摘要：The high pressure waves generated due to muzzle blast flow of tank gun during firing is a critical issue to examine. The impulsive noise from the gun has various negative effects such as damage of human bodies, damage of structures, creating an environmental, social problem and also military problems such as exposure of location of troops. This high pressure impulsive sound, generated during the blast flow, was studied and attenuated. An axisymmetric computational domain was constructed by employing Spalart Allmaras turbulence model. Approximately 90% of pressure and 20 dB of sound level are reduced due to the use of the three baffle silencer at the muzzle end of the gun barrel, in comparison with the tank gun without silencer. Also, the sound pressure level at different points in the ambient region shows the same attenuation in results. This study will be helpful to understand the blast wave characteristics and also to get a good idea to design silencer for large caliber weapon system.

摘要：The objective of this study is to identify cost-optimal efficiency packages at several levels of building energy savings.A two-story residential building located in Jordan is selected as a case *** software is used to predict the annual energy usage of a twostory residence in Irbid,***-time experimental data from a single isolated controlled room was used to verify the proposed *** addition to energy analysis,the economic,environmental,and social benefits of the proposed design have been *** sequential search optimization approach is used to estimate the minimum cost of the building while considering various design *** addition,the impact of various energy conservation techniques on residential buildings is assessed,and the payback period for each program is ***,the optimal combination of design to achieve energy efficiency measures has been identified in several climate *** simulations results predict that the annual electricity consumption can be reduced up to 50%if the proper combinations of energy conservation measures are selected at the lowest *** payback period is 9.3 ***,energy efficiency measures can lead to a total of 9470 jobs/year job *** study provide practical framework to link between energy performance criteria and economic goals of *** the energy performance requirements to economic targets provides guidelines for homeowners,contractors,and policymakers for making a suitable decision regarding the retrofitting of existing residential *** study focuses on developing new methodologies that support minimizing costs during a building’s lifecycle while maximizing environmental benefits which can not be identified by a series of parametric analyses using individual energy-efficient measures.

摘要：As energy crisis and environment pollution all around the world threaten the widespread use of fossil fuels,compressed natural gas(CNG)vehicles are explored as an alternative to the conventional gasoline powered *** of the limited space available for the car,the composite pressure vessel(TypeⅡ)has been applied to the CNG vehicles to reach large capacity and weight lightening *** pressure vessel(TypeⅡ)is composed of a composite layer and a metal *** metal liner is formed by the deep drawing and ironing(D.D.I.)process,which is a complex process of deep drawing and *** cylinder part is reinforced by composite layer wrapped through the filament winding process and is bonded to the liner by the curing *** this study,an integrated design method was presented by establishing the techniques for FE analysis of entire processes(D.D.I.,filament winding and curing processes)to manufacture the CNG composite pressure vessel(TypeⅡ).Dimensions of the dies and the punches of the 1 st(cup drawing),2 nd(redrawing-ironing 1-ironing 2)and 3 rd(redrawing-ironing)stages were calculated theoretically,and shape of tractrix die to be satisfied with the minimum forming load was suggested for life improvement and manufacturing costs in the *** of the composite material was determined in the filament winding process,finally,conditions of the curing process(number of heating stage,curing temperature,heating rate and time)were proposed to reinforce adhesive strength between the composite layers.

摘要：RBF model,a new type of artificial neural network model was developed to design the content of carbon in low-alloy engineering *** errors of the ANN model are：MSE 0.052 1,MSRE 17.85%,and VOF 1.932 *** results obtained are *** method is a powerful aid for designing new steels.

摘要：Based on gradient control of carbon partitioning between martensite and austenite during heat treatment of steels,a stepping-quenching-partitioning(S-Q-P) process is developed for high strength *** S-Q-P process involves several quenching processes at progressively lower temperatures between martensite-start(Ms) and martensite-finish(Mf) temperatures,each followed by a partitioning treatment at either the initial quenching temperature or above that temperature.A novel microstructure is designed based on the S-Q-P *** and distributions of retained austenite and high-carbon martensite surrounded by martensite laths can be manipulated by the partitioning duration and temperature,and quenching temperature of the S-Q-P *** element Si is employed in the S-Q-P steel to suppress formation of carbides and create suitable amount of retained austenite.A steel of 0.39C-1.22Mn-1.12Si-0.23Cr(wt.%) treated by the S-Q-P process is endowed with some special microstructural characteristics:some strips of retained austenite located at edges of martensite blocks with high density of dislocations and between martensite laths,some small blocks of twinned martensites distributed among bundles of the low-carbon martensite *** mechanical properties of the medium carbon steel after the S-Q-P process can reach ultimate tensile strength(Rm) of 1240 MPa,total elongation(EI) of 25%,and product of strength and ductility(PSD) of 31.2 GPa% that are much more improved than those after the conventional quenching-tempering(Q-T) and currently prevailing quenching-partitioning(Q-P) *** PSD of the tested steel after the S-Q-P process increases by 67% and 32% as compared with those after the Q-T and Q-P processes,respectively.

摘要：Microfluidic device with patterned microstructures on the substrate surface was used to regulate cell adhesion,morphology,and functions in tissue *** developed a microfluidic device which employing microscale patterned microstructures to achieve enhanced cell adhesion and *** hydrogel substrates with micro-wavy and lattice-patterned microstructures were fabricated using standing surface acoustic waves and ultraviolet *** seeding the L929 mouse fibroblast cells onto the patterned substrate of the microfluidic device,we determined that the viability and proliferation rate of cell migration can be greatly ***,L929 cells showed two types of gathering modes after 48 h of *** growth was guided by the patterned substrate used in the microfluidic device and showed differences in the location ***,the developed microfluidic device with patterned microstructures can extend the application of in vitro cell culturing for future drug development and disease diagnosis.

摘要：Commercially pure titanium and titanium alloys have been among the most commonly used materials for biomedical applications since the 1950 *** to the excellent mechanical tribological properties,corrosion resistance,biocompatibility,and antibacterial properties of titanium,it is getting much attention as a biomaterial for ***,titanium promotes osseointegration without any additional adhesives by physically bonding with the living bone at the implant *** properties are crucial for producing high-strength metallic alloys for biomedical *** alloys are manufactured into the three types ofα,β,andα+β.The scientific and clinical understanding of titanium and its potential applications,especially in the biomedical field,are still in the early *** review aims to establish a credible platform for the current and future roles of titanium in *** first explore the developmental history of ***,we review the recent advancement of the utility of titanium in diverse biomedical areas,its functional properties,mechanisms of biocompatibility,host tissue responses,and various relevant antimicrobial *** research will be directed toward advanced manufacturing technologies,such as powder-based additive manufacturing,electron beam melting and laser melting deposition,as well as analyzing the effects of alloying elements on the biocompatibility,corrosion resistance,and mechanical properties of ***,the role of titania nanotubes in regenerative medicine and nanomedicine applications,such as localized drug delivery system,immunomodulatory agents,antibacterial agents,and hemocompatibility,is investigated,and the paper concludes with the future outlook of titanium alloys as biomaterials.

摘要：Drop-on-demand (DOD) bioprinting has been widely used in tissue engineering due to its highthroughput efficiency and cost effectiveness. However, this type of bioprinting involves challenges such as satellite generation, too-large droplet generation, and too-low droplet speed. These challenges reduce the stability and precision of DOD printing, disorder cell arrays, and hence generate further structural errors. In this paper, a multi-objective optimization (MOO) design method for DOD printing parameters through fully connected neural networks (FCNNs) is proposed in order to solve these challenges. The MOO problem comprises two objective functions: to develop the satellite formation model with FCNNs;and to decrease droplet diameter and increase droplet speed. A hybrid multi-subgradient descent bundle method with an adaptive learning rate algorithm (HMSGDBA), which combines the multisubgradient descent bundle (MSGDB) method with Adam algorithm, is introduced in order to search for the Pareto-optimal set for the MOO problem. The superiority of HMSGDBA is demonstrated through comparative studies with the MSGDB method. The experimental results show that a single droplet can be printed stably and the droplet speed can be increased from 0.88 to 2.08 m·s^-1 after optimization with the proposed method. The proposed method can improve both printing precision and stability, and is useful in realizing precise cell arrays and complex biological functions. Furthermore, it can be used to obtain guidelines for the setup of cell-printing experimental platforms.

摘要：Extensive numerical investigations of the performance and flow structure in an unshrouded tandem-bladed centrifugal compressor are presented in comparison to a conventional *** characteristics are explored for various tip clearance levels,axial spacings and circumferential *** impeller was modified to tandem-bladed design with no modifications in backsweep angle,meridional gas passage and camber distributions in order to have a true comparison with conventional *** degradation is observed for both the conventional and tandem designs with increase in tip ***-equation models for correlating stage characteristics with tip clearance are *** two designs,it is clearly evident that the conventional design shows better performance at moderate flow ***;near choke flow,tandem design gives better results primarily because of the increase in throat *** point flow rate also seems to drop for tandem compressor resulting in increased range of operation.

摘要：This paper presents the design and manufacture process of a wheel-less,modular snake robot with series elastic actuators to reliably measure motor torque signal and investigate the effectiveness of active stiffness control for achieving adaptive snake-like locomotion.A polyurethane based elastic element to be attached between the motor and the links at each joint was designed and manufactured using water jet cutter,which makes the final design easier to develop and more cost-effective,compared to existing snake robots with torque measurement *** reliability of such torque measurement mechanism was examined using simulated dynamical model of pedal wave motion,which proves the efficacy of the design.A distributed control system was also designed,which with the help of an admittance controller,enables active control of the joint stiffness to achieve adaptive snake robot pedal wave locomotion to climb over obstacles,which unlike existing methods does not require prior information about the location of the *** effectiveness of the proposed controller in comparison to open-loop control strategy was verified by the number of *** results show the capability of the robot to successfully climb over obstacles with the height of more than 55%of the diameter of the snake robot modules.