A NOVEL SLIGHTLY COMPRESSIBLE MODEL FOR LOW MACH NUMBER PERFECT GAS FLOW CALCULATION

By analyzing the characteristics of low Mach number perfect gas flows, a novel Slightly Compressible Model (SCM) for low Mach number perect gas flows is derived. In view of numerical calculations, this model is proved very efficient, for it is kept within thep-v frame but does not have to satisfy the time consuming divergence-free condition in order to get the incompressible Navier-Stokes equation solution. Writing the equations in the form of conservation laws, we have derived the characteristic systems which are necessary for numerical calculations. A cell-centered finite-volume method with flux difference upwind-biased schemes is used for the equation solutions and a new Exact Newton Relaxation (ENR) implicit method is developed. Various computed results are presented to validate the present model. Laminar flow solutions over a circular cylinder with wake developing and vortex shedding are presented. Results for inviscid flow over a sphere are compared in excellent agreement with the exact analytic incompressible solution. Three-dimensional viscous flow solutions over sphere and prolate spheroid are also calculated and compared well with experiments and other incompressible solutions. Finally, good convergent performances are shown for sphere viscous flows.

Effect of pouring temperature on semi-solid slurry of ZL101 alloy prepared by slightly electromagnetic stirring

The semi-solid slurry of ZL101 alloy is prepared by a combination technology of low superheat pouring and slightly electromagnetic stirring. The effects of pouring temperature on the slurry prepared by the technology are investigated. The results indicate that it is feasible to prepare the slurry with globular primary phases by low superheat pouring and slightly electromagnetic stirring, and that the pouring temperature has an important effect on the morphology and the size of primary α-AI in ZL101 alloy. By applying suitable slightly electromagnetic stirring combining with relatively increased pouring temperature, i.e., in a practical way to apply low superheat pouring technology, is capable of obtaining appropriate semi-solid slurry of ZL101 alloy with globular shape of primary phase. Compared with the samples made by low superheat pouring only without stirring, the samples prepared by applying both slightly electromagnetic stirring and low superheat pouring can enable to achieve the same grain size and morphology of the primary phase with that of pouring at 15-35℃ higher.

Treatment of Slightly Polluted Wastewater in an Oil Refinery Using a Biological Aerated Filter Process

The slightly polluted wastewater from oil refinery contains some COD, oil pollutants and suspended solids （SS）. A small-scale fixed film biological aerated filter （BAF） process was used to treat the wastewater. The influences of hydraulic retention time （HRT）, air/water volume flow ratio and backwashing cycle on treatment efficiencies were investigated. The wastewater was treated by the BAF process under optimal conditions： the HRT of 1.0 h, the air/water volume flow ratio of about 5 ： 1 and the backwashing cycle of every 4-7 days. The results showed that the average removal efficiency of COD, oil pollutants and SS was 84.5%, 94.0% and 83.4%, respectively. And the average effluent concentration of COD, oil pollutants and SS was 12.5, 0.27, 14.5 mg·L^-1, respectively. The experimental results demonstrated that the BAF process is a suitable and highly efficient method to treat the wastewater.

Application of a Stereo Constructed Wetland Mode to the Treatment of Slightly Polluted Source Water

[Objective] The study aimed to discuss the application of a stereo constructed wetland to the treatment of slightly polluted source water. [Method] In this study, a new stereo constructed wetland mode was put forward, and a pilot project of water ecological purification in Xinsheng River, the diversion channel of Shijiuyang Waterwork in Jiaxing City, were analyzed. Afterwards, the impact factors of water purification by the technology were discussed from water quality and quantity, season and climate, species configuration, management and maintenance. [Result] Under three different hydraulic loading conditions, the pilot project effectively improved water SD and DO level, and reduced SS, CODCr, NH3-N, TN and TP significantly in summer and autumn, so that effluent water quality reached surface water standard at Grade III. [Conclusion] The stereo constructed wetland mode composed of constructed wetland and underwater forest used to treat slightly polluted source water is feasible and has a good promotion prospect.

Biomediated Precipitation of Calcium Carbonate in a Slightly Acidic Hot Spring,Yunnan Province

A slightly acidic hot spring named ＂Female Tower＂（t=73.5°C, pH=6.64） is located in the Jifei Geothermal Field, Yunnan Province, southwestern China. The precipitates in the hot spring are composed of large amounts of calcite, aragonite and sulfur. Scanning electron microscopy（SEM） analyses reveal that the microbial mats were formed from various coccoid or rod-shaped filamentous microbes. Transmission electron microscopy（TEM） shows that the intracellular sulfur granules are commonly associated with these microbes. A culture-independent molecular phylogenetic analysis demonstrates that the majority of the bacteria in the spring are sulfur-oxidizing bacteria. In the spring water, H2S concentration is up to 60 ppm, while SO4-（2-） concentration is only about 10 ppm. We speculate that H2S might derive from sulfur-oxidizing bacteria in this hot spring water, leading to the intracellular formation of sulfur granules. Meanwhile, this reaction increased the p H in the micronscale microdomains, which fosters the precipitation of calcium carbonate in the microbial mats. The results of this study indicate that the sulfur-oxidizing bacteria might play an important role in calcium carbonate precipitation in slightly acidic hot spring environments.

Nonlinear transverse vibrations of a slightly curved beam carrying a concentrated mass

In this study, a slightly curved Euler Bernoulli beam carrying a concentrated mass was handled. The beam was resting on an elastic foundation and simply supported at both ends. Effects of the concentrated mass on nonlin- ear vibrations were investigated. Sinusoidal and parabolic type functions were used as curvature functions. Equations of motion have cubic nonlinearities because of elongations during vibrations. Damping and harmonic excitation terms were added to the equations of motion. Method of mul- tiple scales, a perturbation technique, was used for solving integro-differential equation analytically. Natural frequen- cies were calculated exactly for different mass ratios, mass locations, curvature functions, and linear elastic foundation coefficients. Amplitude-phase modulation equations were found by considering primary resonance case. Effects of nonlinear terms on natural frequencies were calculated. Frequency-amplitude and frequency-response graphs were plotted. Finally effects of concentrated mass and chosen curvature function on nonlinear vibrations were investigated.

Advanced Treatment of Wastewater and Slightly Deteriorated Raw Water by Biological Activated Carbon Method under Rich Oxygen Condition

Rich oxygen-biological activated carbon(RO-BAC)method developed from traditional BAC method is a sys-tem in which high pressure is applied to improve the oxy-gen concentration of the influent.Experiment withwastewater and the slightly deteriorated raw water showsthe system is an effective option for advanced treatmentof industry wastewater and pretreatment of slightly dete-riorated raw water.The experiment results and the in-fluential factors are discussed in this paper.

Effects of Drinking Slightly Acidic Electrolytic Water on Growth Performance and Behavior of Broilers

[Objective]The paper was to study the effects of drinking slightly acidic electrolytic water on growth performance and behavior of Rose 308 broilers,and to provide reference for the application of slightly acidic electrolytic water in broiler breeding.[Method]A total of 300 healthy 10-day-old Rose 308 broilers with similar body weight were randomly divided into five groups,three replicates each group,20 broilers each replicate.The broilers in control group were supplied with normal drinking water,and the broilers in experimental groups consumed slightly acidic electrolytic water with 0.3,0.5,0.7,1.0 mg/L residual chlorine,respectively.The test lasted 21 d.[Result]At 10-30 days of age,the water consumption of broilers in 0.7 and 1.0 mg/L electrolytic water groups were increased by 9.27%and 7.67%respectively compared with the control group(M<0.05).The average daily feed intake(ADFI)of broilers in 0.7 and 1.0 mg/L electrolytic water groups were increased compared with the control group(Q0.05).The average daily gain(ADG)of broilers in 0.7 mg/L electrolytic water group was 11.99%lower than that in control group(M<0.05).The feed gain ratio(F/G)of broilers in 0.5 mg/L electrolytic water group was 12.29%lower than that in control group(M<0.05),and the mortality was the lowest in 0.5 mg/L electrolytic water group.The standing,feeding and drinking frequency of broilers in experimental groups were higher than that in control group,and the flapping behavior of broilers in 0.5 mg/L electrolytic water group was the lowest.[Conclusion]Drinking slightly acidic electrolytic water has positive effect on the growth and behavior of broilers.

Reflected Beam Displacements of a Slightly Divergent Ultrasonic Gaussian Beam on a Water-Glass Interface Near Rayleigh Angle Incidence

Two reflected beams of a slightly divergent ultrasonic Gaussian beam on a water-glass interface are observed and recorded by a Schlieren system. The lateral displacements of the two reflected beams are measured for incident angle θi in a wide range of 10° around the Rayleigh angle θc. The displacements decrease as the incident angle increases, which is different from the previous predictions for bounded plane-wave beams, where the displacements have extremum at the Rayleigh angle θc.The explanation is based on the fact that the Gaussian beam generated by an ultrasonic transducer with a button (or strip) back electrode is actually slightly divergent. We extend Bertoni and Tamir's theory (Appl. Phys. 2 (1973) 157) to this case, and our calculated curves of the displacements against the incident angle are in agreement with the experimental results for |θi - θc| < 2°.

Propagation, reflection, and transmission of SH-waves in slightly compressible, finitely deformed elastic media

The propagation, reflection, and transmission of SH waves in slightly com- pressible, finitely deformed elastic media are considered in this paper. The dispersion relation for SH-wave propagation in slightly compressible, finitely deformed layer over- lying a slightly compressible, finitely deformed half-space is derived. The present paper Mso deals with the reflection and refraction （transmission） phenomena due to the SH wave incident at the plane interface between two distinct slightly compressible, finitely deformed elastic media. The closed form expressions for the amplitude ratios of reflection and refraction coefficients of the reflected and refracted SH waves are obtained from suit- able boundary conditions. For the numerical discussions, we consider the Neo-Hookean form of a strain energy function. The phase speed curves, the variations of reflection, and transmission coefficients with the angle of incidence, and the plots of the slowness sections are presented by means of graphs.

China farm produce prices rebound slightly

Xinhua reported on May 2 that China’s farm produce prices mostly rebounded, ending a five-consecutive-week downward trend as persistent rainfall limited market supplies, new data has shown.

Foreign Trade Recovering Slightly

China’s foreign trade from January to May According to Customs figures,China’s total import and export value from January to May reached 9.16trillion yuan,down 3.2%year on year(the same below).In terms of the U.S.dollar,the total import and export value for the first five months reached$1.14trillion,down 8.6%.In May alone,the total import and export value was$2.02 trillion,up 2.8%.Among which,

Optical Measurements to Reveal Roles of Slightly Crosslinked Poly (dimethyldiallylammonium chloride) s in Fixing Anionic Dyes on Cotton Fabric

The roles of slightly crosslinked poly( dimethyldiallylammonium chloride) s( PDMDAACs) in fixing anionic dyes on cotton fabric were verified more precisely by optical analysis technologies,to achieve the new theoretical guides for the widely applications. Firstly,one method of optical CIELAB color difference analysis was designed to exactly measure the values of dyefixing performances, so that the suitable molecular weights and structures of the slightly crosslinked PDMDAACs could be precisely confirmed to play a role in the development of their dye-fixing performances. Secondly,the FT-IR absorption shift of the dye on dyed cotton sample fixed by slightly crosslinked PDMDAACs was nearly in agreement with that of forming water-insoluble color lakes,indicating that the expected color lakes could be formed on dyed cotton fabric,and would play a role in further development of the fastness of dyes on cotton fabric. Thirdly,the FT-IR spectra of fixed undyed cotton samples and that of fixed dyed cotton samples both showed the absorptions of slightly crosslinked PDMDAACs,further revealing that the slightly crosslinked PDMDAACs could be penetrated into cotton fabric and be convenient to interact with dyes when fixing. However,those absorptions of the slightly crosslinked PDMDAACs fixed on cotton samples would be absent after being adequately washed to a constant weight,suggesting that the fixing interactions of the slightly crosslinked PDMDAAC and cotton fabric were very weak.

Births in China Reduced Slightly Year-to-year in Line with the Law of Population Change

On January 19,National Bureau of Statistics announced that births in 2015 were 16.55 million,a slight drop of 320 000 compared to 2014.How should we consider the reduction of births after implementation of the selective two-child policy？

The logistics industry in the U.S.grew slightly in December 2022

The logistics industry in the United States grew slightly in December 2022,and the country's Logistics Managers Index(LMI)reached 54.6,up 1 percentage point from 53.6 in November 2022,but still far below the high point in 2021.The inventory levels of downstream enterprises in the United States is much higher than that of upstream enterprises(62.8 to 53.3,respectively),which indicates the differentiation observed in December.

Prosperity index of specialized market drops slightly

The prosperity monitoring results of the China Commercial Circulation Association of Textile and Apparel(CATA)show that in December 2020,the national textile and apparel specialized market manager’s prosperity index was 50.16,a decrease of 0.59 percentage points from November’s 50.75;the specialized market merchant’s prosperity index was 50.80,a decrease of 0.66 percentage points from November’s 51.46.In December,the prosperity index of the textile and apparel specialized market declined slightly on the basis of the peak sales season in November,and the prosperity index was generally better.

The prosperity index of textile and apparel specialized market fluctuates slightly in Aug.

The prosperity monitoring results of the China Commercial Circulation Association of Textile and Apparel(CATA)show that in August 2021,the national textile and apparel specialized market manager's prosperity index was 50.38,unchanged with July;the specialized market merchant’s prosperity index was 49.60,down 0.13 percentage points from 49.73 in July.In August,the textile and apparel specialized market prosperity index was stable and fluctuated slightly.

从“微饮”立论射血分数保留的心力衰竭早期防治思想

射血分数保留的心力衰竭(heart failure with preserved ejection fraction, HFpEF)是目前心血管领域的治疗难点,防治前线前移对于减缓或逆转HFpEF发病进程至关重要。聚焦HFpEF早期的中医防治,是发挥中医治未病优势的关键。通过梳理仲景提出的“微饮”内涵和证治,结合HFpEF早期的发病机制,提出HFpEF早期以微饮内停上焦为主要病机,临证应以苓桂术甘汤为主祛饮通阳,以期阻断饮证进一步发展,截断HFpEF发展进程。从“微饮”立论HFpEF早期防治,可以防微杜渐,具有重要的临床意义。

聊城市农田土壤污染评价及农业功能分区

为探索聊城市农田土壤污染状况及农业功能分区,以2017~2020年采集的74个表层土样为研究对象,测定了8种重金属元素(Cd、Hg、As、Cu、Pb、Cr、Zn和Ni)、BHC_(s)、DDT_(s)和BaP的含量。依据《土壤环境质量农用地土壤污染风险管控标准》和《绿色食品产地环境质量》作为评价标准,采用污染指数法开展了土壤环境质量评价和农业功能分区研究。采用ANOVA和LSD多重比较,确定了污染物的空间分布差异及其来源。依据山东省土壤背景值进行了重金属潜在生态风险评价。结果表明,除3个DDTs污染样点和1个Cd污染样点外,其他样点均处于清洁水平。在空间分布上,DDTs和Cr含量存在极显著差异,BaP和Hg存在显著差异。农业功能分区结果表明,绿色食品种植区、无公害食品种植区、观察种植区和污染区面积分别占研究区总面积的78.13%、9.45%、6.52%和5.90%。土壤环境生态风险水平以轻微为主,占总面积的77.03%。Hg和Cd在生态风险评估中占有较大比率,应高度警惕和严格监管。

竹材微炭化干燥工艺中液体产物特性分析

在固定床反应器上采用微炭化工艺干燥处理竹材,并对干燥尾气进行冷凝回收,探讨微炭化干燥工艺对竹材干燥冷凝液体产物特性的影响。研究结果表明:竹材于210℃微炭化干燥处理得到冷凝液体主要含有酸、醛、酯、酮和酚类物质。微炭化工艺对竹材干燥液体产物特性有显著影响,210℃时醛类物质质量分数达22.14%,250℃时醇、酚类物质质量分数分别为25.13%、28.33%;升温速率造成酸、醛类物质先增加后减少,10℃/min时最大,分别为67.89%、22.14%,酮类物质变化趋势则相反,20℃/min时最大,为21.35%;随氮气流量增大,酸类物质增加,由51.84%增至81.71%,醛类、酮类物质减少,分别由26.07%、10.95%降至8.36%、2.58%。竹材微炭化干燥液体产物成分与木、竹醋液相似,具有用作植物生长促进剂、土壤改良剂等潜力。