Solid-liquid state pressure bonding of Si_3N_4 ceramics with aluminum based alloys and its mechanism

Solid liquid state pressure bonding of Si 3N 4 ceramics with aluminum based alloys, which contain a small amount of intermetallic compounds Al 3Ti or Al 3Zr, was investigated. With this new method, the heat resistant properties of the bonding zone metal are improved, and the joints’ strengths at high temperature is increased. The joints’ shear strength at room temperature and at 600 ℃ reach 126～133 MPa and 32～34 MPa, respectively, with suitable bonding pressure. The reaction between aluminum and Si 3N 4 ceramics, which produces Al Si N O type compounds is the dominant interfacial reaction, while the reactions between the second active element Ti or Zr in the aluminum based alloys and Si 3N 4 ceramics also occur to some extend. [

A Sensorless State Estimation for A Safety-Oriented Cyber-Physical System in Urban Driving:Deep Learning Approach

In today's modern electric vehicles,enhancing the safety-critical cyber-physical system(CPS)'s performance is necessary for the safe maneuverability of the vehicle.As a typical CPS,the braking system is crucial for the vehicle design and safe control.However,precise state estimation of the brake pressure is desired to perform safe driving with a high degree of autonomy.In this paper,a sensorless state estimation technique of the vehicle's brake pressure is developed using a deep-learning approach.A deep neural network(DNN)is structured and trained using deep-learning training techniques,such as,dropout and rectified units.These techniques are utilized to obtain more accurate model for brake pressure state estimation applications.The proposed model is trained using real experimental training data which were collected via conducting real vehicle testing.The vehicle was attached to a chassis dynamometer while the brake pressure data were collected under random driving cycles.Based on these experimental data,the DNN is trained and the performance of the proposed state estimation approach is validated accordingly.The results demonstrate high-accuracy brake pressure state estimation with RMSE of 0.048 MPa.

Estimation of earth pressure against retaining walls with different limited displacement modes based on elastic theory

The earth pressure acting on retaining walls due to creep and consolidation is under limited equilibrium conditions(limited displacement). Linear elastic constitutive theory can be applied to determine earth pressure distribution along retaining walls under limited displacement condition. In addition,tangent modulus in Duncan-Chang nonlinear elastic model was introduced to reflect the variations of soil modulus with confining pressure, and boundary strains were derived from Rankine active earth pressure, Rankine passive earth pressure, static earth pressure and principal stress direction deflection.According to the above four boundary strains, earth pressure on retaining walls was divided into five state zones. By comparing the calculation results obtained from the equations proposed in this paper with those of experimental tests, the following conclusions can be drawn: earth pressure distribution was always nonlinear along retaining walls for translation displacement(T mode), rotation displacement around wall base(RB mode), and translation + rotation displacement around wall base(RBT mode). Also,calculated earth pressure distributions along with the depth of wall were found to be consistent with measured values under three displacement modes.Additionally, a parametric study was carried out to evaluate the effects of internal friction angle and backfill soil cohesion on earth pressure. It could be seen from the above series of studies that the earth pressure equations derived in this work could be well applied in practical engineering in designing retaining walls.

基于PSR模式的江苏省区域生态环境可持续能力评价

基于压力—状态—响应(PSR)指标框架模式,从环境本底—环境压力—环境效应—社会响应等4个方面选出23个指标组成指标体系,采用全排列多边形综合图示指标法对江苏省区域生态环境可持续能力进行了评价,根据综合得分指数并结合ArcGIS软件对其进行空间表达,将江苏省13个地级市的生态环境可持续能力分成5类。评价结果显示,南京、无锡、常州、扬州、连云港的可持续能力较强,宿迁、淮安、盐城的可持续能力最弱。江苏省生态环境可持续能力具有显著的区域差异,南部地区自然条件优于北部地区,但南部地区环境压力较大;揭示了造成这种差异的原因。

Effect of continuous positive airway pressure treatment on elderly Chinese patients with obstructive sleep apnea in the prethrombotic state

Objectives To characterize the prethrombotic state ( PTS) in elderly Chinese patients with obstructive sleep apnea hypopnea syndrome (OSAHS) and the effect of nasal continuous positive airway pressure (nCPAP) ventilation on their PTS.Methods Forty-one elderly patients with moderate and severe OSAHS were enrolled into the OSAHS group and underwent nCPAP treatment. Their blood samples were drawn at 6:00 am and 4:00 pm before and during nCPAP treatment, respectively, to test hemocrit, platelet aggregation (PAG), whole blood viscosity (WBV), plasma fibrinogen (fng), prothrombin time (PT) and activated partial thromboplastin time (APTT). All blood factors were also tested in a control group consisting of 32 healthy elderly Chinese with neither OSAHS nor cerebrocardiac vascular disease.Results In the OSAHS group there was a significantly higher hemocrit, WBV, fng, and a significantly shorter PT and APTT at 6:00 am compared to 4:00 pm before nCPAP treatment, while there was no significant difference among all blood test factors between 6:00 am and 4:00 pm on day 30 of the nCPAP treatment. In the OSAHS group, the hemocrit, WBV, PAG and plasma fng were significantly lower and the PT and APTT were significantly longer at 6:00 am on day 30 of the nCPAP treatment compared to 6:00 am before the nCPAP treatment. A significantly lower hemocrit, but a much longer PT and APTT were observed at 4:00 pm on day 30 of the treatment, compared with 4:00 pm before the treatment. No significant difference among the blood test factors was found between 6:00 am and 4:00 pm blood in the control group or between the control and OSAHS groups after 30 days of nCPAP treatment.Conclusion In elderly Chinese OSAHS patients, PTS could be effectively eliminated by nCPAP treatment.

Optimum Heating of Thick-Walled Pressure Components Assuming a Quasi-steady State of Temperature Distribution

As a result of the development of wind farms,the gas- steam blocks,which shall quickly ensure energy supply in case the wind velocity is too low,are introduced to the energy system.To shorten the start-up time of the gas-steam and conventional blocks,the structure of the basic components of the blocks are changed,e.g.by reducing the diameter of the boiler,the thickness of its wall is also reduced.The attempts were also made to revise the currently binding TRD 301 regulations,replacing them by the EN 12952-3 European Standard,to reduce the allowable heating and cooling rates of thick walled boiler components.The basic assumption,on which the boiler regulations allowing to calculate the allowable temperature change rates of pressure components were based,was the quasi- steady state of the temperature field in the simple shaped component,such as a slab,cylindrical or spherical wall.

Research on Ecological Carrying Pressure in the Greater Dunhuang Region based on the Relationship between Supply and Consumption

The Greater Dunhuang Region has experienced ecological degradation in the past 100 years caused by human factors such as ecological immigration, expansion of arable land, and the construction of reservoirs. At present, through the restoration of various ecological projects, the progress of ecological deterioration has slowed down. Ensuring that the development and construction of the Greater Dunhuang Region Cultural Tourism Economic Circle does not threaten ecological security is the top priority of the regional sustainable development plan. Based on the balance between supply and consumption of the ecosystem, this study assesses the pressure of ecological consumption in the Greater Dunhuang Region, and analyzes the patterns and trends in the ecological carrying status. The results reveal three important aspects of the ecological carrying pressure in this Region.(1) After 2000,the ecological supply in the Greater Dunhuang Region experienced a fluctuating growth trend. In the entire ecosystem, the farmland ecosystem provides more than 55% of the ecological supply, and areas with relatively high supply capacity are concentrated in a small number of valleys.(2) The Greater Dunhuang Region is under greater production pressure and there is less pressure from living consumption. The production consumption intensity has exceeded the ecological supply since 2014. The production and consumption structure of the Greater Dunhuang Region is dominated by animal husbandry production and consumption, accounting for more than 65% of the total production and consumption.(3) The Greater Dunhuang Region has been in a state of rich and surplus from 2000 to 2017. However, Dunhuang City turned into a surplus state in 2017 due to the pressure of the fast-growing tourist population. The Greater Dunhuang Region urgently needs to alleviate the ecological pressure through the development of eco-friendly industries. It is necessary to develop an ecological protection resource utilization model that focuses on the development of ecological and cultural services in pastoral areas to ease the pressure on the ecosystem from animal husbandry production.