Development of the Sealed-Type Triple-Point-of-Argon Cell for Long-Stem SPRT Calibration at KRISS

A system was fabricated to realize the triple point of argon for the calibration of long-stem standard platinum resistance thermometers. A cryostat was constructed so that the temperature could be controlled quasi-adiabatically, and the melting was realized using the continuous-heating method. The combined uncertainty of the realization of the triple point of argon for a confidence level of 95% was 0.6 mK.     

一种新型的幅宽1500 mm的卷绕式真空镀膜机

幅宽1500mm卷绕式真空镀膜机，是为了满足1500mm幅宽的聚脂薄膜（PET）、定向聚丙烯薄膜（OPP）、聚丙烯流涎薄膜（CPP）、聚乙烯薄膜（PVC）的真空镀铝而设计的。和通常的卷绕式真空镀膜机相比，具有真空度高，抽真空的时间短，卷取性能好，镀膜幅度宽，镀膜速度快。跑偏量小，镀膜层牢固、均匀等优点。是一种理想的卷绕式真空镀膜机。     

Investigation on the optimal control of gas cooler pressure for a CO2 refrigeration system with an internal heat exchanger

CO₂ is one of good refrigerants considering the environmental and safe issues. However, its control is a much more complicated problem compared to the conventional refrigerants. Most of the previous studies have applied regressive approach to this problem, but it requires large amount of effort and cost. This study deals with issues on controlling CO₂ refrigeration system and developing new control method. In this study, the performance characteristics of a CO₂ refrigeration system were investigated considering refrigerant charge amount and a novel real-time control method proposed by Kim and Kim (2012) was validated. Through the validation, the real-time controller showed acceptable estimation performance even in case of insufficient refrigerant charge. In addition, a new concept of control analysis was devised considering gas cooler performance. This approach helps the comprehensive understanding of determination mechanism to achieve maximum coefficient of performance, which is applicable to develop a new control method.     

Automatic control of gas pressure in a vacuum system

This paper describes the development of a microprocessor based system to be used for the automatic setting of the gas pressure within a vacuum chamber.The requirements of the system have been presented by five modes of operation which are easily set up by thumb wheel and on/off switches on a panel. The microprocessor system automatically balances the rates of the pumping system and gas inlet to set and maintain the requested gas pressure. The gas inlet needle valve is controlled by either an ac or de motor. The use of computer software allows the system to be readily adapted for use with the commonly used needle valves, pressure gauges and pumping systems. It allows for non linear transducers and mechanical wear and additional modes of operation may be easily added when required. The system is intended for use as a subsystem of a microprocessor controlled vacuum system for laboratory or industrial use.The technique has been illustrated by controlling the pressure over the range 1–20 torr in a conventionally pumped vacuum system.     

Investigation of the stability of a technological system in combined processes of thermomechanical treatment

Consideration is given to combined thermomechanical methods of surface formation: rotational cutting with plasma heating and surface plastic deformation of a coating in electromagnetic welding. Unstable states of a technological system are investigated. Ways of controlling the stability and enhancing the efficiency of the combined methods of thermomechanical treatment are outlined.Notation V ₁ andV ₂ volumes of the ingot and the workpiece respectivy - Re=vt/v Reynolds number - Pr=v/gw Prandtl number - Pe=vt/ Peclet number - v rate of treatment - t treated layer thickness - v and coefficients of kinematic viscosity and thermal diffusivity - S feed rate - v resultant velocity of motions - _z and _{x z} stresses of the treated material in the direction of the main motionv and in the direction of the moment of shaping that takes account of the interdependence of the motionsv andS [1] - _y and _{y z} stresses of a ferropowder medium in the direction perpendicular to the surface formed and in the direction of rotation on a plane perpendicular to it [2] - ^* and specific electrical conductivity and electrical resistance of the powder medium - Ra mean arithmetical deviation of the profile of the microrelief of the surface - Q welding efficiency (the increase in the coating mass) - HRC _e Rockwell hardness - B magnetic induction - I current strength - L distance from the heating source to the tool - K=v _r/v kinematic coefficient of the rotational tool - v _r self-rotational speed of the tool - P forces of deformation of the surface Belarusian Agrarian Technical University, Minsk. Polotsk State University, Novopolotsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 4, pp. 598–604, July–August, 1995.     

燃油系统旋涡泵压力脉动的控制研究

为了改善燃油泵噪声、振动、声振粗糙度(noise,vibration and harshness,NVH)性能,提高燃油泵声音品质,开展了燃油系统旋涡泵压力脉动的控制研究。采用计算流体动力学(Computational Fluid Dynamics,CFD)数值模拟方法和理论分析方法分析燃油系统微型旋涡泵的压力脉动特性,并采用随机叶片分布方法设计了2种非均布程度不同的非等距叶轮。基于CFD数值模拟结果和理论分析结果,提出一种改进的非等距叶轮设计方法。燃油泵噪声试验结果验证了该设计与控制方案的可行性。结果显示:相较于等距叶轮,随机非等距叶轮燃油泵的中高频段尖锐噪声消失,NVH性能提升;随机非等距叶轮能够显著分散叶频峰值,非均布程度的增加显著增大了随机非等距叶轮的叶频脉动幅值下降幅度。因此,采用随机叶片分布方法,有助于改善旋涡泵的压力脉动特性,对改善燃油泵的NVH性能具有重要的工程应用价值。     

Investigation of wear resistance and microstructure of a newly developed chromium and vanadium containing iron‐based hardfacing alloy

Plasma transferred arc (PTA) welded Ni and Co‐based alloys have gained high acceptance in many industrial applications for the wear protection of components. Recently, the cost of nickel and cobalt is rising drastically. This paper presents the development of a cost‐effective high chromium and vanadium containing iron‐based hardfacing alloy with high hardness and wear resistance. The welding processing of the alloy is carried out by PTA welding of atomized powders. Investigations on powder production as well as on weldability are presented. The coatings are metallographically studied by optical microscopy, SEM, EDX and micro‐hardness measurements. The wear resistance properties of the coatings are examined using pin on disk, dry sand rubber wheel and Miller testing, the corrosion properties are determined by immersion corrosion tests. The newly developed iron‐based alloy has nearly the same wear resistance as Ni‐based alloys with fused tungsten carbides at a higher level of corrosion resistance and much lower cost.     

溅射镀膜系统的压力控制的一种新设想

通过对一般溅射镀膜装置特点以及镀膜过程中存在问题的分析，指出：由于溅射镀膜时的工作压力处于扩散泵的恒定排气量区（第一级喷口过载区）．扩故泵在这种环境下工作，返流严重，并且由于喷流不稳定现象导致压力难于控制。提出了一种由扩散泵机组作为溅射镀膜油气系统的改进型设计方案。理论分析表明：使用该方案，扩散泵进气口压力维持在恒定抽速区．返流减小，镀膜室工作压力也易于稳定。     

减温减压装置前馈温度控制系统设计

集中供热系统中减温减压装置在蒸汽负荷扰动时引起较大的温度动态误差,现就其产生的原因及减温减压装置系统结构的基础上,提出了理论效果良好的流量静态前馈温度调节控制环节.结果表明,该设计在蒸汽负荷扰动时对抑制温度调节的动态误差与设计意图基本相符,从而为设定满足生产工艺要求且较为经济的蒸汽温度提供了现实的可能性.     

Metallographic investigation of TiC nucleants in the newly developed Al-Ti-C grain refiner

For grain refinement of aluminium and its alloys, a new aluminium-based master alloy containing TiC nucleants was developed a few years ago, by reacting carbon with Al-Ti binary alloy melt. However, as the melt was held at the usual melting temperatures of below 1273 K, the resultant master alloy lost its grain-refining efficiency, and so this phenomenon was called the poisoning effect. Nevertheless, a superheating treatment of the melt at higher temperatures (> 1523 K) rejuvenated the nucleant particles. The present investigation, dealing with electron diffraction of carbide particles extracted from the poisoned master alloy, revealed massive formation of Al₄C₃ and Ti₃AlC, of which Al₄C₃ appears to account for the poisoning of TiC nucleants. On the other hand, subsequent electron diffraction studies on the rejuvenated nucleants confirmed that they were essentially composed of uncontaminated TiC.     

Investigation of the reconfigurable control system for an agile manufacturing cell

A new type of manufacturing cell, with characteristics of reconfigurability, reusability and scalability, needs to be developed. To achieve the agile reconfiguration of a manufacturing cell, the cell control system must be rapidly and efficiently generated or modified. In this paper, a multi-agent based architecture is defined that supports the design and implementation of highly reconfigurable control systems for agile manufacturing cells, which are comprised of resource agents (material processing agents, material handling agents, and material storage agents), a control agent, and an information agent, in order to reduce costs and increase the control system's agility with respect to the changing environment. Different agents in the cell control system can be organized dynamically, communicate with each other through messages, and cooperate with each other to perform flexibly the task in the cell control system. The structure of the agents is proposed and the message-passing between agents is discussed in detail.     

离心式压缩机转子系统稳定性控制方法研究

针对离心压缩机转子失稳已成高效长周期运转主要障碍问题,通过分析失稳机理及影响因素,研究压缩机转子系统稳定性控制方法。结合工程案例,采用有限元方法对转子进行瞬态动力学分析,研究转速及因密封等部件交叉刚度对转子稳定性影响。研究转子振动位移反馈与速度反馈方法对转子失稳振动的控制效果。结果表明,两种方法均能有效提高转子系统稳定性。对比在达到相同控制效果时执行机构能量消耗表明,通过位移反馈方式能以更低能耗达到控制效果。该结果可为离心压缩机转子稳定性控制与提高提供新的思路及可行性。     

On the stability and bullwhip effect of a production and inventory control system

This paper focuses on the discrete-time automatic pipeline, inventory and order-based production control system (APIOBPCS), a well-established production and inventory control model. The feedback mechanism within the replenishment rule enables the model to mitigate the bullwhip effect, but introduces a stability problem. In this research, a comprehensive stability analysis is conducted for arbitrary lead times using difference equation theory. On the basis of stability, a state space approach is advocated to analyse the impact of replenishment parameters, demand processes, and lead times on the robustness of the bullwhip effect. The stability results demonstrate that the production control system can easily be destabilised without incorporating the work-in-progress (WIP) feedback loop. Furthermore, it reveals that the stability problem for long lead times can be simplified with the stability condition independent of the lead time. The results obtained in this study provide useful guidelines for the selection of replenishment parameters to guarantee stability and mitigate the bullwhip effect.     

Low‐cycle fatigue behavior of a newly developed cast aluminum alloy for automotive applications

The drive for increasing fuel efficiency and decreasing anthropogenic greenhouse effect via lightweighting leads to the development of several new Al alloys. The effect of Mn and Fe addition on the microstructure of Al‐Mg‐Si alloy in as‐cast condition was investigated. The mechanical properties including strain‐controlled low‐cycle fatigue characteristics were evaluated. The microstructure of the as‐cast alloy consisted of globular primary α‐Al phase and characteristic Mg₂Si‐containing eutectic structure, along with Al₈(Fe,Mn)₂Si particles randomly distributed in the matrix. Relative to several commercial alloys including A319 cast alloy, the present alloy exhibited superior tensile properties without trade‐off in elongation and improved fatigue life due to the unique microstructure with fine grains and random textures. The as‐cast alloy possessed yield stress, ultimate tensile strength, and elongation of about 185 MPa, 304 MPa, and 6.3%, respectively. The stress‐strain hysteresis loops were symmetrical and approximately followed Masing behavior. The fatigue life of the as‐cast alloy was attained to be higher than that of several commercial cast and wrought Al alloys. Cyclic hardening occurred at higher strain amplitudes from 0.3% to 0.8%, while cyclic stabilization sustained at lower strain amplitudes of ≤0.2%. Examination of fractured surfaces revealed that fatigue crack initiated from the specimen surface/near‐surface, and crack propagation occurred mainly in the formation of fatigue striations.     

EAST低温系统大型压缩机组自动控制的实现

针对EAST低温系统大型串并联螺杆压缩机组控制中存在的压力调节长时间滞后、能量滑阀动作具有不确定性、控制模型难于建立等难点,采用专家规则与数字增量式PID算法相集合的复合控制方法,将复杂的多变量耦合控制回路分解为特定条件下的单变量回路,结合顺序控制逻辑分析,实现了压缩机组的全自动控制。经过EAST降温实验验证,该策略取得了良好的控制效果,满足低温系统的运行要求。详细描述了该控制系统各个执行机构的控制原理和压缩机的控制过程。     

Investigation of phases and stability of solid electrolytes in the NASICON system

In order to study the phase change and stability of the NASICON structure, sodium, lithium and magnesium ions were chosen to substitute the zirconium ion at octahedral sites in the NASICON network. It was found that the zirconium ion can not be replaced by these ions. All the synthesized products are Na_1+xZr₂Si_xP_3?xO₁₂ and phosphate salts. NASICON immersed in liquid sodium at 300°C also results phosphate salt and ZrO₂. It was found that an appropriate excess of sodium phosphate in NASICON will improve the chemical stability, corrosion against sodium and mechanical properties.     

Phase diagram of the Mg-O system at a pressure of 2 GPa

Thermodynamic calculation and experimental studies of the phase quilibria in the Mg-O system have been performed and the system phase diagram at a pressure of 2 GPa has been constructed. The system is characterized by the existence of just one eutectic equilibrium at 1100 K, in which magnesium, MgO magnesium oxide, and a liquid phase take part.     

Improvement of body force method analysis by using a newly developed boundary element

A higher order boundary element, suitable for the body force method (BFM) calculation of 2D or 3D notch problems, is proposed. The interpolation function used in the present element is defined so as to express the exact form of the basic density function in the problem of an elliptic hole under remote load. The availability of the present element in the standing point of the boundary integration for 2D analysis is presented. Some basic 2D and 3D notch problems are solved using standard PC and high accuracy of the present BFM is confirmed.     

Effect of grafted smart polymer architectures on interaction with hydrophobic molecules in newly developed induction heating chromatography system

We investigated the effect of grafted polymer architectures of temperature-responsive poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide) (P(NIPAAm-co-CIPAAm)) as an ‘on–off’ switchable surface trap for the effective separation of bioactive molecules in a self-heating, temperature-responsive chromatography system. P(NIPAAm-co-CIPAAm)s were covalently grafted onto amino-modified magnetite–silica composites by a “grafting-to” method. Different architectures of grafted polymers on the magnetite–silica composites were successfully prepared by varying the composition of CIPAAm while keeping their grafted polymer densities constant (i.e., introducing more CIPAAm content provided more immobilizing points and reduced grafted polymer chain mobility). Heat was generated at the composite surface by exposing the magnetite–silica composites to an alternating magnetic field (AMF). Raising the temperature above the lower critical solution temperature (LCST) of the polymer resulted in a hydrophilic to hydrophobic phase change in the grafted P(NIPAAm-co-CIPAAm) layers. To assess the effect of grafted P(NIPAAm-co-CIPAAm) architectures on their interaction with bioactive compounds above their LCST, P(NIPAAm-co-CIPAAm)-grafted magnetite–silica composites were packed into a glass column of an aqueous liquid chromatography system and the elution profiles for steroids were analyzed as a function of temperature. At the ‘on’ state of the AMF, the retention times for hydrophobic steroids dramatically increased according to the trend: hydrocortisone < dexamethasone < testosterone, because self-heating of the grafted composites increased the hydrophobic interactions between the steroids and the polymer layer. Of particular interest is that reduced retention times were observed when CIPAAm content rose above 15 mol%. This result indicates that the complete dehydration of P(NIPAAm-co-CIPAAm) above the LCST was restricted when the polymer was immobilized via multiple amide bonds. The proposed system could be very useful for separation of bioactive compounds because their elution profiles can be easily controlled only by ‘on–off’ switching of an AMF, thus eliminating the need for toxic organic solvents and heating/cooling processes of the entire mobile phase.