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To explore the evolution mechanism of multistage machining processes and torsional fatigue behaviour based on strain energy for the first time and provide process optimization of axis parts of low-alloy medium-carbon steel for service performance, four multistage machining processes were applied to the 45CrNiMoVA steel, including the rough turning process (RT), RT + the finish turning process (FRT), FRT+ the grinding process (GFRT) and RT+ the finish turning process on dry cutting condition (FRT0). The result showed that the FRT process’s average low-cycle torsional fatigue life increased by 50% when it evolved from the RT process. The lower surface roughness of Ra 1.3 μm caused the total strain energy to increase by 163.8 Pa mm/mm instead of the unchanged strain energy density, and the crack feature evolved from some specific bulges to flat shear plane characteristics. When the GFRT process evolved from the FRT process, its average fatigue life increased by 1.45 times, compared with the RT process. Plastic strain amplitude decreased by 21%, and the strain energy density decreased by 4% due to more considerable compressive residual stress (-249 MPa). Plastic deformation layer depth had a consistent tendency with surface roughness. In this paper, surface integrity evolutions on cyclic characteristics and fatigue behaviour have also been explained. A fatigue life prediction model based on the energy method for machined surface integrity is proposed.

Laser Shock Peening (LSP) is a well-established surface treatment commonly used to improve mechanical properties of material's surfaces. To further understand the relationship between tensile property and fatigue life improvement of high strength low alloy steel in the LSP process, LSP treatment of 32CrNi high strength low alloy steel was carried out by YAG laser with pulse energy of 15 J, and tensile property was tested by electronic universal material testing machine. Surface morphology, residual stress and tensile fracture of the specimens before and after LSP were observed by white light interferometer (WLI), X-ray measuring apparatus and scanning electron microscope (SEM). Result shows that LSP did not change tensile strength of 32CrNi steel but cause yield characteristic transform from obvious yield point to no yield phenomenon which is the only factor benefiting fatigue life, indicating that the increment of fatigue life was probably related to the disappearance of yield phenomenon. Formation mechanisms of tensile fractures and yield phenomenon induced by LSP at room temperature were also discussed and completely revealed. Deeper compressive residual stress and flat grains contributed to the transition of yield characteristic and lower elongation rate of 32CrNi steel subjected to LSP.

Spinel LiNi0.5Mn1.5O4, which is considered as one of the most attractive candidates for high energy density battery due to its high voltage platform over 4.7 V, suffers from the side reactions with electrolyte, strong oxidability of Ni4+ and therefore the complicated and frangible Solid Electrolyte Interfaces (SEI) layer that hinders the practical application of LiNi0.5Mn1.5O4. In this work, traditional co-precipitation method is applied and improved by anion and cation doping method to construct superior interface on the surface of LiNi0.5Mn1.5O4 to suppress side reactions especially at high temperature. Detailed properties including structure, morphology and electrochemical performance of pristine sample, single-doped and co-doped samples are probed. Physical characterizations reveal that the co-doped sample with regular octahedron has a moderate grain size and specific surface area between Al and F single doping, and holds the advantages of rate performance and capacity retention causing by Al doping and better stability under high temperature constructing by F. It exhibits the best capacity retention of 92% after 200 cycles under 55 °C, which is higher than that of the pristine sample (87%). Analysis of the electrode after cycling shows that doping reduces the thickness of the electrode interface film and the content of inorganic substances such as LiF to improve the interface characteristics and the high temperature cycling performance. This work has certain significance for the commercial application of LiNi0.5Mn1.5O4.

AISI 321 stainless steel has excellent resistance to intergranular corrosion and is generally used in nuclear power reactor vessels and other components. The as-cast and wrought structures are quite different in hot workability, so physical simulation, electron back-scatter diffraction, and hot processing maps were used to study the mechanical behavior and microstructure evolution of as-cast nuclear grade 321 stainless steel in the temperature range of 900–1200 °C and strain rate range of 0.01–10 s−1. The results showed that the flow curve presented work-hardening characteristics. The activation energy was calculated as 478 kJ/mol. The fraction of dynamic recrystallization (DRX) increased with increasing deformation temperature and decreasing strain rate. DRX grain size decreased with increasing Z value. Combining the hot working map and DRX state map, the suggested hot working window was 1000–1200 °C and 0.01–0.1 s−1. The main form of instability was necklace DRX. The nucleation mechanism of DRX was the migration of subgrains. The δ phase reduced the activation energy and promoted DRX nucleation of the tested steel.

Fluorescent materials in the recent past have found numerous novel applications in various fields such as medicine, environment, electronics and coatings. For smart coating applications, durability, responsiveness and repeatable functionalities are desirable especially in their solid state. However, due to the known aggregation-caused quench (ACQ) effect, many traditional fluorescent molecules’ intensity tends to diminish at aggregated state. This ultimately affects the traditional fluorescent materials’ use in these applications. To develop smart coatings with suitable properties and responsiveness, herein, a novel aggregation-induced emission (AIE)-based composite fluorescent latex was prepared and systematically studied. Briefly, the approach involved first grafting tetraphenylethene (TPE) derivant onto the silica sol. The resultant modified silica sol could then emit strong fluorescent light courtesy of TPE’s restricted intramolecular rotation. Further, the modified silica sol was used as the surface to emulsion polymerize acrylic latex, forming a fluorescent composite core-shell structure. As a smart and responsive fluorescent composite coating, when cured, it showed fluorescent responsiveness to the external stimuli, such as water and toluene vapor, demonstrating possible application in smart paints.

In general, mechanical properties of most materials under dynamic loading are completely different from those under static/quasi-static loading. In this paper, a comparative study between the selective laser melted Ti-6Al-4V alloy and its heat-treated counterpart was carried out. After heat treatment, the microstructure transformed from full fine acicular α' into basket-weave morphology with coarsened α + β lamella, grain boundaries α tended to globularization, and the volume fractions of β phase and LAGBs increased due to the α′→α + β transformation and increasing of dislocation density respectively. During high strain rate tension, strain was dispersive in the elastic deformation region, then it began to concentrate at the centre of samples and increased until fractured as loading time increased. As expected, evident reduction in the UTS and σy and increase in the e were caused by heat treatment, however both of them increased as the strain rate increased due to the twinning deformation occurred in the α/β interface phase, thus contributed to improving the strength and plasticity of SLMed TC4 alloy under high strain rate loading simultaneously. This work provided a relationship between microstructure and dynamic responses of SLMed TC4 alloy, which contributes to exploiting the performance potential of SLMed alloy.

With the rapid development of modern science and technology, many new and high-end practical technologies have ushered in unprecedented development opportunities, especially computer information technology has made great progress. Because it has its own unique practical advantages, it has been gradually used in the process of domestic power engineering cost, greatly improving the reasonable degree of power engineering cost in China, making enterprises have greater economic benefits. Technical personnel of power engineering cost.

The performance of velocity & displacement-dependent damper (VDD), inspired by the semi-active control, is analyzed. The main differences among passive, displacement-dependent and semi-active dampers are compared on their damping properties. Valve assemblies of VDD are modelled to get an insight into its working principle. The mechanical structure composed by four valve assemblies helps to enable VDD to approach the performance by those semi-active control dampers. The valve structure parameters are determined by the suggested two-step process. Hydraulic model of the damper is built with AMEsim. Simulation result of F-V curves, which is similar to those of semi-active control damper, demonstrates that VDD could achieve the similar performance of semi-active control damper. The performance of a quarter vehicle model employing VDD is analyzed and compared with semi-active suspension. Simulation results show that VDD could perform as good as a semi-active control damper. In addition, no add-on hardware or energy consumption is needed for VDD to achieve the remarkable performance.

This study presents an integrated predictive model for the long-term performance assessment of ground source heat pump (GSHP) systems, which comprehensively considers the dynamic heat loads of the buildings and heat pump units (HPUs), the 3D dynamic heat transfer process in the ground heat exchangers (GHEs) and the energy consumption by the system accessories particularly the pumps. The model achieved significantly improved predictions than the conventional models and was in satisfactory agreement with the field-test data of an in-operation GSHP system, demonstrating the importance of systematic consideration of the dynamic system operational characteristics and 3D heat transfer processes in the GHEs. The model was also utilized to analyse the performance degradation of GSHP system induced by the soil thermal imbalance. It was found that increasing the thermal imbalance ratio of the accumulative building load from 35% to 76% led to a 10.7 °C further increase in GHE outlet water temperature, a half-folded cooling COP of the HPU and a shorter life-span.

Compared to the sensible heat storage, latent heat storage with phase change material offers an alternative approach with higher energy storage density as well as less space requirement, and has been widely used in actual applications in recent years. A performance evaluation approach is necessary to judge whether a system design is feasible. In this study, typical solar latent heat storage systems were described and a performance evaluation approach was proposed. Five design cases including different mass flow rates of heat transfer fluid and solar collecting areas were subsequently evaluated by the proposed method for one example of the typical solar latent storage systems. A 3D numerical model was also established to simulate the transient melting process inside the latent heat storage unit and validated by experiment. The model was used to obtain the transient correlation between the inlet temperature and the outlet temperature of the storage unit. The evaluation results showed that the water mass flow rate has a slight effect on the thermal performance of the solar latent heat storage system while the collecting area has a significant one, and case 1 with the solar collecting area of 2 m 2 and the water mass flow rate of 0.028 kg/s showed the best thermal performance among the five designed cases. Based on the investigation of five designed cases, it is concluded that the proposed approach can be used for performance evaluation of the solar latent heat storage systems and assist relevant professionals to optimize the system design.

Cotton is an important renewable biopolymer with extensive applications in various fields including textiles. In the current study a soy protein (SP) crosslinked cotton fabric (SPCCF) was prepared through the reaction of carboxyl cotton fabric with soy protein without using crosslinking agents. FTIR analysis of SPCCF samples indicated that carboxyl groups in oxycellulose fabric have reacted with amino groups of SP to give the corresponding C-N bond, that was also reconfirmed by XPS spectra and TGA/DTG analyses of the grafted fabrics. The resulting SPCCF fabrics acquired under the optimized conditions exhibited the improved tensile strength and capillary effect as compared to the oxidized cotton fabric. The ungrafted and grafted fabrics were further evaluated for dyeing property, as a result, the SPCCF fabrics showed markedly improved colour strength when dyed with acid dyes. The fastness properties of dyeability for the dyed SPCCF fabrics were also good compared with that of ungrafted fabrics by dyeing. Shikonin as a kind of Chinese medicine was found to immobilize on the SPCCF fabric through treatment with shikonin aqueous solution, such fabric displayed effective antibacterial activities against both gram-positive and gram-negative bacteria with durability of 30 washes. These results suggest that the SPCCF can be suitable for medical protective textiles by immobilizing drugs.

A novel miniature air-borne antenna with circular polarization and wide angle coverage is presented. The antenna is formed with two pairs of modified printed monopoles that are orthogonally placed, and each pair of them coupled with interdigital capacitors and grounding strip lines at the outside. Radiating elements are fed by a power distribution network printed on the bottom. The antenna has a compact size of only 0.17 λ × 0.17 λ × 0.13 (λ is the wavelength corresponding to center frequency in free space) and a shape matching the aircraft nose, which makes it attractive for small-scale air-borne applications. A prototype was fabricated and measured. The measured results agree well with the simulation ones, which reveals that the antenna works on the GPS band (1.575 GHz) and achieves a wide angle coverage (3-dB axial-ratio beamwidth is 112°, from -55° to +57° off the boresight).

As large amount of energy required in the baking process, the heating source like heat pump are more energy-efficient and environmental friendly than the traditional heating approach using coal. Based on the heat pump curing process in one curing barn located in Chongqing, China, the influential parameters of heat pump performance were analyzed with experimental data. The operation performance equations of heat pump in each process stage were obtained by data fitting, and then sensitivity analysis had been conducted to obtain the quantitative effects on heat pump performance from parameters including ambient temperature, controlled temperature and working load rate. This research method can contribute to improve the heat pump performance in agriculture baking.

Environment control system of the near-space capsule is of great importance to maintain a comfortable environment and working conditions for crew members as well as onboard equipments. Temperature, as the most important parameter, is controlled by the phase change cool storage device in crew capsule. To improve the design of environment control system, a numerical study of the thermal environment within a crew capsule suspending in the stratosphere was conducted in this article. The main structure and thermodynamic parameters of the phase change cool storage device were calculated. The numerical results showed that the air temperature distribution of the crew capsule was reasonably good with a variation range between 21°C∼27°C. To test the effect of this new method, a simulative capsule was set up to address an experimental study. The experimental results showed that, the indoor temperature rise was effectively suppressed under the temperature treatment compared to none—temperature treatment. This researc...

In order to develop an effective and non -poisonous bacterial fertilizer for disease prevention and control of Panax notoginseng (Sanqi), 10300 strains of actinomycetes from soils with Sanqi planting yield with serious diseases and fr om animal feces were screened by using various pathogens Sanqi. Five strains of them with high and broad -spectrum anti-microbial activities were selected and prepared to the composite actinomycete fertilizer (CAF). Several tests in Sanqi continuous farming field in Wens han were carried out by using 20 to 35kg/Chinese mu. The test results shown that the survival Sanqi plants were more average 94.69% in plot using 20kg CAF, but only 69.33% in positive control plot. The yield in field using 15, 25 and 35kg/mu CAF were 4.3, 4.7, and 5.0kg/6m 2 respectively, but the positive control was 3.9kg, and increased 11, 21 and 30 % yield respectively. Comparison with chemical pesticides even single agricultural antibiotic, composite actinomycete fertilizer had many advantage s for disease (especially soil-borne disease) prevention and control of perennial crops. The CAF can be developed into an effective and non-poisonous bacterial fertilizer for disease prevention and control of Sanqi.

Partial discharge (PD) detection is an important method for detecting defects in power transformers, and several PD detection methods reported in literature have their respective advantage and disadvantages. In this paper, a simplified PD coupler attached to the tap of the bushing, whose reliability is verified by the EMTP simulation, is proposed in order to extend the application of on-site tap PD detection. Experiments were carried out on 110 kV transformer models to compare the sensitivity of the sensor with some other popular PD detection methods. The characteristics of the detected signals suggest that the proposed coupler has satisfactory sensitivity as well as potential to solve some on-site noise-rejection problems by introduction of ultra-high frequency amplifiers, and thus could be suitable in future for online PD monitoring applications in substations.

In stick-slip positioning, friction between the stick-slip surfaces plays a critical role in positioning accuracy. Positioning performance varies when the load to drive changes. In this paper, by using a form-closed cam, the driving unit is separated from the moving unit to eliminate load influence. The stage is capable of operating in either a stepping mode or a scanning mode. Numerical modeling was conducted to analyze the static and dynamic characteristics of the stage design. In experiments, a number of parameters were tested on the constructed stage, and positioning performance was measured via laser-doppler vibrometry. Experimental results demonstrate that in the stepping mode, the stage has a travel range of 2 mm with incremental step sizes ranging from 30 nm to 2.3 μm. In the scanning mode, the stage has a positioning resolution of 1.15 nm. The measured results also confirm that load variations on the stage have little influence on contact friction force and positioning performance.

The objective of this paper is to apply combined experimental and computational modeling to investigate the influence of different coating thickness on the operation characteristics of solid–liquid two-phase flow centrifugal pump. According to the characteristics of sediment flow in the Yellow River Basin, the effects of polyurethane coating thickness on the energy performance and pressure fluctuation are analyzed under the condition of solid–liquid two-phase flow and clean water. Meanwhile, the internal flow characteristics and radial force of the coated pump under the condition of solid–liquid two-phase flow are studied. The results show that the blade inlet and outlet of impeller are easy to wear, and the pressure fluctuation at the outlet of the model pump can be reduced by spraying proper coating thickness. The model pump with coating increases the low-speed zone of internal flow, which is mainly due to the increase of the viscous bottom layer area. The variation amplitude of radial force in sediment-laden water decreases with the increase of coating thickness.

To further understand the effects of LSP on large components of high strength steel and provide improved solutions, this paper conducts research on effects of surface integrity on fatigue life in the LSP process with absorbent coating (LSPC), without absorbent coating (LSPN), without absorbent coating but with axial polishing (LSPP) respectively. The research also put a baseline specimens (BSL) before LSP for a comparison. Results show that average fatigue life in the LSPN process is 47.8% shorter than that of baseline specimens, and crack site area presents an obvious splitting-like tearing step. In the LSPC process, fatigue life is 31.7% longer than that of baseline specimens, and crack initiation site develops from surface to subsurface. In the LSPP process, the specimens show the longest fatigue life of 2.53 × 105cycles, with multiple fine microcracks developing simultaneously. Axial polishing removes ablative layer and tensile residual stress in the LSPN process and reduces dislocation pile-ups and refines grains in the LSPC process, resulting in a surface roughness of Ra 0.61 μm, surface residual stress of −531MPa and microhardness of 405HV0.025.Thus, the fatigue performances were found to be significantly affected by multiple surface integrity indicators induced by different LSP processes. In this paper, the effect of LSP on surface integrity on the subface and its influence on crack initiation and propagation have also been discussed, the crack initiation mechanisms in different processes were explained by using Murakami's K max equation.

The optimized structure strength design and finite element analysis method for very high pressure (VHP) rotors of the 700°C ultra-super-critical (USC) steam turbine are presented. The main parameters of steam and the steam thermal parameters of blade stages of VHP welded rotors as well as the start and shutdown curves of the steam turbine are determined. The structure design feature, the mechanical models and the typical position of stress analysis of the VHP welded rotors are introduced. The steady and transient finite element analysis are implemented for steady condition, start and shutdown process, including steady rated condition, 110% rated speed, 120% rated speed, cold start, warm start, hot start, very hot start, sliding-pressure shutdown, normal shutdown and emergency shutdown, to obtain the temperature and stress distribution as well as the stress ratio of the welded rotor. The strength design criteria and strength analysis results of the welded rotor are given. The results show that the strength design of improved structure of the VHP welded rotor of the 700°C USC steam turbine is safe at the steady condition and during the transient start or shutdown process.

Purpose – Three test platforms for long-term continuous loading are adopted to test the actuator prototypes of the 500-meter aperture spherical radio telescope (FAST). However, the wire ropes that are the key components of these platforms often break during testing. The purpose of this paper is to present an effective dimension design method for these wire ropes. This method is based on fatigue reliability theory. Design/methodology/approach – Three types of stresses are introduced into the total stress model of the wire rope according to the complicated stress conditions. The fatigue strength of the ropes is also discussed in this paper. Then, the total stress model and the results of fatigue strength analysis are applied to set the optimization function for these wire ropes. Subsequently, this optimization function is used to calculate the reliability of previously developed wire ropes in relation to the actuator test platform. Findings – The wire rope is unreliable, which is a finding that corresponds to those of previous tests. Upon drawing the optimal curve from the optimization function (whose optimal objective is the wire diameter), a wire rope is optimized for the FAST actuator test platforms. Finally, this optimized rope is used on the new actuator test platform. No fracture phenomenon has been detected in tests conducted over the past six months. Originality/value – The fatigue reliability theory-based optimization function for wire ropes can be adopted for the universal dimension design of other wire ropes.

The popularity of electric vehicles may lead to negative effects on the power system if the charging procedures of plug-in electric vehicles (PEVs) are uncoordinated. In order to solve the problem, the hierarchical and zonal dispatching architecture and a new bi-level optimization model are respectively presented for the charging/discharging schedules of the PEVs. The upper level model is devoted to minimizing the system load variance so as to implement peak load shifting by optimizing the dispatching plan of all periods for each electric vehicle aggregator (EVA), and the lower one is aimed at tracing the dispatching scheme determined by the upper decision-maker through presenting an optimal schedule of charging and discharging for electric vehicles in the charging areas. Two highly efficient commercial solvers, AMPL/IPOPT and AMPL/CPLEX respectively, are employed to solve the developed optimization problem. Finally, the testing IEEE system consisting of 5 agents and 30 nodes is adopted to illustrate the characteristics of the model and solving method presented in this paper.

In traditional FC ceramic package, we mostly use the solder bump. But in high speed signal transmission FC package, the solder bump doesn't have good electrical performance as the signal frequency higher and higher, so we advise to use the Au bump instead of the solder bump, because of the Au bump has better electrical performance compared to the solder bump. For the same size of Au bump and solder bump, the Au bump has less resistance than the solder bump, so the Au bump has little parasitic effect in high speed signal transmission. In the signal transmission loss, the Au bump not only has low insertion loss but also has good ductility which is easy to be molded for transmission line impedance match, thus reduce the return loss in high speed signal transmission. In this paper, we built the Au bump model in package design software firstly, and then simulated the parasitic parameters, return loss and insertion loss respectively of the Au bump in EM simulation software. Lastly, we compared the return loss and insertion loss of the Au bump with the solder bump. From the simulation results, we can see that the insertion loss and return loss of Au bump and solder bump have no distinct difference when the signal frequency is below 5GHz. But when the signal frequency is above 5GHz, the solder bump has a distinct deteriorated on electrical performance, then the Au bump is still well. From this study, we can give a beneficial suggestion for the package design of high speed signal FC package device.