初探灯泡贯流式机组轮叶操作油管间隙过大处理

灯泡贯流式水轮机组与立式轴流机组相比,有显著的优越性,在开发低水头水力资源方面具有广阔的发展前景。介绍了广东省潮州供水枢纽西溪电站机组轮叶操作油管间隙过大的处理过程及处理方案。

AES算法的高速实现

文章简要介绍了新的高级加密标准AES算法(Rijndael)的加密解密流程,分析了该算法自身的特点,解开了算法内部的轮循环,代之以流水线的方式实现。而且还分析了每次轮操作的内部过程,对轮操作内部的执行进行合并和简化,从而高速实现了AES算法的加密和解密。

并行AES算法加密解密电路的高效实现

介绍了AES算法的基本原理,为了在加密和解密过程中轮操作能够共用,结合算法的结构特点,设计了等效的轮操作结构,使用迭代的方式设计了通用的AES算法加密解密电路结构,通过外部输入信号控制其工作在加密或解密状态,整个加密解密系统电路由6个AES算法核并行组成,以提高算法处理速度.综合仿真结果显示,系统电路时钟频率为177.9 MHz,处理速度达到5.69Gb/s.

AES算法的研究

AES是为了取代旧的DES而制定的,它具有较高的安全性能。本文主要介绍了高级加密标准AES算法的加密解密流程,分析了每次轮操作的内部过程,对轮操作内部的执行进行合并和简化,从而高速实现了AES算法。

AES算法的FPGA优化实现

简要介绍了新一代高级加密标准AES算法(Rijndael)的设计原理,对其实现流程进行了详细阐述。以资源优化为目标,在对轮操作进行简化合并的基础上,完成了该算法加密部分的FPGA优化实现。

面向HT的CCMP算法的面积优化实现方法

根据802.11iAES加密/解密算法的要求,配合给定的系统时钟频率,提出了较为节约面积的、极为规则的AES运算电路的实现方法。通过分析系统时钟与系统数据吞吐量的要求,给出了较为合理的面向HT(High Throughput)的802.11i CCMP AES算法系统架构,对其中的AES运算单元的实现方法进行分析比较,得出了较小面积的AES运算单元的实现方案。用Design Compiler做综合分析后发现,优化后的面积比现有的方法至少下降了31,从而有效地降低了IC的成本。

Mass transfer in gas–liquid stirred reactor with various triple-impeller combinations

The gassed power demand and volumetric mass transfer coefficient （kca） were investigated in a fully baffled, dished-base stirred vessel with a diameter of 0.30 m agitated by five triple-impeller combinations. Six types of impellers （six-half-elliptical-blade disk turbine （HEDT）, four-wide-blade hydrofoil impeller （WH） pumping down （D） and pumping up （U）, parabolic-blade disk turbine （PDT）, and CBY narrow blade （N） and wide blade （W）） were used to form five combinations identified by PDT ＋ 2CBYN, PDT ＋ 2CBYw, PDT ＋ 2WHD, HEDT ＋ 2WHD and HEDT ＋ 2WHo, respectively. The results show that the relative power demand of HEDT ＋ 2WHu is higher than that of other four impeller combinations under all operating conditions. At low superficial gas velocity （uc）, kLa differences among impeller combinations are not obvious. However when UG iS high, PDT ＋ 2WHD shows the best mass transfer performance and HEDT ＋ 2WHu shows the worst mass trans- fer performance under all operating conditions. At high uc and a given power input, the impeller combinations with high agitation speed and big projection cross-sectional area lead to relatively high values of kLa. Based on the experimental data, the regressed correlations of gassed power number with Froude number and gas flow number, and kLa with power consumption and superficial gas velocity are obtained for five different impeller combinations, which could be used as guidance for industrial design.

An efficient design tool based on FEM for evaluating effects of components properties and operating conditions on interaction of tire with rigid road

It is noted that any variation in operating conditions has a considerable effect on the tire/road interaction. Furthermore,choosing a range of proper values for carcass stiffness is very essential for both tire safety and effective driving action. In this work,an elaborated 3D model fully compliant with the geometrical size of radial tire 185/60 R15 is worked up, for evaluating the effects of components properties and working conditions on deformation and stress/strain fields created inside the tire. For the simulation, the tire structure is assumed to be composed of tread, carcass ply, and bead. The mechanical behavior of rubber as main component of tire is described by Mooney-Rivlin material model. The comparison of the obtained results and laboratory tests demonstrates the validity and high accuracy of analysis.

Analysis on Causes of Scaling in Flue Gas Turbine of FCCU and Countermeasures

Causes of scale deposition in flue gas turbine expander of FCCU were analyzed based on some aspects,including the types and operating conditions of flue gas turbines,properties and composition of feedstocks and catalysts,and operating conditions of the reactor and regenerator.Some countermeasures were proposed for preventing scale deposition in flue gas turbine of FCCU.

Decoupling Control of Lateral Dynamics for 4WS Vehicle

An four wheel steering (4WS) feedback control system that simultaneously achieves both body sideslip angle and yaw rate responses always desirable regardless of changes in vehicle dynamics. Quantitative feedback theory (QFT) is offered as the main tool for designing the control law. Inverted decoupling is also employed to make multivariable quantitative feedback design easier. Various nonlinear analyses are carried out and show that the proposed control system is a robust decoupling controller which not only makes body sideslip angle and yaw rate of the vehicle track the desired reference input signals respectively, but also satisfies the requirement of robustness for the control system. The results also indicate that the control system can make it available to realize ideal lateral steering dynamics tracking for vehicles.

Effect of some operational variables on bubble size in a pilot-scale mechanical flotation machine

This work aims to provide a relationship of how the key operational variables of frother type and impeller speed affect the size of bubble （D32）. The study was performed using pilot-scale equipment （0.8 m^3） that is up to two orders of magnitude larger than equipment used for studies performed to date by others, and incorporated the key process variables of frother type and impeller speed. The results show that each frother family exhibits a unique CCC95-HLB relationship dependent on n （number of C-atoms in alkyl group） and m （number of propylene oxide group）. Empirical models were developed to predict CCC95 from HLB associated with other two parameters a and ft. The impeller speed-bubble size tests show that D32 is unaffected by increased impeller tip speed across the range of 4.6 to 9.2 m/s （representing the industrial operating range）, although D32 starts to increase below 4.6 m/s. The finding is valid for both coalescing and non-coalescing conditions. The results suggest that the bubble size and bubble size distribution （BSD） being created do not change with increasing impeller speed in the quiescent zone of the flotation.

Comparative Performance of Fixed-Speed and Variable-Speed Wind Turbine Generator Systems

In the early development of the wind energy, the majority of the wind turbines have been operated at constant speed. Subsequently, the number of variable-speed wind turbines installed in wind farms has increased. In this paper, a comparative performance of fixed and variable speed wind generators with Pitch angle control has been presented. The first is based on a squirrel cage Induction Generator （IG） of 315 kW rated power, connected directly to the grid. The second incorporated a Permanent Magnet Synchronous Generator （PMSG） of 750 kW rated power. The performances of each studied wind generator are evaluated by simulation works and variable speed operation is highlighted as preferred mode of operation.

Accidents during Tanker Accident in Confined Spaces

One of the major hazards when working onboard Tankers is working in confined spaces, improving the procedures in working in such spaces is obvious, but developing the equipments used in rescue operation is rare to happen, that＇s why this paper is focusing on differentiating between the manual ＆ more developed equipments used specially in rescuing the crew in such an adequate time, to save the workers＇ life. The manual way is called ＂MUCKY CRANE＂ which is used for rescue purposes onboard tankers, in any of the confined spaces, should be replaced by excel crane which is air or hydraulic driven machine, to achieve better results. As safety precautions measures taken in such tasks are not enough for the required objective achievement. Such safety procedures have been discussed and critical situations have been pointed out.

Performance Analysis of the Aeration Valves and Its Protections at the Generating Units in ITAIPU Hydroelectric Power Plant

With the growing energetic need present in the world, it is increasingly necessary for the researches and facilities to seek a better use of renewable natural resources. This paper is applied in the study of the performance of the aeration system of the Francis turbines present in Itaipu Hydroelectric Power Plant. When a Francis turbine operates off its optimal conditions, a vortex is formed inside the draft tube that, besides produces cavitation and pressure fluctuations, can pulse at frequencies with risk of resonance with hydraulic system, producing efforts and vibrations that may cause structural failures in the turbines, generators and civil parts of the power house. These damaging effects can be reduced using atmospheric aeration of the turbines. Because of this, the availability and effectively of the aeration system is fundamental to smooth the behavior of the turbines, helping preserve the health of the power plant. An analysis of the performance of the aeration system will be done using maintenance records and disturbances analysis reports （RAP）, allowing verification of the operating conditions of the turbine and fatality of water inlet in air pipes. Through the improvements detected, it is possible to reduce machine stoppages by tripping, thus increasing the availability of the turbines.

Single Platform Integration Environment for Turbine Rotor Design and Analysis

The present article covers briefly state of the art software interoperability technical solutions and the development of the first module of a new single platform D ＆ A （design ＆ analysis） tool for simulation and prediction of stress and burst behavior of turbine rotating disc a preliminary design stage. This platform singularity requires integration of multiple CAD （computer assisted design） ＆ FEA （finite element analysis） tools processing in batch mode and driven from a SPIE （single platform integration environment）. This first module is also to demonstrate, for an axial turbine disc hub axi-symmetric component, feasibility and usefulness of such a platform at preliminary design stage. Expected benefits of the D ＆ A single platform are to improve output accuracy, reduce cycle time, improve process quality and improve resource productivity.

AES算法的快速低功耗ASIC实现

论文根据一种改进的AES密码算法,提出了其低功耗ASIC设计与实现的方法。通过分析CMOS电路功耗产生原因,介绍了动态功耗管理、门控时钟和操作数隔离等低功耗设计方法,给出了该AES密码算法详细的低功耗实现方案。用Power Compiler做功耗分析后发现,优化后的功耗比优化前的功耗降低了43%,满足低功耗的要求。

Investigation of the combustion deterioration of an automotive diesel engine under transient operation

With increasingly stringent emission regulations and demand for fuel economy by the public,the combustion and emission problems of automotive diesel engines during transient operation have become vital and urgent issues.In this study,combustion deterioration has been experimentally analyzed using a heavy-duty turbocharged diesel engine running under transient conditions(constant speed and increasing torque).Optimization of the transient combustion process was performed by adjusting the fuel injection parameters.The results indicated that the notable combustion deterioration relative to steady state operation while transient was a function of the delay in the air-supply to the turbocharged engine,and took the form of combustion phasing delay,resulting in rapidly increasing smoke emission and fuel consumption.However,the delay in combustion phasing can be controlled by advancing the fuel injection timing,effectively increasing thermal efficiency.Unfortunately,smoke and NO x emissions increased at the same time.The deterioration in combustion phasing can also be improved by increasing injection pressure,resulting in decreased smoke emission while NO x emission increased.It is worth noting that the effective thermal efficiency first increased and then decreased as fuel injection pressure increased during transient operation.

Experimental and Numerical Investigation of Centrifugal Pumps with Asymmetric Inflow Conditions

Most of the times pumps operate off best point states.Reasons are changes of operating conditions,modifications,pollution and wearout or erosion.As consequences non-rotational symmetric flows,transient operational conditions,increased risk of cavitation,decrease of efficiency and unpredictable wearout can appear.Especially construction components of centrifugal pumps,in particular intake elbows,contribute to this matter.Intake elbows causes additional losses and secondary flows,hence non-rotational velocity distributions as intake profile to the centrifugal pump.As a result the impeller vanes experience permanent changes of the intake flow angle and with it transient flow conditions in the blade channels.This paper presents the first results of a project,experimentally and numerically investigating the consequences of non-rotational inflow to leading edge flow conditions of a centrifugal pump.Therefore two pumpintake-elbow systems are compared,by only altering the intake elbow geometry:a common single bended 90°elbow and a numerically optimized elbow(improved regarding rotational symmetric inflow conditions and friction coefficient).The experiments are carried out,using time resolved stereoscopic PIV on a full acrylic pump with refractions index matched(RIM)working fluid.This allows transient investigations of the flow field simultaneously for all blade leading edges.Additional CFD results are validated and used to further support the investigation i.e.for comparing an analog pump system with ideal inflow conditions.

Experimental Study of Operation Performance for Hydrocarbon Fuel Pump with Low Specific Speed

In this paper, a small flow rate hydrocarbon turbine pump was used to pressurize the fuel supply system of scramjet engine. Some experiments were carried out to investigate the characteristics of turbine pump driven by nitrogen or combustion gas under different operating conditions. A experimental database with regard to the curves of the rotational speed, mass flow rate and net head with regard to centrifugal pump were plotted. These curves were represented as functions of the pressure and temperature at turbine inlet/outlet and the throttle diameter at downstream of centrifugal pump. A sensitivity study has been carried out based on design of experiments. The experimental was employed to analyze net head of centrifugal and throttle characteristics. The research results can accumulate foundations for the close loop control system of turbine pump.

Unsteady Numerical Simulation of Hot Streak/Blades Interaction and Film Cooling

Deeply research on management and application of hot streak is an important way to breakthrough technique obstacle of aero engine hot components.Numerical method is a useful instrument to investigate the correlative problems.Firstly the paper developed independently three dimensional unsteady parallel computational code-MpiTurbo based on Fortran 90 and MPI at Linux operating system.Then unsteady numerical simulation was carried out to investigate impacts of the factors,which included circumferential locations of hot streak and clocking positions of blade rows,on the thermal environment of a 1+1 counter-rotating turbine.The results clearly indicated that clocking positions of hot streak/blade row and blade row/blade row had great influence on the time-averaged temperature distribution of the third blade row.Therefore,it can be effective for improving thermal environment of turbine to optimize blade parameters and clocking positions.Lastly film cooling layout was designed by the repetitious steady simulation based on source term method.And the flow structure detail was given by the unsteady simulation.