A study on the variation of the performance and the cost of power generation in a combined heat and power plant with the change of the user facility’s return temperature

Journal of Mechanical Science and Technology - A combined heat and power (CHP) system generates electricity from thermal energy and generates heat by utilizing the remaining thermal energy. The...     

Unusual arrangement of the inclinations of lattice planes and Ψ splitting

The X-ray stress measurements method has been most widely used to obtain the residual stresses after samples had been subjected to friction, turning, grinding etc. There is one problem, however: the stresses obtained when the incident X-rays are in the working direction are different from those obtained when the incident X-rays are in the opposite direction to the working direction, even if the other geometrical conditions between the incident X-rays and the specimen are the same (Ψ splitting).Transmission electron diffraction patterns of very-fined-grained (less than 200 nm) oxygen-free high conductivity copper which had been repeatedly subjected to unidirectional friction showed unidirectional spot displacements. This suggests that the inclinations of the lattice planes were arranged in an unusual way; this could be one cause of Ψ splitting. This concept is completely different from those already reported, which attribute Ψ splitting to the residual stresses which have a component normal to the worked surface or to the phase stress in the affected layer.     

The Development Mechanism and the Technical Characteristics of the Modern Cutting Technology

Introduction Since 1980s cuttingtechnology has developedrapidly inthe developed countries .Uptothe end of 20 centuryor the beginningof 21 centurythe cuttingtechnology has en- teredthe development phase of modern cuttingtechnology featuringthe highcuttingspeed and high performance ma- chining.Looking back to the history of cutting technolo- gy,one century has passedsincethe metal cutting became one of the machiningtechnologiesfromthe very beginning of 20 century. Since then,cutting technology h…     

Use of the Reflection of Near‐Infrared Light for the Nondestructive Examination of Blood Flow and Other Applications

Abstract

Reflection of near‐infrared light is measured by commercial equipment. We found that samples in motion and at rest show differences in the intensity of reflection of a laser beam. This may suggest the possibility of its use to detect organ necrosis in vivo. In addition, we find the possibility of the use of this reflection of the near‐infrared light for the non‐destructive inspection of internal changes in perishables, e.g., their degree of ripeness.     

MAGE Spectrometer for the Investigation of Hadron–Nucleus Interactions and the Identification of Final Nuclear States

A combined spectrometer is composed of a wide-aperture magnetic spectrometer with proportional chambers and a -spectrometer based on a Ge(Li) detector. The respective momentum and the angular resolutions of the magnetic spectrometer are FWHM/p(%) = 0.59p (GeV/c) + 1.1 and 0.5–1 mrad; its average efficiency for 0°–5° angles is 85%. The energy resolution of the -spectrometer is 8 and 16 keV for 0.5- and 2.0-MeV photons, respectively; the average angular acceptance is 1.5 msr.     

Development of a Setup for the Discrimination of β+ and γ Rays

Abstract

A β⁺–γ discrimination set‐up was developed and applied to the ²²Na radioisotope. The radioisotope emits positrons (β⁺) and these positrons create γ rays by annihilating with electrons. These annihilation γ rays were used here, and the discrimination between these positrons and γ rays was investigated by the coincidence measurement between time signals and the energy signals. The detection system presented here uses a 3 inch (diameter) by 3 inch (length) NaI(Tl) inorganic scintillation detector for γ detection and 3 inch (diameter) by 3 inch (length) plastic scintillation detector for β⁺ detection.     

Applicability and generality of the modified Grübler-Kutzbach criterion

A generally applicable criterion for all mechanism mobility has been an active domain in mechanism theory lasting more than 150 years. It is stated that the Modified Grübler-Kutzbach criterion for mobility has been successfully used to solve the mobility of many more kinds of mechanisms, but never before has anyone proven the applicability and generality of the Modified Grübler-Kutzbach criterion in theory. In order to fill the gap, the applicability and generality of the Modified Grübler-Kutzbach Criterion of mechanism mobility is systematically demonstrated. Firstly, the mobility research background and the Modified Grübler-Kutzbach criterion are introduced. Secondly, some new definitions, such as half local freedom, non-common constraint space of a mechanism and common motion space of a mechanism, etc, are given to demonstrate the correctness and broad applicability of the Modified Grübler-Kutzbach criterion. Thirdly, the general applicability of the Modified Grübler-Kutzbach criterion is demonstrated based on screw theory. The mobilities of the classical DELASSUS mechanisms and a modern planar parallel mechanism, are determined through the Modified Grübler-Kutzbach criterion, which are as examples to show the practical application of the Modified Grübler-Kutzbach criterion.     

The Mathematical Simulation and Study of the Electrical Resistance of the Friction Zone of the Hip Joint Endoprosthesis with a Metal–Metal Friction Pair

The paper has described a model of the static load on the hip joint that takes into account the anthropological parameters and a mathematical model of the change in the resistance of the endoprosthesis under the influence of an external load at different rotation angles of the cup component. The theoretical studies have revealed the character of the changes and assessed the possible ranges of variations in the diagnostic parameter that are required to develop diagnostic equipment and methods for testing and interpreting diagnostic information during the tribotesting of individual types of implants.     

Modeling and analysis of the effects of processing parameters on the performance characteristics in the high pressure die casting process of Al–SI alloys

The high pressure die casting (HPDC) process has achieved remarkable success in the manufacture of aluminum–silicon (Al–SI) alloy components for the modern metal industry. Mathematical models are proposed for the modeling and analysis of the effects of machining parameters on the performance characteristics in the HPDC process of Al–SI alloys which are developed using the response surface methodology (RSM) to explain the influences of three processing parameters (die temperature, injection pressure and cooling time) on the performance characteristics of the mean particle size (MPS) of primary silicon and material hardness (HBN) value. The experiment plan adopts the centered central composite design (CCD). The separable influence of individual machining parameters and the interaction between these parameters are also investigated by using analysis of variance (ANOVA). With the experimental values up to a 95% confidence interval, it is fairly well for the experimental results to present the mathematical models of both the mean particle size of primary silicon and its hardness value. Two main significant factors involved in the mean particle size of primary silicon are the die temperature and the cooling time. The injection pressure and die temperature also have statistically significant effect on microstructure and hardness.     

Effect of γ irradiation on the scintillation and optical properties of lead tungstate crystals

The radiation hardness of a test batch of lead tungstate crystals grown by a new technology at the Bogoroditsk Technochemical Plant for the PANDA experiment has been measured. The optical properties of the crystals have been investigated at temperatures ranging from +20 to ?20°C under irradiation with a ¹³⁷Cs radionuclide source. The light yield in the crystal is seen to considerably increase with a decrease in its temperature. In addition, the loss of the crystal transparency under irradiation at low temperatures is higher than under irradiation at room temperature. As a result, at a fixed dose rate, the signal from the crystal at a negative temperature may be considerably greater than the signal at room temperature even if the accumulated dose is high.     

Effects of Gas Composition,Humidity and Temperature on the Tribology of the Head/Disk Interface—Part II: Model and Analysis

A qualitative model for the effect of water condensation on the frictional behavior of unlubricated and lubricated carbon-overcoated disks is presented. The model suggests that for unlubricated disks adsorbed water acts as a lubricant, protecting the unlubricated disk surface from direct solid/solid contact and direct exposure to the environment. For lubricated disks, the interaction between adsorbed water and lubricant molecules seems to be responsible for the effect of humidity on the frictional behavior of lubricated disks. The effect of temperature on the frictional behavior of the head/disk interface is discussed in terms of surface energy, lubricant viscosity and mobility.     

Analysis of the Contribution of Adhesion and Hysteresis to Shoe–Floor Lubricated Friction in the Boundary Lubrication Regime

Slip and fall accidents cause frequent occupational injuries. Despite recent evidence that boundary lubrication is relevant to slipping, few studies have examined the mechanisms that contribute to shoe?Cfloor friction in this lubrication regime. This study aims to identify the contributions of adhesion and hysteresis to friction in boundary lubrication. Three shoe materials (40 Shore A hardness polyurethane, 60 Shore A hardness rubber, and 70 Shore A hardness rubber), two floor materials (vinyl and marble), and six lubricants (water, 1.5?% detergent, 25?% glycerol?C75?% water, 50?% glycerol?C50?% water, 75?% glycerol?C25?% water, and canola oil) were tested at a single sliding speed (0.01?m?s^?1). Dry adhesion and hysteresis were quantified for each of the shoe?Cfloor combinations and lubricated adhesion was quantified for all shoe?Cfloor-fluid combinations. The contribution of adhesion and hysteresis to shoe?Cfloor-lubricant friction was affected by both the shoe and floor material due to differences in hardness and roughness. Lubricated adhesion was complex and multifactorial with contributions from the shoe, fluid, shoe?Cfloor interaction, floor-lubricant interaction, and shoe-lubricant interactions. A simple regression model including two fluid coefficients and the dry adhesion friction force was able to predict 49?% of the lubricated adhesion friction variability.     

The optimization of annealing and cold-drawing in the manufacture of the Ni�CTi shape memory alloy ultra-thin wire

In this paper, the mechanical properties of the Ni?C50.5?at.%?CTi alloy super-elastic wires manufactured by a conditioned multi-passed process of annealing and cold-drawing have been studied. The annealing temperature of 450~800°C, time of 20?min~3?h and the cold-drawing amount of 6.9%~39% were chosen. Their effects on the thermo, mechanical, and surface morphology of the Ni?CTi wires have been studied. The differential scanning calorimetry and tensile-recovery tests were adopted to obtain the phase transformation temperatures and mechanical hysteresis of the Ni?CTi SMA wires with different treatment conditions. The results show that the phase transition temperature of Ni?CTi wire can be changed by varying the annealing temperature and time; cold-drawing deformation and subsequent annealing have a great influence on the super-elasticity. The process with 39% cold-drawing amount, 600°C and 20?min annealing is shown to be effective in the manufacturing.     

Effect of the cut-off frequency on rough-point and flat-surface contacts?

In the past years, contact between two bodies has been studied from various ways that do not consider the cut-off frequency effect on the contact mechanism. This paper reports the correlation between rough point contact and flat surface contact at different cut-off frequencies of filter. The similarity and difference between the two types of contact mechanisms are presented for materials with linear or elasticperfectly plastic deformation. The conjugate gradient method (CGM) is used for analysing the rough point contact, while the rough flat surface contact is studied with an improved CGM in which the influence coefficient for the elastic deformation of the rough flat surface is obtained with finite element method. Numerical results show that for the above two types of contacts, their von Mises stress and maximum shear stress are greatly affected by the cut-off frequency of a high-pass filter. Moreover, a decrease in the cut-off frequency leads to an increase in the contact area and a decrease in the approach for the rough flat surface contact, while the opposite variations is for the point contact between rough bodies with the small radii.     

The Control and Data-Acquisition System of the СПРУТ-VI Instrument Package

The control and data-acquisition system of the -VI instrument package mounted on board the Mir space station in 1999 is described. The system was based on two onboard microcomputers installed both inside and outside a pressurized compartment. The system unified the operation of various sets of equipment (radiation monitoring, radiometric, wave, materials science, and magnetic) and allowed the transfer of large data arrays from detectors located on the outer surface of the station. It was possible to reprogram the entire system under space flight conditions. An off-line data-recording unit, which was later brought back to Earth, was used.     

Vibration modeling and analysis of wire during the WEDM process

During the wire electrical discharge machining (WEDM) process, the vibrations of the wire generated by the gap force is the main cause of imprecision. To achieve more precise results with better accuracy, understanding of the vibration management of the wire is essential. In this article, the wire’s vibration behavior is introduced briefly, followed by an exploration of an equation, derived from Hamilton’s principle, which expresses the vibration of a wire moving axially. This equation is presented under some simplified assumptions. In addition, the relationship between the maximum amplitude of the vibration and the main relative variables is presented. The solution demonstrates that a thicker workpiece results in a larger amplitude of vibration, yet the axial speed of the wire has no impact on the maximum amplitude.     

Relationship between the thickness of β-FeSi2 thin film and the solar photo wavelength

The β-FeSi2 thin film has been applied in the research field of the solar cell,and the thickness of β-FeSi2 absorption layer was chosen through the experiments.However,Up to now neither the optimal thi...     

Electrical and electrochemical properties of the MEH–PPV and MEH–PPV doped calix[4]arene derivative layers for the detection of Cu and Na ions

A modified ITO electrode based on conducting polymer (MEH–PPV) matrix doped with the calix[4]arene molecules (β-ketoimine calix[4]arene) is deposited by spin coating. The carrier transport mechanism of the MEH–PPV and MEH–PPV:β-ketoiminecalix[4]arene films is investigated by using I–V characteristics measurements. The conduction mechanisms in these thin films are identified to be a space-charge-limited current (SCLC). The dielectric behavior of the MEH–PPV and the composite β-ketoimine calix[4]arene/MEH–PPV thin films are investigated by impedance spectroscopy (IS). The Cole–Cole plots are studied showing single semicircles and the solid interfaces are modeled by an equivalent circuit. The characteristics of chemical sensors based on MEH–PPV and MEH–PPV doped β-ketoimine calix[4]arene thin films for the detection of Cu²⁺ and Na⁺ ions are investigated by electrochemical impedance spectroscopy (EIS). The experimental impedance data of the modified electrodes are modeled by an equivalent circuit using the Z-View software. The inclusion of calixarene molecules into conducting polymer (MEH–PPV) exhibited considerable rise charge transfer resistance and improves sensing properties.     

Generation of the second harmonic of laser radiation in powders of pure and doped potassium nitrate in the temperature interval of 25–160 °C

The temperature dependence of the intensity of generation of the second harmonic of laser radiation with λ = 1.064 µm in various powders of extra-pure potassium nitrate is studied. The powders are obtained from crystals grown in a KNO₃-Ba(NO₃)₂—H₂O water-salt system. It is demonstrated that the centrosymmetric phase is crystallized from pure solutions. If Ba(NO₃)₂ is added to the solution, non-centrosymmetric phases of KNO₃ or 2KNO₃ · Ba(NO₃)₂ double salt are formed. As the crystals are cooled down from the temperature of 160 °C, the samples display a ferroelectric phase transition and a hysteresis relaxation dependence of the nonlinear optical response due to the method of sample preparation.     

Project of Guilin Rubber Machinery for the Ministry of Commerce Has Been Checked and Accepted

A few days ago, the ＂1725（70#）hydraulic tire curing press＂, the exporting project researched and developed for the Ministry of Commerce has been checked and accepted. This project was born by Guilin Rubber Machinery Group Co., Ltd.