Assessment of the variation factor for a limiting load disabling a system

Formulas are derived that allow assessment of the variation factor of the limiting load that disables a complex system containing sequentially connected elements. The variation factor of the limiting load of a system is shown to be limited from below by the variation factor of the limiting load of a balanced-life system, where the variation factor of the limiting load of an element equals the minimal variation factor. The limitation from above is determined by the maximal variation factor of the limiting load of an element.     

Asymptotic analysis of a wedge crack in an anisotropic dielectric material

The asymptotic problem of a conducting crack emanating from the vertex of a wedge in an anisotropic dielectric material under purely electric loading is investigated. The wedge crack in an isotropic material is solved using a conformal mapping technique. The solution of the wedge crack in an anisotropic dielectric material is obtained from that for the transformed isotropic problem after applying a linear transformation method. The electric field intensity factor for the anisotropic wedge crack is obtained in the closed form. The effects of crack and wedge angles as well as anisotropic parameters on the electric field intensity factor are illustrated. The electric field intensity factor is numerically calculated by using the J integral and finite element analysis to validate the exact solution of the electric field intensity factor.     

Design of a transverse-flux permanent-magnet linear generator and controller for use with a free-piston stirling engine

Transverse-flux with high efficiency has been applied in Stirling engine and permanent magnet synchronous linear generator system, however it is restricted for large application because of low and complex process. A novel type of cylindrical, non-overlapping, transverse-flux, and permanent-magnet linear motor(TFPLM) is investigated, furthermore, a high power factor and less process complexity structure research is developed. The impact of magnetic leakage factor on power factor is discussed, by using the Finite Element Analysis(FEA) model of stirling engine and TFPLM, an optimization method for electro-magnetic design of TFPLM is proposed based on magnetic leakage factor. The relation between power factor and structure parameter is investigated, and a structure parameter optimization method is proposed taking power factor maximum as a goal. At last, the test bench is founded, starting experimental and generating experimental are performed, and a good agreement of simulation and experimental is achieved. The power factor is improved and the process complexity is decreased. This research provides the instruction to design high-power factor permanent-magnet linear generator.     

Optimizing convexity defect in a tile industry using fuzzy goal programming

In most designed experiments, the main focus is to find the factor settings that optimize a quality response regardless of engineer’s preferences about factor settings. Further, in tiles industry convexity defects result in huge quality costs as well as production losses. This research, therefore, aims at optimizing convexity defect while considering process engineers’ preferences using fuzzy goal programming (FGP). Three two-level key process factors are considered, including below-rollers temperature, above-rollers temperature, direct blow air. Experiments are conducted with two repetitions; in each the convexity is measured on four tiles. Two optimization techniques are employed to determine the combination of optimal factor settings, including the Taguchi method and latter technique. The Taguchi approach and FGP approach provide relative improvements of 61.2% and 41.2%, respectively. Although the former technique reduces convexity larger than latter approach, it failed to satisfy the preferences on the settings of process factors. In contrast, the optimal factor settings obtained using FGP completely satisfy engineers’ preferences. In conclusion, FGP successfully optimizes process performance and completely satisfies process engineers’ preferences in tiles industry.     

Finite crack propagation in a micropolar elastic solid

The dynamic propagation of a finite crack under mode-1 loading in a micropolar elastic solid is investigated. By using an integral transform method, a pair of two-dimensional singular integral equations governing stress and couple stress is formulated in terms of displacement transverse to the crack, macro and micro rotations, and microinertia. These equations are solved numerically, and solutions for dynamic stress intensity and couple stress intensity factors are obtained by utilizing the values of the strengths of the square root singularities in macrorotation and the gradient of microrotation at the crack tips. The motion of the crack tips and the load on the crack surface are not prescribed in the formulation of the problem. Therefore, the method of solution is applicable to nonuniform rates of propagation of a crack under an arbitrary time-dependent load on the crack surface. As an example, the diffraction of a micropolar dilatational wave by a stationary crack is considered. The behavior of the microrotation field and the dynamic couple stress intensity factor, influenced by microinertia, in addition to the dynamic stress intensity factor, are examined. The classical elasticity solution for the corresponding problem arises as a special case when the micropolar moduli are dropped from the present solution.     

Analysis of a kinked crack in an anisotropic material under antiplane deformation

This paper analyzes the asymptotic problem of a kinked crack in an anisotropic material under antiplane deformation. Using the linear transformation method proposed in this paper, a solution to the asymptotic problem of a kinked crack in an anisotropic material can be obtained from the solution of the corresponding isotropic kinked crack problem. The exact solution of the stress intensity factor for the kinked crack in the anisotropic material is obtained from the solution of the isotropic problem. The effect of the kink angle and two anisotropic parameters on the stress intensity factor is discussed for the inclined orthotropic material as well as the anisotropic material. In order to verify the exact solution of the stress intensity factor, numerical calculations are performed by using finite element analysis.     

Discussion on calculation of the local flexibility due to the crack in a pipe

The stress intensity factor plays an important role in the calculation of the local flexibility due to the crack in a cracked structure. Many researches on the stress intensity factors in a cracked beam or rotor have been made, but there are some difficulties in calculating the stress intensity factors in a cracked pipe. Maiti et al. obtained the local flexibility due to the crack in a pipe experimentally by deflection and natural frequency methods without calculating the stress intensity factor. In this paper, the stress intensity factor in a cracked pipe can be calculated by dividing a cracked pipe into a series of thin annuli, and a method to calculate the local flexibility due to the crack in a pipe is presented. The experiment results are given to verify the effectiveness of such a method.     

Operational Features of a Cold-Cathode Duoplasmatron in a Mode with a Small Pulse Off-Duty Factor

The operational features of a duoplasmatron generating an ion current with a pulse duration of 35 and 220 s and at a repetition rate of 1, 5, and 25 Hz are described. Methods for reducing the flow of a nonionized gas from the ion source penetrating into the accelerator are presented. It is shown that a cold-cathode duoplasmatron can be used in linear accelerators operating in the mode of generation of charged-particle current pulses with a small off-duty factor.     

Analysis of a conducting crack in an electrostrictive ceramic under combined electric and mechanical loading

A conducting crack in an electrostrictive ceramic under combined electric and mechanical loading is investigated. Analysis based on linear dielectric model predicts that the surfaces of the crack are not open completely but they are contact near the crack tip. The complete solution for the crack with a contact zone in a linear electrostrictive ceramic under combined electric and mechanical loading is obtained by using the complex variable formula. The asymptotic problems for a semi-infinite crack with a partial opening zone as well as for a fully open semi-infinite crack in a nonlinear electrostrictive ceramic are analyzed in order to investigate the effect of the electrical nonlinearity on the stress intensity factor under small scale nonlinear conditions. Particular attention is devoted to a finite crack in the nonlinear electrostrictive ceramic subjected to combined electric and mechanical loading. The stress intensity factor for the finite crack under small scale nonlinear conditions is obtained from the asymptotic analysis.     

Results of testing a radio interferometer with digital signal processing in a 400-MHz band

Results of testing the astronomical radio interferometer at the Svetloe-Zelenchukskaya observatory using digital signal processing channels with 400-MHz bands are presented. Observation data were recorded in the VDIF format with a 2048-Mbit/s rate by the Mark 5C terminal. Simultaneously, data obtained using the standard equipment of the Quasar complex were recorded. The observation results were processed by both the DiFX experimental software correlator and APK standard correlator, which is a part of the Quasar complex. Due to the used wideband data acquisition system, the sensitivity of the radio interferometer went up by a factor of 4.7–4.8, and the accuracy of determining the time position of the correlation response increased by a factor of 1.6. The experiment confirmed the efficiency of the new wideband digital data acquisition system and possibility of its applications in astronomical radio interferometers with small (～13 m) antennas.     

The stress and strain concentrations of out-of-plane bending plate containing a circular hole

The elastic stress and strain fields of a finite thickness plate containing a circular hole subjected to out-of-plane bending are systematically investigated using the finite element method. It is found that the stress and strain concentration factors of the finite thickness plate are different except at the notch root of the free surface even if the plate is in elasticity state. The through-thickness distributions of strain components are not linear with the distance from the mid-plane in the stress concentration region. The nonlinearity of these distributions is very severe near the free surface especially in thick plate. The Euler-Bernoulli hypothesis and Kane-Mindlin's plate theory may not be reasonable to be used in the stress concentration region especially near the free surface. The maximum stress and strain do not always occur on the free surface and their locations depend on the moment ratio and the plate thickness. The maximum stress and strain concentration factors occur on the free surface only in thin plates of small moment ratio. The differences between the maximum value and surface value of stress concentration factor increase with the plate thickness and the moment ratio. This relation of strain concentration factor is similar to the one of stress concentration factor. But the difference magnitude of stress concentration factor is larger than that of strain concentration factor in same plate.     

Optimization of a reversed trapezoidal fin using a 2-D analytic method

A reversed trapezoidal fin with variable fin base thickness is optimized based on the fixed fin volume by using a two-dimensional analytic method. The variation of temperature along the normalized Y position at the fin tip is presented. For fixed fin volumes, the maximum heat loss, the corresponding optimum fin effectiveness, fin base height and fin tip length as a function of the fin base thickness, fin shape factor and the fin volume are presented. One of the results shows that both the optimum heat loss and the optimum fin length increase with the increase of the value of fin shape factor.     

激光非接触式彩管荫罩Q值测量机研制

为提高彩管荫罩Q值测量的效率和精度，提出了一种综合运用开放式数控和激光非接触式测量原理的测量方法，并研制出了Q值测量机样机。介绍了系统的主体结构，机械传动执行机构和控制结构；激光三角测量法和Q值测量的原理及软件功能。给出了测量实例数据，通过与现有接触式测量机的测量数据比较，得出了在保证测量精度的基础上，该测量机可以大大提高测量效率的结论。     

Measurements of a harmonic generation factor of radio absorbing materials in the microwave range

It is proposed to use a model of the coaxial measuring cell for estimating an intensity level of harmonics of a radio absorbing material (RAM) in the microwave range. Measurement results of the harmonic factor of a film RAM are given. It is shown that the harmonic factor substantially increases, as the power level of the sounding frequency rises, and its dependence on the length of the studied samples is also shown.     

Simulation-based metamodels for the analysis of scheduling decisions in a flexible manufacturing system operating in a tool-sharing environment

This paper presents the salient aspects of developing simulation-based metamodels for scheduling a typical flexible manufacturing system (FMS) operating in a tool-sharing environment. A discrete-event simulation model of the FMS is developed for the purpose of experimentation. Seven scheduling rules from the literature are incorporated in the simulation model for part scheduling decision. The performance measures considered for analysis are mean flow time, mean tardiness, and percentage of tardy parts. Simulation experiments have been carried out for various scenarios arising out of the settings of the mean interarrival time of parts for processing in the system and due-date factor. The simulation results are used to develop regression-based metamodels. These metamodels have been subjected to systematic analysis. The metamodels are found to offer a good prediction of the performance of FMS within the domain of their definition.     

Broken rotor bars detection by a new non-invasive diagnostic procedure

A new technique of diagnosing data for broken rotor bars in induction motors derived from two of the three stator currents, the Beirut diagnostic procedure (BDP) is presented in this paper. The theoretical principles directly related to the application of this diagnostic technique are described, emphasizing the use of a severity factor in order to evaluate the extension of the fault. Defining the severity factor as the normalized amplitude of the fault characteristic frequency enables us to draw up a table of comparison of several usual electric diagnostic methods. Besides the traditional one-phase current spectrum analysis, values of the severity factor related to electrical signals like the instantaneous powers, the current space vector modulus and finally related to the new Beirut diagnostic method are analyzed with respect to the variation of the power factor angle and of the sum of the two current side-band angular displacement. The BDP offers several advantages over the usual motor current signature analyses (MCSA) methods: it is shown how the proposed severity factor applied to the new diagnostic technique is not dependent on motor parameters such as the power factor angle and the fault type which is not the case of the instantaneous powers. In addition, the BDP has the advantage of detecting easily fault characteristic frequencies, which is not possible via diagnostic methods that use the detection of two side-band components as in the simple current spectrum.By theoretical analysis, computer simulations, and laboratory experiments, it is shown that the new method enhances the reliability of diagnostics of broken rotor bars in induction motor.     

Modeling of silicon nanoparticle formation in inductively coupled plasma using a modified collision frequency function

A model is presented to describe particle growth in inductively coupled plasma. The model consists of plasma chemistry and a coagulation module that adopts a modified collision frequency function. The modified collision frequency function is modified by a collision correlation factor that reflects the repulsive force of the particle charge in plasma in order to describe the reduction of coagulation among medium size particles (around 100 nm). In this model, plasma state and concentration of nuclei are determined by a spatially averaged global model in the plasma chemistry module. Particle growth is calculated by a coagulation module. To verify the validity of the model, comparison analysis is performed between experimental data obtained with PBMS and models, some of which are modified by a collision correlation factor. The analysis is performed with respect to dependencies on synthesis time, plasma source power and chamber pressure. From the analysis, we confirm the validity of the model that adopts a modified collision frequency function for the plasma condition.     

Acoustic damping of gas-liquid scheme injectors with a recess in a subscale combustor

Acoustic damping induced by a gas-liquid scheme injector is investigated numerically for acoustic stability by adopting an acoustic analysis. The injector consists of four parts of a main cylindrical passage, an inlet blockage, an induction bulge, and a recess at the injector outlet. Purely acoustic behavior in the combustor with a single injector is investigated for acoustic tuning of the injector and the effect of each part of the injector on acoustic damping is studied for high-temperature condition. Sinusoidal and short impulse acoustic oscillations are excited. Damping capacity of the injector is evaluated by the quantitative parameter of damping factor. From the numerical results, it is found that each injector has its own tuning length for maximum damping. An induction bulge and a recess deform the wave-form inside the injector appreciably near the inlet and the outlet, respectively. The deformation of a half-wave form makes the tuning length longer. All the wave-forms inside the optimally tuned injectors show similar forms to that of a half-wave. All the injectors have the same damping mechanism as that of a half-wave resonator. The smaller the amplitude level of the wave is at the injector outlet, the larger damping is induced by the injector. As a recess increases, both the optimal tuning length and the maximum damping factor increase. For application of the injector to an actual combustor, the optimal tuning length needs to be corrected considering high-speed flow inside the injector and high-temperature field in a chamber.     

Microdefect interacting with a main crack : A general treatment

A general solution is obtained to the two-dimensional problem of the interaction between a main crack and an arbitrarily located and oriented elliptical hole near its tip under mode I and mode II loading conditions. The analysis is based on the complex potentials of Muskhelishvili and an appropriate superposition procedure. The stress-intensity factor at the main crack is obtained in a general series form and approximate closed-form solutions are also derived using a perturbation procedure. The present solutions are verified by comparison with existing ones for special cases. Numerical examples are provided to show the effect of geometry, location and orientation of the microdefect on the stress-intensity factor of the main crack. Shielding and amplification effects resulting from the presence of the microdefect have also been examined.     

An Increase in the Energy Yield and Giant-Pulse Generation Efficiency in a Laser with Self-injection of the Initiating Radiation

Optical laser systems that ensure generation of giant pulses from a narrow-band initiating free-running oscillation upon change in the Qfactor of the laser cavity and (or) in the amplification factor in it are described. The result of experimental studies of the parameters of a giant-pulse radiation generated by this type of ruby lasers with electrooptical switching of a branched combined cavity are presented.