ANALYTICAL SOLUTION OF FILLING AND EXHAUSTING PROCESS IN PNEUMATIC SYSTEM

The filling and exhausting processes in a pneumatic system are involved with many factors, and numerical solutions of many partial differential equations are always adapted in the study of those processes, which have been proved to be troublesome and less intuitive. Analytical solutions based on loss-less tube model and average friction tube model are found respectively by using fluid net theory, and they fit the experimental results well. The research work shows that： Fluid net theory can be used to solve the analytical solution of filling and exhausting processes of pneumatic system, and the result of loss-less tube model is close to that of average friction model, so loss-less tube model is recommended since it is simpler, and the difference between filling time and exhausting time is determined by initial and final pressures, the volume of container and the section area of tube, and has nothing to do with the length of the tube.

A numerical simulation on the infrared radiation of hot exhausting nozzles with a coupled flow and heat transfer model

A coupled model among flow field,solid temperature,species concentration and gas radiation,which was based on statistical narrow-band correlated-k model,was employed to predict the infrared radiations from hot exhausting nozzles. The parameters of narrow-band model were deduced from HITEMP line-by-line database. Several methods to increase computational efficiency and to save computational resources were employed,thus all the complicated computations could be operated on a personal computer. The predictions for three cases have been conducted to validate the accuracy of the methods mentioned above,including the temperature distribution of a water-cooling nozzle in rocket engines,the carbon dioxide absorptivity at the wavelength of 4.3 micron and the infrared radiation of a cylindrical furnace. Finally,the aerothermodynamic and infrared characteristics of two nozzles were predicted. It was shown that the infrared radiation intensity of chevron ejecting nozzle were obviously smaller than that of common axisymmetric convergent-divergent nozzle.

The Thermal Character of the Underwater Heat Exhausting Source

The underwater heat exhausting source can cause the thermal difference of the surrounding and surface water.In this paper,the thermal character caused by the underwater heat exhausting source is studied by numerical simulation and experiment.The results show that the thermal floating distance is related with the sailing velocity of the underwater target.The higher the velocity is,the longer the hot wake is,and the broader the hot scope is.The relative distance of the thermal floating spot is almost in a logarithmic law with the velocity.The experimental results are accordant with the numerical simulation,and the obvious hot wake can be observed by the moving underwater heat exhausting source testing with temperature sensors and infrared camera.

Fridman’s Invariant, Squeezing Functions, and Exhausting Domains

We show that if a bounded domain Ω is exhausted by a bounded strictly pseudoconvex domain D with C^2 boundary, then Ω is holomorphically equivalent to D or the unit ball, and show that a bounded domain has to be holomorphically equivalent to the unit ball if its Fridman's invariant has certain growth condition near the boundary.

AN EXHAUSTING EFFORT

As the United States marks the fifth anniversary of the September 11 terrorist attacks, will it change its controversial antiterrorism strategy? Five years after the United States launched its war on terror, the terrorist threat the world faces is mounting instead of declining, experts say. For many years before the Al Qaeda attacks on the United States on September 11, 2001, the world suffered one major terrorist attack every two years, but since then,

面向未来低碳道路养护的超薄罩面功能性研究综述

Highway maintenance mileage reached 5.25 million kilometers in China by 2021.Ultra-thin overlay is one of the most commonly used maintenance technologies,which can significantly enhance the economic and environmental benefits of pavements.To promote the low-carbon development of ultrathin overlays,this paper mainly studied the mechanism and influencing factors of several ultra-thin overlay functions.Firstly,the skid resistance,noise reduction,rutting resistance,and crack resistance of ultrathin overlays were evaluated.The results indicated that the high-quality aggregates improved the skid and rutting resistance of ultra-thin overlay by 5%-20%.The optimized gradations and modified binders reduced noise of ultra-thin overlay by 0.4-6.0 dB.The high viscosity modified binders improved the rutting resistance of ultra-thin overlay by about 10%-130%.Basalt fiber improved the cracking resistance of ultra-thin overlay by more than 20%.Due to the thinner thickness and better road performance,the performance-based engineering cost of ultra-thin overlay was reduced by about 30%-40%compared with conventional overlays.Secondly,several environmentally friendly functions of ultra-thin overlay were investigated,including snow melting and deicing,exhaust gas purification and pavement cooling.The lower thickness of ultra-thin overlay was conducive to the diffusion of chloride-based materials to the pavement surface.Therefore,the snow melting effect of self-ice-melting was better.In addition,the ultra-thin overlay mixture containing photocatalytic materials could decompose 20%-50%of the exhaust gas.The colored ultra-thin overlay was able to reduce the temperature of the pavement by up to 8.1℃.The temperature difference between the upper and lower surfaces of the ultra-thin overlay containing thermal resistance materials could reach up to 12.8℃.In addition,numerous typical global engineering applications of functional ultra-thin overlay were summarized.This review can help better understand the functionality of ultra-thin overlays and promote the realization of future multi-functional and low-carbon road maintenance.

Revolutionizing tumor immunotherapy:unleashing the power of progenitor exhausted T cells

In exploring persistent infections and malignancies, a distinctive subgroup of CD8^(+) T cells, progenitor exhausted CD8^(+) T(Tpex) cells, has been identified. These Tpex cells are notable for their remarkable self-renewal and rapid proliferation abilities. Recent strides in immunotherapy have demonstrated that Tpex cells expand and differentiate into responsive exhausted CD8^(+) T cells, thus underscoring their critical role in the immunotherapeutic retort. Clinical examinations have further clarified a robust positive correlation between the proportional abundance of Tpex cells and enhanced clinical prognosis. Tpex cells have found noteworthy applications in the formulation of inventive immunotherapeutic approaches against tumors. This review describes the functions of Tpex cells in the tumor milieu, particularly their potential utility in tumor immunotherapy. Precisely directing Tpex cells may be essential to achieving successful outcomes in immunotherapy against tumors.

Study of the Influence of the Distance between Smoke Outlets and Fire Source on Smoke Flow Characteristics in Tunnel Fires

This paper explores the smoke flow characteristics in tunnel fires,giving a particular emphasis on the effects of different distances between the smoke outlets and the fire source.It examines the smoke behavior under different conditions,including variations in heat release rates,exhaust volumetric flow rates,spacing between smoke outlets,and the longitudinal fire source positions.Results indicate that altering the fire source positions and the smoke outlets in the tunnel leads to variations in the properties of smoke flow both the fire source upstream and downstream;the distance between fire source and smoke outlet increases gradually,airflow rate decreases initially and eventually reaches a stable state.Similarly,smoke mass flow rate exhibits an increasing trend that eventually reaches a stable state.Moreover,the heat exchange between the tunnel walls and hot smoke increases as the smoke outlet moves further away from the fire source.This interaction leads to a reduction in the heat exhaust coefficient and a decrease in the distance the smoke spreads.This study investigates the impact of altering the relative longitudinal fire source positions and smoke outlet on smoke flow characteristics by numerical simulation.A theoretical analytical method is used to give a predictive model for the heat exhaust coefficient and the smoke spreading distance.This research can support the theory and technical process of tunnel smoke exhaust prevention and control.

New perspective on the treatment of rheumatic arthritis based on“strengthening body resistance(Fú Zhèng)”in the theory of co-inhibitory receptor-regulated T-cell immunity

Co-inhibitory receptors serve as crucial regulators of T-cell function,playing a pivotal role in modulating the delicate balance between immune tolerance and autoimmunity.Initially identified in autoimmune disease models,co-inhibitory receptors,including CTLA-4,PD-1,TIM-3,and TIGIT,were found to be integral to immune regulation.Their blockade or absence in these models resulted in the induction or exacerbation of autoimmune diseases.Additionally,scholars have observed that co-inhibitory receptors on lymphocytes hold the potential to influence the prognosis in the context of chronic inflammation.Consequently,the blocking of co-suppressor receptors has emerged as a novel therapeutic approach for inhibiting refractory inflammatory diseases,particularly rheumatoid arthritis.From the standpoint of traditional Chinese medicine(TCM),the treatment of rheumatoid arthritis based on the“strengthening body resistance(FúZhèng)”theory can be construed as the regulation of co-suppressor receptors to modulate the body’s immune function in combating chronic inflammation.This article provides a succinct overview of the role of co-suppressor receptors in anti-inflammatory processes and explores the research prospects of co-suppressor receptor intervention in the treatment of rheumatoid arthritis.The exploration integrates the“strengthening body resistance(FúZhèng)”theory with relevant Chinese medicine formulations.

Heat Recovery from Automotive Exhaust Using Heat Pipes with Limited Fluid Charge

Experiments were conducted in this study to examine the thermal performance of a thermosyphon,made from Inconel alloy 625,could recover waste heat from automobile exhaust using a limited amount of fluid.The thermosyphon has an outer diameter of 27 mm,a thickness of 2.6 mm,and an overall length of 483 mm.The study involved directing exhaust gas onto the evaporator.This length includes a 180-mm evaporator,a 70-mm adiabatic section,a 223-mm condenser,and a 97-mm finned exchanger.The study examined the thermal performance of the thermosyphon under exhaust flow rates ranging from 0–10 g/sec and temperatures varying from 300℃–900℃.The influence of three parameters—inclination angle(5°–45°),water mass(2–5.3 g),and the quantity of non-condensable gas Argon(0–0.6 g)—was investigated to assess their impacts on the thermosyphon’s thermal efficiency.The experimental findings revealed that with 3 g of water and 0.0564 g of argon in the thermosyphon,the condenser reached its highest temperature at around 200℃.The ideal fuel loading rate for the thermosyphon falls between 0.2 and 0.7 g/s.Moreover,as inclination angles rise,outer wall temperatures of the thermosyphon increase.This is attributed to the explicit expansion of the effective heating area within the evaporation section,coupled with an amplified gravitational component of the water flux.Additionally,an upsurge in the quantity of non-condensable gas(NCG)can mitigate temperature gradients on the outer wall,resulting in a decline in the thermosyphon’s performance.The insulation applied to the adiabatic section demonstrated efficacy in augmenting temperature gradients on the outer wall,thereby improving the overall performance of the thermosyphon.As the water charge within the thermosyphon increases,there is a corresponding rise in heat transfer rates both from the exhaust to the thermosyphon and from the thermosyphon to the fuel.

Study on the Influence of Setting Parameters of Tunnel Centralized Smoke Extraction System on Fire Smoke Flow and Temperature Decay

The centralized smoke exhaust system of shield tunnel is an important determinant for tunnel fire safety,and the use of different design parameters of the tunnel smoke exhaust system will affect the smoke exhaust effect in the tunnel,and the influence of different design parameters on the smoke exhaust effect and temperature attenuation of the tunnel can help engineers in designing a more effective centralized smoke exhaust system for the tunnel.In this paper,the Fire Dynamic Simulator(FDS)is utilized to examine smoke exhaust vent settings for a centralized exhaust system in shield tunnel with both flat and sloped conditions,including slopes of+4.5%and−4.5%,under a 30MWfire power with a 150m^(3)/s smoke exhaust rate.The results suggest that maintaining a vent spacing of 60m and a vent size of 4.0 m×1.5 m is a reasonable configuration for centralized smoke exhaust systems in both flat and slope shield tunnels.This choice helpsminimize construction costs and prevent excessive smoke accumulation.It also promotes favorable conditions for maintaining temperature distribution at 2-m height,visibility,smoke spread distance,and temperature below the ceiling,all below the threshold values,while ensuring high smoke extraction efficiency.However,in the slope section,the chimney effect can disrupt exhaust efficiency,visibility,ceiling temperature,and temperature distribution at a height of 2 m.Employing different opening methods,such as having 2 vents up and 4 vents down in a+4.5%slope and 4 vents up and 2 vents down in a−4.5%slope,can help mitigate these effects.Furthermore,the temperature decay formula for shield tunnels follows a bi-exponential decay pattern,and different design parameters of centralized smoke exhaust systems have minimal effects on temperature decay in shield tunnels.

EGR的热效应和稀释效应对柴油机燃烧和排放的影响

以改进的KIVA-3V程序为计算平台,在转速为1,600,r/min,每循环喷油量为52.8,mg工况下,分别进行了EGR的热效应和稀释效应对柴油机燃烧和排放影响的数值模拟.结果表明,EGR的热效应对滞燃期影响较大,而稀释效应成为制约最高爆发压力和缸内温度的主要因素,且随着氧气体积分数的降低,热效应对最高爆发压力的影响增强;EGR导致碳烟排放增加是由于EGR的稀释效应,低温燃烧时碳烟排放的降低是EGR的稀释效应和热效应相互作用的结果;相比稀释效应,EGR的热效应是实现低温燃烧的主要因素,高进气热容更易改善NOx和碳烟排放的折衷关系.

One-step hydrothermal synthesis of Cu-SAPO-34/cordierite and its catalytic performance on NO_x removal from diesel vehicles

Cu-SAPO-34/cordierite catalysts were prepared via one-step hydrothermal synthesis method and their performances to remove NO x from the diesel vehicle exhaust were evaluated. The morphology, structure, Cu content and valence state were characterized by SEM, XRD, ICP and XPS, respectively. The experimental results show the active component Cu of the catalysts via in situ synthesis could significantly improve the selective catalytic reduction （SCR） activities of NOx and the optimal Cu content is in the range of 0.30%-0.40%（mass fraction）. No N 2 O is detected by gas chromatograph （GC） during the evaluation process, which implies that NOx is almost entirely converted to N2 over Cu-SAPO-34/cordierite catalyst. The conversion rate of NOx to N2 by NH3 over catalyst could almost be up to 100%in the temperature range of 300-670 ℃with a space velocity of 12000 h-1 and it is still more than 60% at 300-620 ℃ under 36000 h-1. The catalysts also show the good hydrothermal and chemical stability at the atmosphere with H 2 O.

INVESTIGATION IN REDUCING EXHAUST EMISSIONS FROM TWO STROKE MOTORCYCLES

Test results of reducing two stroke motorcycle emissions with new type carburettors and electronic fuel injection systems are presented. Analyses and comparison between different systems are discussed. The adoption of electronically controlled injection and corresponding electronic control technique is an effective measure of prolonged vitality to improve emissions from two stroke motorcycles. Suggestions about the strategic steps of China′s motorcycle emission control are proposed.

两种排气法在静脉输液应用中的效果比较

目的:探讨一种新的静脉输液排气法。方法:住院输液患者中选取360例,用简单随机法分为两组,每组180例。A组采用常规排气法,B组采用新排气法,两组均使用同一种液体同样型号的输液器且操作者为同一护士。结果:B组莫菲氏滴管下段输液管中出现气泡的发生率与A组比较明显减少(χ2=40.9,P<0.01),差异有显著性。结论:运用新排气法操作简单,可提高一次排气成功率,明显缩短排气时间目的。

Computation of Electromagnetic Properties of Mildly Overexpanded and Underexpanded Rocket Exhaust Plume

An improved near far field divided coupled method was established to investigate the electromagnetic properties of mildly overexpanded and underexpanded rocket exhaust plumes. Firstly, axisymmetric Navier Stokes equations incorporated with k ε two equation turbulence models were solved using time dependent approach to calculate the pressure of the near filed. Secondly, parabolized axisymmetric Navier Stokes equations incorporated with finite rate chemical kinetics models were marching on the detailed pressure map of the near field. The termination of the near field would yield the initial line for the far field. In addition, in the far field, the spatial marching method was directly used under the constant pressure condition, but considering more complicated chemically reacting process. Finally, the electromagnetic parameters of the whole plume were calculated with the electron conductive model. The calculated results of the overexpanded and underexpanded rocket exhaust plume were discussed. The predicted microwave attenuation accorded with the experimental results. This improved method is feasible for calculating the microwave attenuation characteristics of mildly non fully expanded rocket exhaust plumes.

WTO法律体系下的专利权耗尽问题研究

引言按照《与贸易有关的知识产权协议》(TRIPS 协议),世界贸易组织(WTO)成员在知识产权权利耗尽问题上应当遵从什么原则?对于这一问题,欧美知识产权界内颇有争议,归结起来主要有三种意见:一种意见认为,从TRIPS 协议中可以得出协议禁止成员采用国际耗尽原则的结论;第二种意见认为,根据 TRIPS 协议,成员有义务采用国际耗尽原则;第三种意见认为,TRIPS 协议没有就权利耗尽问题作出规定。

大学英语教师职业倦怠现状的调查研究(英文)

This study aims to examine the prevalence of job burnout and its probable causes among College English teachers. Data were collected among a random sampling of 270 College English Teachers who filled out the Chinese Maslach Burnout Inventory ( CMBI) and a socio-demographic inventory. The findings indicate that College English Teachers register a low-to-average degree of job burnout with the detection rate of 75. 4% . Group differences on the three dimensions are determined by different factors. Reduced personal accomplishment shows significant difference on gender and marital status. Emotional exhaustion shows significant difference on highest degree and number of years on the job. Differences on all three dimensions are observed concerning academic title and school type,though not significant.

The research of economic development law in resourceful city

The resource advantage of resourceful region has made the region develop very fast. However because the resource is of exhausting character, this means that the region has hidden troubles of economic depression. The paper analyzes the formation of resourceful region and the law of resourceful regions economic development, and then the paper brings forward that the resourceful region has a potential danger of economic depression. Considering Chinas economic development practice, the paper puts forward a basic way of thinking. That is: we must attach importance to the problem of industrial structure when we pay attention to existing resource advantage in order to avoid the simplification of regional industrial structure and to avoid entering a vicious cycle.

关于数论中的穷竭原则(英文)

The contents of the paper are to appear in book form shortly [4]and it has been given in the author's lectures at Abdus Salam School of Math Sci.GC Univ.Lahore,Pakistan in Feb.,2011.We mean by the exhaustion principle that in a certain way,there is a rule which exhaust all the elements of a system,i.e.,a sort of classification.We shall illustrate this principle by significant examples.Since our examples are related to groups,the exhaustion is mostly of the form of a disjoint union of subsets Hd(dn) exhausting the whole group G:G=∪dnHd(disjoint).