational fluid dynamics model effectively coupled to experiments. The boundary conditions are obtained through one-dimensional working process simulation results and experiments. As the opposed-piston relative dynamic characteristics of opposed-piston two-stroke engine depend on different design and operating parameters including the opposed-piston motion phase difference and crank-connecting rod ratio, a numerical simulation program was built using MATLAB/Simulink to define opposed-piston motion profiles based on equivalent crank angle of opposed crank-connecting rod mechanism. The opposed-piston motion phase difference only affects scavenging timing while crank-connecting rod ratio affects scavenging timing and duration. Scavenging timing and duration are the main factors which affect scavenging performance. The results indicate that a match of opposed-piston motion phase difference and crank-connecting rod ratio has the potential to achieve high scavenging and trapping efficiency with a right flow in cylinder.

  7. Development and verification of a reciprocating test rig designed for investigation of piston ring tribology

    DEFF Research Database (Denmark)

    Pedersen, Michael Torben; Imran, Tajammal; Klit, Peder

    2009-01-01

    This paper describes the development and verification of a reciprocating test rig, which was designed to study the piston ring tribology. A crank mechanism is used to generate a reciprocating motion for a moving plate, which acts as the liner. A stationary block acting as the ring package is loaded......, which is suitable for the study of piston ring tribology....

  8. Investigations of piston motion in transverse and longitudinal direction; Untersuchung der Kolbenbewegung in Motorquer- und Motorlaengsrichtung

    Energy Technology Data Exchange (ETDEWEB)

    Kuenzel, R.

    1997-12-31

    The book reviews literature on piston motion and presents a newly developed measuring and evaluation method in which the piston motion is recorded by probes inside the cylinder tube. All stages are represented, from the original lubricating gap signal to the calculated piston shaft load pattern. Using a variety of experimental findings, it is shown how the noise of longitudinal and transverse piston motion can be reduced. Influencing parameters such as piston shape, piston bolt axial displacement, piston bolt clearance, connecting rod stiffness and production-dpendent nonsymmetries of the connecting rod and piston are gone into. (orig./AKF) [Deutsch] Das Buch gibt einen Ueberblick ueber die Behandlung der Kolbenbewegung in der Literatur und stellt ein speziell entwickeltes Mess- und Auswerteverfahren vor, bei dem die raeumliche Bewegung des Kolbens durch Sensoren im Zylinderrohr erfasst wird. Die Darstellungen enthalten alle Schritte vom urspruenglich gemessenen Schmierspaltsignal bis hin zum errechneten Tragbild am Kolbenschaft. Anhand von vielzaehligen Versuchsergebnissen wird aufgezeigt, wie beim Dieselmotor auf die Bewegung des Kolbens in Motorquer- und Motorlaengsrichtung akustisch guenstig Einfluss genommen werden kann. Es werden Einflussparameter wie Kolbenform, Kolbenbolzendesachsierung, Spielgebung am Kolbenbolzen, Pleuelsteifigkeit und diverse fertigungsbedingte Bauteilunsymmetrien an Pleuel und Kolben behandelt. (orig./AKF)

  9. Computer Aided Design of Kaplan Turbine Piston with\tSolidWorks

    Directory of Open Access Journals (Sweden)

    Camelia Jianu

    2010-10-01

    Full Text Available The paper presents the steps for 3D computer aided design (CAD of Kaplan turbine piston made in SolidWorks.The present paper is a tutorial for a Kaplan turbine piston 3D geometry, which is dedicaded to the Parts Sketch and Parts Features design and Drawing Geometry and Drawing Annotation.

  10. [Premature ejaculation: pills or sexology?].

    Science.gov (United States)

    Wisard, M; Audette, N

    2008-03-26

    Premature ejaculation (PE) is a frequent male sexual complaint that affects 20 to 30% of men. The exact aetiology is unknown: psychological/behavioristic and biogenic etiologies have been proposed. The introduction of selective serotonin reuptake inhibitors (SSRI) was revolutionary in the medical treatment of PE. However precautions should be taken because of potential adverse side effects. There is no clear consensus as to whether SSRI may represent an eventual cure of PE or will be required for life. The sexocorporal approach is an other treatment of PE, but convincing scientific treatment data are also lacking.

  11. Positional moulding in premature hydrocephalics.

    Directory of Open Access Journals (Sweden)

    Kumar R

    2002-04-01

    Full Text Available Seven premature hydrocephalics presenting with lambdoid positional moulding (LPM were reviewed. All were treated for hydrocephalus secondary to aqueductal stenosis, Dandy Walker Syndrome and infection. Parenchymal hemorrhage, intraventricular bleed, cortical atrophy, septal agenesis, cortical anomalies and subdural hygroma were the other common associations. These children did not show expected improvement in their higher mental functions at 6 months to 5.4 years of follow-up, following the management of hydrocephalus. It was not the LPM but associated intracranial anomalies, which were most probably responsible for their poor outcome. The differentiation from posterior plagiocephaly is also highlighted.

  12. Metabolic bone disease of prematurity

    Directory of Open Access Journals (Sweden)

    Stacy E. Rustico, MD

    2014-09-01

    Full Text Available Metabolic bone disease (MBD of prematurity remains a significant problem for preterm, chronically ill neonates. The definition and recommendations for screening and treatment of MBD vary in the literature. A recent American Academy of Pediatrics Consensus Statement may help close the gap in institutional variation, but evidence based practice guidelines remain obscure due to lack of normative data and clinical trials for preterm infants. This review highlights mineral homeostasis physiology, current recommendations in screening and monitoring, prevention and treatment strategies, and an added perspective of a bone health team serving a high volume referral neonatal intensive care center.

  13. Current therapies for premature ejaculation.

    Science.gov (United States)

    Gur, Serap; Kadowitz, Philip J; Sikka, Suresh C

    2016-07-01

    Premature ejaculation (PE) subjectively affects 20-30% of men globally. Until recently, understanding of PE was hampered by the absence of a widely accepted definition, paucity of evidence-based clinical studies, and the absence of an appropriate animal model. Here, we elaborate on the current definition of PE, its pathogenesis, currently available therapies, and future treatment prospects. Most treatments for PE are 'off-label' and include selective serotonin reuptake inhibitors (SSRIs), topical anesthetics, tramadol, and phosphodiesterase type 5 (PDE5) inhibitors. Such knowledge of the benefit and limitations of each treatment will help to direct future drug design and formulations.

  14. Premature ventricular contractions associated with isotretinoin use.

    Science.gov (United States)

    Alan, Sevil; Ünal, Betül; Yildirim, Aytül

    2016-01-01

    Isotretinoin has been considered a unique drug for acne treatment. However, it is associated with numerous adverse effects. Isotretinoin can trigger premature ventricular contractions. This report describes a 33-year-old-woman who presented with palpitations for 1 week while undergoing 1-month isotretinoin treatment for mild-moderate facial acne. An electrocardiogram and Holter monitoring showed premature ventricular contractions during isotretinoin (Roaccutane, Roche) treatment. Isotretinoin-related premature ventricular contractions were strongly suggested in this case due to the existence of documented premature ventricular contractions on electrocardiograms and the disappearance of these premature ventricular contractions two weeks after termination of the treatment To the authors' knowledge, there has been 1 reported case of premature ventricular contractions linked to isotretinoin use; this report describes a second such case.

  15. Premature ventricular contractions associated with isotretinoin use*

    Science.gov (United States)

    Alan, Sevil; Ünal, Betül; Yildirim, Aytül

    2016-01-01

    Isotretinoin has been considered a unique drug for acne treatment. However, it is associated with numerous adverse effects. Isotretinoin can trigger premature ventricular contractions. This report describes a 33-year-old-woman who presented with palpitations for 1 week while undergoing 1-month isotretinoin treatment for mild-moderate facial acne. An electrocardiogram and Holter monitoring showed premature ventricular contractions during isotretinoin (Roaccutane, Roche) treatment. Isotretinoin-related premature ventricular contractions were strongly suggested in this case due to the existence of documented premature ventricular contractions on electrocardiograms and the disappearance of these premature ventricular contractions two weeks after termination of the treatment To the authors' knowledge, there has been 1 reported case of premature ventricular contractions linked to isotretinoin use; this report describes a second such case. PMID:28099609

  16. Bearing and gearing systems for rotary piston engines. Lager- und Getriebeanordnung einer Rotationskolbenmaschine

    Energy Technology Data Exchange (ETDEWEB)

    Eiermann, D.

    1991-03-14

    The proposed bearing and gearing system for rotary piston engines is provided with a trochoidal liner and triangular piston which is controlled by a synchromesh gear consisting of ring gear and pinion. The ring gear toothing is worked from the piston bore by shaping or broaching a depth of teeth which corresponds to the depth of the bore. A second, concentric bore inside the piston bore reaches from off the synchromesh gear to the ring gear and truncates the toothing of the latter. The stubs which are left hold the shell of the eccentric bearing. Cooling ducts are formed by the spaces in between. Since the bearing shell rests on the tooth stubs alone, the heat transfer from piston to eccentric bearing is considerably reduced.

  17. A dual-piston ring-driven X-spring transducer

    Science.gov (United States)

    Butler, Alexander L.; Butler, John L.; Pendleton, Robert L.; Ead, Richard M.

    2004-05-01

    Tonpilz transducers generally consist of a stack of piezoelectric material sandwiched between a single piston and an inertial tail mass or between two pistons. The result is a transducer with a large length-to-diameter ratio. The X-spring transducer design, based on U.S. Patent 4845688, allows a means for a shorter transducer length through an orthogonal piezoelectric drive system coupled to the pistons by lever arms. We present here a low-frequency, dual-piston piezoelectric ceramic ring driven version with a length of only 10 in. and a diameter of 19 in. Both single-element and two-element array results are presented. The measured response is shown to be in agreement with the finite-element model with a smooth, wideband 300- to 550-Hz response for this dual-piston, ring-driven X-spring transducer. [Work supported by a Phase II SBIR, through NUWC, Newport, RI 02841.

  18. Demonstration of a free piston Stirling engine driven linear alternator, phase I report

    Energy Technology Data Exchange (ETDEWEB)

    Goldwater, B.; Piller, S.; Rauch, J.; Cella, A.

    1977-03-30

    The results of the work performed under Phase I of the free piston Stirling engine demonstrator program are described. The objective of the program is to develop a 2 kW free piston Stirling engine/linear alternator energy conversion system, for an isotopic heat source, with a greater than 30% overall efficiency. Phase I was a 15-month effort to demonstrate the feasibility of the system through analysis and experimental testing of the individual components. An introduction to Stirling engines and the details of the tasks completed are presented in five major sections: (1) introduction to Stirling engine; (2) preliminary design of an advanced free piston Stirling demonstrator engine; (3) design and test of a 1 kWE output linear alternator; (4) test of a model free piston Stirling engine; and (5) development of a free piston Stirling engine computer simulation code.

  19. A pinned polymer model of posture control

    CERN Document Server

    Chow, C C; Chow, Carson C; Collins, J J

    1995-01-01

    A phenomenological model of human posture control is posited. The dynamics are modelled as an elastically pinned polymer under the influence of noise. The model accurately reproduces the two-point correlation functions of experimental posture data and makes predictions for the response function of the postural control system. The physiological and clinical significance of the model is discussed.

  20. Duodenocolic fistula due to safety pin ingestion.

    Science.gov (United States)

    Cay, Ali; Imamoğlu, Mustafa; Sarihan, Haluk; Sayil, Ozgür

    2004-01-01

    The authors describe the case of a 16-month-old boy with benign duodenocolic fistula due to safety pin ingestion who presented with abdominal pain, diarrhea and weight loss. Etiology, symptomatology, diagnosis and management are discussed and the literature is reviewed. Early diagnosis and surgical management are necessary to avoid serious morbidity.

  1. Turban pin aspiration: new fashion, new syndrome.

    Science.gov (United States)

    Ilan, Ophir; Eliashar, Ron; Hirshoren, Nir; Hamdan, Kasem; Gross, Menachem

    2012-04-01

    Turban pin aspiration syndrome is a new clinical entity afflicting young Islamic girls wearing a turban.The goal of this study was to present our experience in diagnosis and treatment of this new entity, define its clinical and epidemiologic features, and shed a new light on the role of fashion in the increased incidence. A retrospective study in a tertiary university hospital. Review of clinical parameters and epidemiologic features of 26 patients diagnosed with turban pin aspiration syndrome admitted to the Hadassah-Hebrew University Hospitals in Jerusalem from 1990 to 2010. All patients were Muslim females with an average age of 16 years. In all cases, the history was positive for accidental aspiration. Most of the pins were located in the trachea (42%). In 20 cases, the pins were extracted by rigid bronchoscopy without major complications. Fluoroscopy-assisted rigid bronchoscopy was used successfully in three cases. In one case, the object was self-ejected by coughing before the bronchoscopy, and two patients were referred to the chest unit for thoracotomy. Clinicians should be aware of this distinct form of foreign body aspiration, its method of diagnosis, and extraction techniques. A cultural investigation showed a difference in the turban-fastening technique of young girls as compared with their mothers. Removal by rigid bronchoscopy is a safe method with a high success rate and should be considered as the preferred extraction method of choice. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

  2. Pinning control of clustered complex networks with different size

    Science.gov (United States)

    Fu, Chenbo; Wang, Jinbao; Xiang, Yun; Wu, Zhefu; Yu, Li; Xuan, Qi

    2017-08-01

    In pinning control of complex networks, it is found that, with the same pinning effort, the network can be better controlled by pinning the large-degree nodes. But in the clustered complex networks, this preferential pinning (PP) strategy is losing its effectiveness. In this paper, we demonstrate that in the clustered complex networks, especially when the clusters have different size, the random pinning (RP) strategy performs much better than the PP strategy. Then, we propose a new pinning strategy based on cluster degree. It is revealed that the new cluster pinning strategy behaves better than RP strategy when there are only a smaller number of pinning nodes. The mechanism is studied by using eigenvalue and eigenvector analysis, and the simulations of coupled chaotic oscillators are given to verify the theoretical results. These findings could be beneficial for the design of control schemes in some practical systems.

  3. Analytical method for reconstruction pin to pin of the nuclear power density distribution

    Energy Technology Data Exchange (ETDEWEB)

    Pessoa, Paulo O.; Silva, Fernando C.; Martinez, Aquilino S., E-mail: ppessoa@con.ufrj.br, E-mail: fernando@con.ufrj.br, E-mail: aquilino@imp.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    An accurate and efficient method for reconstructing pin to pin of the nuclear power density distribution, involving the analytical solution of the diffusion equation for two-dimensional neutron energy groups in homogeneous nodes, is presented. The boundary conditions used for analytic as solution are the four currents or fluxes on the surface of the node, which are obtained by Nodal Expansion Method (known as NEM) and four fluxes at the vertices of a node calculated using the finite difference method. The analytical solution found is the homogeneous distribution of neutron flux. Detailed distributions pin to pin inside a fuel assembly are estimated by the product of homogeneous flux distribution by local heterogeneous form function. Furthermore, the form functions of flux and power are used. The results obtained with this method have a good accuracy when compared with reference values. (author)

  4. Pinning control of complex networked systems synchronization, consensus and flocking of networked systems via pinning

    CERN Document Server

    Su, Housheng

    2013-01-01

    Synchronization, consensus and flocking are ubiquitous requirements in networked systems. Pinning Control of Complex Networked Systems investigates these requirements by using the pinning control strategy, which aims to control the whole dynamical network with huge numbers of nodes by imposing controllers for only a fraction of the nodes. As the direct control of every node in a dynamical network with huge numbers of nodes might be impossible or unnecessary, it’s then very important to use the pinning control strategy for the synchronization of complex dynamical networks. The research on pinning control strategy in consensus and flocking of multi-agent systems can not only help us to better understand the mechanisms of natural collective phenomena, but also benefit applications in mobile sensor/robot networks. This book offers a valuable resource for researchers and engineers working in the fields of control theory and control engineering.   Housheng Su is an Associate Professor at the Department of Contro...

  5. Finite-temperature Casimir effect in piston geometry and its classical limit

    Energy Technology Data Exchange (ETDEWEB)

    Lim, S.C. [Multimedia University, Faculty of Engineering, Cyberjaya, Selangor Darul Ehsan (Malaysia); Teo, L.P. [Multimedia University, Faculty of Information Technology, Cyberjaya, Selangor Darul Ehsan (Malaysia)

    2009-03-15

    We consider the Casimir force acting on a d-dimensional rectangular piston due to a massless scalar field with periodic, Dirichlet and Neumann boundary conditions and an electromagnetic field with perfect electric-conductor and perfect magnetic-conductor boundary conditions. The Casimir energy in a rectangular cavity is derived using the cut-off method. It is shown that the divergent part of the Casimir energy does not contribute to the Casimir force acting on the piston, thus renders an unambiguously defined Casimir force acting on the piston. At any temperature, it is found that the Casimir force acting on the piston increases from -{infinity} to 0 when the separation a between the piston and the opposite wall increases from 0 to {infinity}. This implies that the Casimir force is always an attractive force pulling the piston towards the closer wall, and the magnitude of the force gets larger as the separation a gets smaller. Explicit exact expressions for the Casimir force for small and large plate separations and for low and high temperatures are computed. The limits of the Casimir force acting on the piston when some pairs of transversal plates are large are also derived. An interesting result regarding the influence of temperature is that in contrast to the conventional result that the leading term of the Casimir force acting on a wall of a rectangular cavity at high temperature is the Stefan-Boltzmann (or black-body radiation) term which is of order T {sup d+1}, it is found that the contributions of this term from the two regions separating the piston cancel with each other in the case of piston. The high-temperature leading-order term of the Casimir force acting on the piston is of order T, which shows that the Casimir force has a nontrivial classical {Dirac_h}{yields}0 limit. Explicit formulas for the classical limit are computed. (orig.)

  6. Premature temporal theta (PT theta).

    Science.gov (United States)

    Hughes, J R; Fino, J J; Hart, L A

    1987-07-01

    A distinctive pattern called premature temporal theta (PT theta) was studied in 436 infants, ranging in age from 24 to 46 weeks. The pattern is seen in early prematurity, maximizes at 29-31 weeks and then diminishes and disappears near term. Usually the pattern is found independently on both temporal areas, but with a right-sided preference. Patients without PT theta or with a significantly low amount had either neurological or non-neurological (medical) conditions. With age there is a tendency for an increase in frequency and a decrease in amplitude. Five different peaks in the amount of this pattern are seen at approximately every month. Unilateral PT theta tends to be seen in older babies, more often on the right side and with an abnormal EEG. An abnormal EEG is usually associated with a delay in both the appearance and disappearance of this wave form. PT theta is also associated mainly with REM or active sleep. A polynomial rather than an exponential or power function best describes these data with changes of age. PT theta may arise from the inferior temporal gyrus and/or especially the transverse gyrus.

  7. Auxin transport through PIN-FORMED 3 (PIN3) controls shade avoidance and fitness during competition

    Science.gov (United States)

    Keuskamp, Diederik H.; Pollmann, Stephan; Voesenek, Laurentius A. C. J.; Peeters, Anton J. M.; Pierik, Ronald

    2010-01-01

    Plants grow in dense vegetations at the risk of being out-competed by neighbors. To increase their competitive power, plants display adaptive responses, such as rapid shoot elongation (shade avoidance) to consolidate light capture. These responses are induced upon detection of proximate neighbors through perception of the reduced ratio between red (R) and far-red (FR) light that is typical for dense vegetations. The plant hormone auxin is a central regulator of plant development and plasticity, but until now it has been unknown how auxin transport is controlled to regulate shade-avoidance responses. Here, we show that low R:FR detection changes the cellular location of the PIN-FORMED 3 (PIN3) protein, a regulator of auxin efflux, in Arabidopsis seedlings. As a result, auxin levels in the elongating hypocotyls are increased under low R:FR. Seedlings of the pin3-3 mutant lack this low R:FR-induced increase of endogenous auxin in the hypocotyl and, accordingly, have no elongation response to low R:FR. We hypothesize that low R:FR-induced stimulation of auxin biosynthesis drives the regulation of PIN3, thus allowing shade avoidance to occur. The adaptive significance of PIN3-mediated control of shade-avoidance is shown in plant competition studies. It was found that pin3 mutants are outcompeted by wild-type neighbors who suppress fitness of pin3-3 by 40%. We conclude that low R:FR modulates the auxin distribution by a change in the cellular location of PIN3, and that this control can be of great importance for plants growing in dense vegetations. PMID:21149713

  8. Investigation of Different Piston Ring Curvatures on Lubricant Transport along Cylinder Liner in Large Two-Stroke Marine Diesel Engines

    DEFF Research Database (Denmark)

    Overgaard, Hannibal Christian; Klit, Peder; Vølund, Anders

    2016-01-01

    A theoretical investigation of the hydrodynamic lubrication of the top compression piston ring in a large two-stroke marine diesel engine is presented. The groove mounted piston ring is driven by the reciprocal motion of the piston. The ring shape follows a circular geometry and the effect...

  9. Optimization study on pin tip diameter of an impact-pin nozzle at high pressure ratio

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, C. Palani; Lee, Kwon Hee [FMTRC, Daejoo Machinery Co. Ltd., Daegu (Korea, Republic of); Park, Tae Choon; Cha, Bong Jun [Engine Components Research Team, Korea Aerospace Research Institute, Daejeon (Korea, Republic of); Kim, Heuy Dong [Dept. of Mechanical Engineering, Andong National University, Andong (Korea, Republic of)

    2016-09-15

    Wet compression system is typically installed in a gas turbine engine to increase the net power output and efficiency. A crucial component of the wet compression system is the nozzle which generates fine water droplets for injection into the compressor. The main objective of present work is to optimize a kind of nozzle called impact-pin spray nozzle and thereby produce better quality droplets. To achieve this, the dynamics occurring in the water jet impinging on the pin tip, the subsequent formation of water sheet, which finally breaks into water droplets, must be studied. In this manuscript, the progress on the numerical studies on impact-pin nozzle are reported. A small computational domain covering the orifice, pin tip and the region where primary atomization occurs is selected for numerical analysis. The governing equations are selected in three dimensional cartesian form and simulations are performed to predict the dynamics of water jet impinging on the pin. Systematic studies were carried out and the results leading to the choice of turbulence model and the effect of pin tip diameter are reported here. Further studies are proposed to show the future directions of the present research work.

  10. Nanowall pinning for enhanced pinning force in YBCO films with nanofabricated structures

    Energy Technology Data Exchange (ETDEWEB)

    Palau, A.; Rouco, V.; Luccas, R.F.; Obradors, X.; Puig, T., E-mail: teresa.puig@icmab.es

    2014-11-15

    Highlights: • High resolution lithography techniques to fabricate artificial pinning centres in high temperature superconductors. • Enhanced critical currents of YBCO films with engineered nanofabricated structures. • Controlled nano-walls with weakened superconductivity acting as strong pinning centres. - Abstract: High resolution nanofabrication tools (Focused Ion Beam and Electron Beam Lithography) have been used to fabricate nano-metric milled structures in high critical current YBCO thin films able to further increase their vortex pinning capabilities. We have demonstrated that pinning forces at 77 K and 3 T are increased by a 70–80% by proper nanostructure designs. Model systems with linear trenches and triangular blind antidots of different sizes, distribution and density have been generated and studied. We demonstrate that specific milled nanostructures can increase the total current through the system at expenses of a limited decrease of cross section. We have identified the length of fabricated nano-walls as the main parameter controlling the pinning potential of nanostructures and thus defined the optimised milling conditions and nanostructure morphology to maximise pinning efficiency.

  11. Free-piston engine-and-hydraulic pump for railway vehicles

    Directory of Open Access Journals (Sweden)

    A. F. Golovchuk

    2013-04-01

    Full Text Available Purpose. The development of the free-piston diesel engine-and-hydraulic pump for the continuously variable hydrostatical transmission of mobile power vehicles. Methodology. For a long time engine builders have been interesting in the problem of developing free piston engines, which have much bigger coefficient of efficiency (40…80%. Such engines don’t have the conversion of reciprocating motion for inner combustion engine piston into rotating motion of crankshaft, from which the engine torque is transferred to the power machine transmission. Free-piston engines of inner combustion don’t have the crank mechanism (CM that significantly reduces mechanical losses for friction. Such engines can be used as compressors. Free-piston engine compressor (FPEC – is a free-piston machine in which energy received from engine’s cylinder is being transferred direct to compressor’s pistons connected with operational pistons of engine without crank mechanism. Part of the pressed air is being consumed for engine cylinder drain and the other part is going to the consumer. Findings. The use of free-piston engines-and-hydraulic pumps as power-transmission plants of power vehicles (diesel locomotives, combine harvester, tractors, cars and other mobile and stationary power installations with the continuously variable transmissions allows cost effectiveness improvement and metal consumption reduction of these vehicles, since the cost effectiveness of FPE is higher by 25-30%, and the metal consumption is lower by 40-50%. Originality. One of the important advantages of the free-piston engines is their simplicity and engine balance. As a result of the crank mechanism absence their construction is much simplified and the vibrations, peculiar to the ordinary engines are eliminated. In such installation the engine pistons are directly connected through the rod to compressor pistons and therefore there are no losses in the bearing bushes. Practical value. The free-piston

  12. Differential Roles of PIN1 and PIN2 in Root Meristem Maintenance Under Low-B Conditions in Arabidopsis thaliana.

    Science.gov (United States)

    Li, Ke; Kamiya, Takehiro; Fujiwara, Toru

    2015-06-01

    Boron (B) is an essential element for plants; its deficiency causes rapid cessation of root elongation. In addition, B influences auxin accumulation in plants. To assess the importance of auxin transport in B-dependent root elongation, Arabidopsis thaliana pin1-pin4 mutants were grown under low-B conditions. Among them, only the pin2/eir1-1 mutant showed a significantly shorter root under low-B conditions than under control conditions. Moreover, the root meristem size of pin2/eir1-1 was reduced under low-B conditions. Among the PIN-FORMED (PIN) family, PIN1 and PIN2 are important for root meristem growth/maintenance under normal conditions. To investigate the differential response of pin1 and pin2 mutants under low-B conditions, the effect of low-B on PIN1-green fluorescent protein (GFP) and PIN2-GFP accumulation and localization was examined. Low-B did not affect PIN2-GFP, while it reduced the accumulation of PIN1-GFP. Moreover, no signal from DII-VENUS, an auxin sensor, was detected under the low-B condition in the stele of wild-type root meristems. Taken together, these results indicate that under low-B conditions PIN1 is down-regulated and PIN2 plays an important role in root meristem maintenance. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  13. Heat transfer analysis of liquid piston compressor for hydrogen applications

    DEFF Research Database (Denmark)

    Kermani, Nasrin Arjomand; Rokni, Masoud

    2015-01-01

    based on the mass and energy balance of the hydrogen, liquid, and the wall of the compression chamber at each time step and positional node with various compression ratios, to calculate the temperature distribution of the system. The amount of heat extracted from hydrogen, directly at the interface......A hydrogen compression technology using liquid as the compression piston is investigated from heat transfer point of view. A thermodynamic model, simulating a single compression stroke, is developed to investigate the heat transfer phenomena inside the compression chamber. The model is developed...... at the interface. Moreover, the results of the sensitivity analysis illustrates that increasing the total heat transfer coefficients at the interface and the wall, together with compression time, play key roles in reducing the hydrogen temperature. Increasing the total heat transfer coefficient at the interface...

  14. Integrated two-cylinder liquid piston Stirling engine

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd, E-mail: todd.sulchek@me.gatech.edu [George W. Woodruff School of Mechanical Engineering and Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

    2014-10-06

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.

  15. Development of new volumetric compressor with rotating cylinder and piston

    Energy Technology Data Exchange (ETDEWEB)

    Sawai, K.; Iida, N.; Futagami, Y.; Hirano, H. [Matsushita Electrical Ind. Co. Ltd., Air-Conditioning Research Lab., Shiga (Japan); Hasegawa, H. [Matsushita Electric Ind. Co. Ltd., Human Environment Systems Development Center, Osaka (Japan); Ishii, N. [Osaka Electro-Communications Lab., Faculty of Engineering, Osaka (Japan)

    1999-07-01

    We developed a new compression mechanism named 'Ellipse Compressor', which can be used in air conditioning and refrigeration. This compression mechanism is basically rotary type machine, which consists of rotating cylinder and rotating piston without vane. It has high potentiality to exhibit high reliability in R410A refrigerant, because of low wear without extreme high pressure on the sliding parts. This paper presents a compression mechanism, theoretical analysis, a prototype model design, performance and loss analysis. Test results indicated that the performance of the prototype model exhibited almost the same as that of scroll compressor for room air conditioner. Durability test on the room air conditioner at heavy heating condition resulted in the low level of wear of the sliding parts, without special materials. (Author)

  16. Heat transfer analysis of liquid piston compressor for hydrogen applications

    DEFF Research Database (Denmark)

    Kermani, Nasrin Arjomand; Rokni, Masoud

    2015-01-01

    at the interface. Moreover, the results of the sensitivity analysis illustrates that increasing the total heat transfer coefficients at the interface and the wall, together with compression time, play key roles in reducing the hydrogen temperature. Increasing the total heat transfer coefficient at the interface......A hydrogen compression technology using liquid as the compression piston is investigated from heat transfer point of view. A thermodynamic model, simulating a single compression stroke, is developed to investigate the heat transfer phenomena inside the compression chamber. The model is developed...... and through the walls, is investigated and compared with the adiabatic case. The results show that depending on heat transfer correlation, the hydrogen temperature reduces slightly between 0.2% and 0.4% compared to the adiabatic case, at 500bar, due to the large wall resistance and small contact area...

  17. Heat Analysis of Liquid piston Compressor for Hydrogen Applications

    DEFF Research Database (Denmark)

    Kermani, Nasrin Arjomand; Rokni, Masoud

    2014-01-01

    of hydrogen temperature from adiabatic case is very small, due to large wall resistance and small contact area at the interface. Moreover, the results illustrates that the increasing of the total heat transfer coefficient at the interface and the wall will play a key role in reducing the hydrogen temperature......A new hydrogen compression technology using liquid as the compression piston is investigated from heat transfer point of view. A thermodynamic model, simulating a single compression stroke, is developed to investigate the heat transfer phenomena inside the compression chamber. The model...... and through the walls, is investigated and compared with the adiabatic case. The amount of heat transfer towards the wall is assessed according to widely used heat transfer models available in the literature.The results show very low sensitivity of the model to different heat transfer correlations. Deviation...

  18. Investigation of Valve Plate in Water Hydraulic Axial Piston Motor

    Institute of Scientific and Technical Information of China (English)

    聂松林; 李壮云; 等

    2002-01-01

    This paper has introduced the developments of water hydraulic axial piston equipments.According to the effects of physicochemical properties of water on water hydraulic components,a novel valve plate for water hydraulic axial motor has been put forward,whose moment exerted by the fluid field between valve plate and bearing plate is balanced entirely.The material screening experiment of valve plate is done on the test rig.Through numerical simulation the effects of some geometry parameters on the performance of water hydraulic motor have been studied.The silencing grooves on the valve plate in water hydraulic motor can reduce the pressure shock and the occurrence of cavitation effectively.It is evident that the appropriate structure should change the wear status between matching paris and reduces the wear and specific pressure of the matching pairs.The specimen with the new type valve plate is used in a tool system.

  19. Integrated two-cylinder liquid piston Stirling engine

    Science.gov (United States)

    Yang, Ning; Rickard, Robert; Pluckter, Kevin; Sulchek, Todd

    2014-10-01

    Heat engines utilizing the Stirling cycle may run on low temperature differentials with the capacity to function at high efficiency due to their near-reversible operation. However, current approaches to building Stirling engines are laborious and costly. Typically the components are assembled by hand and additional components require a corresponding increase in manufacturing complexity, akin to electronics before the integrated circuit. We present a simple and integrated approach to fabricating Stirling engines with precisely designed cylinders. We utilize computer aided design and one-step, planar machining to form all components of the engine. The engine utilizes liquid pistons and displacers to harness useful work from heat absorption and rejection. As a proof of principle of the integrated design, a two-cylinder engine is produced and characterized and liquid pumping is demonstrated.

  20. Layered clustering multi-fault diagnosis for hydraulic piston pump

    Science.gov (United States)

    Du, Jun; Wang, Shaoping; Zhang, Haiyan

    2013-04-01

    Efficient diagnosis is very important for improving reliability and performance of aircraft hydraulic piston pump, and it is one of the key technologies in prognostic and health management system. In practice, due to harsh working environment and heavy working loads, multiple faults of an aircraft hydraulic pump may occur simultaneously after long time operations. However, most existing diagnosis methods can only distinguish pump faults that occur individually. Therefore, new method needs to be developed to realize effective diagnosis of simultaneous multiple faults on aircraft hydraulic pump. In this paper, a new method based on the layered clustering algorithm is proposed to diagnose multiple faults of an aircraft hydraulic pump that occur simultaneously. The intensive failure mechanism analyses of the five main types of faults are carried out, and based on these analyses the optimal combination and layout of diagnostic sensors is attained. The three layered diagnosis reasoning engine is designed according to the faults' risk priority number and the characteristics of different fault feature extraction methods. The most serious failures are first distinguished with the individual signal processing. To the desultory faults, i.e., swash plate eccentricity and incremental clearance increases between piston and slipper, the clustering diagnosis algorithm based on the statistical average relative power difference (ARPD) is proposed. By effectively enhancing the fault features of these two faults, the ARPDs calculated from vibration signals are employed to complete the hypothesis testing. The ARPDs of the different faults follow different probability distributions. Compared with the classical fast Fourier transform-based spectrum diagnosis method, the experimental results demonstrate that the proposed algorithm can diagnose the multiple faults, which occur synchronously, with higher precision and reliability.

  1. CFD analysis of a diaphragm free-piston Stirling cryocooler

    Science.gov (United States)

    Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan

    2016-10-01

    This paper presents a Computational Fluid Dynamics (CFD) analysis of a novel free-piston Stirling cryocooler that uses a pair of metal diaphragms to seal and suspend the displacer. The diaphragms allow the displacer to move without rubbing or moving seals. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicated the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. The diaphragm's large diameter and short stroke produces a significant radial component to the oscillating flow fields inside the cryocooler which were not modelled in the one-dimensional analysis tool Sage that was used to design the prototypes. Compared with standard pistons, the diaphragm geometry increases the gas-to-wall heat transfer due to the higher velocities and smaller hydraulic diameters. A Computational Fluid Dynamics (CFD) model of the cryocooler was constructed to understand the underlying fluid-dynamics and heat transfer mechanisms with the aim of further improving performance. The CFD modelling of the heat transfer in the radial flow fields created by the diaphragms shows the possibility of utilizing the flat geometry for heat transfer, reducing the need for, and the size of, expensive heat exchangers. This paper presents details of a CFD analysis used to model the flow and gas-to-wall heat transfer inside the second prototype cryocooler, including experimental validation of the CFD to produce a robust analysis.

  2. Using IR Imaging of Water Surfaces for Estimating Piston Velocities

    Science.gov (United States)

    Gålfalk, M.; Bastviken, D.; Arneborg, L.

    2013-12-01

    The transport of gasses dissolved in surface waters across the water-atmosphere interface is controlled by the piston velocity (k). This coefficient has large implications for, e.g., greenhouse gas fluxes but is challenging to quantify in situ. At present, empirical k-wind speed relationships from a small number of studies and systems are often extrapolated without knowledge of model performance. It is therefore of interest to search for new methods for estimating k, and to compare the pros and cons of existing and new methods. Wind speeds in such models are often measured at a height of 10 meters. In smaller bodies of water such as lakes, wind speeds can vary dramatically across the surface through varying degrees of wind shadow from e.g. trees at the shoreline. More local measurements of the water surface, through wave heights or surface motion mapping, could give improved k-estimates over a surface, also taking into account wind fetch. At thermal infrared (IR) wavelengths water has very low reflectivity (depending on viewing angle) than can go below 1%, meaning that more than 99% is heat radiation giving a direct measurement of surface temperature variations. Using an IR camera at about 100 frames/s one could map surface temperature structures at a fraction of a mm depth even with waves present. In this presentation I will focus on IR imaging as a possible tool for estimating piston velocities. Results will be presented from IR field measurements, relating the motions of surface temperature structures to k calculated from other simultaneous measurements (flux chamber and ADV-Based Dissipation Rate), but also attempting to calculate k directly from the IR surface divergence. A relation between wave height and k will also be presented.

  3. 5-kWe Free-piston Stirling Engine Convertor

    Science.gov (United States)

    Chapman, Peter A.; Vitale, Nicholas A.; Walter, Thomas J.

    2008-01-01

    The high reliability, long life, and efficient operation of Free-Piston Stirling Engines (FPSEs) make them an attractive power system to meet future space power requirements with less mass, better efficiency, and less total heat exchanger area than other power convertor options. FPSEs are also flexible in configuration as they can be coupled with many potential heat sources and various heat input systems, heat rejection systems, and power management and distribution systems. Development of a 5-kWe Stirling Convertor Assembly (SCA) is underway to demonstrate the viability of an FPSE for space power. The design is a scaled-down version of the successful 12.5-kWe Component Test Power Converter (CTPC) developed under NAS3-25463. The ultimate efficiency target is 25% overall convertor efficiency (electrical power out over heat in). For the single cylinder prototype now in development, cost and time constraints required use of economical and readily available materials (steel versus beryllium) and components (a commercially available linear alternator) and thus lower efficiency. The working gas is helium at 150 bar mean pressure. The design consists of a displacer suspended on internally pumped gas bearings and a power piston/alternator supported on flexures. Non-contacting clearance seals are used between internal volumes. Heat to and from the prototype convertor is done via pumped liquid loops passing through shell and tube heat exchangers. The preliminary and detail designs of the convertor, controller, and support systems (heating loop, cooling loop, and helium supply system) are complete and all hardware is on order. Assembly and test of the prototype at Foster- Miller is planned for early 2008, when work will focus on characterizing convertor dynamics and steady-state operation to determine maximum power output and system efficiency. The device will then be delivered to Auburn University where assessments will include start-up and shutdown characterization and

  4. Accomplishments in free-piston stirling tests at NASA GRC

    Science.gov (United States)

    Schreiber, Jeffrey G.; Skupinski, Robert C.

    2002-01-01

    A power system based on the Stirling Radioisotope Generator (SRG) has been identified for potential use on deep space missions, as well as for Mars rovers that may benefit from extended operation. The Department of Energy (DOE) has responsibility for developing the generator and the NASA Glenn Research Center (GRC) is supporting DOE in this effort. The generator is based on a free-piston Stirling power convertor that has been developed by the Stirling Technology Company (STC) under contract to DOE. The generator would be used as a high-efficiency alternative to the Radioisotope Thermoelectric Generators (RTGs) that have been used on many previous missions. The increased efficiency leads to a factor of 3 to 4 reduction in the inventory of plutonium required to heat the generator. GRC has been involved in the development of Stirling power conversion technology for over 25 years. The support provided to this project by GRC has many facets and draws upon the lab's scientists and engineers that have gained experience in applying their skills to the previous Stirling projects. This has created a staff with an understanding of the subtleties involved in applying their expertise to Stirling systems. Areas include materials, structures, tribology, controls, electromagnetic interference, permanent magnets, alternator analysis, structural dynamics, and cycle performance. One of the key areas of support to the project is in the performance testing of the free-piston Stirling convertors. Since these power convertors are the smallest, lowest power Stirling machines that have been tested at GRC, a new laboratory was equipped for this project. Procedures and test plans have been created, instrumentation and data systems developed, and Stirling convertors have been tested. This paper will describe the GRC test facility, the test procedures that are used, present some of the test results and outline plans for the future. .

  5. Genome-wide identification and evolution of the PIN-FORMED (PIN) gene family in Glycine max.

    Science.gov (United States)

    Liu, Yuan; Wei, Haichao

    2017-07-01

    Soybean (Glycine max) is one of the most important crop plants. Wild and cultivated soybean varieties have significant differences worth further investigation, such as plant morphology, seed size, and seed coat development; these characters may be related to auxin biology. The PIN gene family encodes essential transport proteins in cell-to-cell auxin transport, but little research on soybean PIN genes (GmPIN genes) has been done, especially with respect to the evolution and differences between wild and cultivated soybean. In this study, we retrieved 23 GmPIN genes from the latest updated G. max genome database; six GmPIN protein sequences were changed compared with the previous database. Based on the Plant Genome Duplication Database, 18 GmPIN genes have been involved in segment duplication. Three pairs of GmPIN genes arose after the second soybean genome duplication, and six occurred after the first genome duplication. The duplicated GmPIN genes retained similar expression patterns. All the duplicated GmPIN genes experienced purifying selection (Ka/Ks < 1) to prevent accumulation of non-synonymous mutations and thus remained more similar. In addition, we also focused on the artificial selection of the soybean PIN genes. Five artificially selected GmPIN genes were identified by comparing the genome sequence of 17 wild and 14 cultivated soybean varieties. Our research provides useful and comprehensive basic information for understanding GmPIN genes.

  6. Pinning Synchronization of One-Sided Lipschitz Complex Networks

    Directory of Open Access Journals (Sweden)

    Fang Liu

    2014-01-01

    Full Text Available This paper studies the pinning synchronization in complex networks with node dynamics satisfying the one-sided Lipschitz condition which is less conservative than the well-known Lipschitz condition. Based on M-matrix theory and Lyapunov functional method, some simple pinning conditions are derived for one-sided Lipschitz complex networks with full-state and partial-state coupling, respectively. A selective pinning scheme is further provided to address the selection of pinned nodes and the design of pinning feedback gains for one-sided Lipschitz complex networks with general topologies. Numerical results are given to illustrate the effectiveness of the theoretical analysis.

  7. Open Loop Heat Pipe Radiator Having a Free-Piston for Wiping Condensed Working Fluid

    Science.gov (United States)

    Weinstein, Leonard M. (Inventor)

    2015-01-01

    An open loop heat pipe radiator comprises a radiator tube and a free-piston. The radiator tube has a first end, a second end, and a tube wall, and the tube wall has an inner surface and an outer surface. The free-piston is enclosed within the radiator tube and is capable of movement within the radiator tube between the first and second ends. The free-piston defines a first space between the free-piston, the first end, and the tube wall, and further defines a second space between the free-piston, the second end, and the tube wall. A gaseous-state working fluid, which was evaporated to remove waste heat, alternately enters the first and second spaces, and the free-piston wipes condensed working fluid from the inner surface of the tube wall as the free-piston alternately moves between the first and second ends. The condensed working fluid is then pumped back to the heat source.

  8. Dynamically balanced, hydraulically driven compressor/pump apparatus for resonant free piston Stirling engines

    Science.gov (United States)

    Corey, John A.

    1984-05-29

    A compressor, pump, or alternator apparatus is designed for use with a resonant free piston Stirling engine so as to isolate apparatus fluid from the periodically pressurized working fluid of the Stirling engine. The apparatus housing has a first side closed by a power coupling flexible diaphragm (the engine working member) and a second side closed by a flexible diaphragm gas spring. A reciprocally movable piston is disposed in a transverse cylinder in the housing and moves substantially at right angles relative to the flexible diaphragms. An incompressible fluid fills the housing which is divided into two separate chambers by suitable ports. One chamber provides fluid coupling between the power diaphragm of the RFPSE and the piston and the second chamber provides fluid coupling between the gas spring diaphragm and the opposite side of the piston. The working members of a gas compressor, pump, or alternator are driven by the piston. Sealing and wearing parts of the apparatus are mounted at the external ends of the transverse cylinder in a double acting arrangement for accessibility. An annular counterweight is mounted externally of the reciprocally movable piston and is driven by incompressible fluid coupling in a direction opposite to the piston so as to damp out transverse vibrations.

  9. Performance analysis of a biodiesel fuelled diesel engine with the effect of alumina coated piston

    Directory of Open Access Journals (Sweden)

    Senthil Kumar Srinivasan

    2017-01-01

    Full Text Available Biodiesel is one of the best alternative fuels to Diesel engine among other sources due to having potential to reduce emissions. Biodiesel is a renewable, biodegradable and environment friendly fuel in nature. The advantages of biodiesel are lower exhaust gas emissions and its biodegradability and renewability compared with petroleum-based diesel fuel. The energy of the biodiesel can be released more efficiently with the concept of semi adiabatic (thermal barrier coated piston engine. The objective of this study is to investigate the performance and emission characteristics of a single cylinder direct injection Diesel engine using 25% biodiesel blend (rubber seed oil methyl ester as fuel with thermal barrier coated piston. Initially the piston crown was coated with alumina (Al2O3 of thickness of 300 micron (0.3 mm by plasma coating method. The results revealed that the brake thermal efficiency was increased by 4% and brake specific fuel consumption was decreased by 9% for B25 with coated piston compared to un-coated piston with diesel. The smoke, CO, and HC emissions were also decreased for B25 blend with coated piston compared with the uncoated piton engine. The combustion characteristics such as peak pressure, maximum rate of pressure rise, and heat release rate were increased and the ignition delay was decreased for B25 blend for the coated piston compared with diesel fuel.

  10. 7 CFR 29.2290 - Premature primings.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Premature primings. 29.2290 Section 29.2290 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... 21) § 29.2290 Premature primings. Ground leaves harvested before reaching complete growth and...

  11. 28 CFR 51.22 - Premature submissions.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 2 2010-07-01 2010-07-01 false Premature submissions. 51.22 Section 51.22 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) PROCEDURES FOR THE ADMINISTRATION OF... § 51.22 Premature submissions. The Attorney General will not consider on the merits: (a) Any proposal...

  12. Premature infants' health at multiple induced pregnancy.

    Directory of Open Access Journals (Sweden)

    Chernenkov Yu.V.

    2015-09-01

    Full Text Available Objective: to define the risk factors adversely influencing prenatal development at premature birth at use of methods of assisted reproductive technology (ART; to estimate premature' infants health from multiple induced pregnancy according to Perinatal Center of Saratov for last 3 years. Material and Methods. Under supervision there were 139 pregnant women with application ART. 202 children (51 twins were born and 5 triplet babies, from them 83 premature infants born from multiple induced pregnancy have been analyzed. Results. The newborns examined by method ART, were distributed as follows: 22-28 weeks — 19 children; 29-32 weeks — 23; 33-36 weeks — 41. Asphyxia at birth was marked at all premature infants. Respiratory insufficiency at birth is revealed in 87,3% of cases. The most frequent pathologies in premature infants are revealed: neurologic infringements and bronchopulmonary pathology occured at all children, developmental anomaly — 33, 8%, retinopathies in premature infants — 26,5%. The mortality causes include: extreme immaturity, cerebral leukomalacia, IVN 3 degrees. Conclusion. The risk factors, premature birth at application of methods ART are revealed: aged primiparas, pharmacological influence, absence of physiological conditions of prenatal development; multifetation. The high percent of birth of children with ELBW and ULBW is revealed. RDCN with further BPD development, retinopathies in premature infants and CNS defeat is more often occured.

  13. [Premature rupture of membranes and chorioamnionitis].

    Science.gov (United States)

    Lopez Garcia, R

    1988-01-01

    Despite advances in perinatal medicine in the past decade, the diagnosis and treatment of premature rupture of membranes remain controversial. Premature rupture occurs in 2.7-7.0% of pregnancies and most cases occur spontaneously without apparent cause. The disparity in reported rates of premature rupture is due to differences in the definition and diagnostic criteria for premature rupture and lack of comparability in the populations studied. Mexico's National Institute of Perinatology has adopted the definition of the American COllege of Gynecology and Obstetrics which views premature rupture as that occurring before regular uterine contractions that produce cervical dilation. 8.8% of its patients have premature rupture according to this definition. 20% of cases occur before the 36th week of pregnancy. Treatment of rupture occurring before 37 weeks must balance the threat of amniotic infection with the dangers of premature birth. Infections appear more common in low income patient populations. Chorioamnionitis is a serious complication of pregnancy and is the main argument against conservative treatment of premature rupture. The rate of maternal infection is directly related to the time elapsing between rupture of the membranes and birth. The rate increases after the 1st 24 hours and is at least 10 times higher after 72 hours. But recent studies suggest that there is no considerable increase in infection if vaginal explorations are avoided and careful techniques are used in treating the patient. Those who advise conservative treatment believe that prenatal outcomes are better because respiratory disease syndrome due to prematurity is avoided. Conservative management requires a white cell count at least every 24 hours and measurement of pulse, maternal temperature, and fetal heart rate ideally every 4 hours. Perinatal mortality rates due to premature rupture of membranes range from 2.5-50%. The principal causes are respiratory disease syndrome, infection, asphyxia

  14. On the identification of piston slap events in internal combustion engines using tribodynamic analysis

    Science.gov (United States)

    Dolatabadi, N.; Theodossiades, S.; Rothberg, S. J.

    2015-06-01

    Piston slap is a major source of vibration and noise in internal combustion engines. Therefore, better understanding of the conditions favouring piston slap can be beneficial for the reduction of engine Noise, Vibration and Harshness (NVH). Past research has attempted to determine the exact position of piston slap events during the engine cycle and correlate them to the engine block vibration response. Validated numerical/analytical models of the piston assembly can be very useful towards this aim, since extracting the relevant information from experimental measurements can be a tedious and complicated process. In the present work, a coupled simulation of piston dynamics and engine tribology (tribodynamics) has been performed using quasi-static and transient numerical codes. Thus, the inertia and reaction forces developed in the piston are calculated. The occurrence of piston slap events in the engine cycle is monitored by introducing six alternative concepts: (i) the quasi-static lateral force, (ii) the transient lateral force, (iii) the minimum film thickness occurrence, (iv) the maximum energy transfer, (v) the lubricant squeeze velocity and (vi) the piston-impact angular duration. The validation of the proposed methods is achieved using experimental measurements taken from a single cylinder petrol engine in laboratory conditions. The surface acceleration of the engine block is measured at the thrust- and anti-thrust side locations. The correlation between the theoretically predicted events and the measured acceleration signals has been satisfactory in determining piston slap incidents, using the aforementioned concepts. The results also exhibit good repeatability throughout the set of measurements obtained in terms of the number of events occurring and their locations during the engine cycle.

  15. Human milk for the premature infant

    Science.gov (United States)

    Underwood, Mark A.

    2012-01-01

    Synopsis Premature infants are a heterogeneous group with widely differing needs for nutrition and immune protection with risk of growth failure, developmental delays, necrotizing enterocolitis, and late-onset sepsis increasing with decreasing gestational age and birth weight. Human milk from women delivering prematurely has more protein and higher levels of many bioactive molecules compared to milk from women delivering at term. Human milk must be fortified for small premature infants to achieve adequate growth. Mother’s own milk improves growth and neurodevelopment and decreases the risk of necrotizing enterocolitis and late-onset sepsis and should therefore be the primary enteral diet of premature infants. Donor milk is a valuable resource for premature infants whose mothers are unable to provide an adequate supply of milk, but presents significant challenges including the need for pasteurization, nutritional and biochemical deficiencies and a limited supply. PMID:23178065

  16. The pin pixel detector--neutron imaging

    CERN Document Server

    Bateman, J E; Derbyshire, G E; Duxbury, D M; Marsh, A S; Rhodes, N J; Schooneveld, E M; Simmons, J E; Stephenson, R

    2002-01-01

    The development and testing of a neutron gas pixel detector intended for application in neutron diffraction studies is reported. Using standard electrical connector pins as point anodes, the detector is based on a commercial 100 pin connector block. A prototype detector of aperture 25.4 mmx25.4 mm has been fabricated, giving a pixel size of 2.54 mm which matches well to the spatial resolution typically required in a neutron diffractometer. A 2-Dimensional resistive divide readout system has been adapted to permit the imaging properties of the detector to be explored in advance of true pixel readout electronics. The timing properties of the device match well to the requirements of the ISIS-pulsed neutron source.

  17. Cheap and Easy PIN Entering Using Eye Gaze

    Directory of Open Access Journals (Sweden)

    Kasprowski Pawel

    2014-03-01

    Full Text Available PINs are one of the most popular methods to perform simple and fast user authentication. PIN stands for Personal Identification Number, which may have any number of digits or even letters. Nevertheless, 4-digit PIN is the most common and is used for instance in ATMs or cellular phones. The main advantage of the PIN is that it is easy to remember and fast to enter. There are, however, some drawbacks. One of them - addressed in this paper - is a possibility to steal PIN by a technique called `shoulder surfing'. To avoid such problems a novel method of the PIN entering was proposed. Instead of using a numerical keyboard, the PIN may be entered by eye gazes, which is a hands-free, easy and robust technique. References:

  18. Timing analysis of PWR fuel pin failures

    Energy Technology Data Exchange (ETDEWEB)

    Jones, K.R.; Wade, N.L.; Katsma, K.R.; Siefken, L.J. (EG and G Idaho, Inc., Idaho Falls, ID (United States)); Straka, M. (Halliburton NUS, Idaho Falls, ID (United States))

    1992-09-01

    Research has been conducted to develop and demonstrate a methodology for calculation of the time interval between receipt of the containment isolation signals and the first fuel pin failure for loss-of-coolant accidents (LOCAs). Demonstration calculations were performed for a Babcock and Wilcox (B W) design (Oconee) and a Westinghouse (W) four-loop design (Seabrook). Sensitivity studies were performed to assess the impacts of fuel pin bumup, axial peaking factor, break size, emergency core cooling system availability, and main coolant pump trip on these times. The analysis was performed using the following codes: FRAPCON-2, for the calculation of steady-state fuel behavior; SCDAP/RELAP5/MOD3 and TRACPF1/MOD1, for the calculation of the transient thermal-hydraulic conditions in the reactor system; and FRAP-T6, for the calculation of transient fuel behavior. In addition to the calculation of fuel pin failure timing, this analysis provides a comparison of the predicted results of SCDAP/RELAP5/MOD3 and TRAC-PFL/MOD1 for large-break LOCA analysis. Using SCDAP/RELAP5/MOD3 thermal-hydraulic data, the shortest time intervals calculated between initiation of containment isolation and fuel pin failure are 10.4 seconds and 19.1 seconds for the B W and W plants, respectively. Using data generated by TRAC-PF1/MOD1, the shortest intervals are 10.3 seconds and 29.1 seconds for the B W and W plants, respectively. These intervals are for a double-ended, offset-shear, cold leg break, using the technical specification maximum peaking factor and applied to fuel with maximum design bumup. Using peaking factors commensurate widi actual bumups would result in longer intervals for both reactor designs. This document also contains appendices A through J of this report.

  19. Research on Measurements for Temperature and Stress of Pistons in Internal Combustion Engine

    Institute of Scientific and Technical Information of China (English)

    DONG Xiao-rui; TAN Jian-song

    2008-01-01

    In both numerical simulation and experimental research for the piston of internal combustion engine, the verification foundations are always insufficient. The reason is the measurements for its transient temperature and stress under actual operation conditions are very difficult. A multi-channel measurement-storage technology is used in the engine bench experiment to measure the piston temperature and stress in real time. The temperature and stress changes in the engine operation process are obtained. They provide reliable instructive criteria for numerical analysis and experiment of the piston working state.

  20. Acoustic radiation field of the truncated parametric source generated by a piston radiator model and experiment

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiaoliang; ZHU Zhemin; DU Gonghuan; TANG Haiqing; LI Shui; MIAO Rongxing

    2001-01-01

    A theoretical model is presented to describe the parametric acoustic field generated by a piston radiator. In the model, the high-frequency primary wave interaction region that is truncated by a low-pass acoustic filter can be viewed as a cylindrical source within the Rayleigh distance of the piston. When the radius of the piston is much smaller than the length of the parametric region, this model is reduced to the Berketey's End-Fire Line Array model. Comparison between numerical calculations and experimental measurement show that the generated parametric sound field (especially near the axis) agrees well with the experiment results.

  1. Design of wireless temperature measurement system for piston based on CC2530

    Science.gov (United States)

    Rongyu, Ge; Jin, Wang; Yimin, Wu; Guodong, Wu

    2016-11-01

    Temperature measurement of piston is important to analysis its temperature field. Since it is difficult to extract the temperature signal in the piston by hard line, a multi-channel wireless measurement system of piston temperature is developed. The wireless SOC CC2530 is used. NTC thermistors with glass package are selected as temperature sensors. The realization of hardware and the design of software flowchart are explained in detail. The actual test demonstrates that the system has high measurement accuracy and strong practical value.

  2. Compression-cast light metal piston for internal combustion engines. Pressgegossener Leichtmetallkolben fuer Verbrennungskraftmaschinen

    Energy Technology Data Exchange (ETDEWEB)

    Mielke, S.; Henning, W.; Weiss, F.; Goelder, K.

    1991-05-16

    In a compression-cast light metal piston for internal combustion engines, fibre bodies made of short ceramic fibres, which are aligned parallel to a plane, are cast in. To improve the resistance to wear of the piston consisting of a heat-resistant magnesium alloy, the piston shank has a metallic, chemically or galvanically separate layer with a thickness of 10 to 30 m, and a hardness of 740 to 850 HV < 0.01, at least in the area of its friction surfaces.

  3. Theoretical study of flow ripple for an aviation axial-piston pump with damping holes in the valve plate

    Institute of Scientific and Technical Information of China (English)

    Guan Changbin; Jiao Zongxia; He Shouzhan

    2014-01-01

    Based on the structure of a certain type of aviation axial-piston pump’s valve plate which adopts a pre-pressurization fluid path (consisting a damping hole, a buffer chamber, and an orifice) to reduce flow ripple, a single-piston model of the aviation axial-piston pump is presented. This sin-gle-piston model comprehensively considers fluid compressibility, orifice restriction effect, fluid resistance in the capillary tube, and the leakage flow. Besides, the instantaneous discharge areas used in the single-piston model have been calculated in detail. Based on the single-piston model, a multi-piston pump model has been established according to the simple hydraulic circuit. The sin-gle-and multi-piston pump models have been realized by the S-function in Matlab/Simulink. The developed multi-piston pump model has been validated by being compared with the numerical result by computational fluid dynamic (CFD). The effects of the pre-pressurization fluid path on the flow ripple and the instantaneous pressure in the piston chamber have been studied and opti-mized design recommendations for the aviation axial-piston pump have been given out.

  4. Mesoscopic pinning forces in neutron star crusts

    CERN Document Server

    Seveso, Stefano; Grill, Fabrizio; Haskell, Brynmor

    2014-01-01

    The crust of a neutron star is thought to be comprised of a lattice of nuclei immersed in a sea of free electrons and neutrons. As the neutrons are superfluid their angular momentum is carried by an array of quantized vortices. These vortices can pin to the nuclear lattice and prevent the neutron superfluid from spinning down, allowing it to store angular momentum which can then be released catastrophically, giving rise to a pulsar glitch. A crucial ingredient for this model is the maximum pinning force that the lattice can exert on the vortices, as this allows us to estimate the angular momentum that can be exchanged during a glitch. In this paper we perform, for the first time, a detailed and quantitative calculation of the pinning force \\emph{per unit length} acting on a vortex immersed in the crust and resulting from the mesoscopic vortex-lattice interaction. We consider realistic vortex tensions, allow for displacement of the nuclei and average over all possible orientation of the crystal with respect to...

  5. 数字式气体活塞压力计的活塞系统设计%Piston-Cylinder Assembly Design of the Digital Piston Pressure Gauge

    Institute of Scientific and Technical Information of China (English)

    王丽; 盛晓岩

    2012-01-01

    The piston-cylinder assembly design method of digital piston pressure gauge is introduced. The design principle, material selection and design of critical dimension are introduced in detail. The result is certified by the performance index of the piston-cylinder assembly and digital piston pressure gauge. Theoretical basis is provided for the rapid development of digital piston pressure gauge.%介绍了数字式气体活塞压力计的关键部件——活塞系统的设计方法,详细阐述了活塞系统的设计原则、材料的选择以及关键尺寸的设计,并通过了活塞系统性能指标和数字式活塞压力计性能指标的验证,为数字式活塞压力计技术的迅速发展提供了理论依据.

  6. Premature Ventricular Complexes and Premature Ventricular Complex Induced Cardiomyopathy.

    Science.gov (United States)

    Latchamsetty, Rakesh; Bogun, Frank

    2015-09-01

    Presentation, prognosis, and management of premature ventricular complexes (PVCs) vary significantly among patients and depend on PVC characteristics as well as patient comorbidities. Presentation can range from incidental discovery in an asymptomatic patient to debilitating heart failure. Prognosis depends on, among other factors, the presence or absence of structural heart disease, PVC burden and other factors detailed in this review. Our understanding of the clinical significance of frequent PVCs, particularly as it relates to development of cardiomyopathy, has advanced greatly in the past decade. In this article, we explore the mechanisms governing PVC initiation and discuss prevalence and frequency of PVCs in the general population. We also explore prognostic implications based on PVC frequency as well as the presence or absence of underlying heart disease. We then take a focused look at PVC-induced cardiomyopathy and identify predictors for developing cardiomyopathy. Finally, we discuss clinical evaluation and management of patients presenting with frequent PVCs. Management can include clinical observation, addressing reversible causes, lifestyle modification, pharmacotherapy, or catheter ablation.

  7. Improved Pinning Center Morphology in HTS with Order-of-Magnitude Increase in Jc and Bpin Compared to Columnar Pinning

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The motivation for continuouscolumnar pinning centers has been to provide maximum Upin. It has been assumed that this provides the best Jc and Bpin. Limitations on Jc and Bpin observed for columnar pinning have been attributed to degradation of the order parameter and Tc. We examine columnar pinning by ionic damage and conclude instead that geometrical effects of columnar pinningon percolation path and on the number of pinning centers are the dominant limitations of columnar pinning, leading to a limit of Bpin~4 T. Evidence suggests that multiple-in-line-defects (MILD) are far better suited to increase Jc and Bpin. The morphology of MILD pinning is reviewed. Ion energy loss per unit distance, Se, is found to be most promising in a regime almost diametrically opposite to that sought to maximize Upin. We expect Jc~106 A/cm2 and Bpin>40 T from MILD pinning,despite sharply decreased Upin.Experimental confirmation is proposed.

  8. Psychosocial interventions for premature ejaculation

    Directory of Open Access Journals (Sweden)

    Tamara Melnik

    Full Text Available BACKGROUND: Premature ejaculation (PE is a very common sexual dysfunction among patients, and with varying prevalence estimates ranging from 3% to 20%. Although psychological issues are present in most patients with premature PE, as a cause or as a consequence, research on the effects of psychological approaches for PE has in general not been controlled or randomised and is lacking in long-term follow up. OBJECTIVE: To assess the efficacy of psychosocial interventions for PE. CRITERIA FOR CONSIDERING STUDIES FOR THIS REVIEW: Trials were searched in computerized general and specialized databases, such as: MEDLINE by PubMed (1966 to 2010; PsycINFO (1974 to 2010; EMBASE (1980 to 2010; LILACS (1982 to 2010; the Cochrane Central Register of Controlled Trials (Cochrane Library, 2010; and by checking bibliographies, and contacting manufacturers and researchers. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials evaluating psychosocial interventions compared with different psychosocial interventions, pharmacological interventions, waiting list, or no treatment for PE. DATA COLLECTION AND ANALYSIS: Information on patients, interventions, and outcomes was extracted by at least two independent reviewers using a standard form. The primary outcome measure for comparing the effects of psychosocial interventions to waiting list and standard medications was improvement in IELT (i.e., time from vaginal penetration to ejaculation. The secondary outcome was change in validated PE questionnaires. MAIN RESULTS: In one study behavioral therapy (BT was significantly better than waiting list for duration of intercourse (MD (mean difference 407.90 seconds, 95% CI 302.42 to 513.38, and couples' sexual satisfaction (MD -26.10, CI -50.48 to -1.72. BT was also significantly better for a new functional-sexological treatment (FS (MD 412.00 seconds, 95% CI 305.88 to 518.12, change over time in subjective perception of duration of intercourse (Women: MD 2

  9. 1987 overview of free-piston Stirling technology for space power application

    Science.gov (United States)

    Slaby, Jack G.; Alger, Donald L.

    1987-01-01

    The Lewis Research Center program concerned with the development of a free-piston Stirling engine for space-power applications is examined. The system mass of a Stirling system is compared to that of a Brayton system for the same peak temperature and output power; the advantages of the Stirling system are discussed. The predicted and experimental performances of the 25 kWe opposed-piston space power demonstrator engine are evaluated. It is determined that in order to enhance performance the regenerator needs to be modified, and the gas bearing flow between the displacer and power piston needs to be isolated in order to increase the operating stroke. Identification and correction of the energy losses, the design and operation of the linear alternator, and heat exchange concepts are considered. The design parameters and conceptual design characteristics for a 25 kWe single-cylinder free-piston Stirling space-power converter are described.

  10. High Specific Power Multiple-Cylinder Alpha Free-Piston Stirling Engine Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed effort will result in a design of a 30 kWe dual opposed alpha free-piston Stirling engine power conversion system for space applications, and provide...

  11. Investigations of high-frequency induction hardening process for piston rod of shock absorber

    Institute of Scientific and Technical Information of China (English)

    Xianhua Cheng; Qianqian Shangguan

    2005-01-01

    The microhardness of piston rods treated with different induction hardening processes was tested. The experimental results reveal that the depth of the hardened zone is proportional to the ratio of the moving speed of the piston rod to the output power of the induction generator. This result is proved correct through the Finite Element Method (FEM) simulation of the thermal field of induction heating. From tensile and impact tests, an optimized high frequency induction hardening process for piston rods has been obtained, where the output power was 82%×80 kW and the moving speed of workpiece was 5364 mm/min. The piston rods, treated by the optimized high frequency induction hardening process, show the best comprehensive mechanical performance.

  12. Design and theoretical analysis of a sliding valve distribution radial piston pump

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Guo; Shengdun, Zhao; Yanghuiwen, Yu [Xian Jiaotong University, Xian (China); Peng, Shang [Xian Engineering University of Armed Police Force, Xian (China)

    2016-01-15

    A Sliding valve distribution radial piston pump (SVDRPP) is presented. In this pump, a new distribution method that uses sliding valves to distribute oil for the piston chambers is developed. With this design, the disadvantages brought by the distribution shaft and the check valves (traditional distribution mechanisms), such as the poor stress state of the shaft and the energy waste for opening the check valves, are expected to be eliminated. In addition, a method of using pressure oil to accomplish the returning stroke of the piston is also proposed, which could be used to replace the usage of springs along with their shortcomings. A pump with five pistons is designed as an example to elaborate the structure and the working principle of SVDRPP. Furthermore, the flow characteristics of SVDRPP are studied, and the formulas of the displacement, the average flow rate and the instantaneous flow rate are deduced.

  13. A thermodynamic study for the optimization of stable operation of free piston Stirling engines

    Energy Technology Data Exchange (ETDEWEB)

    Rogdakis, E.D.; Bormpilas, N.A.; Koniakos, I.K. [National Technical Univerisity, Athens (Greece). Dept. of Mechanical Engineering

    2004-03-01

    One of the most novel applications of the Stirling cycle is in the free piston configuration that was initially designed by W. Beale. In free piston Stirling engines (FPSEs), there are no mechanical linkages coupling the pistons or displacers, the motions of the reciprocating components follow the working gas pressure variations. Fillipo de Monte and G. Benvenuto have recently proposed a linearization technique of the dynamic balance equations. The aim of this paper is to predict the thermodynamic conditions for stable operation of FPSEs and their modeling. The equations of the angular velocity are solved analytically in terms of the working gas mass and the displacer-piston phase angle of the machine. Using the criterion of stable engine cyclic steady operation, a mathematically rigorous form is obtained for the main parameters of the engine. Furthermore, for simplicity reasons, thermodynamic magnitudes are obtained using the Schmidt analysis (isothermal model). (author)

  14. Adaptive individual-cylinder thermal state control using piston cooling for a GDCI engine

    Energy Technology Data Exchange (ETDEWEB)

    Roth, Gregory T; Husted, Harry L; Sellnau, Mark C

    2015-04-07

    A system for a multi-cylinder compression ignition engine includes a plurality of nozzles, at least one nozzle per cylinder, with each nozzle configured to spray oil onto the bottom side of a piston of the engine to cool that piston. Independent control of the oil spray from the nozzles is provided on a cylinder-by-cylinder basis. A combustion parameter is determined for combustion in each cylinder of the engine, and control of the oil spray onto the piston in that cylinder is based on the value of the combustion parameter for combustion in that cylinder. A method for influencing combustion in a multi-cylinder engine, including determining a combustion parameter for combustion taking place in in a cylinder of the engine and controlling an oil spray targeted onto the bottom of a piston disposed in that cylinder is also presented.

  15. Sexuality in pregnancy and premature labour.

    Science.gov (United States)

    Georgakopoulos, P A; Dodos, D; Mechleris, D

    1984-09-01

    The relation of sexual behaviour during pregnancy to the initiation of labour was investigated in 358 patients of whom 58 were delivered after premature labour and 300 were delivered spontaneously at term. In all patients the mean weekly coital frequency and the frequency of orgasm were investigated by means of a retrospective questionnaire. There was no significant difference in coital or orgasmic frequency between the women who had a premature labour and those who had a spontaneous delivery at term. This was also true when those having premature labour were divided into those starting labour with ruptured membranes and those starting with contractions.

  16. Acute appendicitis in a premature baby

    Energy Technology Data Exchange (ETDEWEB)

    Beluffi, Giampiero; Alberici, Elisa [Department of Radiodiagnosis, Section of Paediatric Radiology, IRCCS Policlinico S. Matteo, Piazzale Golgi 2, 27100 Pavia PV (Italy)

    2002-07-01

    A case of acute appendicitis in a premature baby in whom diagnosis was suggested on plain films of the abdomen is presented. In this baby air in a hollow viscus suspected of being an enlarged appendix was the clue to diagnosis. The diagnostic dilemma of this rare and life-threatening condition in premature babies and newborns is underlined. The relevance of different imaging modalities and of different findings in this age group is discussed. Awareness of this rare condition and possible differential diagnosis in newborns and premature babies is stressed. (orig.)

  17. [Premature newborn: a case presentation].

    Science.gov (United States)

    Pastor Rodríguez, Jesús David; Pastor Bravo, María Del Mar; López García, Visitación; Cotes Teruel, María Isabel; Mellado, Jesús Eulogio; Cárceles, José Jara

    2010-01-01

    A case is presented of a premature newborn of 27 weeks gestation and weighing 420 grams who was delivered as a result of a maternal pre-eclampsia and retarded intra-uterine growth. During the 125 days of hospitalisation, an individual care plan based on the Virginia Henderson model was devised and applied to both the child and her parents using NANDA diagnostics, interventions according to the NIC classification, and the expected results according to the NOC classification. The Marjory Gordon functional patterns were used for the initial assessment. By applying the pre-term newborn (PTNB) plan, all their needs were provided and were modified throughout the hospital stay, with new needs that were added to the established ones. These required a continuous assessment with the subsequent adapting of the care plan. Likewise, the care required by the parents varied from the initial grief due to the possible loss of their child to learning the alarm signs and the home care that their child would need. The child was finally discharged weighing 2900 grams and with normal neurological and psychomotor development, although with a lower weight appropriate to her age. Currently, at 2 years old, the child has a normal neurological and psychomotor development, but with weight and size lower than the P(3) percentile. She requires speech therapy treatment due to paralysis of the right vocal cord.

  18. Psychosexual therapy for premature ejaculation.

    Science.gov (United States)

    Althof, Stanley E

    2016-08-01

    Premature ejaculation (PE) is a male sexual dysfunction that creates considerable anguish for the man, his partner and their relationship. PE is not one disorder but includes the four subtypes (lifelong, acquired, natural and subjective) each with unique psychological concerns and issues. Psychological treatment for men and couples with PE addresses sexual skills/techniques but also focuses on issues of self-esteem, performance anxiety and interpersonal conflict. The outcome studies for psychotherapy alone are difficult to interpret and compare because of poor methodological design (lack of control groups, small sample size, poor outcome measures and lack of follow-up). However, the few studies that surmount these methodological hurdles suggest that psychological intervention offers men and couples a promising treatment option. Combination pharmaco- and psychotherapy is the most promising intervention for lifelong and acquired PE and offers superior efficacy to drug alone. This is because men and couples learn sexual skills, address the intrapsychic, interpersonal and cognitive issues that precipitate and maintain the dysfunction.

  19. The epidemiology of premature ejaculation.

    Science.gov (United States)

    Saitz, Theodore Robert; Serefoglu, Ege Can

    2016-08-01

    Vast advances have occurred over the past decade with regards to understanding the epidemiology, pathophysiology and management of premature ejaculation (PE); however, we still have much to learn about this common sexual problem. As a standardized evidence-based definition of PE has only recently been established, the reported prevalence rates of PE prior to this definition have been difficult to interpret. As a result, a large range of conflicting prevalence rates have been reported. In addition to the lack of a standardized definition and operational criteria, the method of recruitment for study participation and method of data collection have obviously contributed to the broad range of reported prevalence rates. The new criteria and classification of PE will allow for continued research into the diverse phenomenology, etiology and pathogenesis of the disease to be conducted. While the absolute pathophysiology and true prevalence of PE remains unclear, developing a better understanding of the true prevalence of the disease will allow for the completion of more accurate analysis and treatment of the disease.

  20. [Sexological intervention on premature ejaculation].

    Science.gov (United States)

    San Martín Blanco, C

    2014-07-01

    Strategies, recommendations and techniques proposed by sex therapy for intervention on premature ejaculation, have represented for nearly four decades the most effective model of intervention in this sexual dysfunction, which currently is complemented by the efficacy of dapoxetine drug treatment. Clinical experience and recent studies support that combined intervention offers the best therapeutic results. In addition in sex therapy, etiologic diagnosis is obtained from the analysis of the interrelationship of the couple. Diagnostic and therapeutic intervention has to be always centered in the relationship, so the techniques and resources must be applied with the expectation of being implemented in the sexual interaction. It will therefore be the relationship that receive treatment, even if medication is used for one of the members of the couple. On the other hand, this model of intervention can be implemented by a professional with training, although not necessarily a specialist. Copyright © 2014 Elsevier España, S.L.U. y Sociedad Española de Medicina Rural y Generalista (SEMERGEN). All rights reserved.

  1. Medical therapy for premature ejaculation

    Science.gov (United States)

    Mohee, Amar; Eardley, Ian

    2011-01-01

    Premature ejaculation (PE) is a common male sexual dysfunction. Advances in PE research have been hampered owing to a nonstandardized definition of PE, until the definition by the International Society of Sexual Medicine (ISSM) in 2009. Once the diagnosis of PE is established through a thorough history, a variety of medical therapies is available, including tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), centrally acting opiates, phosphodiesterase 5 inhibitors and topical desensitizing creams. Most of these treatments increase the intravaginal ejaculation latency time (IELT) and patient satisfaction scores, with the most convincing evidence for SSRIs and topical creams. Daily SSRIs such as paroxetine, although efficacious, do have a substantial and prolonged side effect profile. Dapoxetine, which is a on-demand SSRI, is the only licensed drug for the treatment of PE, increasing IELT by a factor of 2.5 to 3 with limited and tolerable side effects. In the near future, the topical aerosol PSD502 is due to be licensed for the treatment of PE, increasing IELT by up to a factor of 6 but having minimal local and negligible systemic side effects. PMID:22046199

  2. Magnetic flux pinning in superconductors with hyperbolic-tessellation arrays of pinning sites

    Science.gov (United States)

    Misko, V. R.; Nori, Franco

    2012-05-01

    We study magnetic flux interacting with arrays of pinning sites (APSs) placed on vertices of hyperbolic tessellations (HTs). We show that, due to the gradient in the density of pinning sites, HT APSs are capable of trapping vortices for a broad range of applied magnetic fluxes. Thus, the penetration of magnetic field in HT APSs is essentially different from the usual scenario predicted by the Bean model. We demonstrate that, due to the enhanced asymmetry of the surface barrier for vortex entry and exit, this HT APS could be used as a “capacitor” to store magnetic flux.

  3. The thermodynamic equilibrium of gas in a box divided by a piston

    CERN Document Server

    Herrera-Gomez, Alberto

    2010-01-01

    The equilibrium conditions of a system consisting of a box with gas divided by a piston are revised. The apparent indetermination of the problem is solved by explicitly imposing the constancy of the internal energy when the Entropy Maximum Principle is applied. The equality of the pressures is naturally concluded from this principle when the piston is allowed to spontaneously move. The application of the Energy Minimum Principle is also revised.

  4. Performance analysis of a 2-stroke micro free-piston swing engine

    Institute of Scientific and Technical Information of China (English)

    Zhang Shimin; Guo Zhiping; Wang Jinsong

    2009-01-01

    The micro free-piston swing engine (MFPSE) is a new structure, free-piston internal combustion engine. The dynamic model integrated MFPSE with a power generator and thermodynamic models in compression, power and scavenge processes based on the open thermodynamic systems were presented. A simulation was executed at given geometric parameters and initial conditions. The results manifest that the working principle of MFPSE is feasible.

  5. An investigation of the fluid-structure interaction of piston/cylinder interface

    Science.gov (United States)

    Pelosi, Matteo

    The piston/cylinder lubricating interface represents one of the most critical design elements of axial piston machines. Being a pure hydrodynamic bearing, the piston/cylinder interface fulfills simultaneously a bearing and sealing function under oscillating load conditions. Operating in an elastohydrodynamic lubrication regime, it also represents one of the main sources of power loss due to viscous friction and leakage flow. An accurate prediction of the time changing tribological interface characteristics in terms of fluid film thickness, dynamic pressure field, load carrying ability and energy dissipation is necessary to create more efficient interface designs. The aim of this work is to deepen the understanding of the main physical phenomena defining the piston/cylinder fluid film and to discover the impact of surface elastic deformations and heat transfer on the interface behavior. For this purpose, a unique fully coupled multi-body dynamics model has been developed to capture the complex fluid-structure interaction phenomena affecting the non-isothermal fluid film conditions. The model considers the squeeze film effect due to the piston micro-motion and the change in fluid film thickness due to the solid boundaries elastic deformations caused by the fluid film pressure and by the thermal strain. The model has been verified comparing the numerical results with measurements taken on special designed test pumps. The fluid film calculated dynamic pressure and temperature fields have been compared. Further validation has been accomplished comparing piston/cylinder axial viscous friction forces with measured data. The model has been used to study the piston/cylinder interface behavior of an existing axial piston unit operating at high load conditions. Numerical results are presented in this thesis.

  6. Piezoelectric sensors to monitor lubricant film thickness at piston-cylinder contacts in a fired engine

    OpenAIRE

    2013-01-01

    The contact between the piston ring and cylinder liner is the most important sealing interface in an automotive engine. Understanding the contact interactions and lubricant film formation at this interface is crucial for the development of fuel-efficient and low emission engines. This article outlines the development of an ultrasonic approach to enable non-invasive measurement of the lubricant film thickness formed between piston and cylinder wall of a fired engine. The sensor system consiste...

  7. Mechanical and thermal analysis of the internal combustion engine piston using Ansys

    Science.gov (United States)

    Cioată, V. G.; Kiss, I.; Alexa, V.; Raţiu, S. A.

    2017-01-01

    The piston is one of the most important components of the internal combustion engine. Piston fail mainly due to mechanical stresses and thermal stresses. In this paper is determined by using the finite element method, stress and displacement distribution due the flue gas pressure and temperature, separately and combined. The FEA is performed by CAD and CAE software. The results are compared with those obtained by the analytical method and conclusions have been drawn.

  8. Control scheme for power modulation of a free piston Stirling engine

    Science.gov (United States)

    Dhar, Manmohan

    1989-01-01

    The present invention relates to a control scheme for power modulation of a free-piston Stirling engine-linear alternator power generator system. The present invention includes connecting an autotransformer in series with a tuning capacitance between a linear alternator and a utility grid to maintain a constant displacement to piston stroke ratio and their relative phase angle over a wide range of operating conditions.

  9. Comparison of free-piston Stirling engine model predictions with RE1000 engine test data

    Science.gov (United States)

    Tew, R. C.

    1984-01-01

    Predictions of a free-piston Stirling engine model are compared with RE1000 engine test data taken at NASA-Lewis Research Center. The model validation and the engine testing are being done under a joint interagency agreement between the Department of Energy's Oak Ridge National Laboratory and NASA-Lewis. A kinematic code developed at Lewis was upgraded to permit simulation of free-piston engine performance; it was further upgraded and modified at Lewis and is currently being validated. The model predicts engine performance by numerical integration of equations for each control volume in the working space. Piston motions are determined by numerical integration of the force balance on each piston or can be specified as Fourier series. In addition, the model Fourier analyzes the various piston forces to permit the construction of phasor force diagrams. The paper compares predicted and experimental values of power and efficiency and shows phasor force diagrams for the RE1000 engine displacer and piston. Further development plans for the model are also discussed.

  10. NOISE IDENTIFICATION FOR HYDRAULIC AXIAL PISTON PUMP BASED ON ARTIFICIAL NEURAL NETWORKS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The noise identification model of the neural networks is established for the 63SCY14-1B hydraulic axial piston pump. Taking four kinds of different port plates as instances, the noise identification is successfully carried out for hydraulic axial piston pump based on experiments with the MATLAB and the toolbox of neural networks. The operating pressure, the flow rate of hydraulic axial piston pump, the temperature of hydraulic oil, and bulk modulus of hydraulic oil are the main parameters having influences on the noise of hydraulic axial piston pump. These four parameters are used as inputs of neural networks, and experimental data of the noise are used as outputs of neural networks. Error of noise identification is less than 1% after the neural networks have been trained. The results show that the noise identification of hydraulic axial piston pump is feasible and reliable by using artificial neural networks. The method of noise identification with neural networks is also creative one of noise theoretical research for hydraulic axial piston pump.

  11. The ecological quasi-turbine, the best of the piston and the turbine[The supremacy of piston engines questioned; La suprematie du moteur a pistons remise en cause]; La quasiturbine ecologique, le meilleur du piston et de la turbine

    Energy Technology Data Exchange (ETDEWEB)

    Saint-Hilaire, R.; Saint-Hilaire, Y.; Saint-Hilaire, G.; Saint-Hilaire, F.

    2001-07-01

    This book presents the theory that forms the basis for quasi-turbines. The quasi-turbine is the culmination of three modern engines: it takes its inspiration from the turbine, perfects the piston, and improves Wankel engines. The quasi-turbine eliminates idle time by modifying the allocations to the various engine strokes and by replacing the progressive torque impulses by plateau impulses. The quasi-turbine optimizes engine performance with an almost constant instantaneous engine torque. The quasi-turbine can be powered by different fuels, including fossil fuels, steam, solar thermal, hydrogen, or diesel. There are several constraints associated with the quasi-turbine theory, each of which was discussed in turn. The quasi-turbine consists of four carriages which support the pivots of four pivoting blades of a variable shaped rotor and which roll as a roller bearing on the interior contour wall of a skating rink-like surface. This surface is also referred to as the Saint-Hilaire confinement profile. Engine technology is improved by increasing the mobile components utilization factor, eliminating all dead times, eliminating the excessive volume during expansion or power stroke, optimizing engine time management, allowing less time for compression and exhaust strokes, and by allowing more time and volume for intake and expansion strokes. The quasi-turbine engine satisfies the criteria of the envisioned hydrogen engine of the future. figs.

  12. Progress in High Power Free-Piston Stirling Convertor Development

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Kirby, Raymond L.; Chapman, Peter A.; Walter, Thomas J.

    2008-01-01

    The U.S. Space Exploration Policy has established a vision for human exploration of the moon and Mars. One option for power for future outposts on the lunar and Martian surfaces is a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kWe. A 25 kW convertor was developed in the 1990s under the SP-100 program. This system consisted of two 12.5 kWe engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA began a new project with Auburn University to develop a 5 kWe, single convertor for use in such a possible lunar power system. Goals of this development program include a specific power in excess of 140 We/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Foster-Miller, Inc. is developing the 5 kWe Stirling Convertor Assembly. The characteristics of the design along with progress in developing the system will be described.

  13. Advanced Controller for the Free-Piston Stirling Convertor

    Science.gov (United States)

    Gerber, Scott S.; Jamison, Mike; Roth, Mary Ellen; Regan, Timothy F.

    2004-01-01

    The free-piston Stirling power convertor is being considered as an advanced power conversion technology to be used for future NASA deep space missions requiring long life radioisotope power systems. This technology has a conversion efficiency of over 25%, which is significantly higher than the efficiency of the Radioisotope Thermal-electric Generators (RTG) now in use. The NASA Glenn Research Center has long been recognized as a leader in Stirling technology and is responsible for the development of advanced technologies that are intended to significantly improve key characteristics of the Stirling convertor. The advanced technologies identified for development also consider the requirements of potential future missions and the new capabilities that have become available in the associated technical areas. One of the key areas identified for technology development is the engine controller. To support this activity, an advanced controller is being developed for the Stirling power convertor. This controller utilizes active power factor correction electronics and microcontroller-based controls. The object of this paper is to present an overview of the advanced controller concept with modeling, simulation and hardware test data.

  14. Progress in High Power Free-Piston Stirling Convertor Development

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Kirby, Raymond L.; Chapman, Peter A.; Walter, Thomas J.

    2008-09-01

    The U.S. Space Exploration Policy has established a vision for human exploration of the moon and Mars. One option for power for future outposts on the lunar and Martian surfaces is a nuclear reactor coupled with a free-piston Stirling convertor at a power level of 30-40 kWe. A 25 kW convertor was developed in the 1990s under the SP-100 program. This system consisted of two 12.5 kWe engines connected at their hot ends and mounted in tandem to cancel vibration. Recently, NASA began a new project with Auburn University to develop a 5 kWe, single convertor for use in such a possible lunar power system. Goals of this development program include a specific power in excess of 140 We/kg at the convertor level, lifetime in excess of five years and a control system that will safely manage the convertors in case of an emergency. Foster-Miller, Inc. is developing the 5 kWe Stirling Convertor Assembly. The characteristics of the design along with progress in developing the system will be described.

  15. The Influence of Cylinder Lubrication on Piston Slap

    Science.gov (United States)

    Gerges, S. N. Y.; de Luca, J. C.; Lalor, N.

    2002-10-01

    A model has been developed for determining the time history of piston slap impact force. This model takes into account the influence of the oil film on the impact behaviour, which was found to be an important factor. However, it was also found that entrapped gas bubbles in the oil are equally significant. Three test rigs were designed and built to study these effects on the impact phenomenon and extensive tests were carried out. The impact force time history has been determined using Reynolds' theory. Results have shown that Reynolds' theory for fluid film squeezing can be applied for oil film damping determination. However, the experimental results have also shown that when gas is entrapped during the impact, this theory considerably overpredicts the magnitude of the impact. An eight-degree-of-freedom lumped parameter model was developed through the dynamic analysis of each component of an internal combustion engine's reciprocating system. The effective damping factor derived from this model was found to be inversely proportional to the oil film thickness cubed, as expected from Reynolds' theory. A dynamic model has been proposed, where the oil film mixed with bubbles is considered to be analogous to a serial spring and damping system. By incorporating a spring in series with this damper, the effect of the bubbles can also be predicted.

  16. Robustness of pinning a general complex dynamical network

    Energy Technology Data Exchange (ETDEWEB)

    Wang Lei, E-mail: lwang@buaa.edu.c [Laboratory of Mathematics, Information and Behavior of the Ministry of Education, Department of Systems and Control, Beihang University, Beijing 100191 (China); Sun Youxian [State Key Laboratory of Industrial Control Technology, Institute of Industrial Process Control, Zhejiang University, Hangzhou 310027 (China)

    2010-04-05

    This Letter studies the robustness problem of pinning a general complex dynamical network toward an assigned synchronous evolution. Several synchronization criteria are presented to guarantee the convergence of the pinning process locally and globally by construction of Lyapunov functions. In particular, if a pinning strategy has been designed for synchronization of a given complex dynamical network, then no matter what uncertainties occur among the pinned nodes, synchronization can still be guaranteed through the pinning. The analytical results show that pinning control has a certain robustness against perturbations on network architecture: adding, deleting and changing the weights of edges. Numerical simulations illustrated by scale-free complex networks verify the theoretical results above-acquired.

  17. A mechanism to pin skyrmions in chiral magnets.

    Science.gov (United States)

    Liu, Ye-Hua; Li, You-Quan

    2013-02-20

    We propose a mechanism to pin skyrmions in chiral magnetic thin films by introducing local maxima of magnetic exchange strength as pinning centers. The local maxima can be realized by engineering the local density of itinerant electrons. The stationary properties and the dynamical pinning and depinning processes of an isolated skyrmion around a pinning center are studied. We carry out numerical simulations of the Landau-Lifshitz-Gilbert (LLG) equation and find a way to control the position of an isolated skyrmion in a pinning center lattice using electric current pulses. The results are verified by a Thiele equation analysis. We also find that the critical current to depin a skyrmion, which is estimated to have order of magnitude 10(7)-10(8) A m(-2), has linear dependence on the pinning strength.

  18. Maternal assessment of pain in premature infants

    Directory of Open Access Journals (Sweden)

    Maria Carolina Correia dos Santos

    2015-12-01

    Full Text Available Objective: to identify mothers' perceptions about the pain in their premature babies in the Neonatal Intensive Care Unit. Methods: evaluative, quantitative study with investigative nature conducted with 19 mothers of hospitalized premature newborns. Data were obtained from closed questions, answered by mothers. Results: from the participants, two (10.5% reported that newborns are unable to feel pain. From the 17 mothers who said that premature babies can feel pain, the majority (94.1% identified crying as a characteristic of pain sensation. Eleven (64.7% stated that uneasiness is a sign of pain in newborns. Conclusion: for the proper management of neonatal pain it is essential that mothers know the signs of pain in premature newborns, and that health professionals instruct this recognition, through the enhancement of the maternal presence and practice of effective communication between professionals and newborns’ families.

  19. Future Applications of Antioxidants in Premature Infants

    Science.gov (United States)

    Lee, Jennifer W.; Davis, Jonathan M.

    2012-01-01

    Purpose of Review This review will examine the unique susceptibility of premature infants to oxidative stress, the role of reactive oxygen species (ROS) in the pathogenesis of common disorders of the preterm infant, and potential for therapeutic interventions using enzymatic and/or non-enzymatic antioxidants. Recent Findings Oxidative stress is caused by an imbalance between the production of ROS and the ability to detoxify them with the help of antioxidants. The premature infant is especially susceptible to ROS-induced damage because of inadequate antioxidant stores at birth, as well as impaired upregulation in response to oxidant stress. Thus, the premature infant is at increased risk for the development of ROS-induced diseases of the newborn, such as bronchopulmonary dysplasia, retinopathy of prematurity, necrotizing enterocolitis, and periventricular leukomalacia. Summary Potential therapies for ROS-induced disease include both enzymatic and non-enzymatic antioxidant preparations. More research is required to determine the beneficial effects of supplemental antioxidant therapy. PMID:21150443

  20. Apnea of prematurity: challenges and solutions

    Directory of Open Access Journals (Sweden)

    Picone S

    2014-06-01

    Full Text Available Simonetta Picone, Roberto Aufieri, Piermichele PaolilloDivision of Neonatology and Neonatal Intensive Care, Department of Maternal and Child Health, Casilino General Hospital, Rome, ItalyAbstract: Apnea of prematurity is a developmental disorder that frequently affects preterm infants, especially those with lower gestational age. Even if apnea of prematurity is by definition a self-limiting condition, it can cause serious problems during the hospital stay and can potentially have long-term neurological and cognitive consequences depending on the severity and intensity of the episodes. The diagnosis of apnea of prematurity can be made only after excluding a number of diseases of the preterm infant in which apnea may be an epiphenomenon. Etiological diagnosis is essential for selection of appropriate treatment, which may be nonpharmacological or involve use of drugs.Keywords: apnea of prematurity, idiopathic and secondary apnea, caffeine

  1. Principles of intramedullary pin and wire fixation.

    Science.gov (United States)

    Howard, P E

    1991-02-01

    Knowledge and experience in the proper use of IM pins, K-wires, and orthopedic wire is a valuable asset to the veterinarian's ability to successfully repair a variety of long bone fractures. Most long bone fractures are amenable to repair with this form of fixation. When the principles of application are violated or the implants are used when contraindicated, complications often occur. Proper use of these implants results in the successful management of complex fractures to the satisfaction of both the animal owner and the veterinarian (Fig 10).

  2. Controlling Flow Turbulence Using Local Pinning Feedback

    Institute of Scientific and Technical Information of China (English)

    TANG Guo-Ning; HU Gang

    2006-01-01

    Flow turbulence control in two-dimensional Navier-Stokes equation is considered.By applying local pinning control only to a sjngle component of flow velocity field,the flow turbulence can be controlled to desirable targets.It is found that with certain number of controllers there exist an optimal control strength at which control error takes minimum value,and larger and smaller control strengths give worse control efficiency.The phvsical mechanism underlying these strange control results is analysed based on the interactions between different types of modes.

  3. Optimum Prestress of Tanks with Pinned Base

    DEFF Research Database (Denmark)

    Brøndum-Nielsen, Troels

    1998-01-01

    Amin Ghali and Eleanor Elliott presented in their paper an interesting suggestion for prestressing of circular tanks without sliding joints. For many prestressed tanks the following construction procedure is adopted:In order to ensure compressive hoop forces in the wall near the base, the wall...... is allowed to slide freely in the radial direction during tensioning (free base).After tensioning such displacements are prevented (pinned base). The present paper addresses the problem of prestress of such tanks.Keywords: circular prestressing; creep properties; prestressed concrete; redistribution...... of stress; stress relaxation; tanks....

  4. Premature dental eruption: report of case.

    LENUS (Irish Health Repository)

    McNamara, C M

    2011-08-05

    This case report reviews the variability of dental eruption and the possible sequelae. Dental eruption of the permanent teeth in cleft palate children may be variable, with delayed eruption the most common phenomenon. A case of premature dental eruption of a maxillary left first premolar is demonstrated, however, in a five-year-old male. This localized premature dental eruption anomaly was attributed to early extraction of the primary dentition, due to caries.

  5. Neuro-ophthalmic manifestations of prematurity

    OpenAIRE

    Preeti Patil Chhablani; Ramesh Kekunnaya

    2014-01-01

    Increasing rates of preterm births coupled with better survival of these infants have resulted in higher prevalence of systemic and ocular complications associated with prematurity. In addition to retinopathy of prematurity, infants who are born preterm may suffer from severe visual impairment as a result of hypoxic ischemic encephalopathy, hypoglycemia, and other metabolic imbalances. The effect of these processes on the anterior visual pathway may result in optic atrophy, optic nerve hypopl...

  6. PECULIARITIES OF BREAST FEEDING OF PREMATURE CHILDREN

    Directory of Open Access Journals (Sweden)

    V.К. Kotlukov

    2011-01-01

    Full Text Available The article presents main strategies of breast feeding of prematurely born infants support, such as use of Philips AVENT breast pumpfor lactation formation and feeding of the infant with native breast milk.Key words: premature infants, nursing mother, breast feeding support, modern accessories for breast feeding support. (Voprosy sovremennoi pediatrii — Current Pediatrics. 2011; 10 (6: 170–175

  7. The pathophysiology of acquired premature ejaculation

    OpenAIRE

    McMahon, Chris G; Jannini, Emmanuele A.; Serefoglu, Ege C.; Hellstrom, Wayne J.G.

    2016-01-01

    The second Ad Hoc International Society for Sexual Medicine (ISSM) Committee for the Definition of Premature Ejaculation defined acquired premature ejaculation (PE) as a male sexual dysfunction characterized by a the development of a clinically significant and bothersome reduction in ejaculation latency time in men with previous normal ejaculatory experiences, often to about 3 minutes or less, the inability to delay ejaculation on all or nearly all vaginal penetrations, and the presence of ne...

  8. Development of 3D pseudo pin-by-pin calculation methodology in ANC

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, B.; Mayhue, L.; Huria, H.; Ivanov, B. [Westinghouse Electric Company LLC, 1000 Westinghouse Drive, Cranberry, PA 16066 (United States)

    2012-07-01

    Advanced cores and fuel assembly designs have been developed to improve operational flexibility, economic performance and further enhance safety features of nuclear power plants. The simulation of these new designs, along with strong heterogeneous fuel loading, have brought new challenges to the reactor physics methodologies currently employed in the industrial codes for core analyses. Control rod insertion during normal operation is one operational feature in the AP1000{sup R} plant of Westinghouse next generation Pressurized Water Reactor (PWR) design. This design improves its operational flexibility and efficiency but significantly challenges the conventional reactor physics methods, especially in pin power calculations. The mixture loading of fuel assemblies with significant neutron spectrums causes a strong interaction between different fuel assembly types that is not fully captured with the current core design codes. To overcome the weaknesses of the conventional methods, Westinghouse has developed a state-of-the-art 3D Pin-by-Pin Calculation Methodology (P3C) and successfully implemented in the Westinghouse core design code ANC. The new methodology has been qualified and licensed for pin power prediction. The 3D P3C methodology along with its application and validation will be discussed in the paper. (authors)

  9. Frequency of neonatal complications after premature delivery

    Directory of Open Access Journals (Sweden)

    Gordana Grgić

    2013-04-01

    Full Text Available Introduction: Preterm delivery is the delivery before 37 weeks of gestation are completed. The incidence of preterm birth ranges from 5 to 15%. Aims of the study were to determine the average body weight, Apgar score after one and five minutes, and the frequency of the most common complications in preterminfants.Methods: The study involved a total of 631 newborns, of whom 331 were born prematurely Aims of this study were to (24th-37th gestational weeks-experimental group, while 300 infants were born in time (37-42 weeks of gestation-control group.Results: Average body weight of prematurely born infants was 2382 grams, while the average Apgar score in this group after the fi rst minute was 7.32 and 7.79 after the fifth minute. The incidence of respiratory distress syndrome was 50%, intracranial hemorrhage, 28.1% and 4.8% of sepsis. Respiratory distresssyndrome was more common in infants born before 32 weeks of gestation. Mortality of premature infants is present in 9.1% and is higher than that of infants born at term.Conclusions: Birth body weight and Apgar scores was lower in preterm infants. Respiratory distress syndrome is the most common fetal complication of prematurity. Intracranial hemorrhage is the second most common complication of prematurity. Mortality of premature infants is higher than the mortality of infants born at term birth.

  10. The pin pixel detector--X-ray imaging

    CERN Document Server

    Bateman, J E; Derbyshire, G E; Duxbury, D M; Marsh, A S; Simmons, J E; Stephenson, R

    2002-01-01

    The development and testing of a soft X-ray gas pixel detector, which uses connector pins for the anodes is reported. Based on a commercial 100 pin connector block, a prototype detector of aperture 25.4 mm centre dot 25.4 mm can be economically fabricated. The individual pin anodes all show the expected characteristics of small gas detectors capable of counting rates reaching 1 MHz per pin. A 2-dimensional resistive divide readout system has been developed to permit the imaging properties of the detector to be explored in advance of true pixel readout electronics.

  11. 327 to 324 Pin tube shipment quality management process plan

    Energy Technology Data Exchange (ETDEWEB)

    HAM, J.E.

    1998-11-05

    The B and W Hanford Company's (BWHC) 327 Facility, in the 300 Area of the Hanford Site, is preparing to ship five Pin Tubes to the 324 Facility for storage and eventual disposition. The Pin Tubes consist of legacy fuel pin pieces and drillings. They will be over-packed in new Pin Tubes and transported to 324 in three shipments. Once received at 324, two of the shipments will be combined for storage as a fissionable material batch, and the other shipment will be added to an existing batch.

  12. [Ingestion of an open safety pin--challenging treatment].

    Science.gov (United States)

    DeRowe, Ari; Fishman, Gadi; Avni, Hadas; Reider, Ivgeny; Ogorek, Daniel

    2003-11-01

    A 9 month old girl at the emergency room appeared with an acute onset of restlessness, drooling and suspected foreign body ingestion. An X-Ray revealed an open safety pin in the child's upper aero-digestive tract. The source of the safety pin was a "Hamsah" good luck charm that was attached to her bed. Open safety pins in the aero-digestive tract are difficult to manage and great care must be taken during removal to prevent further injury. Parents should be counseled regarding the presence of safety pins in the child's surroundings in order to prevent such hazards.

  13. Changing the flux flow state in weak pinning superconducting films

    Energy Technology Data Exchange (ETDEWEB)

    Leo, A., E-mail: antoleo@sa.infn.it [Physics Department E.R. Caianiello, University of Salerno, Via Giovanni Paolo II, 132, Stecca 9, I-84084 Fisciano, SA (Italy); CNR-SPIN Salerno, Via Giovanni Paolo II, 132, Stecca 9, I-84084 Fisciano, SA (Italy); Grimaldi, G. [CNR-SPIN Salerno, Via Giovanni Paolo II, 132, Stecca 9, I-84084 Fisciano, SA (Italy); Nigro, A. [Physics Department E.R. Caianiello, University of Salerno, Via Giovanni Paolo II, 132, Stecca 9, I-84084 Fisciano, SA (Italy); CNR-SPIN Salerno, Via Giovanni Paolo II, 132, Stecca 9, I-84084 Fisciano, SA (Italy); Bruno, E.; Priolo, F. [Matis IMM-CNR and Physics-Astronomy Department, Catania University, CT 95123 (Italy); Pace, S. [Physics Department E.R. Caianiello, University of Salerno, Via Giovanni Paolo II, 132, Stecca 9, I-84084 Fisciano, SA (Italy); CNR-SPIN Salerno, Via Giovanni Paolo II, 132, Stecca 9, I-84084 Fisciano, SA (Italy)

    2014-08-15

    Highlights: • We analyzed the effect of light ion irradiation on weak pinning superconductors. • We found the light ion irradiation has a strong impact on current currying stability. • We compared the results to the ones of the case of moderate strong pinning materials. - Abstract: The current carrying dissipative state well above the critical current it is known to be related to the pinning properties of the material and to the microscopic mechanisms of vortex dynamics. Moreover, it has been demonstrated that in low temperature superconducting films exhibiting moderately strong pinning the light ion irradiation has the effect of changing the distribution of the pinning centers without changing their pinning strength and this results into an increase of current stability in the flux flow state. Here we present the results of light ion irradiation on weak pinning superconducting films focusing on the influence of pinning properties of the material in the flux flow state. We realize that the possibility to switch to low dissipations by changing weak pinning is not straightforward.

  14. On the Influence of Piston and Cylinder Density in Tribodynamics of a Radial Piston Digital Fluid Power Displacement Motor

    DEFF Research Database (Denmark)

    Johansen, Per; Roemer, Daniel Beck; Andersen, Torben O.;

    2015-01-01

    In the past three decades an increasing amount of research has been performed in the field of tribodynamics of fluid power pumps and motors. The main incentives for this research are optimization of reliability and eciency through the study of loss and wear mechanisms. These mechanisms are very d...... assessment of the applicability, of the force balance condition, if it is used in multibody tribodynamic simulations of radial piston digital fluid power displacement motors....... analysis or optimization. The coupling between multibody dynamics and fluid mechanics depend on the formulation of the solid body motion equations, where two approaches have historically been used. One approach is where the external forces on any lubricated joint are balanced by the fluid forces......, such that solid body inertia is neglected. The other approach includes the inertia terms in the calculation of microdynamics. The inclusion of inertia terms entails a need for smaller time steps in comparison to the force balance approach, wherefore it is of interest to analyze the influence of the inertia term...

  15. Pin-ups: pictures that fascinate and seduce Pin-ups: fotografias que encantam e seduzem

    Directory of Open Access Journals (Sweden)

    Maria Irene Pellegrino de Oliveira Souza

    2010-08-01

    Full Text Available Starting from photography studies, social anthropology and body visual, this article approaches the social construction of the feminine image through times. It narrates the history of erotic pinups photography and its fetishist elements. Pin-ups have aroused in the end of 19tcentury and it represents the free spirit of women. Slowly, it provokes the breakup of sensuality and sexuality feminine traditionalism. The article also discusses women’s sensuality as a desire object. The pin-ups sensual demure – with a mystery atmosphere – stimulated the eroticism at the beginning of the 20 century and, until nowadays, it provokes admiration, sigh and desire. Com base em estudos sobre fotografia, antropologia social e visual do corpo, este artigo aborda a imagem feminina socialmente construída através dos tempos. Narra o histórico da fotografia erótica de pin-ups e seus elementos fetichistas. As pin-ups surgiram no final do século XIX e representaram o espírito “livre” das mulheres. Sutilmente, incitavam o rompimento do tradicionalismo da época quanto à sensualidade e sexualidade feminina. O artigo aborda também a sensualidade feminina como objeto de desejo. O recato sensual das pin-ups – com ar de mistério – alavancou o erotismo no início do século XX e, até os dias atuais, provoca admiração, suspiros e desejos.

  16. Lightning Pin Injection Testing on MOSFETS

    Science.gov (United States)

    Ely, Jay J.; Nguyen, Truong X.; Szatkowski, George N.; Koppen, Sandra V.; Mielnik, John J.; Vaughan, Roger K.; Wysocki, Philip F.; Celaya, Jose R.; Saha, Sankalita

    2009-01-01

    Lightning transients were pin-injected into metal-oxide-semiconductor field-effect transistors (MOSFETs) to induce fault modes. This report documents the test process and results, and provides a basis for subsequent lightning tests. MOSFETs may be present in DC-DC power supplies and electromechanical actuator circuits that may be used on board aircraft. Results show that unprotected MOSFET Gates are susceptible to failure, even when installed in systems in well-shielded and partial-shielded locations. MOSFET Drains and Sources are significantly less susceptible. Device impedance decreased (current increased) after every failure. Such a failure mode may lead to cascading failures, as the damaged MOSFET may allow excessive current to flow through other circuitry. Preliminary assessments on a MOSFET subjected to 20-stroke pin-injection testing demonstrate that Breakdown Voltage, Leakage Current and Threshold Voltage characteristics show damage, while the device continues to meet manufacturer performance specifications. The purpose of this research is to develop validated tools, technologies, and techniques for automated detection, diagnosis and prognosis that enable mitigation of adverse events during flight, such as from lightning transients; and to understand the interplay between lightning-induced surges and aging (i.e. humidity, vibration thermal stress, etc.) on component degradation.

  17. Optimizing Dynamical Network Structure for Pinning Control

    Science.gov (United States)

    Orouskhani, Yasin; Jalili, Mahdi; Yu, Xinghuo

    2016-04-01

    Controlling dynamics of a network from any initial state to a final desired state has many applications in different disciplines from engineering to biology and social sciences. In this work, we optimize the network structure for pinning control. The problem is formulated as four optimization tasks: i) optimizing the locations of driver nodes, ii) optimizing the feedback gains, iii) optimizing simultaneously the locations of driver nodes and feedback gains, and iv) optimizing the connection weights. A newly developed population-based optimization technique (cat swarm optimization) is used as the optimization method. In order to verify the methods, we use both real-world networks, and model scale-free and small-world networks. Extensive simulation results show that the optimal placement of driver nodes significantly outperforms heuristic methods including placing drivers based on various centrality measures (degree, betweenness, closeness and clustering coefficient). The pinning controllability is further improved by optimizing the feedback gains. We also show that one can significantly improve the controllability by optimizing the connection weights.

  18. Medio-lateral entry pin versus lateral entry pin for displaced pediatric supracondylar fractures: A comparative, prospective study

    Directory of Open Access Journals (Sweden)

    Manoj Kandel

    2016-01-01

    Full Text Available Background & Objectives: Supracondylar fracture is one of the commonest fractures in children. Although the technique of pinning is controversial, percutaneous medio-lateral entry pinning is theoretically considered more stable biomechanical construct. The drawback of this method is injury to ulnar nerve which is not encountered in only lateral entry pinning.Materials & Methods: This was a prospective, comparative and observational study done in 60 patients which was alternately divided into two groups. The first group (A underwent medio-lateral entry pinning and the second group (B underwent lateral entry pinning. They were followed for 24 weeks and the outcome was assessed using Flynn’s criteria.Results: At twenty-four weeks, the mean loss of range of motion of elbow in medio-lateral pinning group was 3.70 degrees (SD±1.93 and that in lateral pinning group was 4.23 degrees (SD ±1.38. The mean loss in carrying angle at twenty-four weeks in medio-lateral group was 2.93 degrees (SD±2.19 and that in lateral group was 4.17 (SD±2.24. There were 2 (6.67% cases of iatrogenic ulnar nerve injury in medio-lateral pinning group. Out of thirty patients, in medio-lateral pinning group, 25 had excellent results, 5 had good results and none had fair or poor results. While out of 30 patients in lateral pinning group, 23 had excellent results, 7 had good results and none had fair or poor results.Conclusion: There is no significant difference in outcome in terms of loss of carrying angle and range of motion between the medio-lateral pinning group and the lateral pinning group at the end of 6 months.Journal of College of Medical Sciences-Nepal, Vol.11(4 2015: 28-31

  19. Finite-temperature Casimir pistons for an electromagnetic field with mixed boundary conditions and its classical limit

    Energy Technology Data Exchange (ETDEWEB)

    Teo, L P [Faculty of Information Technology, Multimedia University, Jalan Multimedia, Cyberjaya, 63100, Selangor Darul Ehsan (Malaysia)], E-mail: lpteo@mmu.edu.my

    2009-03-13

    In this paper, the finite-temperature Casimir force acting on a two-dimensional Casimir piston due to an electromagnetic field is computed. It was found that if mixed boundary conditions are assumed on the piston and its opposite wall, then the Casimir force always tends to restore the piston toward the equilibrium position, regardless of the boundary conditions assumed on the walls transverse to the piston. In contrast, if pure boundary conditions are assumed on the piston and the opposite wall, then the Casimir force always tends to pull the piston toward the closer wall and away from the equilibrium position. The nature of the force is not affected by temperature. However, in the high-temperature regime, the magnitude of the Casimir force grows linearly with respect to temperature. This shows that the Casimir effect has a classical limit as has been observed in other literature.

  20. Space Power Free-Piston Stirling Engine Scaling Study

    Science.gov (United States)

    Jones, D.

    1989-01-01

    The design feasibility study is documented of a single cylinder, free piston Stirling engine/linear alternator (FPSE/LA) power module generating 150 kW-electric (kW sub e), and the determination of the module's maximum feasible power level. The power module configuration was specified to be a single cylinder (single piston, single displacer) FPSE/LA, with tuning capacitors if required. The design requirements were as follows: (1) Maximum electrical power output; (2) Power module thermal efficiency equal to or greater than 20 percent at a specific mass of 5 to 8 kg/kW(sub e); (3) Heater wall temperature/cooler wall temperature = 1050 K/525 K; (4) Sodium heat-pipe heat transport system, pumped loop NaK (sodium-potassium eutectic mixture) rejection system; (5) Maximum power module vibration amplitude = 0.0038 cm; and (6) Design life = 7 years (60,000 hr). The results show that a single cylinder FPSE/LA is capable of meeting program goals and has attractive scaling attributes over the power range from 25 to 150 kW(sub e). Scaling beyond the 150 kW(sub e) power level, the power module efficiency falls and the power module specific mass reaches 10 kg/kW(sub e) at a power output of 500 kW(sub e). A discussion of scaling rules for the engine, alternator, and heat transport systems is presented, along with a detailed description of the conceptual design of a 150 kW(sub e) power module that meets the requirements. Included is a discussion of the design of a dynamic balance system. A parametric study of power module performance conducted over the power output range of 25 to 150 kW(sub e) for temperature ratios of 1.7, 2.0, 2.5, and 3.0 is presented and discussed. The results show that as the temperature ratio decreases, the efficiency falls and specific mass increases. At a temperature ratio of 1.7, the 150 kW(sub e) power module cannot satisfy both efficiency and specific mass goals. As the power level increases from 25 to 150 kW(sub e) at a fixed temperature ratio, power

  1. Nanoengineering of Flux Pinning Sites in High-Tc Superconductors

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Volume pinning forces were determined for a variety of bulk high-Tcsuperconductors of the 123-type from magnetization measurements. By means of scaling of the pinning forces, the acting pinning mechanisms in various temperature ranges were identified. The Nd-based superconductors and some YBCO crystalsexhibited a dominating pinning of the δTc-type (i.e., small, superconducting pinning sites). In contrast to this, the addition of insulating 211 particles provided pinning of the δl-type; providing effective pinning in the entire temperature range acting as a "background" pinning mechanism for the peak effect. Due to the small coherence lengths of the high-Tc compounds, effective pinning sites are defects or particles of nanometer size relative to ξ3. Integral magnetic measurements of the magnetization as a function of temperature in large applied magnetic fields (up to 7 T) revealed that practically all high-Tc compounds were spatially inhomogeneous, which could be caused byoxygen deficiency (YBCO), solid solutions of Nd/Ba (NdBCO and other light rare earth compounds), intergrowths (Bi-based superconductors), and doping by pair-breaking dopants like Zn, Pr. This implies that the superconducting sample consists of stronger and weaker superconducting areas, coupled together. In large appliedfields, this coupling gets broken and the magnetization versus temperature curves revealed more than one superconducting transition. In contrast, irradiation experiments by neutrons, protons, and heavy-ions enabled the artificial introduction of very effective pinning sites into the high-Tc superconductors, thus creating a large variety of different observations using magnetic data. From all these observations, we construct a pinning diagram for bulk high-Tc superconductors explaining many features observed in high-Tc samples.

  2. Fundamental Characteristics of a Pinned Photodiode CMOS Pixels

    NARCIS (Netherlands)

    Xu, Y.

    2015-01-01

    This thesis gives an insightful analysis of the pinned photodiode 4T CMOS pixel from three different aspects. Firstly, from the charge accumulated aspect, the PPD full well capacity and related parameters of influence are investigated such as the pinning voltage, and transfer gate potential barrier.

  3. IMp: The customizable LEGO(®) Pinned Insect Manipulator.

    Science.gov (United States)

    Dupont, Steen; Price, Benjamin; Blagoderov, Vladimir

    2015-01-01

    We present a pinned insect manipulator (IMp) constructed of LEGO® building bricks with two axes of movement and two axes of rotation. In addition we present three variants of the IMp to emphasise the modular design, which facilitates resizing to meet the full range of pinned insect specimens, is fully customizable, collapsible, affordable and does not require specialist tools or knowledge to assemble.

  4. Premature Ejaculation and Utilization of Cognitive Techniques

    Directory of Open Access Journals (Sweden)

    Serkan AKKOYUNLU

    2013-03-01

    Full Text Available Introduction: Premature ejaculation is the most common male sexual dysfunction leading to distress in many couples. Master and Johnson emphasized the concept of early learned experiences and Kaplan emphasized lack of sensory awareness. For treatment sex therapists mainly utilize start-stop and squeeze techniques as homework. Couples enter sex therapy with some cognitive distortions and beliefs about sex and sexuality. These beliefs are also named sexual myths. For some couples using techniques to challenge cognitive distortions and maladaptive beliefs about sex and sexuality can be used. In this paper by presenting a case we discussed how cognitive techniques can be used along with behaviour techniques with couples. Case: Presenting clients are five years married couple who are thirty and twenty nine years old respectively. They attended to the outpatient clinic with the request of the female client. Their main complaint was premature ejaculation. They were diagnosed premature ejaculation using clinical interview. In treatment besides start and stop technique, cognitive techniques were utilized to address dysfunctional beliefs about sexuality. Discussion: Premature ejaculation is a male sexual dysfunction that causes distress and intimacy problems between couples. Stop start and squeeze techniques were accepted as the choice of treatment but their effectiveness is questioned recently. Also cognitive distortions and maladaptive beliefs may hamper therapy progress. Besides that, behavioral techniques utilizing cognitive techniques to lessen the degree of dysfunctional beliefs about sex and sexuality may help the couple to overcome premature ejaculation and enhance sexual satisfaction and intimacy.

  5. The optimal path of piston motion for Otto cycle with linear phenomenological heat transfer law

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    An Otto cycle engine with internal and external irreversibilities of friction and heat leakage, in which the heat transfer between the working fluid and the environment obeys linear phenomenological heat transfer law [q ∝△(T -1)], is studied in this paper. The optimal piston motion trajectory for maximizing the work output per cycle is derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston trajectories for the cases of with and without piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum deceleration boundary segments, respectively. Numerical examples for optimal configuration are provided, and the obtained results are compared with those obtained with Newton’s heat transfer law [q ∝△(T )]. The results also show that optimizing the piston motion can improve power and efficiency of the engine by more than 9%. This is primarily due to the decrease in heat leakage loss on the initial portion of the power stroke.

  6. Modeling and Simulation on Axial Piston Pump Based on Virtual Prototype Technology

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bin; XU Bing; XIA Chunlin; YANG Huayong

    2009-01-01

    A particular emphasis is placed on the virtual prototype technology (VPT) of axial piston pump. With this technology it is convenient and flexible to build a complicated 3D virtual based on real physical model. The actual kinematics pairs of the parts were added on the model. The fluid characters were calculated by hydraulic software. The shape of the parts, the flexible body of parts, etc were improved in this prototype. So the virtual prototype of piston pump can work in computer like a real piston pump, and the flow ripple, pressure pulsation, motion principle, stress of parts, etc can be investigated. The development of the VPT is introduced at the beginning, and the modeling process of the virtual prototype is explained. Then a special emphasis is laid on the relationship between the dynamics model and the hydraulic model, and the simulations on the flow ripple, pressure pulsation, motion principle, the stress and strain distribution of the middle shaft and piston are operated. Finally, the advantages and disadvantages of the VPT are discussed. The improved virtual prototype of piston pump more tally with the real situation and the VPT has a great potential in simulation on hydraulic components.

  7. Compact high-efficiency linear cryocooler in single-piston moving magnet design for HOT detectors

    Science.gov (United States)

    Rühlich, I.; Mai, M.; Rosenhagen, C.; Withopf, A.; Zehner, S.

    2012-06-01

    State of the art Mid Wave IR-technology has the potential to rise the FPA temperature from 77K to 130-150K (High Operation Temperature, HOT). Using a HOT FPA will significantly lower SWaP and keep those parameters finally dominated by the employed cryocooler. Therefore, compact high performance cryocoolers are mandatory. AIM has developed the SX040 cooler, optimized for FPA temperatures of about 95K (presented at SPIE 2010). The SX040 cooler incorporates a high efficient dual piston driving mechanism resulting in a very compact compressor of less than 100mm length. Higher compactness - especially shorter compressors - can be achieved by change from dual to single piston design. The new SX030 compressor has such a single piston Moving Magnet driving mechanism resulting in a compressor length of about 60mm. Common for SX040 and SX030 family is a Moving Magnet driving mechanism with coils placed outside the helium vessel. In combination with high performance plastics for the piston surfaces this design enables lifetimes in excess of 20,000h MTTF. Because of the higher FPA temperature and a higher operating frequency also a new displacer needs to be developed. Based on the existing 1/4" coldfinger interface AIM developed a new displacer optimized for an FPA temperature of 140K and above. This paper gives an overview on the development of this new compact single piston cryocooler. Technical details and performance data will be shown.

  8. Efficiency at maximum power output for an engine with a passive piston

    Science.gov (United States)

    Sano, Tomohiko G.; Hayakawa, Hisao

    2016-08-01

    Efficiency at maximum power (MP) output for an engine with a passive piston without mechanical controls between two reservoirs is studied theoretically. We enclose a hard core gas partitioned by a massive piston in a temperature-controlled container and analyze the efficiency at MP under a heating and cooling protocol without controlling the pressure acting on the piston from outside. We find the following three results: (i) The efficiency at MP for a dilute gas is close to the Chambadal-Novikov-Curzon-Ahlborn (CNCA) efficiency if we can ignore the sidewall friction and the loss of energy between a gas particle and the piston, while (ii) the efficiency for a moderately dense gas becomes smaller than the CNCA efficiency even when the temperature difference of the reservoirs is small. (iii) Introducing the Onsager matrix for an engine with a passive piston, we verify that the tight coupling condition for the matrix of the dilute gas is satisfied, while that of the moderately dense gas is not satisfied because of the inevitable heat leak. We confirm the validity of these results using the molecular dynamics simulation and introducing an effective mean-field-like model which we call the stochastic mean field model.

  9. Simulating Rectified Motion of a Piston in a Housing Subjected to Vibrational Acceleration

    Science.gov (United States)

    Clausen, Jonthan; Torczynski, John; Romero, Louis; O'Hern, Timothy

    2014-11-01

    We employ ALE finite element simulations to investigate the behavior of a piston in a housing subjected to vertical vibrations. The housing is filled with a viscous liquid to damp the piston motion and has bellows at both ends to represent air bubbles present in real systems. The piston has a roughly cylindrical hole along its axis, and a post attached to the housing penetrates partway into this hole. Protrusions from the hole and the post form a gap with a length that varies as the piston moves and forces liquid through this gap. Under certain conditions, nonlinearities in the system can drive the piston to move downward and compress the spring that holds it up against gravity. This behavior is investigated using ALE finite element simulations, and these results are compared with theoretical predictions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  10. The optimal path of piston motion for Otto cycle with linear phenomenological heat transfer law

    Institute of Scientific and Technical Information of China (English)

    XIA ShaoJun; CHEN LinGen; SUN FengRui

    2009-01-01

    An Otto cycle engine with internal and external irreversibilities of friction and heat leakage, in which the heat transfer between the working fluid and the environment obeys linear phenomenological heat transfer law [q∝△(T-1)], is studied in this paper. The optimal piston motion trajectory for maximizing the work output per cycle is derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston trajectories for the cases of with and without piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum deceleration boundary segments,respectively. Numerical examples for optimal configuration are provided, and the obtained results are compared with those obtained with Newton's heat transfer law [q∝△(T)]. The results also show that optimizing the piston motion can improve power and efficiency of the engine by more than 9%. This is primarily due to the decrease in heat leakage loss on the initial portion of the power stroke.

  11. Development of cryogenic free-piston reciprocating expander utilizing phase controller

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jeong Min; Park, Ji Ho; Kim, Kyung Joong; Jeong, Sang Kwon [Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2016-06-15

    A free-piston reciprocating expander is a device which operates without any mechanical linkage to a stationary part. Since the motion of the floating piston is only controlled by the pressure difference at two ends of the piston, this kind of expander may indispensably require a sophisticated active control system equipped with multiple valves and reservoirs. In this paper, we have suggested a novel design that can further reduce complexity of the previously developed cryogenic free-piston expander configuration. It is a simple replacement of both multiple valves and reservoirs by a combination of an orifice valve and a reservoir. The functional characteristic of the integrated orifice-reservoir configuration is similar to that of a phase controller applied in a pulse tube refrigerator so that we designate the one as a phase controller. Depending on the orifice valve size in the phase controller, the different PV work which affects the expander performance is generated. The numerical model of this unique free-piston reciprocating expander utilizing a phase controller is established to understand and analyze quantitatively the performance variation of the expander under different valve timing and orifice valve size. The room temperature experiments are carried out to examine the performance of this newly developed cryogenic expander.

  12. Optimal paths of piston motion of irreversible diesel cycle for minimum entropy generation

    Directory of Open Access Journals (Sweden)

    Ge Yanlin

    2011-01-01

    Full Text Available A Diesel cycle heat engine with internal and external irreversibility’s of heat transfer and friction, in which the finite rate of combustion is considered and the heat transfer between the working fluid and the environment obeys Newton’s heat transfer law [q≈ Δ(T], is studied in this paper. Optimal piston motion trajectories for minimizing entropy generation per cycle are derived for the fixed total cycle time and fuel consumed per cycle. Optimal control theory is applied to determine the optimal piston motion trajectories for the cases of with piston acceleration constraint on each stroke and the optimal distribution of the total cycle time among the strokes. The optimal piston motion with acceleration constraint for each stroke consists of three segments, including initial maximum acceleration and final maximum deceleration boundary segments, respectively. Numerical examples for optimal configurations are provided, and the results obtained are compared with those obtained when maximizing the work output with Newton’s heat transfer law. The results also show that optimizing the piston motion trajectories could reduce engine entropy generation by more than 20%. This is primarily due to the decrease in entropy generation caused by heat transfer loss on the initial portion of the power stroke.

  13. Heat transfer enhancement by pin elements

    Energy Technology Data Exchange (ETDEWEB)

    Sahiti, N.; Durst, F.; Dewan, A. [LSTM-Erlangen, Institute of Fluid Mechanics, Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Cauerstrasse 4, D-91058 Erlangen (Germany)

    2005-11-01

    Heat transfer enhancement is an active and important field of engineering research since increases in the effectiveness of heat exchangers through suitable heat transfer augmentation techniques can result in considerable technical advantages and savings of costs. Considerable enhancements were demonstrated in the present work by using small cylindrical pins on surfaces of heat exchangers. A partly quantitative theoretical treatment of the proposed method is presented. It uses simple relationships for the conductive and convective heat transfer to derive an equation that shows which parameters permit the achievement of heat transfer enhancements. Experiments are reported that demonstrate the effectiveness of the results of the proposed approach. It is shown that the suggested method of heat transfer enhancements is much more effective than existing methods, since it results in an increase in heat transfer area (like fins) and also an increase in the heat transfer coefficient. (author)

  14. Cracking Bank PINs by Playing Mastermind

    Science.gov (United States)

    Focardi, Riccardo; Luccio, Flaminia L.

    The bank director was pretty upset noticing Joe, the system administrator, spending his spare time playing Mastermind, an old useless game of the 70ies. He had fought the instinct of telling him how to better spend his life, just limiting to look at him in disgust long enough to be certain to be noticed. No wonder when the next day the director fell on his chair astonished while reading, on the newspaper, about a huge digital fraud on the ATMs of his bank, with millions of Euros stolen by a team of hackers all around the world. The article mentioned how the hackers had 'played with the bank computers just like playing Mastermind', being able to disclose thousands of user PINs during the one-hour lunch break. That precise moment, a second before falling senseless, he understood the subtle smile on Joe's face the day before, while training at his preferred game, Mastermind.

  15. Flux pinning characteristics and irreversibility line in high temperature superconductors

    Science.gov (United States)

    Matsushita, T.; Ihara, N.; Kiuchi, M.

    1995-01-01

    The flux pinning properties in high temperature superconductors are strongly influenced by thermally activated flux motion. The scaling relation of the pinning force density and the irreversibility line in various high temperature superconductors are numerically analyzed in terms of the flux creep model. The effect of two factors, i.e., the flux pinning strength and the dimensionality of the material, on these properties are investigated. It is speculated that the irreversibility line in Bi-2212 superconductors is one order of magnitude smaller than that in Y-123, even if the flux pinning strength in Bi-2212 is improved up to the level of Y-123. It is concluded that these two factors are equally important in determination of the flux pinning characteristics at high temperatures.

  16. Nano-engineered pinning centres in YBCO superconducting films

    Science.gov (United States)

    Crisan, A.; Dang, V. S.; Mikheenko, P.

    2017-02-01

    For practical applications of superconducting materials in applied magnetic fields, artificial pinning centres in addition to natural ones are required to oppose the Lorentz force. These pinning centres are actually various types of defects in the superconductor matrix. The pinning centres can be categorised on their dimension (volume, surface or point) and on their character (normal cores or Δκ cores). Different samples have been produced by Pulsed Laser Deposition, with various thicknesses, temperatures and nanostructured additions to the superconducting matrix. They have been characterized by SQUID Magnetic Properties Measurement System and Physical Properties Measurement System, as well as by Transmission Electron Microscopy (TEM). Correlations between pinning architecture, TEM images, and critical currents at various fields and field orientations will be shown for a large number of YBa2Cu3Ox films with various types and architectures of artificial pinning centres.

  17. New Pin Puller Based on SMA Technology for Space Applications

    Science.gov (United States)

    Nava, Nestor; Collado, Marcelo; Cabás, Ramiro

    2014-07-01

    Two different versions of the Pin Puller were designed during this activity, such as one with 100 N and other with 500 N of pull force. The design of both versions is based on spheres which support the pin at the initial position and a compression spring driving once the release takes place by means of the SMA. The mechanical design of the Pin Pullers has been conceived in order to optimize the device's weight, reduce the parts complexity, and achieve a suitable stiffness. A qualification test campaign for the Pin Puller with 500 N of pull force has been developed in order to check the success of the proposed mechanism for space applications. The main performed tests have been thermal-vacuum actuation, thermal-vacuum cycling, sine vibration, and random vibration. The Pin Puller has presented successful results of actuation during the test campaign

  18. In vitro analysis of self-shearing retentive pins.

    Science.gov (United States)

    Collard, E W; Caputo, A A; Standlee, J P; Duncanson, M G

    1981-02-01

    Combining stress, analysis, microscopic examination, mechanical testing of the shear mechanism, and retention of the Reten Pin leads to the following conclusions: 1. The suggested 0.006 inch pin-channel mismatch induces high lateral and apical stresses. Microscopically, this was seen to correlate with injury to the dentin. 2. The degree of retention was increased by using a smaller pin-channel mismatch. This correlates with smaller stresses and reduced dentinal damage. 3. The shear mechanism acts in a uniform manner, with a relatively small variation from the mean. It is suggested that for the best results the manufacturer should supply larger twist drills and pins with a somewhat deeper self-shearing groove to minimize apical involvement during shearing of the handle from the pin.

  19. Pinning Lur’e Complex Networks via Output Feedback Control

    Directory of Open Access Journals (Sweden)

    Fang Liu

    2014-01-01

    Full Text Available Without requiring the full-state information of network nodes, this paper studies the pinning synchronization in a network of Lur’e dynamical systems based on the output feedback control strategy. Some simple pinning conditions are established for both undirected and directed Lur’e networks by using M-matrix theory and S-procedure technique. With the derived stability criteria, the pinning synchronization problem of large-scale Lur’e networks can be transformed to the test of a low-dimensional linear matrix inequality. Some remarks are further given to address the selection of pinned nodes and the design of pinning feedback gains. Numerical results are provided to demonstrate the effectiveness of the theoretical analysis.

  20. Retractable Pin Tools for the Friction Stir Welding Process

    Science.gov (United States)

    1998-01-01

    Two companies have successfully commercialized a specialized welding tool developed at the Marshall Space Flight Center (MSFC). Friction stir welding uses the high rotational speed of a tool and the resulting frictional heat created from contact to crush, 'stir' together, and forge a bond between two metal alloys. It has had a major drawback, reliance on a single-piece pin tool. The pin is slowly plunged into the joint between two materials to be welded and rotated as high speed. At the end of the weld, the single-piece pin tool is retracted and leaves a 'keyhole,' something which is unacceptable when welding cylindrical objects such as drums, pipes and storage tanks. Another drawback is the requirement for different-length pin tools when welding materials of varying thickness. An engineer at the MSFC helped design an automatic retractable pin tool that uses a computer-controlled motor to automatically retract the pin into the shoulder of the tool at the end of the weld, preventing keyholes. This design allows the pin angle and length to be adjusted for changes in material thickness and results in a smooth hole closure at the end of the weld. Benefits of friction stir welding, using the MSFC retractable pin tool technology, include the following: The ability to weld a wide range of alloys, including previously unweldable and composite materials; provision of twice the fatigue resistance of fusion welds and no keyholes; minimization of material distortion; no creation of hazards such as welding fumes, radiation, high voltage, liquid metals, or arcing; automatic retraction of the pin at the end of the weld; and maintaining full penetration of the pin.

  1. Serum fructosamine and retinopathy of prematurity.

    Science.gov (United States)

    Bozdag, Senol; Oguz, Serife Suna; Gokmen, Tulin; Tunay, Zuhal; Tok, Levent; Uras, Nurdan; Erdeve, Omer; Dilmen, Ugur

    2011-12-01

    To determine whether serum fructosamine which is a good marker for detecting hyperglycemia during the previous 2 to 3 wk in infants could predict the development of retinopathy of prematurity in very low birth weight infants. One hundred sixty seven premature infants who had a birth weight of < 1500 g and a gestational age of less than 32 wk were investigated in the present study. Blood glucose was measured at the bedside and infants were recorded as hyperglycemic if their mean blood glucose levels were higher than 150 mg/dL. Serum corrected fructosamine level was obtained from the cord blood at birth and after the first month of life. The infants' eyes were examined by ophthalmologists to detect retinopathy of prematurity at the gestational age of 32 wk or at four wk after birth, whichever came first. Corrected fructosamine was 319.6 ± 59.6 and 272.8 ± 50.6 mmol/l for group 1 on 1(st) and 30(th) day respectively; 320 ± 61.7 and 268.2 ± 47.3 mmol/l for groups 2 + 3 on 1(st) and 30(th) day respectively which did not differ between groups (p = 0.766 and p = 0.665), whereas duration of hyperglycemia was 1.69 ± 1.1 day in group 1 compared with 3.05 ± 2.4 day in groups 2 + 3 which was significantly different (p = 0.019). The multivariate regression analysis indicated that the duration of hyperglycemia in days was significantly correlated with the development of retinopathy of prematurity (OR 3.26; 95% CI 1.09-9.80; p = 0.035). Although the duration of hyperglycemia may contribute to the development of retinopathy of prematurity, serum corrected fructosamine does not have a good predictive value in developing retinopathy of prematurity in very-low-birth-weight (VLBW) infants.

  2. Design and construction of the X-2 two-stage free piston driven expansion tube

    Science.gov (United States)

    Doolan, Con

    1995-01-01

    This report outlines the design and construction of the X-2 two-stage free piston driven expansion tube. The project has completed its construction phase and the facility has been installed in the new impulsive research laboratory where commissioning is about to take place. The X-2 uses a unique, two-stage driver design which allows a more compact and lower overall cost free piston compressor. The new facility has been constructed in order to examine the performance envelope of the two-stage driver and how well it couple to sub-orbital and super-orbital expansion tubes. Data obtained from these experiments will be used for the design of a much larger facility, X-3, utilizing the same free piston driver concept.

  3. Test Method Designed to Evaluate Cylinder Liner-Piston Ring Coatings for Advanced Heat Engines

    Science.gov (United States)

    Radil, Kevin C.

    1997-01-01

    Research on advanced heat engine concepts, such as the low-heat-rejection engine, have shown the potential for increased thermal efficiency, reduced emissions, lighter weight, simpler design, and longer life in comparison to current diesel engine designs. A major obstacle in the development of a functional advanced heat engine is overcoming the problems caused by the high combustion temperatures at the piston ring/cylinder liner interface, specifically at top ring reversal (TRR). Therefore, advanced cylinder liner and piston ring materials are needed that can survive under these extreme conditions. To address this need, researchers at the NASA Lewis Research Center have designed a tribological test method to help evaluate candidate piston ring and cylinder liner materials for advanced diesel engines.

  4. Efficiency of a new internal combustion engine concept with variable piston motion

    Directory of Open Access Journals (Sweden)

    Dorić Jovan Ž.

    2014-01-01

    Full Text Available This paper presents simulation of working process in a new IC engine concept. The main feature of this new IC engine concept is the realization of variable movement of the piston. With this unconventional piston movement it is easy to provide variable compression ratio, variable displacement and combustion during constant volume. These advantages over standard piston mechanism are achieved through synthesis of the two pairs of non-circular gears. Presented mechanism is designed to obtain a specific motion law which provides better fuel consumption of IC engines. For this paper Ricardo/WAVE software was used, which provides a fully integrated treatment of time-dependent fluid dynamics and thermodynamics by means of onedimensional formulation. The results obtained herein include the efficiency characteristic of this new heat engine concept. The results show that combustion during constant volume, variable compression ratio and variable displacement have significant impact on improvement of fuel consumption.

  5. A new sliding joint to accommodate recoil of a free-piston-driven expansion tube facility

    Science.gov (United States)

    Gildfind, D. E.; Morgan, R. G.

    2016-11-01

    This paper describes a new device to decouple free-piston driver recoil and its associated mechanical vibration from the acceleration tube and test section of The University of Queensland's X3 expansion tube. A sliding joint is introduced to the acceleration tube which axially decouples the facility at this station. When the facility is fired, the upstream section of the facility, which includes the free-piston driver, can recoil upstream freely. The downstream acceleration tube remains stationary. This arrangement provides two important benefits. Firstly, it eliminates nozzle movement relative to the test section before and during the experiment. This has benefits in terms of experimental setup and alignment. Secondly, it prevents transmission of mechanical disturbances from the free-piston driver to the acceleration tube, thereby eliminating mechanically-induced transducer noise in the sensitive pressure transducers installed in this low-pressure tube. This paper details the new design, and presents experimental confirmation of its performance.

  6. A Piston-Rotaxane with Two Potential Stripes: Force Transitions and Yield Stresses

    Directory of Open Access Journals (Sweden)

    Edith M. Sevick

    2013-10-01

    Full Text Available We examine a rod piston-rotaxane system, where the positions of several mobile rings on the axle are controlled by an external force acting on one of the rings. This allows us to access the translational entropy of the rings. For a simple rotaxane molecule with an axle that has uniform ring-axle interactions along its length, the molecule behaves like a miniature piston filled with a one-dimensional ideal gas. We then examine the effect of two stripes on the axle, having different ring-axle interactions with the mobile rings, so that one section is of high energy (repulsive for the rings and another section is of lower energy (or attractive. This kind of rotaxane can exhibit rapid changes in displacement or force, and in particular, this molecule can exhibit a yield stress in which the piston suddenly compresses under a small increase in the applied force.

  7. Piston surface heat transfer during combustion in large marine diesel engines

    DEFF Research Database (Denmark)

    Jensen, Michael Vincent; Walther, Jens Honore

    2010-01-01

    limited. The numerical investigation focused on the simulation of a hot turbulent gas jet impinging on a wall under very high pressure, thus approximating the process of the actual impingement of hot combustion gasses on the piston surface during combustion. The surface heat flux at the wall......In the design process of large marine diesel engines information on the maximum heat load on the piston surface experienced during the engine cycle is an important parameter. The peak heat load occurs during combustion when hot combustion products impinge on the piston surface. Although the maximum...... instrumentation and high engine running costs compared to automotive engines. Therefore the investigation in this work was carried out numerically with the use of a computational fluid dynamics (CFD) code. At the same time, numerical work on detailed in-cylinder wall heat transfer in engines has been quite...

  8. Final design of a free-piston hydraulic advanced Stirling conversion system

    Science.gov (United States)

    Wallace, D. A.; Noble, J. E.; Emigh, S. G.; Ross, B. A.; Lehmann, G. A.

    1991-01-01

    Under the US Department of Energy's (DOEs) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for solar distributed receiver systems. The final design is described of an engineering prototype advanced Stirling conversion system (ASCS) with a free-piston hydraulic engine output capable of delivering about 25 kW of electric power to a utility grid. The free-piston Stirling engine has the potential for a highly reliable engine with long life because it has only a few moving parts, has noncontacting bearings, and can be hermetically sealed. The ASCS is designed to deliver maximum power per year over a range of solar input with a design life of 30 years (60,000 h). The system includes a liquid Nak pool boiler heat transport system and a free-piston Stirling engine with high-pressure hydraulic output, coupled with a bent axis variable displacement hydraulic motor and a rotary induction generator.

  9. Tribological Performance of Different Geometries of Piston Rings in Marine Diesel Engines

    DEFF Research Database (Denmark)

    Imran, Tajammal; Klit, Peder; Felter, Christian

    are manufactured from real piston ring material. The mating slider is manufactured from cylinder liner material. Experiments are conducted at five different speeds and a fixed dead-weight loading. The friction force and the bulk temperature of the test specimen are recorded as a function of crank angle position...... centres. A theoretical model is developed to predict the performance of piston rings throughout the entire cycle. This model is based on Reynolds equation coupled with a pressure-density relation for modelling of cavitation. It is assumed that the infinite width bearing assumption is valid, which...... effectively reduces the spatial dimension by 1. The viscosity of the oil is based on a tabulated viscosity-temperature relation and the measured temperature of the piston ring segments. Thus, it is not necessary to include the energy equation in the theoretical model. Asperity interaction is included...

  10. Analysis of a system modelling the motion of a piston in a viscous gas

    Science.gov (United States)

    Maity, Debayan; Takahashi, Takéo; Tucsnak, Marius

    2016-09-01

    We study a free boundary problem modelling the motion of a piston in a viscous gas. The gas-piston system fills a cylinder with fixed extremities, which possibly allow gas from the exterior to penetrate inside the cylinder. The gas is modeled by the 1D compressible Navier-Stokes system and the piston motion is described by the second Newton's law. We prove the existence and uniqueness of global in time strong solutions. The main novelty brought in by our results is that they include the case of nonhomogeneous boundary conditions which, as far as we know, have not been studied in this context. Moreover, even for homogeneous boundary conditions, our results require less regularity of the initial data than those obtained in previous works.

  11. Interring Gas Dynamic Analysis of Piston in a Diesel Engine considering the Thermal Effect

    Directory of Open Access Journals (Sweden)

    Wanyou Li

    2015-01-01

    Full Text Available Understanding the interaction between ring dynamics and gas transport in ring pack systems is crucial and needs to be imperatively studied. The present work features detailed interring gas dynamics of piston ring pack behavior in internal combustion engines. The model is developed for a ring pack with four rings. The dynamics of ring pack are simulated. Due to the fact that small changes in geometry of the grooves and lands would have a significant impact on the interring gas dynamics, the thermal deformation of piston has been considered during the ring pack motion analysis in this study. In order to get the temperature distribution of piston head more quickly and accurately, an efficient method utilizing the concept of inverse heat conduction is presented. Moreover, a sensitive analysis based on the analysis of partial regression coefficients is presented to investigate the effect of groove parameters on blowby.

  12. Flat mirror tilt and piston measurement based on structured light reflection.

    Science.gov (United States)

    Li, Lulu; Zhao, Wenchuan; Wu, Fan; Liu, Yong

    2014-11-03

    This paper presents a simple method for flat mirror tilt and piston measurement. The method only needs an LCD screen and a CCD camera. LCD screen displays structured light pattern, and camera takes the pattern's virtual image (VI) reflected by the mirror. Pose relationship between camera coordinate system and VI coordinate system can be calculated by camera calibration. Through coordinate transition, the relative tilt and piston of the mirror can be obtained. This method is simple in both structure and principle, and experiments prove that it can measure the flat mirror tilt for about 1″ accuracy and piston for less than 1um accuracy. And under the guidance of our method, a mirror can be adjusted to a specified pose.

  13. Tribological Performance of Different Geometries of Piston Rings in Marine Diesel Engines

    DEFF Research Database (Denmark)

    Imran, Tajammal; Klit, Peder; Felter, Christian

    effectively reduces the spatial dimension by 1. The viscosity of the oil is based on a tabulated viscosity-temperature relation and the measured temperature of the piston ring segments. Thus, it is not necessary to include the energy equation in the theoretical model. Asperity interaction is included...... centres. A theoretical model is developed to predict the performance of piston rings throughout the entire cycle. This model is based on Reynolds equation coupled with a pressure-density relation for modelling of cavitation. It is assumed that the infinite width bearing assumption is valid, which...... in the model. Conservation of oil is ensured by considering the amount of oil outside the piston ring/liner interface. In order to validate the theoretical model a reciprocating lab scale test apparatus has been developed. Straight test specimens with radii of curvature of 80 mm, 160 mm, and 240 mm...

  14. A pinning puzzle: two similar, non-superconducting chemical deposits in YBCO-one pins, the other does not

    Energy Technology Data Exchange (ETDEWEB)

    Sawh, Ravi-Persad; Weinstein, Roy; Gandini, Alberto; Skorpenske, Harley; Parks, Drew, E-mail: Weinstein@uh.ed [Beam Particle Dynamics Laboratories, University of Houston, Houston, TX 77204-5005 (United States); Department of Physics, University of Houston, Houston, TX 77204-5005 (United States); Texas Center for Superconductivity at UH, University of Houston, Houston, TX 77204-5002 (United States)

    2009-09-15

    The pinning effects of two kinds of U-rich deposits in YBCO (YBa{sub 2}Cu{sub 3}O{sub 7-{delta}}) are compared. One is a five-element compound, (U{sub 0.6}Pt{sub 0.4})YBa{sub 2}O{sub 6}, which is a paramagnetic double perovskite which forms as profuse stable nanosize deposits, and pins very well. The other is a four-element compound, (U{sub 0.4}Y{sub 0.6})BaO{sub 3}, which is a ferromagnetic single perovskite which forms as profuse stable nanosize deposits and pins very weakly or not at all. The pinning comparison is done with nearly equal deposit sizes and number of deposits per unit volume for the two compounds. Evidence for the pinning capability, chemical makeup, x-ray diffraction signature, and magnetic properties of the two compounds is reported.

  15. The circadian variation of premature atrial contractions

    DEFF Research Database (Denmark)

    Larsen, Bjørn Strøier; Kumarathurai, Preman; Nielsen, Olav W

    2016-01-01

    AIMS: The aim of the study was to assess a possible circadian variation of premature atrial contractions (PACs) in a community-based population and to determine if the daily variation could be used to assess a more vulnerable period of PACs in predicting later incidence of atrial fibrillation (AF...... variation in heart rate. After adjusting for relevant risk factors, the risk of AF was equal in all time intervals throughout the day. CONCLUSION: Premature atrial contractions showed a circadian variation in subjects with frequent PACs. No specific time interval of the day was more predictive of AF than...

  16. Design of an interferometric system for piston measurements in segmented primary mirrors

    Science.gov (United States)

    Arasa, Josep; Laguarta, Ferran; Pizarro, Carlos; Tomas, Nuria; Pinto, Agusti

    2000-10-01

    Recently, telescopes with segmented primary mirrors are becoming increasingly popular due to their ability of achieving large apertures without the inconveniences caused by the fabrication and handling of monolithic surfaces with 8m (or over) in diameter. The difference in position of each pair of adjacent segments along the local normal of their interface (called piston hereafter), however, needs to be precisely measured in order to provide a diffraction- limited image. If a system yielding the nanometric accuracy required in piston measurements worked in daylight hours, the resultant saving in observation time would be an important advance on a majority of the state-of-the-art piston measurement systems. An interferometric piston measurement instrument accomplishing such objectives has been designed starting from the usual Michelson configuration at the CD6 (Terrassa, Spain), and its final test has been carried out in the test workbench of the Instituto de Astrofisica de Canarias (IAC, Canary Islands, Spain). Its optical layout relies on projecting the reference arm of the interferometer onto one of the segments of the pair considered, along the direction of the local normal to the surface while the measurement arm is projected onto the interface which divides the pair of segments considered. The field of view and its illumination are calculated to be equivalent in both segments. The lateral shift of the fringes in both interferograms determines the piston error present. A combination of monochromatic and white light is used, in order to remove the (lambda) /2 phase ambiguities present in piston measurements without losing the required resolution in the measurement. In this paper, the optical design of this interferometric piston measurement instrument will be presented. The particular configuration used in the interferometer, the implementation of an imaging system allowing to see both the interface of the segments and the interference fringes, the effect of the

  17. A feasibility assessment of magnetic bearings for free-piston Stirling space power converters

    Energy Technology Data Exchange (ETDEWEB)

    Curwen, P.W.; Rao, D.K.; Wilson, D.S. [Mechanical Technology Inc., Latham, NY (United States)

    1992-06-01

    This report describes work performed by Mechanical Technology Incorporated (MTI) under NASA Contract NAS3-26061, {open_quotes}A Feasibility Assessment of Magnetic Bearings for Free-Piston Stirling Space Engines.{close_quotes} The work was performed over the period from July 1990 through August 1991. The objective of the effort was to assess the feasibility and efficacy of applying magnetic bearings to free-piston Stirling-cycle power conversion machinery of the type currently being evaluated for possible use in future long-term space missions.

  18. HPGR simulation from piston-die tests with an itabirite ore

    Directory of Open Access Journals (Sweden)

    Hakan Benzer

    Full Text Available Abstract The Minas Rio project, owned by Anglo American, has HPGRs in open circuit operated as a tertiary/quaternary crushing stage. Currently this type of equipment is designed from HPGR tests on laboratory scale and pilot scale tests. This paper presents a methodology for simulating HPGR from piston-die tests on laboratory scale and a mathematical model developed in Hacettepe University in Turkey. The parameters determined from the results of the piston-die tests were used to validate the HPGR testing on pilot scale. Finally, the model was used to predict the particle size distribution in the HPGR product on industrial scale.

  19. A transient tribodynamic approach for the calculation of internal combustion engine piston slap noise

    Science.gov (United States)

    Dolatabadi, N.; Littlefair, B.; De la Cruz, M.; Theodossiades, S.; Rothberg, S. J.; Rahnejat, H.

    2015-09-01

    An analytical/numerical methodology is presented to calculate the radiated noise due to internal combustion engine piston impacts on the cylinder liner through a film of lubricant. Both quasi-static and transient dynamic analyses coupled with impact elasto-hydrodynamics are reported. The local impact impedance is calculated, as well as the transferred energy onto the cylinder liner. The simulations are verified against experimental results for different engine operating conditions and for noise levels calculated in the vicinity of the engine block. Continuous wavelet signal processing is performed to identify the occurrence of piston slap noise events and their spectral content, showing good conformance between the predictions and experimentally acquired signals.

  20. Separation of combustion noise and piston-slap in diesel engine—Part II: Separation of combustion noise and piston-slap using blind source separation methods

    Science.gov (United States)

    Servière, C.; Lacoume, J.-L.; El Badaoui, M.

    2005-11-01

    This paper is devoted to blind separation of combustion noise and piston-slap in diesel engines. The two phenomena are recovered only from signals issued from accelerometers placed on one of the cylinders. A blind source separation (BSS) method is developed, based on a convolutive model of non-stationary mixtures. We introduce a new method based on the joint diagonalisation of the time varying spectral matrices of the observation records and a new technique to handle the problem of permutation ambiguity in the frequency domain. This method is then applied to real data and the estimated sources are validated by several physical arguments. So, the contribution of the piston-slap and the combustion noise can be recovered for all the sensors. The energy of the two phenomena can then be given with regards to the position of the accelerometers.

  1. Effects of piston elastic deformation on piston secondary motion and skirt lubrication characteristics%活塞弹性变形对活塞二阶运动及裙部润滑特性的影响

    Institute of Scientific and Technical Information of China (English)

    阮登芳; 许金霞; 高鑫

    2015-01-01

    为揭示活塞弹性变形对活塞二阶运动及裙部润滑特性的影响规律,基于有限元法建立活塞和缸套的结构动力学模型,耦合活塞二阶运动方程及裙部流体动力润滑模型,分析活塞弹性对活塞二阶运动和裙部润滑特性的影响。结果表明:不同曲轴转角下活塞主、次推力面的变形不同,做功行程中变形明显,而且最大变形量出现的区域随曲轴转角的变化而改变;考虑活塞弹性变形后,活塞二阶运动一般比不考虑活塞弹性变形有所增加,在压缩和做功行程中增加明显;活塞裙部的最小油膜厚度增加,而总摩擦功耗降低,做功行程中两者变化明显;油膜压力场峰值出现位置及油膜压力分布规律改变,油膜压力场峰值减小。该研究为活塞裙部型线设计及配缸间隙选择提供参考。%Piston skirt-liner is one of the primary friction pairs influencing the friction power loss of an internal combustion engine, so it is feasible to improve the fuel economy of engines by studying the lubrication characteristics of the piston skirt-liner to reduce the friction power loss. The piston skirt lubrication is related to the piston secondary motion and the elastic deformation of the piston and liner, and there exists a strong coupled relationship between them. Therefore, it may be more reasonable to couple the elastic deformation equation of piston and liner than ignore the deformation of piston and liner, when the piston skirt lubrication and the piston secondary motion equations are solved. In order to reveal the effects of the piston elastic deformation on the piston secondary motion and skirt lubrication characteristics, the structural dynamics equations of the piston and liner were established based on the finite element modal reduction method, the piston secondary motion equation, the average Reynolds equation and the possible solid-to-solid contact equation in mixed lubrication

  2. Dissecting Pin1 and phospho-pRb regulation.

    Science.gov (United States)

    Rizzolio, Flavio; Caligiuri, Isabella; Lucchetti, Chiara; Fratamico, Robert; Tomei, Valentina; Gallo, Gaia; Agelan, Alexis; Ferrari, Giovanni; Toffoli, Giuseppe; Klein-Szanto, Andres J; Giordano, Antonio

    2013-01-01

    The activity of the Retinoblastoma protein, the master regulator of the cell cycle, is finely regulated by phosphorylation. CDKs and cyclins are major players in phosphorylation and it has been recently discovered that the prolyl isomerase Pin1 is an essential protein that orchestrates this process. In this article, we report new findings regarding the role of Pin1 in the pRb pathway. Our data suggest that PI3K, CDKs, and the Pin1 axis have a critical role in sustaining the complete phosphorylation of pRb. Furthermore, we analyze the correlation between Pin1 and pRb phosphorylation in vivo. We show that, in human malignant glioma tissue microarrays (TMA) and in Pin1 knockout (KO) mice, there is a positive correlation between Pin1 and pRb phosphorylation. Prospectively, our findings suggest that the synergism between CDKs, Pin1, and PI3K inhibitors hold great promise for targeted pharmacological treatment of cancer patients, with the possibility of reaching high effectiveness at tolerated doses.

  3. A systematic review of the effect of piston diameter in stapes surgery for otosclerosis on hearing results

    NARCIS (Netherlands)

    Wegner, Inge; Verhagen, Jessica J; Stegeman, Inge; Vincent, Robert; Grolman, Wilko

    2015-01-01

    OBJECTIVE: To evaluate the effect of piston diameter in primary stapedotomy for otosclerosis patients measured by hearing outcome. DATA SOURCES: PubMed, Embase, and the Cochrane Library. REVIEW METHODS: A systematic search was conducted. Studies reporting original data on the effect of piston diamet

  4. A systematic review of the effect of piston diameter in stapes surgery for otosclerosis on hearing results

    NARCIS (Netherlands)

    Wegner, Inge; Verhagen, Jessica J; Stegeman, Inge; Vincent, Robert; Grolman, Wilko

    2015-01-01

    OBJECTIVE: To evaluate the effect of piston diameter in primary stapedotomy for otosclerosis patients measured by hearing outcome. DATA SOURCES: PubMed, Embase, and the Cochrane Library. REVIEW METHODS: A systematic search was conducted. Studies reporting original data on the effect of piston

  5. Alar Pinning in Rigid External Distraction for Midfacial Hypoplasia.

    Science.gov (United States)

    Yu, Jenny L; Woo, Albert S

    2017-09-01

    Distraction osteogenesis with a rigid external distractor is a widely accepted treatment for midfacial hypoplasia. In this study, the authors introduce the utilization of alar pinning with the external halo distractor for maxillary advancement, in place of an oral splint. A retrospective chart review was conducted of 7 patients who successfully underwent distraction osteogenesis using the alar pinning technique. Midfacial hypoplasia was secondary to Crouzon syndrome (n = 4), Apert syndrome (n = 1), Pfeiffer syndrome (n = 1), or bacterial meningitis (n = 1). Three patients were managed with monobloc osteotomies, 2 with Le Fort III osteotomies, 1 with Le Fort III osteotomy and frontoorbital advancement, and 1 with Le Fort I osteotomy alone. Patient charts were analyzed for postoperative course and complications relating to the alar pins. Two patients had minor complications specifically related to the alar pins. One patient had concern for a mild skin infection at a pin site that resolved with oral antibiotics. The other patient had loosening of an alar pin, which did not require operative management. Retrospective chart review indicated that all patients were pleased with their results from the distraction, and no patients opted for further advancement. Utilization of alar pin sites for external distraction is a feasible and reasonable option for treatment of midfacial hypoplasia involving a Le Fort osteotomy or monobloc procedure. Fixation sites within the alar crease minimize the visibility of pin site scars and eliminate the need for a custom-made oral splint, which prevents usage of the upper dentition and frequently requires consulting a dentist or orthodontist for fabrication. Alar pinning with an external halo distraction system for management of midfacial hypoplasia has minimal complications and is an alternative to using a custom-made oral splint.

  6. AMH as Predictor of Premature Ovarian Insufficiency

    DEFF Research Database (Denmark)

    Lunding, Stine Aa; Aksglæde, Lise; Anderson, Richard A

    2015-01-01

    CONTEXT: The majority of Turner syndrome (TS) patients suffer from accelerated loss of primordial follicles. Low circulating levels of anti-Müllerian hormone (AMH) may predict the lack of spontaneous puberty in prepubertal girls and imminent premature ovarian insufficiency (POI) in TS women...

  7. Premature ovarian failure and ovarian autoimmunity

    NARCIS (Netherlands)

    J.A. Schoemaker (Joop); H.A. Drexhage (Hemmo); A. Hoek (Annemieke)

    1997-01-01

    textabstractPremature ovarian failure (POF) is defined as a syndrome characterized by menopause before the age of 40 yr. The patients suffer from anovulation and hypoestrogenism. Approximately 1% of women will experience menopause before the age of 40 yr. POF is a

  8. [Nontraumatic chylopericardium and chylothorax in premature neonates].

    Science.gov (United States)

    Avrel'kina, E A; Ignat'eva, E N; Fediarova, M A; Pliukhin, S V

    2014-01-01

    Deaths of extremely premature babies undiagnosed as having spontaneous chylopericardium (CP) and chylothorax (CT) are analyzed. The specific features of these death cases are the polyetiology of CP/CT and the similarity of their pathogenesis in the absence of specific clinical symptomatology.

  9. Catheter ablation of parahisian premature ventricular complex.

    Science.gov (United States)

    Kim, Jun; Kim, Jeong Su; Park, Yong Hyun; Kim, June Hong; Chun, Kook Jin

    2011-12-01

    Catheter ablation is performed in selected patients with a symptomatic premature ventricular complex (PVC) or PVC-induced cardiomyopathy. Ablation of PVC from the His region has a high risk of inducing a complete atrioventricular block. Here we report successful catheter ablation of a parahisian PVC in a 63-year-old man.

  10. Liver Abscess: Increasing Occurrence in Premature Newborns

    Directory of Open Access Journals (Sweden)

    OKTAV BOSNALI

    2013-03-01

    Full Text Available Neonatal liver abscess is a very rare condition associated with high morbidity and mortality rates. There seems to be an increasing trend of this rare condition amongst the newborns admitted to neonatal intensive care units. We report a case of liver abscess in a premature newborn and briefly review the literature and discuss its management.

  11. Liver Abscess: Increasing Occurrence in Premature Newborns

    Science.gov (United States)

    Bosnalı, Oktav; Moralıoğlu, Serdar; Pektaş, Osman

    2013-01-01

    Neonatal liver abscess is a very rare condition associated with high morbidity and mortality rates. There seems to be an increasing trend of this rare condition amongst the newborns admitted to neonatal intensive care units. We report a case of liver abscess in a premature newborn and briefly review the literature and discuss its management. PMID:26023443

  12. Liver Abscess: Increasing Occurrence in Premature Newborns

    Directory of Open Access Journals (Sweden)

    Oktav Bosnalı

    2013-04-01

    Full Text Available Neonatal liver abscess is a very rare condition associated with high morbidity and mortality rates. There seems to be an increasing trend of this rare condition amongst the newborns admitted to neonatal intensive care units. We report a case of liver abscess in a premature newborn and briefly review the literature and discuss its management.

  13. Premature mortality in Japan due to ozone

    Science.gov (United States)

    Nawahda, Amin; Yamashita, Ken; Ohara, Toshimasa; Kurokawa, Junichi; Ohizumi, Tsuyoshi; Chen, Fang; Akimoto, Hajime

    2013-12-01

    In Japan, all 47 prefectures conduct routine air quality monitoring at 1145 stations throughout the country to assess environmental effects. This study aims to provide a better understanding of possible estimations of premature mortality in Japan caused by exposure to monitored and modeled concentrations of tropospheric ozone during the period from January to December, 2005. The spatial distribution and temporal variation of ozone concentrations were modeled using the Models-3 Community Multiscale Air Quality modeling system coupled with the Regional Emission Inventory in Asia (CMAQ/REAS). Premature mortality caused by exposure to ozone was calculated assuming a relative risk (RR) value of 1.003 [95% Confidence Interval (CI): 1.001-1.004] for concentrations above 35 ppb according to the SOMO35 index (annual Sum of daily maximum 8-h Ozone Means Over 35 ppb) recommended by WHO (2008). Based on CMAQ/REAS simulations, the estimated all-cause premature mortality in 2005 is about 13,000 (95% CI: 4320-17,300) cases. This value is 2.5 times greater than the estimated premature mortality based on monitored ozone concentrations, which is 5220 (95% CI: 1740-6960) cases.

  14. Optimal oxygen saturation in premature infants

    Directory of Open Access Journals (Sweden)

    Meayoung Chang

    2011-09-01

    Full Text Available There is a delicate balance between too little and too much supplemental oxygen exposure in premature infants. Since underuse and overuse of supplemental oxygen can harm premature infants, oxygen saturation levels must be monitored and kept at less than 95% to prevent reactive oxygen species-related diseases, such as retinopathy of prematurity and bronchopulmonary dysplasia. At the same time, desaturation below 80 to 85% must be avoided to prevent adverse consequences, such as cerebral palsy. It is still unclear what range of oxygen saturation is appropriate for premature infants; however, until the results of further studies are available, a reasonable target for pulse oxygen saturation (SpO2 is 90 to 93% with an intermittent review of the correlation between SpO2 and the partial pressure of arterial oxygen tension (PaO2. Because optimal oxygenation depends on individuals at the bedside making ongoing adjustments, each unit must define an optimal target range and set alarm limits according to their own equipment or conditions. All staff must be aware of these values and adjust the concentration of supplemental oxygen frequently.

  15. New Information About Premature Births (For Consumers)

    Centers for Disease Control (CDC) Podcasts

    2006-10-06

    A new study finds that prematurity is the most frequent cause of infant death in the United States. Learn more.  Created: 10/6/2006 by CDC Division of Reproductive Health.   Date Released: 10/6/2006.

  16. Human cytomegalovirus infections in premature infants by ...

    African Journals Online (AJOL)

    Owner

    clinical importance of CMV infection in premature infants by breast-feeding is still unclear. This mini- ... Transmission of CMV by natural routes relates ... infection from the fresh breast milk containing the virus. ... As a result of transmission during the course of delivery ... hepatitis was speculated to be caused by primary.

  17. Premature ovarian failure and ovarian autoimmunity

    NARCIS (Netherlands)

    J.A. Schoemaker (Joop); H.A. Drexhage (Hemmo); A. Hoek (Annemieke)

    1997-01-01

    textabstractPremature ovarian failure (POF) is defined as a syndrome characterized by menopause before the age of 40 yr. The patients suffer from anovulation and hypoestrogenism. Approximately 1% of women will experience menopause before the age of 40 yr. POF is a heter

  18. Premature ovarian failure and ovarian autoimmunity

    NARCIS (Netherlands)

    J.A. Schoemaker (Joop); H.A. Drexhage (Hemmo); A. Hoek (Annemieke)

    1997-01-01

    textabstractPremature ovarian failure (POF) is defined as a syndrome characterized by menopause before the age of 40 yr. The patients suffer from anovulation and hypoestrogenism. Approximately 1% of women will experience menopause before the age of 40 yr. POF is a heter

  19. Laterality in Prematurely-Born Children.

    Science.gov (United States)

    Segalwitz, Sidney J.; Chapman, Jacqueline S.

    The study examined the relationship between perinatal stress and decreased right handedness and decreased left cerebral dominance for speech with 215 children born prematurely, followed from birth, and tested at age 5. Results indicated that neither hand preference nor hand performance correlated with degree of perinatal stress and that eye…

  20. Influence of the skin effect in a rail gun on the parameters of the moving plasma piston

    Science.gov (United States)

    Iuferev, V. S.; Gnedina, M. L.; Gnedin, N. Iu.

    1992-01-01

    The problem of the motion of the plasma piston in a rail gun launcher is solved with allowance for the skin effect using plane geometry and the quasi-stationary approximation. The temperature along the piston is assumed to be constant, and the piston is assumed to move as a whole at a velocity equal to that of the accelerated projectile. It is shown that current displacement toward the rear of the piston due to the skin effect leads to an increase in the gasdynamic pressure in the plasma, with a resulting reduction in the extension of the plasmoid. The latter effect is particularly pronounced when the mass of the plasma exceeds that of the piston.

  1. "Safety pin"--a question to its safety!

    Science.gov (United States)

    Thapa Chettri, S; Bhattarai, M; Karki, S; Regmi, S; Mathur, N N

    2010-03-01

    Foreign body ingestion is not an uncommon problem in children. They can ingest various foreign objects and one of such objects is a safety pin. The ingestion of such foreign body is not widely reported in the literature. This case highlights the risk of accidental ingestion of safety pin used on child's clothing to protect him from cold that can result in lethal complications. In a poor developing country like Nepal, this case serves to address all mothers alerting them of their ignorance while using safety pin in infants. In addition, physicians are reminded to obtain a detailed inquiry of suspected foreign body ingestion in every child with the history of dysphagia.

  2. Noises of p-i-n UV photodetectors

    Science.gov (United States)

    Gasparyan, Ferdinand V.; Korman, Can E.; Melkonyan, Slavik V.

    2007-06-01

    Investigations of the static characteristics, responsivity, internal noises, and detectivity of the forward biased p-i-n photodetectors made on wide bandgap compensated semiconductors operating in double injection regime are presented. Noise related calculations are performed by utilizing "Impedance Field Method". Numerical simulations are made assessing 4H-SiC and GaN biased p-i-n photodiodes noise related characteristics. It is shown that forward biased p-i-n photodiodes have low level of thermal and generation-recombination noises and high values of sensitivity and detectivity at the room temperature.

  3. RESEARCH ON REDUCING PREMATURITY RUPTURE OF MEMBRANE

    Directory of Open Access Journals (Sweden)

    Maria URSACHI (BOLOTA

    2016-12-01

    Full Text Available The membranes surrounding the amniotic cavity are composed from amnion and chorion, tightly adherent layers which are composed of several cell types, including epithelial cells, trophoblasts cells and mesenchyme cells, embedded in a collagenous matrix. They retain amniotic fluid, secret substances into the amniotic fluid, as well as to the uterus and protect the fetus against upward infections from urogenital tract. Normally, the membranes it breaks during labor. Premature rupture of the amniotic sac (PRAS is defined as rupture of membranes before the onset of labor. Premature rupture of the fetal membrane, which occurs before 37 weeks of gestation, usually, refers to preterm premature rupture of membranes. Despite advances in the care period, premature rupture of membranes and premature rupture of membranes preterm continue to be regarded as serious obstetric complications. On the term 8% - 10% of pregnant women have premature rupture of membranes; these women are at increased risk of intrauterine infections, where the interval between membrane rupture and expulsion is rolled-over. Premature rupture of membranes preterm occurs in approximately 1% of all pregnancies and is associated with 30% -40% of preterm births. Thus, it is important to identify the cause of pre-term birth (after less than 37 completed weeks of "gestation" and its complications, including respiratory distress syndrome, neonatal infection and intraventricular hemorrhage. Objectives: the development of the protocol of the clinical trial on patients with impending preterm birth, study clinical and statistical on the socio-demographic characteristics of patients with imminent preterm birth; clinical condition of patients and selection of cases that could benefit from the application of interventional therapy; preclinical investigation (biological and imaging of patients with imminent preterm birth; the modality therapy; clinical investigation of the effectiveness of short

  4. Acute renal failure in premature neonates

    Directory of Open Access Journals (Sweden)

    Doronjski Aleksandra

    2009-01-01

    Full Text Available Background/Aim. Hemodynamic stress is the leading cause of acute renal failure (ARF in premature neonates. Incidence of ARF in this population is between 8 and 24%. The aim of this study was to determine the frequency of presence of ARF in premature neonates, as well as its impact on their survival. Methods. A retrospective study of 114 premature neonates [(gestational age, GA less than 37 gestation weeks (gw] admitted to the Intensive Care Unit (ICU at the Pediatric Clinic, Institute of Child and Youth Healthcare of Vojvodina in 2007 was conducted. Serum creatinine, urea and bilirubine were determined on the 3rd day of life in 65 newborns who met inclusion criteria. ARF was diagnosed in 16 newborns (n=16/65; 25%. Results. The premature neonates with ARF had significantly lower GA [<28 gw - 8/16 (50% vs. 5/49 (10%; p < 0.05], birth weight (BW (1 265 g vs. 1615 g; p < 0.05 and systolic blood pressure (43.37 mm Hg vs. 52.7 mmHg; p < 0.05 than ones without ARF. Non-olyguric ARF was diagnosed in 62% of newborns with ARF (n=10/16, while the rest had the olyguric type (n = 6/16; 38%. Twenty-five percent of premature neonates with ARF (n = 4/16 died in contrast to 10% of premature neonates without ARF (n = 5/49. ARF was treated conservatively in all but 3 cases when peritoneal dialysis was performed. Renal function has recovered completely in all of the survivors. In order to determine their predictivity in relation to ARF, following parameters were analyzed: GA, BW < 1 500 g, presence of concomitant sepsis and intracranial hemorrhage grade III/IV. BW < 1 500 g demonstrated the highest sensitivity (se 0.75, while GA < 28 gw, sepsis and intracranial hemorrhage grade III/IV showed high specificity (sp = 0.90, 0.89 0.88, respectively. Conclusion. Acute renal failure frequently occurs in population of premature neonates and requires meticulous fluid and electrolyte balance, especially in the case of low birth weight and extreme immaturity.

  5. Impact of rotavirus vaccine on premature infants.

    Science.gov (United States)

    Roué, Jean-Michel; Nowak, Emmanuel; Le Gal, Grégoire; Lemaitre, Thomas; Oger, Emmanuel; Poulhazan, Elise; Giroux, Jean-Dominique; Garenne, Armelle; Gagneur, Arnaud

    2014-10-01

    Infants born preterm are at a higher risk of complications and hospitalization in cases of rotavirus diarrhea than children born at term. We evaluated the impact of a rotavirus vaccination campaign (May 2007 to May 2010) on hospitalizations for rotavirus gastroenteritis in a population of children under 3 years old born prematurely (before 37 weeks of gestation) in the Brest University Hospital birth zone. Active surveillance from 2002 to 2006 and a prospective collection of hospitalizations for rotavirus diarrhea were initiated in the pediatric units of Brest University Hospital until May 2010. Numbers of hospitalizations for rotavirus diarrhea among the population of children born prematurely, before and after the start of the vaccination program, were compared using a Poisson regression model controlling for epidemic-to-epidemic variation. A total of 217 premature infants were vaccinated from 2007 to 2010. Vaccine coverage for a complete course of three doses was 41.9%. The vaccine safety in premature infants was similar to that in term infants. The vaccination program led to a division by a factor of 2.6 (95% confidence interval [CI], 1.3 to 5.2) in the number of hospitalizations for rotavirus diarrhea during the first two epidemic seasons following vaccine introduction and by a factor of 11 (95% CI, 3.5 to 34.8) during the third season. We observed significant effectiveness of the pentavalent rotavirus vaccine on the number of hospitalizations in a population of prematurely born infants younger than 3 years of age. A multicenter national study would provide better assessment of this impact. (This study [Impact of Systematic Infants Vaccination Against Rotavirus on Gastroenteritis Hospitalization: a Prospective Study in Brest District, France (IVANHOE)] has been registered at ClinicalTrials.gov under registration no. NCT00740935.).

  6. A Division in PIN-Mediated Auxin Patterning during Organ Initiation in Grasses

    Science.gov (United States)

    O'Connor, Devin L.; Runions, Adam; Sluis, Aaron; Bragg, Jennifer; Vogel, John P.

    2014-01-01

    The hormone auxin plays a crucial role in plant morphogenesis. In the shoot apical meristem, the PIN-FORMED1 (PIN1) efflux carrier concentrates auxin into local maxima in the epidermis, which position incipient leaf or floral primordia. From these maxima, PIN1 transports auxin into internal tissues along emergent paths that pattern leaf and stem vasculature. In Arabidopsis thaliana, these functions are attributed to a single PIN1 protein. Using phylogenetic and gene synteny analysis we identified an angiosperm PIN clade sister to PIN1, here termed Sister-of-PIN1 (SoPIN1), which is present in all sampled angiosperms except for Brassicaceae, including Arabidopsis. Additionally, we identified a conserved duplication of PIN1 in the grasses: PIN1a and PIN1b. In Brachypodium distachyon, SoPIN1 is highly expressed in the epidermis and is consistently polarized toward regions of high expression of the DR5 auxin-signaling reporter, which suggests that SoPIN1 functions in the localization of new primordia. In contrast, PIN1a and PIN1b are highly expressed in internal tissues, suggesting a role in vascular patterning. PIN1b is expressed in broad regions spanning the space between new primordia and previously formed vasculature, suggesting a role in connecting new organs to auxin sinks in the older tissues. Within these regions, PIN1a forms narrow canals that likely pattern future veins. Using a computer model, we reproduced the observed spatio-temporal expression and localization patterns of these proteins by assuming that SoPIN1 is polarized up the auxin gradient, and PIN1a and PIN1b are polarized to different degrees with the auxin flux. Our results suggest that examination and modeling of PIN dynamics in plants outside of Brassicaceae will offer insights into auxin-driven patterning obscured by the loss of the SoPIN1 clade in Brassicaceae. PMID:24499933

  7. Birthing and Parenting a Premature Infant in a Cultural Context

    Science.gov (United States)

    Brooks, Jada L.; Holdtich-Davis, Diane; Docherty, Sharron L.; Theodorou, Christina S.

    2015-01-01

    The purpose of this longitudinal qualitative descriptive study was to explore American Indian (AI) mothers’ perceptions of parenting their premature infants over their first year of life in the context of their culture, including the birth and hospitalization experience. A convenience sample of 17 AI mothers and their premature infants were recruited from either a neonatal intensive care unit (NICU) or pediatric clinic in the southeast. Semistructured interviews were conducted at two time points. Through content analytic methods, three broad categories were revealed: descriptions of having a premature infant in the NICU, descriptions of parenting a premature infant, and the influence of Lumbee culture on parenting a premature infant. Certain aspects of AI culture appear to be important in having a premature infant in the NICU and in parenting a premature infant. We recommend that healthcare providers deliver culturally appropriate care that fully supports AI mothers and their premature infants. PMID:25721716

  8. Birthing and Parenting a Premature Infant in a Cultural Context.

    Science.gov (United States)

    Brooks, Jada L; Holdtich-Davis, Diane; Docherty, Sharron L; Theodorou, Christina S

    2016-02-01

    The purpose of this longitudinal qualitative descriptive study was to explore American Indian mothers' perceptions of parenting their premature infants over their first year of life in the context of their culture, including the birth and hospitalization experience. A convenience sample of 17 American Indian mothers and their premature infants were recruited from either a neonatal intensive care unit (NICU) or pediatric clinic in the southeast. Semistructured interviews were conducted at two time points. Through content analytic methods, three broad categories were revealed: descriptions of having a premature infant in the NICU, descriptions of parenting a premature infant, and the influence of Lumbee culture on parenting a premature infant. Certain aspects of American Indian culture appear to be important in having a premature infant in the NICU and in parenting a premature infant. We recommend that health care providers deliver culturally appropriate care that fully supports American Indian mothers and their premature infants. © The Author(s) 2015.

  9. A PWR Thorium Pin Cell Burnup Benchmark

    Energy Technology Data Exchange (ETDEWEB)

    Weaver, Kevan Dean; Zhao, X.; Pilat, E. E; Hejzlar, P.

    2000-05-01

    As part of work to evaluate the potential benefits of using thorium in LWR fuel, a thorium fueled benchmark comparison was made in this study between state-of-the-art codes, MOCUP (MCNP4B + ORIGEN2), and CASMO-4 for burnup calculations. The MOCUP runs were done individually at MIT and INEEL, using the same model but with some differences in techniques and cross section libraries. Eigenvalue and isotope concentrations were compared on a PWR pin cell model up to high burnup. The eigenvalue comparison as a function of burnup is good: the maximum difference is within 2% and the average absolute difference less than 1%. The isotope concentration comparisons are better than a set of MOX fuel benchmarks and comparable to a set of uranium fuel benchmarks reported in the literature. The actinide and fission product data sources used in the MOCUP burnup calculations for a typical thorium fuel are documented. Reasons for code vs code differences are analyzed and discussed.

  10. Multi-pin chemiresistors for microchemical sensors

    Science.gov (United States)

    Ho, Clifford K.

    2007-02-20

    A multi-pin chemiresistor for use in microchemical sensors. A pair of free-standing, bare wires is supported by an electrically insulating support, and are oriented parallel to each other and spaced closely together. A free-standing film of a chemically sensitive polymer that swells when exposed to vapors of a volatile chemical is formed in-between the pair of closely-spaced wires by capillary action. Similar in construction to a thermocouple, this "chemicouple" is relatively inexpensive and easy to fabricate by dipping the pair of bare wires into a bath of well-mixed chemiresistor ink. Also, a chemiresistor "stick" is formed by dipping an electrically insulating rod with two or more linear or spiral-wrapped electrical traces into the bath of well-mixed chemiresistor ink, which deposits a uniform coating of the chemically sensitive polymer on the rod and the electrical traces. These "sticks" can be easily removed and replaced from a multi-chemiresistor plug.

  11. Thermal experiment of silicon PIN detector

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong-Fei; ZOU Ji-Qing; SHI Wei-Hong; ZOU Hong; HU Ran-Sheng; TIAN Da-Yu

    2008-01-01

    The experiment of this paper is the thermal test of the leakage current of silicon PIN detector.Raising temperature may cause the detector to increase leakage current,decrease depletion and increase noise.Three samples are used in the experiment.One (called △E) is the sample of 100 tan in thickness.The other two (called E1 and E2) are stacks of five detectors of 1000 μm in thickness.All of them are 12 mm in diameter.The experiment has been done for 21 hours and with power on continuously.The samples have undergone more than 60 ℃ for about one hour.They are not degenerated when back to the room temperature.The depletion rate is temperature and bias voltage related.With the circuit of the experiment and temperature at 35 ℃,△E is still depleted while E1 and E2 are 94.9% and 99.7% depleted respectively.The noises of the samples can be derived from the values at room temperature and the thermal dependence of the leakage currents.With the addition of the noise of the pre-amplifier,the noises of E1,E2 and AE at 24 ℃ are 16.4,16.3,and 10.5 keV (FWHM) respectively while at 35 ℃ are about 33.6,33.1,and 20.6 keV (FWHM) respectively.

  12. Superconducting vortex pinning with artificial magnetic nanostructures.

    Energy Technology Data Exchange (ETDEWEB)

    Velez, M.; Martin, J. I.; Villegas, J. E.; Hoffmann, A.; Gonzalez, E. M.; Vicent, J. L.; Schuller, I. K.; Univ. de Oviedo-CINN; Unite Mixte de Physique CNRS/Thales; Univ. Paris-Sud; Univ.Complutense de Madrid; Univ. California at San Diego

    2008-11-01

    This review is dedicated to summarizing the recent research on vortex dynamics and pinning effects in superconducting films with artificial magnetic structures. The fabrication of hybrid superconducting/magnetic systems is presented together with the wide variety of properties that arise from the interaction between the superconducting vortex lattice and the artificial magnetic nanostructures. Specifically, we review the role that the most important parameters in the vortex dynamics of films with regular array of dots play. In particular, we discuss the phenomena that appear when the symmetry of a regular dot array is distorted from regularity towards complete disorder including rectangular, asymmetric, and aperiodic arrays. The interesting phenomena that appear include vortex-lattice reconfigurations, anisotropic dynamics, channeling, and guided motion as well as ratchet effects. The different regimes are summarized in a phase diagram indicating the transitions that take place as the characteristic distances of the array are modified respect to the superconducting coherence length. Future directions are sketched out indicating the vast open area of research in this field.

  13. Ideal glass transitions by random pinning

    Science.gov (United States)

    Cammarota, Chiara; Biroli, Giulio

    2012-01-01

    We study the effect of freezing the positions of a fraction c of particles from an equilibrium configuration of a supercooled liquid at a temperature T. We show that within the random first-order transition theory pinning particles leads to an ideal glass transition for a critical fraction c = cK(T) even for moderate supercooling; e.g., close to the Mode-Coupling transition temperature. First we derive the phase diagram in the T - c plane by mean field approximations. Then, by applying a real-space renormalization group method, we obtain the critical properties for |c - cK(T)| → 0, in particular the divergence of length and time scales, which are dominated by two zero-temperature fixed points. We also show that for c = cK(T) the typical distance between frozen particles is related to the static point-to-set length scale of the unconstrained liquid. We discuss what are the main differences when particles are frozen in other geometries and not from an equilibrium configuration. Finally, we explain why the glass transition induced by freezing particles provides a new and very promising avenue of research to probe the glassy state and ascertain, or disprove, the validity of the theories of the glass transition. PMID:22623524

  14. Numerical Evaluation of Flow and Heat Transfer in Plate-Pin Fin Heat Sinks with Various Pin Cross-Sections

    OpenAIRE

    Zhou, Feng; Catton, Ivan

    2011-01-01

    A numerical investigation of the thermal and hydraulic performance of twenty different plate-pin fin heat sinks with various shapes of pin cross-section (square, circular, elliptic, NACA profile and dropform) and different ratios of pin widths to plate fin spacing (0.3, 0.4, 0.5 and 0.6) was performed. Finite Volume Method based CFD software, Ansys CFX, was used as the 3-D Reynolds-averaged Navier-Stokes Solver. A k-ω based Shear-Stress-Transport model was used to predict the turbulent flow a...

  15. Procedure of recovery of pin-by-pin fields of energy release in the core of VVER-type reactor for the BIPR-8 code

    Science.gov (United States)

    Gordienko, P. V.; Kotsarev, A. V.; Lizorkin, M. P.

    2014-12-01

    The procedure of recovery of pin-by-pin energy-release fields for the BIPR-8 code and the algorithm of the BIPR-8 code which is used in nodal computation of the reactor core and on which the recovery of pin-by-pin fields of energy release is based are briefly described. The description and results of the verification using the module of recovery of pin-by-pin energy-release fields and the TVS-M program are given.

  16. Integration of Gas Nitrocarburising and Oxidising in a Mass Production Line for Brake Pistons

    Institute of Scientific and Technical Information of China (English)

    Gero Walkowiak; Dieter M(u)ller; Uwe Zeibig

    2004-01-01

    The combination of wear- and corrosion resistance is a demand to a multitude of automotive parts. Several metallic coatings as hard/soft chromium or electroless nickel have been the conventional surface protection e.g. on parts as brake pistons and shock absorber or gas spring piston rods. The Corr-I-Dur(R) process - a special gasnitrocarburising and oxidising technology - has a huge potential not only in substituting those coatings but also in delivering surfaces with higher quality.The benefits of the replacement of soft chromium with Corr-I-Dur(R) and the implementation of the process in the customers production line with an annual capacity of 17 million brake pistons is described in this presentation. Starting with the demands on wear- and corrosion resistance the way of process development and the design of applicative equipment is shown. The result is a tailor-made surface solution with superior quality for deep drawn brake pistons. Two main disadvantagesoutgassing of the chromium layer and reduced corrosion resistance on the inner diameter - are eliminated by the replacement with Corr-I-Dur(R). The process-sure achievement of enhanced corrosion resistance, uniform layer thickness, negligible distortion as well as environmental and economical advantages make Corr-I-Dur(R) an excellence choice for this application.

  17. The Development of a Control System for a 5 Kilowatt Free Piston Stirling Engine Convertor

    Science.gov (United States)

    Kirby, Raymond L.; Vitale, Nick

    2008-01-01

    The new NASA Vision for Exploration, announced by President Bush in January 2004, proposes an ambitious program that plans to return astronauts to the moon by the 2018 time frame. A recent NASA study entitled "Affordable Fission Surface Power Study" recommended a 40 kWe, 900 K, NaK-cooled, Stirling convertors for 2020 launch. Use of two of the nominal 5 kW convertors allows the system to be dynamically balanced. A group of four dual-convertor combinations that would yield 40 kWe can be tested to validate the viability of Stirling technology for space fission surface power systems. The work described in this paper deals specifically with the control system for the 5 kW convertor described in the preceding paragraph. This control system is responsible for maintaining piston stroke to a setpoint in the presence of various disturbances including electrical load variations. Pulse starting of the Free Piston Stirling Engine (FPSE) convertor is also an inherent part of such a control system. Finally, the ability to throttle the engine to match the required output power is discussed in terms of setpoint control. Several novel ideas have been incorporated into the piston stroke control strategy that will engender a stable response to disturbances in the presence of midpoint drift while providing useful data regarding the position of both the power piston and displacer.

  18. Influence of piston position on the scavenging and swirling flow in two-stoke diesel engines

    DEFF Research Database (Denmark)

    Obeidat, Anas; Haider, Sajjad; Meyer, Knud Erik

    2011-01-01

    We study the eect of piston position on the in-cylinder swirling flow in a low speed large two-stroke marine diesel engine model. We are using Large Eddy Simulations in OpenFOAM, with three different models for the turbulent flow: a one equation model (OEM), a dynamic one equation model (DOEM...

  19. Stochastic stability assessment of a semi-free piston engine generator concept

    Science.gov (United States)

    Kigezi, T. N.; Gonzalez Anaya, J. A.; Dunne, J. F.

    2016-09-01

    Small engines, as power generators with low-noise and vibration characteristics, are needed in two niche application areas: as electric vehicle range extenders and as domestic micro Combined Heat and Power systems. A recent semi-free piston design known as the AMOCATIC generator fully meets this requirement. The engine potentially allows for high energy conversion efficiencies at resonance derived from having a mass and spring assembly. As with free-piston engines in general, stability and control of piston motion has been cited as the prime challenge limiting the technology's widespread application. Using physical principles, we derive in this paper two important results: an energy balance criterion and a related general stability criterion for a semi-free piston engine. Control is achieved by systematically designing a Proportional Integral (PI) controller using a control-oriented engine model for which a specific stability condition is stated. All results are presented in closed form throughout the paper. Simulation results under stochastic pressure conditions show that the proposed energy balance, stability criterion, and PI controller, operate as predicted to yield stable engine operation at fixed compression ratio.

  20. A 1987 overview of free-piston Stirling technology for space power application

    Science.gov (United States)

    Slaby, Jack G.; Alger, Donald L.

    1987-01-01

    An overview is presented of the NASA Lewis Research Center free-piston Stirling engine activities directed toward space-power application. NASA Lewis serves as the project office to manage the newly initiated NASA SP-100 Advanced Technology Program. One of the major elements of this five-year program is the development of advanced power conversion concepts of which the Stirling cycle is a viable growth candidate. Under this program the status of the 25 kWe opposed-piston Space Power Demonstrator Engine (SPDE) is presented. Included in the SPDE discussion are comparisons between predicted and experimental engine performance, enhanced performance resulting from regenerator modification, increased operating stroke brought about by isolating the gas bearing flow between the displacer and power piston, identifying excessive energy losses and recommending corrective action, and a better understanding of linear alternator design and operation. Technology work is also conducted on heat exchanger concepts, both design and fabrication. Design parameters and conceptual design features are also presented for a 25 kWe, single-cylinder free-piston Stirling space-power converter.

  1. The Atmospheric piston simulator as an integral part of the calibration unit of LINC - NIRVANA

    Science.gov (United States)

    Follert, R.; Herbst, T. M.; Bizenberger, P.; DeBonis, F.

    2010-07-01

    The atmospheric piston simulator is an integral part of the calibration unit of LINC-NIRVANA, the Fizeau interferometric imager for the Large Binocular Telescope. The calibration unit will be necessary to align and set up the different opto - mechanical subsystems of the instrument. It will assist in (1) the alignment of the optics via reference fibers; (2) establishing zero optical path difference using a balanced fiber splitter; (3) flat fielding of the detectors with an integrating sphere; (4) correction of the non-common path aberrations using a fiber-based phase diversity source; and (5) calibration of the adaptive optics with a rotating reference fiber plate. Substantial testing and verification of the fringe tracker under as realistic as possible conditions in the lab is desirable, since the performance of the fringe tracker will ultimately determine the high angular resolution imaging capability of LINC-NIRVANA as a whole. We are therefore also constructing an atmospheric piston simulator working in the J and H photometric bands. As with many of the other calibration unit sub-systems, our design concept is mainly fiber based. Opto - electronic phase modulators will be used to introduce the piston sequences. The control system of the piston modulators will allow for easy implementation of different vibration power spectra. This will enable us to test and demonstrate the capabilities of the fringe tracker under realistic conditions.

  2. Design and Fabrication of a 5-kWe Free-Piston Stirling Power Conversion System

    Science.gov (United States)

    Chapman, Peter A.; Walter, Thomas J.; Brandhorst, Henry W., Jr.

    2008-01-01

    Progress in the design and fabrication of a 5-kWe free-piston Stirling power conversion system is described. A scaled-down version of the successful 12.5-kWe Component Test Power Converter (CTPC) developed under NAS3-25463, this single cylinder prototype incorporates cost effective and readily available materials (steel versus beryllium) and components (a commercial linear alternator). The design consists of a displacer suspended on internally pumped gas bearings and a power piston/alternator supported on flexures. Non-contacting clearance seals are used between internal volumes. Heat to and from the prototype is supplied via pumped liquid loops passing through shell and tube heat exchangers. The control system incorporates several novel ideas such as a pulse start capability and a piston stroke set point control strategy that provides the ability to throttle the engine to match the required output power. It also ensures stable response to various disturbances such as electrical load variations while providing useful data regarding the position of both power piston and displacer. All design and analysis activities are complete and fabrication is underway. Prototype test is planned for summer 2008 at Foster-Miller to characterize the dynamics and steady-state operation of the prototype and determine maximum power output and system efficiency. Further tests will then be performed at Auburn University to determine start-up and shutdown characteristics and assess transient response to temperature and load variations.

  3. Lubrication of Piston Rings in Large 2–and 4–stroke Diesel Engines

    DEFF Research Database (Denmark)

    Felter, Christian Lotz

    is fulfilled in a quasi-static sense a concrete example is analyzed using the Reynolds equation. Next a free surface 2D code based on the compressible Navier–Stokes equations is developed. The main idea is to model also the oil film outside the piston ring. Through time integration the movement of the inlet...

  4. Investigation of friction characteristics in segmented piston ring liner assembly of IC engine

    Directory of Open Access Journals (Sweden)

    Tejaskumar Chaudhari

    2016-09-01

    Full Text Available The friction at the piston ring cylinder liner assembly (PRLA is a major contributor in the total friction losses in the I.C. engine. New materials, coatings and high-tech machining processes that previously were considered to be too expensive and therefore only used in complex applications are today becoming more affordable. A significant amount of the total power loss in a modern automotive engine is due to the Friction interaction between the top compression ring and the cylinder liner, especially at the TDC and BDC where boundary lubrication exists. The change in piston speed is accompanied with change the lubrication regime in the cylinder, which results change in friction between the ring and the liner during the entire stroke of the piston. Theoretical modelling of friction force from the various sources of friction will be compared to experimental results for analysing the tribological characteristics. The appropriate sample of piston ring and cylinder liner pair is developed for studying the different tribological parameters on Reciprocating Tribometer. The variable parameters are engine speed, oil viscosity, and load. The experimental results and observations are studied under different operating conditions in speed ranges from 300 rpm to 1500 rpm with constant load of 60 N. It can be seen that as speed increases, the friction force and friction coefficient also decreases.

  5. Avco Lycoming/NASA contract status. [on reduction of emissions from aircraft piston engines

    Science.gov (United States)

    Duke, L. C.

    1976-01-01

    The standards promulgated by the Environmental Protection Agency (EPA) for carbon monoxide (CO), unburned hydrocarbon (HC), and oxides-of-nitrogen (NOx) emissions were the basis in a study of ways to reduce emissions from aircraft piston engines. A variable valve timing system, ultrasonic fuel atomization, and ignition system changes were postulated.

  6. Diseño de un sujetador rápido para mecanizado de pistones

    OpenAIRE

    Di Giusto, Marco Agustín.

    2013-01-01

    Proyecto Integrador (II)--FCEFN-UNC, 2013 Trata el estudio de una solución de automatización de una célula de fabricación, con el objetivo de aumentar la productividad y la competitividad de Pistones Persan, fabricante de partes de motor ubicado en Córdoba

  7. Investigation into piston-slap-induced vibration for engine condition simulation and monitoring

    Science.gov (United States)

    Geng, Z.; Chen, J.

    2005-04-01

    Piston slap is a common impact phenomenon existing in the reciprocating engine. It is also a major cause of the complex transient vibration response related to the impact excitation inside the engine. In order to correlate the piston-slap impact with the slap-induced vibration and consequently find out an effective approach for the engine dynamic behaviour simulation and working condition monitoring, an in-depth investigation from theoretical modelling to experimental verification is made in this paper. Firstly, the piston-slap phenomenon inside the reciprocating engine is briefly discussed from the viewpoint of engine mechanics. Based upon this, a nonlinear model is developed to simulate the slap-induced vibration response. Using numerical integration procedure, the slap-induced vibration response and its correlation with the inner-cylinder piston-slap impact are reasonably evaluated. Guided by the simulating results and, by introducing a fast wavelet-packet decomposition and reconstruction algorithm, a specially designed experiment is made to practically measure and extract the slap-induced impact message inside the 6190Z LC diesel engine. Comparison between the simulation and practically measured and reconstructed engine vibration signals verifies the effectiveness and practicality of this approach for more detailed academic research and engineering application.

  8. Pins, dowels, and other retentive devices in posterior teeth.

    Science.gov (United States)

    Jacobi, R; Shillingburg, H T

    1993-07-01

    Devices used to increase retention of restorations to severely damaged posterior teeth are described, with an emphasis on pins and dowels. Advantages and disadvantages of different techniques and measures to help prevent and correct problems are presented.

  9. Characterization of vortex pinning through the Campbell length

    Science.gov (United States)

    Willa, Roland; Geshkenbein, Vadim B.; Blatter, Gianni

    Vortex pinning is decisive in establishing dissipation-free current flow in a type-II superconductor; knowledge and optimization of the pinning landscape (pinscape) is of major importance for applications. The ac magnetic response, characterized by the Campbell penetration depth λC, provides valuable information on the pinscape, besides the critical current density jc. While microscopic derivations of jc are available both in the weak and strong pinning limits, this is not the case for the Campbell length, whose understanding has remained on a phenomenological level so far. Based on the microscopic theory of strong pinning, we have established a proper link between the Campbell length and the pinscape parameters. This new quantitative formalism captures all experimentally observed signatures, among which are the dependence of λC on the vortex state preparation and the hysteresis in λC upon thermal cycling the field-cooled state.

  10. PIN1 in breast development and cancer: a clinical perspective.

    Science.gov (United States)

    Rustighi, Alessandra; Zannini, Alessandro; Campaner, Elena; Ciani, Yari; Piazza, Silvano; Del Sal, Giannino

    2017-02-01

    Mammary gland development, various stages of mammary tumorigenesis and breast cancer progression have the peptidyl-prolyl cis/trans isomerase PIN1 at their centerpiece, in virtue of the ability of this unique enzyme to fine-tune the dynamic crosstalk between multiple molecular pathways. PIN1 exerts its action by inducing conformational and functional changes on key cellular proteins, following proline-directed phosphorylation. Through this post-phosphorylation signal transduction mechanism, PIN1 controls the extent and direction of the cellular response to a variety of inputs, in physiology and disease. This review discusses PIN1's roles in normal mammary development and cancerous progression, as well as the clinical impact of targeting this enzyme in breast cancer patients.

  11. 8 Pin RIC Socket for Hearing Aid Applications

    DEFF Research Database (Denmark)

    Islam, Aminul; Hansen, Hans Nørgaard; Davids, Søren;

    2012-01-01

    process and the other one is fully automated process. This paper presents the entire process chain for both the concepts and makes a comparative analysis based on the experimental investigation and validation. The work presented here can be a source of valuable information for industrial users......The current paper presents the development of an 8 Pin RIC (Receiver in the canal) Socket for hearing instruments within the framework of the COTECH project. There are 8 industrial demonstrators developed in COTECH based on the converged product and process design. Sonion’s 8 Pin RIC Socket is one...... of them. 8 Pin RIC Socket is a functionally versatile product which can combine many different functions and presents many advantages compared with the previous 3 Pin RIC Socket. For the demonstrator production of the new Socket, two different production concepts were chosen- one based on semi-automated...

  12. Pinning impulsive directed coupled delayed dynamical network and its applications

    Science.gov (United States)

    Lin, Chunnan; Wu, Quanjun; Xiang, Lan; Zhou, Jin

    2015-01-01

    The main objective of the present paper is to further investigate pinning synchronisation of a complex delayed dynamical network with directionally coupling by a single impulsive controller. By developing the analysis procedure of pinning impulsive stability for undirected coupled dynamical network previously, some simple yet general criteria of pinning impulsive synchronisation for such directed coupled network are derived analytically. It is shown that a single impulsive controller can always pin a given directed coupled network to a desired homogenous solution, including an equilibrium point, a periodic orbit, or a chaotic orbit. Subsequently, the theoretical results are illustrated by a directed small-world complex network which is a cellular neural network (CNN) and a directed scale-free complex network with the well-known Hodgkin-Huxley neuron oscillators. Numerical simulations are finally given to demonstrate the effectiveness of the proposed control methodology.

  13. Alterations in Functional Connectivity for Language in Prematurely Born Adolescents

    Science.gov (United States)

    Schafer, Robin J.; Lacadie, Cheryl; Vohr, Betty; Kesler, Shelli R.; Katz, Karol H.; Schneider, Karen C.; Pugh, Kenneth R.; Makuch, Robert W.; Reiss, Allan L.; Constable, R. Todd; Ment, Laura R.

    2009-01-01

    Recent data suggest recovery of language systems but persistent structural abnormalities in the prematurely born. We tested the hypothesis that subjects who were born prematurely develop alternative networks for processing language. Subjects who were born prematurely (n = 22; 600-1250 g birth weight), without neonatal brain injury on neonatal…

  14. 14 CFR 1214.806 - Premature termination of Spacelab flights.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Premature termination of Spacelab flights... FLIGHT Reimbursement for Spacelab Services § 1214.806 Premature termination of Spacelab flights. If a... are, in NASA's judgment, adversely affected by such premature termination. The basis for proration...

  15. [Py-Desmanet pinning in distal radius fractures].

    Science.gov (United States)

    Alexa, O; Popia, I

    2009-01-01

    Internal fixation by pinning is one of the most used methods of surgical treatment in fractures of the distal extremity of the radius. As in stable fractures a styloid pinning is satisfactory, in unstable fractures however we must resort to different patterns of pin insertion, in order to effectively prevent the secondary displacement of the fractured fragments. The elastic pinning described by Py and Desmanet is one of the possibilities of inserting the pins. The principle of this method is to use the bending-induced tension in the pins to counteract the postero-lateral displacing forces. The authors have treated by this technique five patients with distal radius fractures (3 women and 2 men) about 56 years of average age, all with good-quality bone, all with Colles' fracture pattern (2-4 cm above the radio-carpal articulation, no articular involvement, posterior displacement of the distal fragment). The reduction of the fractures was achieved by closed manipulation and controlled intraoperatively with the C-arm. We preferred to reduce the fractures before inserting the pins, although this is not compulsory, according to the authors of the technique. The approach was minimally-invasive, through two 1-cm long incisions. The pins, previously blunted and curved along the last centimeters, were introduced using a "T"-shaped handle. The potential complications, consisting of injuries of the many elements which cross the region, were avoided by sufficiently long incisions and identification and retraction of these elements (tendons, nervous branches) in order not to penetrate them with the pins. The aftertreatment consisted of immediate mobilization of the wrist in one patient, 21-day splinting in other two and 30-day splinting in the last two, depending on the intraoperative assessment of the stability of the fixation. The pins were removed at 45 days postoperatively in all cases. There were no complications such as loss of reduction or pin migration. In all cases

  16. An experimental study of a pin-fin heat exchanger

    OpenAIRE

    Ramthun, David L.

    2003-01-01

    Approved for public release; distribution is unlimited A detailed experimental study has been carried out on the heat transfer and pressure drop characteristics of a compact heat exchanger with pin fins. A modular wind-tunnel with a rectangular cross-section duct-flow area was constructed that would accommodate the heat exchanger test section with varying pin designs. The flow in the tunnel was achieved through a suction-type blower, and a leading entrance length section was added to achie...

  17. Anisotropic flux pinning in high T{sub c} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kolesnik, S. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, PL-02668, Warszawa (Poland); Igalson, J. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, PL-02668, Warszawa (Poland); Skoskiewicz, T. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, PL-02668, Warszawa (Poland); Szymczak, R. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, PL-02668, Warszawa (Poland); Baran, M. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, PL-02668, Warszawa (Poland); Pytel, K. [Institute of Atomic Energy, Swierk (Poland); Pytel, B. [Institute of Atomic Energy, Swierk (Poland)

    1995-02-09

    In this paper we present a comparison of the results of FC magnetization measurements on several Pb-Sr-(Y,Ca)-Cu-O crystals representing various levels of flux pinning. The pinning centers in our crystals have been set up during the crystal growth process or introduced by neutron irradiation. Some possible explanations of the observed effects, including surface barrier, flux-center distribution and sample-shape effects, are discussed. ((orig.)).

  18. Investigating the interactions of yeast prions: [SWI+], [PSI+], and [PIN+].

    Science.gov (United States)

    Du, Zhiqiang; Li, Liming

    2014-06-01

    Multiple prion elements, which are transmitted as heritable protein conformations and often linked to distinct phenotypes, have been identified in the budding yeast, Saccharomyces cerevisiae. It has been shown that overproduction of a prion protein Swi1 can promote the de novo conversion of another yeast prion [PSI(+)] when Sup35 is co-overproduced. However, the mechanism underlying this Pin(+) ([PSI(+)] inducible) activity is not clear. Moreover, how the Swi1 prion ([SWI(+)]) interacts with other yeast prions is unknown. Here, we demonstrate that the Pin(+) activity associated with Swi1 overproduction is independent of Rnq1 expression or [PIN(+)] conversion. We also show that [SWI(+)] enhances the appearance of [PSI(+)] and [PIN(+)]. However, [SWI(+)] significantly compromises the Pin(+) activity of [PIN(+)] when they coexist. We further demonstrate that a single yeast cell can harbor three prions, [PSI(+)], [PIN(+)], and [SWI(+)], simultaneously. However, under this condition, [SWI(+)] is significantly destabilized. While the propensity to aggregate underlies prionogenesis, Swi1 and Rnq1 aggregates resulting from overproduction are usually nonheritable. Conversely, prion protein aggregates formed in nonoverexpressing conditions or induced by preexisting prion(s) are more prionogenic. For [PSI(+)] and [PIN(+)] de novo formation, heterologous "facilitators," such as preexisting [SWI(+)] aggregates, colocalize only with the newly formed ring-/rod-shaped Sup35 or Rnq1 aggregates, but not with the dot-shaped mature prion aggregates. Their colocalization frequency is coordinated with their prion inducibility, indicating that prion-prion interactions mainly occur at the early initiation stage. Our results provide supportive evidence for the cross-seeding model of prionogenesis and highlight a complex interaction network among prions in yeast.

  19. Open safety pin ingestion presenting as incarcerated umbilical hernia.

    Science.gov (United States)

    Mirza, Bilal; Sheikh, Afzal

    2011-09-01

    Foreign body ingestion is common in children. Sharp foreign bodies are potentially harmful and can result various complications. An 8-month-old infant presented with incarcerated umbilical hernia. With a suspicion of strangulation, operation was performed that revealed a loop of ileum being stuck in the umbilical defect. The loop of ileum was freed from the umbilicus which demonstrated open ends of safety pin piercing out of bowel lumen. The enterotomy followed by removal of safety pin was performed.

  20. Open Safety Pin Ingestion Presenting as Incarcerated Umbilical Hernia

    OpenAIRE

    Bilal Mirza; Afzal Sheikh

    2011-01-01

    Foreign body ingestion is common in children. Sharp foreign bodies are potentially harmful and can result various complications. An 8-month-old infant presented with incarcerated umbilical hernia. With a suspicion of strangulation, operation was performed that revealed a loop of ileum being stuck in the umbilical defect. The loop of ileum was freed from the umbilicus which demonstrated open ends of safety pin piercing out of bowel lumen. The enterotomy followed by removal of safety pin was p...

  1. Open Safety Pin Ingestion Presenting as Incarcerated Umbilical Hernia

    Directory of Open Access Journals (Sweden)

    Bilal Mirza

    2011-11-01

    Full Text Available Foreign body ingestion is common in children. Sharp foreign bodies are potentially harmful and can result various complications. An 8-month-old infant presented with incarcerated umbilical hernia. With a suspicion of strangulation, operation was performed that revealed a loop of ileum being stuck in the umbilical defect. The loop of ileum was freed from the umbilicus which demonstrated open ends of safety pin piercing out of bowel lumen. The enterotomy followed by removal of safety pin was performed.

  2. AtPIN: Arabidopsis thaliana Protein Interaction Network

    Directory of Open Access Journals (Sweden)

    Silva-Filho Marcio C

    2009-12-01

    Full Text Available Abstract Background Protein-protein interactions (PPIs constitute one of the most crucial conditions to sustain life in living organisms. To study PPI in Arabidopsis thaliana we have developed AtPIN, a database and web interface for searching and building interaction networks based on publicly available protein-protein interaction datasets. Description All interactions were divided into experimentally demonstrated or predicted. The PPIs in the AtPIN database present a cellular compartment classification (C3 which divides the PPI into 4 classes according to its interaction evidence and subcellular localization. It has been shown in the literature that a pair of genuine interacting proteins are generally expected to have a common cellular role and proteins that have common interaction partners have a high chance of sharing a common function. In AtPIN, due to its integrative profile, the reliability index for a reported PPI can be postulated in terms of the proportion of interaction partners that two proteins have in common. For this, we implement the Functional Similarity Weight (FSW calculation for all first level interactions present in AtPIN database. In order to identify target proteins of cytosolic glutamyl-tRNA synthetase (Cyt-gluRS (AT5G26710 we combined two approaches, AtPIN search and yeast two-hybrid screening. Interestingly, the proteins glutamine synthetase (AT5G35630, a disease resistance protein (AT3G50950 and a zinc finger protein (AT5G24930, which has been predicted as target proteins for Cyt-gluRS by AtPIN, were also detected in the experimental screening. Conclusions AtPIN is a friendly and easy-to-use tool that aggregates information on Arabidopsis thaliana PPIs, ontology, and sub-cellular localization, and might be a useful and reliable strategy to map protein-protein interactions in Arabidopsis. AtPIN can be accessed at http://bioinfo.esalq.usp.br/atpin.

  3. A Versatile Mixed-Signal Pin Approach for Cost-Effective Test of Automotive ICs

    Institute of Scientific and Technical Information of China (English)

    Credence Systems Corporation

    2004-01-01

    @@ (上接第9期51页) Figure 3:3 different pins types which cover a wide range of requirements: - DPIN: The digital mixed signal pin for high speed digital requirements - VPIN digital mixed-signal pin with high voltage digital test capability. With the 30 V swing and 50 MHz data rate the pin fits excellent for automotive requirements.

  4. Dipentamethylene thiuram monosulfide is a novel inhibitor of Pin1

    Energy Technology Data Exchange (ETDEWEB)

    Tatara, Yota; Lin, Yi-Chin; Bamba, Yoshimasa; Mori, Tadashi [Molecular Enzymology, Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, 1-1 Amamiya, Tsutsumidori, Aoba, Sendai, Miyagi 981-8555 (Japan); Uchida, Takafumi, E-mail: uchidat@biochem.tohoku.ac.jp [Molecular Enzymology, Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, 1-1 Amamiya, Tsutsumidori, Aoba, Sendai, Miyagi 981-8555 (Japan)

    2009-07-03

    Pin1 is involved in eukaryotic cell proliferation by changing the structure and function of phosphorylated proteins. PiB, the Pin1 specific inhibitor, blocks cancer cell proliferation. However, low solubility of PiB in DMSO has limited studies of its effectiveness. We screened for additional Pin1 inhibitors and identified the DMSO-soluble compound dipentamethylene thiuram monosulfide (DTM) that inhibits Pin1 activity with an EC50 value of 4.1 {mu}M. Molecular modeling and enzyme kinetic analysis indicated that DTM competitively inhibits Pin1 activity, with a K{sub i} value of 0.05 {mu}M. The K{sub D} value of DTM with Pin1 was determined to be 0.06 {mu}M by SPR technology. Moreover, DTM specifically inhibited peptidyl-prolyl cis/trans isomerase activity in HeLa cells. FACS analysis showed that DTM induced G0 arrest of the HCT116 cells. Our results suggest that DTM has the potential to guide the development of novel antifungal and/or anticancer drugs.

  5. Self-pinning of a nanosuspension droplet: Molecular dynamics simulations

    Science.gov (United States)

    Shi, Baiou; Webb, Edmund B.

    2016-07-01

    Results are presented from molecular dynamics simulations of Pb(l) nanodroplets containing dispersed Cu nanoparticles (NPs) and spreading on solid surfaces. Three-dimensional simulations are employed throughout, but droplet spreading and pinning are reduced to two-dimensional processes by modeling cylindrical NPs in cylindrical droplets; NPs have radius RNP≅3 nm while droplets have initial R0≅42 nm . At low particle loading explored here, NPs in sufficient proximity to the initial solid-droplet interface are drawn into advancing contact lines; entrained NPs eventually bind with the underlying substrate. For relatively low advancing contact angle θadv, self-pinning on entrained NPs occurs; for higher θadv, depinning is observed. Self-pinning and depinning cases are compared and forces on NPs at the contact line are computed during a depinning event. Though significant flow in the droplet occurs in close proximity to the particle during depinning, resultant forces are relatively low. Instead, forces due to liquid atoms confined between the particles and substrate dominate the forces on NPs; that is, for the NP size studied here, forces are interface dominated. For pinning cases, a precursor wetting film advances ahead of the pinned contact line but at a significantly slower rate than for a pure droplet. This is because the precursor film is a bilayer of liquid atoms on the substrate surface but it is instead a monolayer film as it crosses over pinning particles; thus, mass delivery to the bilayer structure is impeded.

  6. Pinned vortex hopping in a neutron star crust

    CERN Document Server

    Haskell, Brynmor

    2015-01-01

    The motion of superfluid vortices in a neutron star crust is at the heart of most theories of pulsar glitches. Pinning of vortices to ions can decouple the superfluid from the crust and create a reservoir of angular momentum. Sudden large scale unpinning can lead to an observable glitch. In this paper we investigate the scattering of a free vortex off a pinning potential and calculate its mean free path, in order to assess whether unpinned vortices can skip multiple pinning sites and come close enough to their neighbours to trigger avalanches, or whether they simply hop from one pinning site to another giving rise to a more gradual creep. We find that there is a significant range of parameter space in which avalanches can be triggered, thus supporting the hypothesis that they may lie at the origin of pulsar glitches. For realistic values of the pinning force and superfluid drag parameters we find that avalanches are more likely in the higher density regions of the crust where pinning is stronger. Physical dif...

  7. Dipentamethylene thiuram monosulfide is a novel inhibitor of Pin1.

    Science.gov (United States)

    Tatara, Yota; Lin, Yi-Chin; Bamba, Yoshimasa; Mori, Tadashi; Uchida, Takafumi

    2009-07-03

    Pin1 is involved in eukaryotic cell proliferation by changing the structure and function of phosphorylated proteins. PiB, the Pin1 specific inhibitor, blocks cancer cell proliferation. However, low solubility of PiB in DMSO has limited studies of its effectiveness. We screened for additional Pin1 inhibitors and identified the DMSO-soluble compound dipentamethylene thiuram monosulfide (DTM) that inhibits Pin1 activity with an EC50 value of 4.1 microM. Molecular modeling and enzyme kinetic analysis indicated that DTM competitively inhibits Pin1 activity, with a K(i) value of 0.05 microM. The K(D) value of DTM with Pin1 was determined to be 0.06 microM by SPR technology. Moreover, DTM specifically inhibited peptidyl-prolyl cis/trans isomerase activity in HeLa cells. FACS analysis showed that DTM induced G0 arrest of the HCT116 cells. Our results suggest that DTM has the potential to guide the development of novel antifungal and/or anticancer drugs.

  8. Analysis on structural characteristics of rotors in twin-rotor cylinder-embedded piston engine

    Institute of Scientific and Technical Information of China (English)

    陈虎; 潘存云; 徐海军; 邓豪; 韩晨

    2014-01-01

    Twin-rotor cylinder-embedded piston engine is proposed for dealing with the sealing problems of rotors in twin-rotor piston engine where the existent mature sealing technologies for traditional reciprocating engine can be applied. The quantity and forms of its sealing surfaces are reduced and simplified, and what’s more, the advantages of twin-rotor piston engine are inherited, such as high power density and no valve mechanism. Given the motion law of two rotors, its kinematic model is established, and the general expression for some parameters related to engine performance, such as the trajectory, displacement, velocity and acceleration of the piston and centroid trajectory, angular displacement, velocity and acceleration of the rod are presented. By selecting different variation patterns of relative angle of two rotors, the relevant variables are compared. It can be concluded that by designing the relative angle function of two rotors, the volume variation of working chamber can be changed. However, a comprehensive consideration for friction and vibration is necessary because velocity and acceleration are quite different in the different functions, the swing magnitude of rod is proportional to link ratioλ, and the position of rod swing center is controlled by eccentricitye. In order to reduce the lateral force, a smaller value ofλshould be selected in the case of the structure, and the value ofe should be near 0.95. There is no relationship between the piston stroke and the variation process of relative angle of two rotors, the former is only proportional to the amplitude of relative angle of two rotors.

  9. Repeat biopsy in patients with initial diagnosis of PIN; La biopsia ripetuta nei pazienti con diagnosi iniziale di PIN

    Energy Technology Data Exchange (ETDEWEB)

    De Matteis, Massimo [Azienda Ospedaliera Policlinico S. Orsola-Malpighi, Bologna (Italy). UO Radiologia Albertoni; Poggi, Cristina; De Martino, Antonietta; Pavlica, Pietro [Azienda Ospedaliera Policlinico S. Orsola-Malpighi, Bologna (Italy). UO Radiologia Palagi, Dipartimento area radiologica; Corti, Barbara [Azienda Ospedaliera Policlinico S. Orsola-Malpighi, Bologna (Italy). UO Anatomia ed istologia patologica, Dipartimento oncologico ed ematologico; Barozzi, Libero [Azienda Ospedaliera Policlinico S. Orsola-Malpighi, Bologna (Italy). UO Radiologia d' urgenza, Dipartimento emergenze ed accettazione

    2005-09-15

    Purpose. Prostatic intra-epithelial neoplasia (PIN) is considered a pre-malignant lesion and the main precursor of invasive prostatic adenocarcinoma. A PIN diagnosis established by prostate needle biopsy poses a difficult clinical management. problem. We retrospectively reviewed our three-year experience in order to identify criteria for referring patients to repeat biopsy. Materials and methods. We reviewed the repeat biopsy records of 72 patients in whom PIN had been detected on initial US-guided needle biopsy of the prostate. All the patients had a minimum of 6 biopsy cores taken, and they all had PSA > 4 ng/ml. Results. Adenocarcinoma was detected in 15 patients out of 50 (30%) with an initial diagnosis of low-grade PIN and in 10 patients out of 22 (45.4%) with high grade PIN, in 7 out of 18 (39%) in whom PSA levels had decreased during the observation interval, in 16 patients out of 46 (35%) in whom the PSA had increased and in 2 patients out of 8 (25%) with stable PSA. Conclusions. Our results seem to confirm that PIN can be considered a precursor of prostatic adenocarcinoma or a histological alteration often associated with it. Patients with low-grade PIN and particularly those with high-grade PIN should be regularly subjected to repeat biopsy at short intervals due to the high frequency of the final diagnosis of carcinoma. No agreement has been reached on the time interval between the first and the second biopsy. The PSA changes during the observation period are not a statistically significant parameter to suggest the repetition of prostatic biopsy. [Italian] Scopo. La neoplasia prostatica intraepiteliale (PIN) e considerata una lesione premaligna ed il precursore principale dell'adenocarcinoma prostatico infiltrante. La diagnosi di PIN ottenuta con l'agobiopsia della prostata rappresenta un difficile problema gestionale clinico. In una valutazione retrospettiva della nostra esperienza di 3 anni si e cercato di individuare i criteri che possano

  10. Pin-Hole Luminosity Monitor with Feedback

    Science.gov (United States)

    Norem, James H.; Spencer, James E.

    Previously, the generalized luminosity { L} was defined and calculated for all incident channels based on an NLC e+e- design. Alternatives were then considered to improve the differing beam-beam effects in the e-e-, eγ and γγ channels. Regardless of the channel, there was a large flux of outgoing, high energy photons that were produced from the beam-beam interaction e.g. beamstrahlung that needs to be disposed of and whose flux depended on { L}. One approach to this problem is to consider it a resource and attempt to take advantage of it by disposing of these straight-ahead photons in more useful ways than simply dumping them. While there are many options for monitoring the luminosity, any method that allows feedback and optimization in real time and in a non-intercepting and non-interfering way during normal data taking is extremely important - especially if it provides other capabilities such as high resolution tuning of spot sizes and can be used for all incident channels without essential modifications to their setup. Our "pin-hole" camera appears to be such a device if it can be made to work with high energy photons in ways that are compatible with the many other constraints and demands on space around the interaction region. The basis for using this method is that it has, in principle, the inherent resolution and bandwidth to monitor the very small spot sizes and their stabilities that are required for very high, integrated luminosity. While there are many possible, simultaneous uses of these outgoing photon beams, we limit our discussion to a single, blind, proof-of-principle experiment that was done on the FFTB line at SLAC to certify the concept of a camera obscura for high energy photons.

  11. Interplay between collective pinning and artificial defects on domain wall propagation in Co/Pt multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Rodriguez, G; Hierro-Rodriguez, A; Perez-Junquera, A; Montenegro, N; Alameda, J M; Velez, M [Dept. Fisica, Universidad de Oviedo-CINN, 33007 Oviedo (Spain); Menendez, J L [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN). Principado de Asturias-Consejo Superior de Investigaciones Cientificas (CSIC)-Univ. Oviedo -UO, Parque Tecnologico de Asturias, 33428 Llanera (Spain); Ravelosona, D, E-mail: mvelez@uniovi.e [Institut d' Electronique Fondamentale, UMR CNRS 8622, Univ. Paris Sud, 91405 Orsay Cedex (France)

    2010-08-04

    The interplay between collective pinning on intrinsic structural defects and artificial pinning at a patterned hole is studied in magnetic multilayers with perpendicular anisotropy. The pinning strength of a patterned hole is measured through its efficiency to stop domain wall (DW) propagation into a consecutive unpatterned nanowire section (using antisymmetric magnetoresistance to detect the direction of DW propagation) whereas collective pinning is characterized by the field dependence of DW velocity. Close to room temperature, collective pinning becomes weaker than artificial pinning so that pinning at the hole compensates nucleation-pad geometry, blocking DW propagation across the nanowire.

  12. Prematurity: an overview and public health implications.

    Science.gov (United States)

    McCormick, Marie C; Litt, Jonathan S; Smith, Vincent C; Zupancic, John A F

    2011-01-01

    The high rate of premature births in the United States remains a public health concern. These infants experience substantial morbidity and mortality in the newborn period, which translate into significant medical costs. In early childhood, survivors are characterized by a variety of health problems, including motor delay and/or cerebral palsy, lower IQs, behavior problems, and respiratory illness, especially asthma. Many experience difficulty with school work, lower health-related quality of life, and family stress. Emerging information in adolescence and young adulthood paints a more optimistic picture, with persistence of many problems but with better adaptation and more positive expectations by the young adults. Few opportunities for prevention have been identified; therefore, public health approaches to prematurity include assurance of delivery in a facility capable of managing neonatal complications, quality improvement to minimize interinstitutional variations, early developmental support for such infants, and attention to related family health issues.

  13. The genetic basis of premature ovarian failure.

    Science.gov (United States)

    Woad, Kathryn J; Watkins, Wendy J; Prendergast, Deborah; Shelling, Andrew N

    2006-06-01

    Premature ovarian failure (POF) is a common condition, affecting approximately 1:100 women. It is characterised by amenorrhea, hypoestrogenism, and elevated gonadotrophin levels in women under the age of 40. It is often an unexpected and distressing diagnosis, which coincides with infertility and menopausal symptoms. There is a well recognised genetic basis to the development of POF. Our laboratory has identified several candidate genes associated with POF.

  14. Progeria: A rare genetic premature ageing disorder

    OpenAIRE

    Jitendra Kumar Sinha; Shampa Ghosh; Manchala Raghunath

    2014-01-01

    Progeria is characterized by clinical features that mimic premature ageing. Although the mutation responsible for this syndrome has been deciphered, the mechanism of its action remains elusive. Progeria research has gained momentum particularly in the last two decades because of the possibility of revealing evidences about the ageing process in normal and other pathophysiological conditions. Various experimental models, both in vivo and in vitro, have been developed in an effort to understand...

  15. The drug treatment of premature ejaculation

    OpenAIRE

    Hisasue, Shin-ichi

    2016-01-01

    The management recommendation for both acquired premature ejaculation (APE) and lifelong PE (LPE) are similar, such as a behavioral/psychotherapy, a pharmacotherapy and a combination of these treatments. For the drug treatment for PE, gold standard is selective serotonin reuptake inhibitors (SSRIs) including dapoxetine or paroxetine. The drug treatment for PE is still developing and some new promising therapeutic options have been proposed. Topical anesthetics, tramadol, and alpha-1 blockers ...

  16. Role of the Arabidopsis PIN6 Auxin Transporter in Auxin Homeostasis and Auxin-Mediated Development

    OpenAIRE

    2013-01-01

    Plant-specific PIN-formed (PIN) efflux transporters for the plant hormone auxin are required for tissue-specific directional auxin transport and cellular auxin homeostasis. The Arabidopsis PIN protein family has been shown to play important roles in developmental processes such as embryogenesis, organogenesis, vascular tissue differentiation, root meristem patterning and tropic growth. Here we analyzed roles of the less characterised Arabidopsis PIN6 auxin transporter. PIN6 is auxin-inducible...

  17. THE PROPERTIES AND MICROSTRUCTURE OF NB-47TI SUPERCONDUCTOR WITH MAGNETIC PINNING CENTERS.

    Energy Technology Data Exchange (ETDEWEB)

    MOTOWIDLO,L.R.RUDZIAK,M.D.WONG,T.COOLEY,L.D.LEE,P.J.

    2004-02-04

    We have investigated Nb-47Ti multifilament wire with artificial pinning centers (APC). The superconducting properties and proximity effect in wires with ferromagnetic and non-magnetic pins will be discussed. Magnetization and transport measurements will be presented and the pinning characteristics will be discussed as a function of magnetic field, temperature and volume percent pins. In addition, field emission scanning electron microscopy of the pin nanostructure will be presented.

  18. The impact of microgeometry pistons with a stepped bearing surface for the friction loss of the internal combustion engine

    Directory of Open Access Journals (Sweden)

    Wroblewski Emil

    2017-01-01

    Full Text Available This paper present the results of experimental piston friction losses on stepped bearing surface microgeometry obtained on the test rig. This test rig is equipped with special temperature control system, which provides better stability to temperature than in standard systems. The results of station tests was discussed. Tests was analyzed depending the moment caused by the friction on the oil temperature in the oil sump. Specified conclusions allow to assess the impact of the stepped profile of the pistons bearing surface microgeometry for different values of engine speed and the oil temperature at the friction losses in the main kinematic engine node which is piston-cylinder.

  19. Experimental Study of the Micro-Arc Oxide Coating Effect on Thermal Properties of an Aluminium Alloy Piston Head

    Directory of Open Access Journals (Sweden)

    N.Yu. Dudareva

    2015-09-01

    Full Text Available The purpose of the present study is to investigate the influence of differently sized microarc oxidation coatings, applied to the bottom of pistons made with an Al-12Si-Mg-Cu-Ni alloy, on its thermal properties by simulating the operation of a real engine. This study is based on the premise that the alumina coating thickness affects the heat transfer and temperature distribution in the piston. The analysis of thermal properties of pistons and suggestions for the optimal thermal barrier coating thickness are presented.

  20. [Prematurity risk according to prematurity risk score and postpartal morbidity of the newborn infants (author's transl)].

    Science.gov (United States)

    Coradello, H; Lubec, G; Simbruner, G

    1981-02-01

    Risk of premature birth was evaluated retrospectively in 610 women in the first days after delivery using the prematurity risk score published by Thalhammer 1973. The calculated risk of premature birth was compared than prospectively to postpartal morbidity of the newborn infants as determined by duration of hospital stay, incidence of respiratory distress syndrome, need of artificial ventilation and mortality. A positive correlation could be found between risk of premature birth and postpartal morbidity of the newborn infants especially in small premature infants with birthweights of 2000 grams and less. The same correlation existed also in two groups of infants out of two different obstetric clinics which showed the same distribution of prenatal risks and the same prenatal care frequencies. It clearly becomes evident that infants with the same prenatal risks but good prenatal care during pregnancy had much lower hospital stays, lower respiratory distress frequencies and lower mortality rates than babies delivered from pregnancies badly cared for. These prenatal care related differences in postpartum morbidity again were much more evident in infants out of lower birth weight classes.

  1. Flux Pinning in Superconducting Niobium-Titanium Alloys

    Science.gov (United States)

    McKinnell, James Charles

    1990-01-01

    By studying Nb-Ti alloys from Nb44wt%Ti to Nb62wt%Ti the low field (2T) current density has been raised from 6500A/mm^2 (4.2^ circK) with standard Nb46.5wt%Ti to 7400A/mm ^2 with Nb58wt%Ti. When standard processing sequences were used, the alloys containing more than 46.5wt%Ti exhibited non-uniform microstructures following a precipitation heat treatment and the hardness rose from 200 DPN to over 300 DPN. By increasing the cold work prior to heat treatment the non-uniform precipitation was avoided. The amount of cold work needed prior to heat treatment to suppress non-uniform precipitation increased as the Ti content of the alloy increased. The volume fraction of precipitate produced during a given heat treatment also increased as the Ti content of the alloy increased. As the Ti content increased, the peak in the reduced pinning force curve shifted from b = 0.5 to b = 0.25. In order to determine whether the change in the flux pinning properties was due to the change in microstructure or due to enhanced Delta H_{c} pinning as the Ti content was increased, a set of wires with similar microstructures was developed. Their flux pinning behavior showed that the higher Ti alloys have pinning force curves which peak at progressively lower reduced fields. Thus Delta H_{c} pinning becomes the dominant pinning mechanism as the Ti content is increased.

  2. The study, design and simulation of a free piston Stirling engine linear alternatorThe study, design and simulation of a free piston Stirling engine linear alternator

    Directory of Open Access Journals (Sweden)

    Teodora Susana Oros

    2014-12-01

    Full Text Available This paper presents a study, design and simulation of a Free Piston Stirling Engine Linear Alternator. There are presented the main steps of the magnetic and electric calculations for a permanent magnet linear alternator of fixed coil and moving magnets type. Finally, a detailed thermal, mechanical and electrical model for a Stirling engine linear alternator have been made in SIMULINK simulation program. The linear alternator simulation model uses a controllable DC voltage which simulates the linear alternator combined with a rectifier, a variable load and a DC-DC converter, which compensates for the variable nature of Stirling engine operation, and ensures a constant voltage output regardless of the load.

  3. Alpha particles spectrometer with photodiode PIN; Espectrometro de particulas alfa con fotodiodo PIN

    Energy Technology Data Exchange (ETDEWEB)

    Chacon R, A.; Hernandez V, R.; Hernandez D, V. M.; Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidades Academicas de Estudios Nucleares e Ingenieria Electrica, Calle Cipres No. 10, Fracc. La Penuela, 09869 Zacatecas (Mexico); Ramirez G, J. [Instituto Nacional de Estadistica Geografia e Informatica, Direccion General de Innovacion y Tecnologia de Informacion, Av. Heroes de Nacozari Sur 2301, Fracc. Jardines del Parque, 20276 Aguascalientes (Mexico)], e-mail: achruiz@hotmail.com

    2009-10-15

    The radiation propagates in form of electromagnetic waves or corpuscular radiation; if the radiation energy causes ionization in environment that crosses it is considered ionizing radiation. To detect radiation several detectors types are used, if the radiation are alpha particles are used detectors proportional type or trace elements. In this work the design results, construction and tests of an alpha particles spectrometer are presented, which was designed starting from a photodiode PIN type. The system design was simulated with a code for electronic circuits. With results of simulation phase was constructed the electronic phase that is coupled to a multichannel analyzer. The resulting electronic is evaluated analyzing the electronic circuit performance before an alphas triple source and alpha radiation that produce two smoke detectors of domestic use. On the tests phase we find that the system allows obtain, in a multichannel, the pulses height spectrum, with which we calibrate the system. (Author)

  4. Pin1 and neurodegeneration: a new player for prion disorders?

    Directory of Open Access Journals (Sweden)

    Elisa Isopi

    2015-07-01

    Full Text Available Pin1 is a peptidyl-prolyl isomerase that catalyzes the cis/trans conversion of phosphorylated proteins at serine or threonine residues which precede a proline. The peptidyl-prolyl isomerization induces a conformational change of the proteins involved in cell signaling process. Pin1 dysregulation has been associated with some neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and Huntington's disease. Proline-directed phosphorylation is a common regulator of these pathologies and a recent work showed that it is also involved in prion disorders. In fact, prion protein phosphorylation at the Ser-43-Pro motif induces prion protein conversion into a disease-associated form. Furthermore, phosphorylation at Ser-43-Pro has been observed to increase in the cerebral spinal fluid of sporadic Creutzfeldt-Jakob Disease patients. These findings provide new insights into the pathogenesis of prion disorders, suggesting Pin1 as a potential new player in the disease. In this paper, we review the mechanisms underlying Pin1 involvement in the aforementioned neurodegenerative pathologies focusing on the potential role of Pin1 in prion disorders.

  5. Exchange anisotropy pinning of a standing spin-wave mode

    Science.gov (United States)

    Magaraggia, R.; Kennewell, K.; Kostylev, M.; Stamps, R. L.; Ali, M.; Greig, D.; Hickey, B. J.; Marrows, C. H.

    2011-02-01

    Standing spin waves in a thin film are used as sensitive probes of interface pinning induced by an antiferromagnet through exchange anisotropy. Using coplanar waveguide ferromagnetic resonance, pinning of the lowest energy spin-wave thickness mode in Ni80Fe20/Ir25Mn75 exchange-biased bilayers was studied for a range of Ir25Mn75 thicknesses. We show that pinning of the standing mode can be used to amplify, relative to the fundamental resonance, frequency shifts associated with exchange bias. The shifts provide a unique “fingerprint” of the exchange bias and can be interpreted in terms of an effective ferromagnetic film thickness and ferromagnet-antiferromagnet interface anisotropy. Thermal effects are studied for ultrathin antiferromagnetic Ir25Mn75 thicknesses, and the onset of bias is correlated with changes in the pinning fields. The pinning strength magnitude is found to grow with cooling of the sample, while the effective ferromagnetic film thickness simultaneously decreases. These results suggest that exchange bias involves some deformation of magnetic order in the interface region.

  6. Research on the Pin Fin Efficiency and Structure

    Directory of Open Access Journals (Sweden)

    Fan Bailin

    2013-06-01

    Full Text Available The performance of pin fin heat sink can be to measure through the temperature field. The temperature field and efficiency of the Pin Fin were analyzed, Pin fin efficiency curve was drowned also the distribution of the temperature field along the length of the pin fin curve was drawn. Thermal resistance was composed by thermal resistance of Aluminum substrate、 thermal resistance of convective heat transfer and the thermal resistance of the cooling liquid. The change rule was studied through the calculation on Aluminum plate thermal resistance、 thermal resistance of convective heat transfer and the thermal resistance of the cooling liquid. Its change regularity was simulated by toolbox In the MATLAB, and it was found that thermal resistance of convective heat transfer effect on the efficiency was most obvious in a certain amount of the heat and flow for thermal resistance of the Pin-fin radiator under the premise. The structural parameters of radiator were related to the size of thermal resistance.

  7. A Flux-Pinning Mechanism for Segment Assembly and Alignment

    Science.gov (United States)

    Gersh-Range, Jessica A.; Arnold, William R.; Peck, Mason A.; Stahl, H. Philip

    2011-01-01

    Currently, the most compelling astrophysics questions include how planets and the first stars formed and whether there are protostellar disks that contain large organic molecules. Although answering these questions requires space telescopes with apertures of at least 10 meters, such large primaries are challenging to construct by scaling up previous designs; the limited capacity of a launch vehicle bounds the maximum diameter of a monolithic primary, and beyond a certain size, deployable telescopes cannot fit in current launch vehicle fairings. One potential solution is connecting the primary mirror segments edgewise using flux-pinning mechanisms, which are analogous to non-contacting damped springs. In the baseline design, a flux-pinning mechanism consists of a magnet and a superconductor separated by a predetermined gap, with the damping adjusted by placing aluminum near the interface. Since flux pinning is possible only when the superconductor is cooled below a critical temperature, flux-pinning mechanisms are uniquely suited for cryogenic space telescopes. By placing these mechanisms along the edges of the mirror segments, a primary can be built up over time. Since flux pinning requires no mechanical deployments, the assembly process could be robotic or use some other non-contacting scheme. Advantages of this approach include scalability and passive stability.

  8. Pin1 inhibitor Juglone prevents diabetic vascular dysfunction.

    Science.gov (United States)

    Costantino, Sarah; Paneni, Francesco; Lüscher, Thomas F; Cosentino, Francesco

    2016-01-15

    Atherosclerosis is a major cause of mortality in patients with diabetes. However, novel breakthrough therapies have yet to be approved in this setting. Prolyl-isomerase-1 (Pin1) is emerging as a key molecule implicated in vascular oxidative stress and inflammation. In the present study, we investigate whether pharmacological inhibition of Pin1 may protect against diabetes-induced oxidative stress, endothelial dysfunction and vascular inflammation. Experiments were performed in human aortic endothelial cells (HAECs) exposed to normal (5 mmol/L) or high glucose (25 mmol/L) concentrations, in the presence of Pin1 inhibitor Juglone (10 μM) or vehicle (kB-dependent inflammatory signatures were determined both in HAECs and aortas from diabetic mice. In HAECs, ambient hyperglycemia increased mitochondrial superoxide anion generation while treatment with Juglone prevented this phenomenon. Pharmacological inhibition of Pin1 also preserved mitochondrial integrity, nitric oxide availability and endothelial expression of adhesion molecules. Interestingly enough, endothelial dysfunction, oxidative stress and NF-kB-driven inflammation were significantly attenuated in diabetic mice chronically treated with Juglone as compared to vehicle-treated animals. Pharmacological inhibition of Pin1 by Juglone prevents hyperglycemia-induced vascular dysfunction. Taken together, our findings may set the stage for novel therapeutic approaches to prevent vascular complications in patients with diabetes. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  9. Posttranslational modification and trafficking of PIN auxin efflux carriers.

    Science.gov (United States)

    Löfke, Christian; Luschnig, Christian; Kleine-Vehn, Jürgen

    2013-01-01

    Cell-to-cell communication is absolutely essential for multicellular organisms. Both animals and plants use chemicals called hormones for intercellular signaling. However, multicellularity of plants and animals has evolved independently, which led to establishment of distinct strategies in order to cope with variations in an ever-changing environment. The phytohormone auxin is crucial to plant development and patterning. PIN auxin efflux carrier-driven polar auxin transport regulates plant development as it controls asymmetric auxin distribution (auxin gradients), which in turn modulates a wide range of developmental processes. Internal and external cues trigger a number of posttranslational PIN auxin carrier modifications that were demonstrated to decisively influence variations in adaptive growth responses. In this review, we highlight recent advances in the analysis of posttranslational modification of PIN auxin efflux carriers, such as phosphorylation and ubiquitylation, and discuss their eminent role in directional vesicle trafficking, PIN protein de-/stabilization and auxin transport activity. We conclude with updated models, in which we attempt to integrate the mechanistic relevance of posttranslational modifications of PIN auxin carriers for the dynamic nature of plant development.

  10. Silicide Schottky Contacts to Silicon: Screened Pinning at Defect Levels

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, T.J.

    1999-03-11

    Silicide Schottky contacts can be as large as 0.955 eV (E{sub v} + 0.165 eV) on n-type silicon and as large as 1.05 eV (E{sub c} {minus} 0.07 eV) on p-type silicon. Current models of Schottky barrier formation do not provide a satisfactory explanation of occurrence of this wide variation. A model for understanding Schottky contacts via screened pinning at defect levels is presented. In the present paper it is shown that most transition metal silicides are pinned approximately 0.48 eV above the valence band by interstitial Si clusters. Rare earth disilicides pin close to the divacancy acceptor level 0.41 eV below the conduction band edge while high work function silicides of Ir and Pt pin close to the divacancy donor level 0.21 eV above the valence band edge. Selection of a particular defect pinning level depends strongly on the relative positions of the silicide work function and the defect energy level on an absolute energy scale.

  11. Heat exchange effects on the performance of a clearance-sealed piston prover for gas flow measurements

    Science.gov (United States)

    Kutin, J.; Bobovnik, G.; Bajsić, I.

    2015-12-01

    This paper deals with heat exchange effects in a compact, high-speed, clearance-sealed version of a piston prover for gas flow measurements that has the temperature measurements limited to the time-averaged temperature of the gas flow. A lumped-element mathematical model is used to study the physical background of the heat exchange effects. Experimental testing is performed to validate the theoretical results, estimate the required temperature homogeneity in the piston prover and propose a modified measurement model that considers the heat exchange effects. These effects are almost linearly related to the temperature difference between the gas flow into the piston prover and the cylinder wall, with the sensitivity coefficient being dependent on the measured flow rate. The piston-prover configuration with the gas temperature sensor in the mixed inlet /outlet flow is found to be advantageous in comparison to a measurement of the inlet temperature.

  12. CRANK-PISTON MODEL OF INTERNAL COMBUSTION ENGINE USING CAD/CAM/CAE IN THE MSC ADAMS

    Directory of Open Access Journals (Sweden)

    Michał BIAŁY

    2017-03-01

    Full Text Available The article presents the modeling and simulation of the crank-piston model of internal combustion engine. The object of the research was the engine of the vehicle from the B segment. The individual elements of the gasoline engine were digitizing using the process of reverse engineering. After converting the geometry, assembling was imported to MSC Adams software. The crank-piston system was specified by boundary conditions of piston forces applied on the pistons crowns. This force was obtain from the cylinder pressure recorded during the tests, that were carried out on a chassis dynamometer. The simulation studies allowed t determine the load distribution in a dynamic state for the selected kinematic pairs.

  13. The design and simulation investigation of a linear alternator dynamometer coupled to a free-piston Stirling engine

    Science.gov (United States)

    Goldberg, L. F.; Lee, K. P.

    1985-12-01

    The design of a linear alternator dynamometer and its control system intended for testing free-piston Stirling engines is described. The characteristics and performance of the dynamometer are demonstrated by a computer simulation in which the dynamometer is coupled to a Sunpower RE1000 free-piston engine. The simulation embodies algorithms which combine the gas dynamics of the engine working spaces with the dynamic behavior of the displacer and the piston/armature assembly. Over a variety of different loading conditions including inertial, gravitational and thermodynamic loads as well as linear, quadratic and Coulombic damping, the dynamometer exhibited a force error of 0.5 percent or 0.006 N at worst. The simulation investigation demonstrates that the dynamometer and its control system possess the necessary characteristics for it to be a practically useful loading device for testing and designing free-piston Stirling engines.

  14. Retinopathy of prematurity outcome in infants with Prethreshold Retinopathy of Prematurity and oxygen saturation > 94% in room air : The High Oxygen Percentage in Retinopathy of Prematurity study

    NARCIS (Netherlands)

    McGregor, ML; Bremer, DL; Cole, C; McClead, RE; Phelps, DL; Fellows, RR; Oden, N

    2002-01-01

    Objectives. To determine the rate of progression from prethreshold to threshold retinopathy of prematurity (ROP) in infants excluded from Supplemental Therapeutic Oxygen for Prethreshold Retinopathy of Prematurity (STOP-ROP) because their median arterial oxygen saturation by pulse oximetry (Spo(2))

  15. Influence of piston position on the scavenging and swirling flow in two-stoke diesel engines

    DEFF Research Database (Denmark)

    Obeidat, Anas; Haider, Sajjad; Meyer, Knud Erik

    2011-01-01

    We study the eect of piston position on the in-cylinder swirling flow in a low speed large two-stroke marine diesel engine model. We are using Large Eddy Simulations in OpenFOAM, with three different models for the turbulent flow: a one equation model (OEM), a dynamic one equation model (DOEM...... closure from a Burgers vortex profile to a solid body rotation while the axial velocity changes from a wake-like profile to a jet-like profile. The numerical results are compared with measurements in a similar geometry [3] and we find a good agreement between simulations and measurements. Furthermore, we......) and Ta Phuoc Loc's model (TPLM). The simulated flows are grid-independent and they are computed in situations analogous to two different piston positions where the air intake ports are uncovered 100% and 50%, respectively. We find that the average flow inside the cylinder changes qualitatively with port...

  16. Analysis of movement of non-cardan joint axial piston pump

    Energy Technology Data Exchange (ETDEWEB)

    Song Qi; Xue Xiaoping

    1984-01-01

    It is difficult to study kinematics of a non-cardan joint axial piston pump due to complexity of its mechanism movement. The current calculation method is tedious and movement of the pump with several parameters cannot be easily analyzed. However, these parameters can be calculated continuously and accurately by computers using the relevant equations. Examples are analyzed by the proposed method. It shows that selection of adequate geometric parameters is virtually a problem of optimizing the structural parameters by taking into account all the relevant parameters. Sufficient attention should be given to the parameter representing the angle between the connection rod and the axis of the piston. The structural parameters of variable and fixed displacement pumps should be dealt with individually.

  17. Initial results of sensitivity tests - Performed on the RE-1000 free-piston Stirling engine

    Science.gov (United States)

    Schreiber, J. G.

    1984-01-01

    Tests have been performed over several years to investigate the dynamics of a free-piston Stirling engine for the purpose of computer code validation. Tests on the 1 kW (1.33 hp) single cylinder engine have involved the determination of the sensitivity of the engine performance to variations in working space pressure, heater and cooler temperatures, regenerator porosity, power piston mass, and displacer dynamics. Maps of engine performance have been recorded with the use of an 81.2 percent porosity regenerator. Both a high-efficiency displacer and a high-power displacer were tested; efficiencies up to 33 percent were recorded, and power output of approximately 1500 W was obtained. Preliminary results of the sensitivity tests are presented, and descriptions of future tests are given.

  18. "Simultaneous measurement of flame impingement and piston surface temperatures in an optically accessible spark ignition engine"

    Science.gov (United States)

    Ding, Carl-Philipp; Honza, Rene; Böhm, Benjamin; Dreizler, Andreas

    2017-04-01

    This paper shows the results of spatially resolved temperature measurements of the piston surface of an optically accessible direct injection spark ignition engine during flame impingement. High-speed thermographic phosphor thermometry (TPT), using Gd3Ga5O12:Cr,Ce, and planar laser-induced fluorescence of the hydroxyl radical (OH-PLIF) were used to investigate the temperature increase and the time and position of flame impingement at the piston surface. Measurements were conducted at two operating cases and showed heating rates of up to 16,000 K/s. The OH-PLIF measurements were used to localize flame impingement and calculate conditioned statistics of the temperature profiles. The TPT coating was characterized and its influence on the temperature measurements evaluated.

  19. The intermetallic bonding between a ring carrier and aluminum piston alloy

    Energy Technology Data Exchange (ETDEWEB)

    Manasijevie, S.; Dolie, N.; Djurdjevic, M.; Misic, N.; Davitkov, N.

    2015-07-01

    This paper presents the results of investigating the formation of intermetallic bond between a ring carrier and aluminum piston alloy. The ring carrier is made of austenitic cast iron (Ni-Resist) in order to increase the wear resistance of the first ring groove and applied in highly loaded diesel engines. Metallographic examination of the quality of al fin bond was done. A metallographic investigation using an optical microscope in combination with the SEM/EDS analysis of the quality of the intermetallic bonding layer was done. The test results show that can be made successfully as well as the formation of metal connection (alfin bond) between the ring carrier and aluminum piston alloy. (Author)

  20. The effect of thermal barrier coated piston crown on engine characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Chan, S.H.; Khor, K.A.

    2000-02-01

    While there have been numerous research papers in recent years describing the theoretical benefits obtained from the use of ceramic components in reciprocating engines, the amount of literature that describes practical results is very limited. Although successes have been reported and ceramic components are now in service in production engines, mainly for reduced in-cylinder heat rejection, many researchers have experienced failures or a drop in engine performance. This article presents the work completed on a low heat rejection engine. Extensive experiments were conducted on a three-cylinder SI Daihatsu engine with piston crowns coated with a layer of ceramic, which consisted of yttria-stabilized zirconia (YSZ). Measurement and comparison of engine performance, in particular fuel consumption, were made before and after the application of YSZ coatings deposited onto the piston crowns. The details of the cylinder pressures during the combustion process were also investigated.