Set Of Valves Research Articles

Generation of a Pareto front for a bi-objective water flooding optimization problem using approximate ensemble gradients

Conflicting objectives are frequently encountered in most real-world problems. When dealing with conflicting objectives, decision makers prefer to obtain a range of possible optimal solutions from which to choose. In theory, methods exists that can produce a range of possible solutions, some of which are “Pareto Optimal”. The application of these methods to solve bi-objective production optimization problems is increasing. A recent paper introduced a method to find points on the boundary of the objective function space by solving a constrained optimization problem using adjoint gradients. In this work, we investigate the applicability of using ensemble optimization (EnOpt) (which relies on approximate ensemble gradients instead of exact adjoint-based gradients) to generate points along a “Pareto” front with acceptable computational effort.. Moreover, we investigate the applicability of this approximate gradient technique to solve constrained optimization problems using the augmented Lagrangian method. Finally, we compare the performance of this bi-objective optimization method to a traditional weighted sum method for bi-objective water flooding optimization of two different synthetic reservoir models. The two objectives used in this work are, undiscounted (0%) net present value (NPV), representing long-term targets and highly discounted (25%) NPV, representing short-term operational targets. The controls are inflow control valve (ICV) settings over time for one model and water injection rate controls for the other. The effect of different starting points and the computational efficiency of the constrained optimization method are also investigated.

Hypertrophic Cardiomyopathy-One Case per Year?: A Clarion Call to Do What Is Right.

Hypertrophic cardiomyopathy (HCM) has fascinated (and scared) cardiologists for years owing, in part, to the relatively fewcasesmostphysicianswill see intheirpractice,coupledwith increased risk for sudden death, complex yet incomplete genetic understanding, and enigmatic hemodynamics. The management of symptomatic patients with HCM evolved over the past (nearly) 6 decades owing to focusedefforts tounderstandthepathophysiologyandperfect the necessary skills to delivery exemplary outcomes.1 We have learned that it is entirelypossible forpatientswithHCMtohave excellent quality of life and normal lifespans, that most patients can be treatedwith pharmacologic therapy, and that for most patients who remain symptomatic, there are procedures that can deliver excellent benefit with low risk. The article by Kim et al2 using a national discharge database samplingmethod examines observed event rates among patients undergoing surgical septal myectomy or percutaneous septal ablation. Some of the findings are not surprising: there is a clear association between procedural volume and complications and there aredifferences in baseline characteristicsbetweenpatientsundergoing the2procedures.Thereare someshocking results: themediannumberofmyectomycases or ablation cases in this database is less than or equal to 1 case per year. Seriously, only 1 case per year? Why would we subject our patients to this? There is somecritical informationmissing as an artifact of the study design: specifically, there are no effectiveness data and thus, a comparison cannot be made between the results of surgical septal myectomy vs septal ablation. More importantly, there is no description of what can be expected if the procedures were performed not just at higher volume centers, but at Centers of Excellence. The study of Kim et al2 in this issue of JAMA Cardiology does go a long way to making an excellent case for having a few highly focused centers that specialize in the care of patients with HCM. The results achievable at major HCM centers are remarkable. In expert hands, surgical myectomy has a greater than 95% efficacy, with mortality rates that are approaching 0% (ie, thousands of cases performed without an operative death), normalization of long-term survival following theprocedure, anda reduction in sudden cardiacdeath.3-5 Similarly, among those patients who respond to septal ablation, the symptomatic improvement canmirror that ofmyectomy, with a procedural mortality rate that is only about 1%.6 Given that there are recognizable differences in complication rates and controversy regarding the association between septal ablation and subsequent sudden cardiac death/ implantable cardioverter defibrillator discharge rates, the American College of Cardiology Foundation/American Heart Association guidelines, as stated in the current article, recommendsurgicalmyectomyas thepreferredstrategy formostpatientswithHCMwith drug-refractory symptoms and that ablation isa reasonablealternative inselect cases.7Theguidelines emphasize that both procedures be performed by experienced centers and recommenda shareddecision-makingprocess, inwhich the fully informed patient is able to choose the procedure based on their own needs and preferences. Looking specifically at the data in the current report,2 regardless of the procedure type, there is an approximate 4-fold increase inmortality comparing the high-volume tertile to the low-volume tertile. Notably, the best mortality rates for myectomy as reported in this article, from their high-volume tertile, arestillnearly 10-foldhigher thanwhat is seenatHCMcenters.8 Thatevenhigher-volumecentersappear tohaveamortality rate that is 10 timesgreater thanwhat isobservedat centerswith focusedexpertise inHCMisanimportantobservationthat isworth seriousdiscussion. Indeed, thismayunderestimate themagnitude of the differences. Based on the data presented, the lowvolumecenterswould expect aprocedure-relateddeath for every 6 attempts, while the highest tertile reported here would expect a death for every 26 attempts. Yet,weknow frompreviouslypublisheddatathatHCMcenterscango1500ormorecases withoutaprocedure-relateddeath.8Sixvs26 is incremental improvement; 26 vs 1500 is improvement measured in magnitudes of order. There should be no debate. For years, the cardiology community has recommended andaccepted that adultswith congenital heart disease should receive their care from regional specialized centers for adults with congenital heart disease.9 Recently, given thewide variability in outcomes following operations for mitral valve disease, a disease and set of procedures that are far more prevalent than HCM, there has been a thoughtful call for these procedures to be restricted to those centers that can demonstrate excellence in benefit and safety.10 Hypertrophic cardiomyopathyhas a complexity andprevalence thatmore closely mimics that of adults with congenital heart disease, but HCM also has important abnormalities of mitral valve function. It is in the best interest of the patients then that they be informed they can expect to have a procedure with a vanishingmortality rateand95%chanceof significant,durable symptomatic benefit. No patient should have a complex procedure done where the volume is 1 per year. The data in this current report,2 coupledwith thewell-establisheddata fromHCMCenters of Excellence, make a clear case that for HCM, not every hospital or operator should be performing these procedures. The low-volume safety data are unacceptable. The middle volume data are not good enough. Even the highest-volume Editor's Note page 334

Core Muscle Activation During Unstable Overhead Squat Using a Water-Filled Training Tube

PURPOSE:Stability and balance are essential components for functional movement. While these components are often developed by exercising on unstable surfaces, another alternative is to use an unstable implement. The purpose of this study was to use a novel water-filled implement (“slosh tube”) to assess the degree of muscle instability created during an overhead squat. METHODS: Eight men (age= 20.1 ± 1.0y, ht=179.8 ± 4.8cm, mass= 89.2 ± 6.9kg) completed three 30s trials of an overhead squat using an 11.4 kg tube that was partially filled with water. A central valve allowed three conditions of water movement: 50% open, 100% open, and a stable(S), closed valve setting. Subjects completed 8-10 repetitions within each condition using a counter-balanced design. Muscle activation was assessed on the right side, with passive EMG electrodes placed over the belly of the vastus lateralis (VLAT), deltoid, rectus abdominus (AB), and paraspinal muscles. Integrated EMG was measured for each repetition and converted to a %MVC for each muscle. Instability was determined using the natural log of the coefficient of variation across repetitions. A two way repeated measures ANOVA across (contraction, condition) was used to examine concentric and eccentric contractions in each muscle. %MVC was also assessed. RESULTS:No significant instability was seen in any muscles for both CON and ECC. LnCV ranged from 3.0-3.5. Percent MVC activated was significantly greater for the Paraspinal muscle (CON= 53.6 ± 7.4, ECC = 45.1± 9.7%) and VLAT (CON= 332.3 ± 147.5, ECC= 288.8 ± 114.5) but not for the AB (CON= 10.6 ± 5.1, ECC= 9.2 ± 4.6) or the Deltoid ( CON= 41.3 ± 19.4, ECC = 39.7 ± 17.7) CONCLUSIONS: We conclude that the overhead squat using an unstable, water-filled tube maintains deltoid and abdominal muscle activation throughout the squat, but does not induce activation instability across the four muscles studied.

Robust optimal design of a neutral valve for hydrostatic transmissions using Grey relational analysis

Problems of pressure impact and improper neutral angle of a neutral valve for hydrostatic transmissions were solved using Taguchi method for robust optimal design with aids of Grey relational analysis and computer simulation. An ITI-Simulation X-based model of a hydrostatic transmission with the neutral valve was developed and used to simulate the pressure impact and extended neutral angle during the pressure modulation when the swash plate angled from neutral to forth or back. The simulation results were converted to the Grey relational coefficients for 108 combinations of 27 design and four operational conditions. The Grey relational grades were also calculated for seven design parameters and each of the design conditions as the performance index. Through three times repeated robust optimal design process, the design parameters reached to the optimal which satisfied the performance goals of the neutral valve set to smaller the better for the pressure impact and nominal the best for the extended neutral valve.

Hardware-In-the-Loop Simulation을 이용한 고분자 전해질 연료전지 냉각시스템 최적 제어기법 연구

Abstract - Polymer electrolyte membrane fuel cell(PEMFC) requires cooling system to maintain the proper operating temperature(about 65℃∼75℃) because the efficiency and power are affected by operating temperature. In order to retain the operating temperature of PEMFC, cooling system and coolant control logic are needed. Hardware-in-the-loop simulation(HILS) is one of effective methods to study and evaluate control algorithm. In this paper, the HILS system was designed to study the coolant control algorithm. The models of HILS system consisted of PEMFC, heat exchanger, and external environment associated with temperature. The hardwares in HILS system are 3-way valves, pumps, and a heat exchanger. The priority control and the control target temperature were investigated to improve the control performance using HILS. The 3-way valve in 1 st cooling circuit was selected as priority control target. The under limit value of 2 nd 3-way valve set as a function of PEMFC power and 2 nd circuit coolant temperature to correct temperature control performance. As a result, the temperature of PEMFC is stably controlled.

Investigation of user behavior and assessment of typical operation mode for different types of firewood room heating appliances in Austria

Firewood heaters like firewood roomheaters, tiled stoves and residential biomass cookers are commonly used for supplying the residences with renewable heat. However, these kinds of appliances were identified as responsible for relevant amounts of gaseous CO and OGC as well as particulate emissions causing negative health effects. Beside technological reasons, the operating conditions and the user behavior are essential reasons for increased emissions, especially in real life operation.Therefore, this study aimed at an investigation and assessment of typical real life user behavior by a survey. Based on the findings effective and customer friendly technological and non-technological optimization approaches for a better and more environmental friendly real life performance were defined.The results of the study showed principally similar user behavior of all considered types of appliances regarding most relevant operation characteristics, i.e. kind, properties and amount of used fuels, ignition procedure and air valve settings. Most effective non-technological optimization approaches were found for an enhancement of external training arrangements and the development of user friendly manuals that aimed mainly at an improvement of the ignition procedure from bottom–up to top–down ignition method. The use of devices with an automatically controlled combustion air supply was identified as promising technological measure.

Magnetic Shape Memory Alloys Modelling and Pneumatic Applications

Very generally material science could be divided into two groups: scientists who try to invent new materials or improve existing ones and those who work on finding the best applications for the modern materials. Among them there is group named “smart materials” or “active materials”, which have ability to change theirs properties according to the external stimulation. One of the relatively most recent smart material is magnetic shape memory alloy, MSMA in abbreviation. The authors of the article focus on testing samples of this material and try to adapt them to use in fluid devices. The paper mentions about some most interesting valves’ designs equipped with smart materials and summaries the previous MSMA research of the authors. It begins with literature overview of smart material applications in pneumatic or hydraulic valves. There is only one example of MSMA application in valve, therefore the overview concerns mainly the use of piezoelectric, thermal shape memory alloys and giant magnetostrictive materials. Next section describes general properties of the magnetic shape memory alloys and underlines the differences between more widely known Thermal Shape Memory Alloys and MSMA materials. One of the most important property is wide, nonsymmetrical hysteresis in static characteristics of the material, which can be seen as advantage or disadvantage, depending on the application. The material preserves its shape until perpendicular magnetic field or additional force appear. The authors mention about modeling MSMA hysteresis aspect. Three different hysteresis models were briefly described: Generalized Prandtl-Ischlinski, Preisach and Krasnosel'skii-Pokrovskii. The last section treats about the current MSMA based valve design concept. It assumes usage of two identical pieces of MSMA materials and energize them oppositely. There is flapper mounted between MSMA samples, which displacement depends on the MSMA elongations. This actuator type is called “push-push” type. Lack of the return spring result in remaining of the flapper in its final position after decreasing of the supply current. The advantage of the solution could be lowering energy consumption of the valve, when the valve setting changes relatively rare during its work. In the future, the presented hysteresis models could improve the work of such MSMA based valve.

Reduction in water losses in water distribution systems using pressure reduction valves

Water loss is a phenomenon frequently observed within water distribution systems (WDSs), that is considerably worsened by an excessive pressure throughout the network. As an alternative option to pipe replacement, the use of pumps working as turbines, throttle control valves (TCVs), or pressure reduction valves (PRVs) can be used to reduce leakage. For a preassigned number of these devices, their positions and settings can be chosen to minimize the water losses in the network or to minimise the costs associated with the leakage. On the other hand, for a preassigned reduction in leakage, the number, the position and the setting of valves could be optimized in order to minimize their installation and maintenance costs. Based on these observations, a procedure for the optimal choice of the number, position and setting of PRVs is devised. The procedure is aimed at reducing the whole cost associated with water loss in urban WDSs, due to the background leakage from joints, and the purchase, installation and maintaining of the PRVs themselves. The effectiveness of the procedure, which is based on the physical modelling of leakage from pipe joints as well as on the use of a genetic algorithm, is proven using a small but realistic example.

Development of a photometric procedure for tin determination in canned foods employing a multicommuted flow analysis approach

This work describes an automated analytical procedure for the photometric determination of tin in canned foods, employing a multicommuted flow analysis process. The flow system manifold comprises a set of three-way solenoid valves to handle solutions and a multisyringe module for fluid propelling.

Design and characterization of a soft magneto-rheological miniature shock absorber for a controllable variable stiffness sole

Abstract The proposed paper discusses the design and characterization of a soft miniature Magneto-Rheological (MR) shock absorber. In particular, the final application considered for the insertion of the designed devices is a controllable variable stiffness sole for patients with foot neuropathy. Such application imposes particularly challenging constraints in terms of miniaturization (cross-sectional area ≤ 1.5 cm2, height ≤ 25 mm) and high sustainable loads (normal loads up to 60 N and shear stresses at the foot/device interface up to 80 kPa) while ensuring moderate to low level of power consumption. Initial design considerations are done to introduce and justify the chosen novel configuration of soft shock absorber embedding a MR valve as the core control element. Successively, the dimensioning of two different MR valves typologies is discussed. In particular, for each configuration two design scenarios are evaluated and consequently two sets of valves satisfying different specifications are manufactured. The obtained prototypes result in miniature modules (external diam. ≤ 15 mm, overall height ≤ 30 mm) with low power consumption (from a minimum of 63 mW to a max. of 110 mW) and able to sustain a load up to 65 N. Finally, experimental sessions are performed to test the behaviour of the realized shock absorbers and results are presented.

Prosepective Study to Evaluate Rate and Frequency of Perturbations of Implanted Programmable Hakim Codman Valve After 1.5-Tesla Magnetic Resonance Imaging

Exposure to magnetic fields may alter the settings of programmable ventriculoperitoneal shunt valves or even cause permanent damages to these devices. There is little information about this topic, none on live patients. To investigate the effects of 1.5-tesla magnetic resonance imaging (MRI) on Hakim-Codman (HC) pressure programmable valves implanted in our hospital. A single-center prospective study to assess the rate of perturbations of HC programmable valve implanted. One hundred consecutive patients implanted for different clinical reasons between 2008 and 2012 were examined. A conventional skull x-ray before and after a standard MRI on 1.5 tesla. We evaluated before and after results, analyzed modification rate, and verified eventual damages to the implanted devices. Implanted HC valves are extremely handy and durable, even if they are likely to change often due to the exposure to magnetic fields. None of the patients complained of heating effects. Oscillations range from 10-30 mm H2O with a patient who reached 50 mm H2O and 1 who reached 60 mm H2O. Global alteration rate was 40%: 10 patients (10%) experienced a 10 mm H2O change; 14 patients (14%) had a 20 mm H2O change; 6 patients (6%) had a 30 mm H2O change; 8 patients (8%) had a 40 mm H2O change; 1 patient had a 50 mm H2O change; and 1 patient had a 60 mm H2O change. HC valves presented a variable perturbation rate, with an alteration rate of 40% with 1.5-telsa MRI. We have not observed malfunctioning hardware as a result of magnetic influence. We claim ​ a cranial x-ray immediately after the MRI because of a high risk (40%) of decalibration, especially in patients with low ventricles compliance.

Cardiovascular Management in Pregnancy: Antithrombotic Agents and Antiplatelet Agents.

Thrombotic complications of pregnancy are a major cause of morbidity and mortality to the mother and fetus. Pulmonary embolism is a leading cause of maternal death and accounts for 10.3% of all maternal deaths in the United States.1,2 Overall, pregnancy increases the risk of venous thromboembolism (VTE) 5-fold, with an additional increase in risk in the postpartum period.3,4 Pregnancy is associated with a hypercoaguable state attributable to relative increases in fibrinogen, plasminogen activator inhibitors, clotting factors VII, VIII, and X, von Willebrand Factor, and platelet adhesion molecules, and relative decreases in protein S activity, as well.5,6 Pregnancy is also a time of dramatic hemodynamic change including a reduction in lower extremity venous flow velocity by up to 50% at the end of the second trimester, which persists until 6 weeks postpartum.7 Recommendations for thrombosis prevention and anticoagulation in pregnant women are derived largely from algorithms from the nonpregnant population. We review the use of both older and new anticoagulants and antiplatelet medications during pregnancy and highlight their clinical utility in conditions including VTE, thrombophilias, mechanical heart valves, antiphospholipid syndrome (APLS), preeclampsia, intrauterine growth restriction (IUGR), and placental abruption. ### Vitamin K Antagonists #### Warfarin Warfarin is a vitamin K antagonist that easily crosses the placenta.8 Exposure in the first trimester is associated with warfarin embryopathy characterized by nasal bone hypoplasia and stippled epiphyses.9 Case series of pregnant women taking warfarin in the setting of mechanical heart valves found warfarin embryopathy rates of 5.6% and 6.4%, respectively.10,11 Warfarin use in the second and third trimester is associated with possible neurological sequelae including seizures, developmental delay, and hypotonia in the developing fetus attributable to intracranial microhemorrhages.12 Increased fetal risk for hemorrhage has been attributed to the greater affinity of albumin for bilirubin …

Iron Deficiency and Hemolytic Anemia Reversed by Ventricular Septal Myectomy

Hemolytic anemia has been reported to occur in the setting of aortic stenosis and prosthetic heart valves, but much more rarely in association with obstructive hypertrophic cardiomyopathy (HC). Of the few descriptions of hemolytic anemia secondary to HC, all but one case involved bacterial endocarditis contributing to left ventricular outflow tract obstruction. We present the case of a 67-year-old man with recurrent hemolytic anemia and HC, without infective endocarditis. Attempts at iron repletion and augmentation of beta-blocker therapy proved his anemia to be refractory to medical management. Ventricular septal myectomy led to the resolution of hemolysis, anemia, and its coexisting symptoms.

Clinically relevant skull models and optical measurement method to evaluate programmable hydrocephalus valve tool kit usability

Five simulated skull models were created to simulate typical clinical conditions experienced while programming implanted adjustable ventriculoperitoneal hydrocephalus shunt valves. These models were created with physician feedback and evaluated by 13 health care professionals. Based on tactile evaluations and qualitative feedback, three models were selected as most clinically relevant. An optical measurement and valve setting method were developed to characterize programming tool movements during valve programming procedure and usability testing that evaluated over 50 health care professionals that program hydrocephalus valves.

A double-blind randomized trial on the clinical effect of different shunt valve settings in idiopathic normal pressure hydrocephalus.

The study aim was to examine the effect of gradually reducing the opening pressure on symptoms and signs in the shunt treatment of idiopathic normal pressure hydrocephalus (iNPH). In this prospective double-blinded, randomized, controlled, double-center study on patients with iNPH, a ventriculoperitoneal shunt with an adjustable Codman Medos Valve was implanted in 68 patients randomized into 2 groups. In 1 group (the 20-4 group) the valve setting was initially set to 20 cm H2O and gradually reduced to 4 cm H2O over the course of the 6-month study period. In the other group (the 12 group), the valve was kept at a medium level of 12 cm H2O during the whole study period. All patients were clinically evaluated using 4 tests preoperatively as well as postoperatively at 1, 2, 3, 4, and 6 months. The test scores between the 2 groups (20-4 and 12) were compared for each clinical evaluation. Fifty-five patients (81%) were able to complete the study. There were no significant differences between the 2 groups (20-4 and 12) preoperatively or at any time postoperatively. Both groups exhibited significant clinical improvement after shunt insertion at all valve settings compared with the preoperative score, with the greatest improvement observed at the first postoperative evaluation. The clinical improvement was significant within the first 3 months, and thereafter no significant improvement was seen in either group. Gradual reduction of the valve setting from 20 to 4 cm H2O did not improve outcome compared with a fixed valve setting of 12 cm H2O. Improvement after shunt surgery in iNPH patients was evident within 3 months, irrespective of valve setting.

Simple flow injection colorimetric system for determination of paraquat in natural water

A simple and low cost flow injection colorimetric system has been developed for determination of paraquat in natural water. The developed method is based on the reduction of paraquat by using sodium dithionite as a reducing agent in an alkaline medium to produce a blue free radical ion that can be detected by a simple light emitting diode-light dependent resistor (LED-LDR) colorimeter. The standard or sample solution was injected via a set of 3-way solenoid valves into a water carrier stream and flowed to merge with reagent to generate a colored product which is proportional to the concentration of paraquat ion in the solution. Under the optimum condition of the system, i.e., mixing coil length 30cm, flow rate 2.0mLmin−1, sample volume 100μL, concentrations of dithionite 0.1% (w/v) and sodium hydroxide 0.06molL−1, a linear calibration graph in the range of 0.2–10.0mgL−1 with a correlation coefficient of 0.9996, and a limit of detection of 0.15mgL−1 were achieved. Relative standard deviation for 9 replicate injections of 1mgL−1 paraquat is 3.7%. A sample throughput of 40 injectionsh−1 was achieved. The limit of detection can be improved by off-line preconcentration of paraquat employing a column packed with Dowex 50WX8-100 (H) cation exchange resin and eluted with 10% (w/v) ammonium chloride in ammonium buffer solution pH 10. The eluting solution was then injected into the FI system for paraquat determination. The proposed system did not suffer from interferences of some possible ions in natural water and other herbicides. Recoveries obtained by spiking 0.5 and 5.0mgL−1 paraquat standard into water samples were in the range of 104–110% and 101–105%, respectively. The developed system can be conveniently applied for screening of paraquat contaminated in natural water.

A jazz-based approach for optimal setting of pressure reducing valves in water distribution networks

This study presents a model for valve setting in water distribution networks (WDNs), with the aim of reducing the level of leakage. The approach is based on the harmony search (HS) optimization algorithm. The HS mimics a jazz improvisation process able to find the best solutions, in this case corresponding to valve settings in a WDN. The model also interfaces with the improved version of a popular hydraulic simulator, EPANET 2.0, to check the hydraulic constraints and to evaluate the performances of the solutions. Penalties are introduced in the objective function in case of violation of the hydraulic constraints. The model is applied to two case studies, and the obtained results in terms of pressure reductions are comparable with those of competitive metaheuristic algorithms (e.g. genetic algorithms). The results demonstrate the suitability of the HS algorithm for water network management and optimization.

Molasses separation using improved SMB distributor

There is potential for wide ranging applications of simulated moving bed (SMB). Several new concepts have been proposed in order to improve the performance and extend the range of application of classical SMB technology by exploiting various additional degrees of freedom. Improving SMB processes aims to reduce production costs and increasing efficiency, thus, this effort results in several configurations of SMB equipment designs with more degrees of freedom than the classical SMB processes.SMB modeling will play a significant role in designing the right process configurations for the separation of value – adding ingredients in the food industry and other branches.We aim to modify our SMB station by using set of valves (electronically controlled valves) instead of the existing rotary valve, by this way a new flows distributor with additional degrees of freedom for binary separation of saccharides and salts, the new configuration will be tested for saccharides separation (molasses) and evaluating the efficiency of the processes.

양방향 압전-유압 하이브리드 구동장치의 성능 시험

Piezoelectric-based hydraulic actuator is a hybrid device consisting of a hydraulic pump driven by piezoelectric stacks that is coupled to a conventional hydraulic cylinder via a set of fast-acting valves. Nowadays, such hybrid actuators are being researched and developed actively in many developed countries by requirement of high performance and compact flight system. In this research, a piezoelectric hybrid actuator has been designed and tested. To achieve bi-directional capabilities in the actuator, solenoid valves were used to control the direction of output fluid. The experimental testing of the actuator in uni-directional and bi-directional modes was performed to examine performance issues related to the solenoid valves. The results showed that the bi-directional performance was slightly lower than uni-directional performance due to air bubble developed in the valve system. A new design to solve the vacuum problem has been proposed to improve the performance of the hybrid actuator.

Effect of Selected Parameters of Pressure Die Casting on Quality of AlSi9Cu3 Castings

Abstract This paper presents the results on the effects of die-casting process on the strength parameters of castings of the aluminium AlSi9Cu3 alloy belonging to the group of EN AB-46000, made on renovated high pressure die-casting machine. Specimens for quality testing were taken from the places of the casting most loaded during the service. The aim of a research was to prove how the new die-casting process control capabilities influence on the tensile strength of the cast material defined as a value of the breaking force of the specimens. It has been found that it is possible to specify a set of recommended settings valves of second (II) and third (III) phase, which are responsible for filling the metal mould on die-casting pressure machine. From the point of view of the finished cast element, it was noticed that exceeding the prescribed values of valve settings does not bring further benefits and even causes unnecessary overload and reduce the durability of the mold. Moreover, it was noticed that reduction of the predetermined setting of the second phase (II) valve leads to the formation of casting defects again.