离心泵最小连续热限制流量的估算

本文依据API610第10版对最小连续热限制流量的定义,为了预防离心泵在小流量下运行时由于物料温度过高而导致汽化产生汽蚀,所以对其进行介绍和讨论从而给出计算方法。

华北热资源限制区实现夏玉米高产高效和机械粒收的适宜种植密度和施氮量

【目的】华北平原夏玉米高效生产不仅取决于产量和肥料利用率,也依赖于高效的机械粒收。本研究探讨了密度与氮肥用量对夏玉米产量形成和收获期籽粒水分含量的影响。【方法】以玉米‘京农科728’为材料,采用裂区试验设计,主区设置2个密度:7.5×10^(4)株/hm^(2)(D_(7.5))和9.0×10^(4)株/hm^(2)(D_(9.0)),副区设置5个施氮(N)水平:0、180、240、300和360 kg/hm^(2)(分别表示为N_(0)、N_(180)、N_(240)、N_(300)和N_(360))。测定了不同密度和氮肥用量下玉米叶片SPAD值、叶面积指数(LAI)、干物质积累(DM)、籽粒灌浆、产量及其构成因素、氮肥偏生产力(PFP_(N))和农学利用效率(AE_(N))。【结果】与D_(7.5)相比,D_(9.0)处理V 6和R 1期L A I和DM分别提高5.0%~26.3%和3.7%~34.8%;籽粒最大灌浆速率(G_(max))提高0.35~1.33 g/(100-grain·d),灌浆速率最大时日期(T_(max))提前4.4天但灌浆持续期缩短6.9~12.2天,穗粒数减少15.0~51.3粒,实现增产2.4%~28.3%,达7.36×10^(3)~12.22×10^(3) kg/hm^(2);PPFN和AE_(N)分别显著提高10.1%~17.2%和72.0%~94.4%。与N_(0)相比,夏玉米叶片SPAD值随施氮量增加显著提高,施氮处理LAI和DM分别提高3.5%~171.3%和5.0%~177.7%;N_(240)~N_(360)水平G_(max)达峰值1.33~1.39 g/(100-grain·d),施氮处理T_(max)提前4.1~4.6天,灌浆速率最大时生长量(W_(max))提高5.7%~9.4%;百粒重提高0.5%~18.4%,穗粒数显著增加62.8~79.2粒,产量提高3.2%~115.7%,达10.10×10^(3)~11.33×10^(3) kg/hm^(2)。在D_(7.5)和D_(9.0)下,随施氮量增加夏玉米PFP_(N)、AE_(N)分别显著降低24.2%~46.6%和21.2%~43.1%、21.1%~32.5%和13.0%~32.9%。【结论】较高的夏玉米密度可以有效提高玉米干物质积累速度,降低籽粒含水量至15.4%~24.8%,满足籽粒机收的要求。施氮量控制在180~240 kg/hm^(2),可进一步降低籽粒收获时的含水量,提高叶片SPAD值、叶面积指数及干物质积累,改善籽粒灌浆提高粒重,实现产量稳定在10.5×10^(3)~11.2×10^(3) kg/hm^(2),氮肥偏生产力和农学利用效率高达47.0~59.7和27.6~30.9 kg/kg。因此,机收夏玉米适宜的密度为9.0×10^(4)株/hm^(2),施氮水平为180~240 kg/hm^(2)。

凸极发电机P-Q图质疑

一些教材里关于发电机在动率因数变动时的运行部分推出的凸极机 P-Q 图(如图1)值得商榷,因为 P-Q 图直接影响安全运行极限的推导。证明如下。

一族线性屈服破坏函数对应的耗散势

在材料塑性本构理论中应用热动力学原理一般有两种方法,一是在引入的屈服(包括硬化)、破坏函数和塑性势概念的基础上,从数学上或者根据试验规律,假设(拟合)其函数形式,然后将热力学定律或准热力学公设作为附加约束引入本构模型;二是直接从热动力学出发,通过构造能量函数(热力学势)、耗散函数及较少的限制条件给出全部的塑性本构理论,而得到的本构理论自动满足热动力学原理。长期以来,针对各种不同材料提出的大量屈服破坏函数,许多都是按照第一种方法给出的,却并未见到进行过严格的热动力学限制的验证。研究从塑性本构理论中上述两种研究方式在热力学定律的满足上的一致性出发,将求屈服函数对应的耗散势的问题归结为关于耗散势的偏微分方程求解问题,从理论上演绎出塑性理论中一族率无关线性屈服破坏函数对应的耗散势函数,从而将屈服破坏函数的热动力学验证问题转化为其对应耗散势的正负判断问题,也沟通了塑性理论中屈服破坏函数同热动力学中耗散势在概念上的联系,对于理解屈服破坏函数的热动力学内涵有重要理论意义。特别地,文中给出的求耗散势的方法具有一般性,不仅适合于线性的屈服破坏函数,也适合于非线性的屈服破坏函数。最后,利用热力学第2定律给出了一族线性屈服破坏函数具体的热力学限制条件。

Temporal stability of Symbiodinium phylotype in scleractinian coral Galaxea fascicularis from a tropical fringing reef in the South China Sea

Symbiodinium sp. occurs in a symbiotic association with various marine invertebrates, including the seleractinian corals. Understanding the flexibility and specificity in coral-algal symbiosis can have important implications for predicting the future of coral reefs in the era of global climate change. In the present study, we conducted Symbiodinium phylotype analysis, based on polymerase chain reaction and restriction fragment length polymorphism （PCR-RFLP）, in the scleractinian coral, Galaxeafascicularis, from a tropical fringing reef in Hainan Island, over a 1-yr period. Our results showed that Galaxea fascicularis could associate with Symbiodinium clade C and D either individually or simultaneously. However, during the sampling period, the Symbiodinium phylotype did not change significantly in the scleractinian coral Galaxeafascicularis, although the seawater temperature decreased sharply in the winter season. This study further suggests that the shift in Symbiodinium communities in response to seasonally fluctuating environments might not be a universal feature of coral-algal associations.

Rat Hepatocyte Glucose Metabolism Is Affected by Caloric Restriction but not by Litter Size Reduction

This work aimed at investigating whether the liver glucose metabolism could have a role in any change of glucose homeostasis that might exist in the reduced-litter rat at the age of 60 days. Additionally, post-weaning caloric restriction and its hepatic effects were explored, as this intervention is reported as a useful measure against obesity and its related disturbances. The animals were raised in litters of nine （control, CG） or three pups during lactation. These small-litter pups were FG （fed freely） or subjected to 30% RG （caloric restriction） after weaning until 60 days of age. The increased adiposity induced by lactational overfeeding was not reversed by caloric restriction. Hepatocyte glucose metabolism and glucose tolerance test were not affected by litter size, but caloric restriction increased liver basal glucose release, diminished gluconeogenesis and retarded the glycemic decay during the insulin tolerance test. Liver glucose metabolism of young adult rats was not affected by lactational overfeeding. Up to this age, however, moderate caloric restriction had a potent influence that might compromise whole-body glucose homeostasis and prompt to insulin resistance.

聚变堆与聚变堆材料——ITER试验包层模件的概念设计

ITER试验包层模件(TBM)系统必须具备以下功能：(1)演示氚的增殖能达到DEMO的技术目标，(2)采用合适的冷却剂排出高温的热能以演示能达到DEMO的技术目标(包括合适的压力降和泵唧功率)，(3)在允许的温度和应力限制下，排出表面热负荷和体积热负荷，(4)按照ITER中子通量的目标，降低真空室的核反应、超导线圈的核发热和辐照损伤，(5)最大限度提供机械结构的自支撑以降低传到真空室的机械载荷，隔离’rBM和真空室之间的热量传递。

Fusion Reactor and Fusion Reactor Materials：Concept Design of the ITER Test Blanket Modules

Performances required: prospect to be adopted in DEMO. Shielding for V.V. and TFC in ITER. Design principles: the peak temperature and stress should not exceed technical limits. The structure of test blanket modules (TBM) should be simple for easy fabrication, and TBM should be robust for reliability.

ASSIMILATION OF OBSERVED SURFACE WIND WITH GRAPES

With the advances of numerical weather simulation and reduced data assimilation updating cycle, surface observation data assimilation becomes more and more important in data assimilation systems It is widely accepted that a better data assimilation system should contain the restriction of thermod^amic processes in the surface layer. Therefore, in this paper, a new surface wind observation operator is utilized in Global and Regional Assimilation PrEdiction System_3D-Variance （GRAPES_3D-Var）, with the restriction of thermodynamic process in the planetary boundary layer （PBL）. In order to research the ability of this new surface wind observation operator in assimilation and forecasting, a series of experiments are operated by using the GRAPES model. The main results indicate that this new method of surface wind observation operator has positive impact on the forecast with the GRAPES model.

Electron Heat Transport during Center Fuelling by Pellet Injection on HL-2A Tokamak

The improved energy confinement has been observed in many tokamaks with center pellet injection since 1980＇s. The pellet enhanced performance （ PEP ） was achieved with high power additional heating in JET and other large tokamaks. The mechanism of the PEP mode has been analyzed theoretically . The analysis shows that a few mechanisms are involved in the reduction of anomalous transport and the relative weight of these mechanisms depends on the experimental conditions. In this paper we report the pellet injection experiment results without auxiliary heating on HL-2A tokamak. Our works focus on the investigation of the electron heat transport in ohmic discharges with center pellet fuelling.

Numerical simulation and model of control-efficiency of thermal crown of work rolls in cold rolling

Aiming at accuracy control of the thermal crown of work rolls in cold rolling,new parameters such as regulation domain and control-efficiency factors were proposed and a numerical analysis model of the thermal crown of work rolls was established using finite difference method to study roll's thermal deformation.Based on simulation results,the influences of control-efficiency factors on thermal crown are presented and the thermal crown of work rolls is analyzed after taking sub-cooling of sprinkling beam into consideration.It has been found that the control-efficiency factor of any position on the roll's surface is linear function of the temperature and the control ability of water temperature is stronger than other control parameters.In addition,the verification of the model has been carried out based on the producing technology data in some factories and the numerical simulation results coincide well with the experimental data.Therefore,this work has important value for on-line control of roll's crown in cold rolling.

为什么计件出了毛病

在大力推行计件工资制时,如果只注意扩大计件面而忽视不同工种的生产特点,不注意推行计件工资的经济效果,便会给生产带来损失。这是我们最近对我厂计件工资工作进行调查研究后深深体会到的一点道理。我厂铸造车间在1956年一年中计件面不断得到扩大,到1956年年底计件工人已占全部生产工人的70%,计件工资已成为这个车间的基本工资形式。推行计件工资的结果,总的说来,劳动生产率有所提高,产品质量有所改进,但是。

Fuel Cells as Energy Systems： Efficiency, Power Limits and Thermodynamic Behavior

Steady-state model of a high-temperature solid oxide fuel cell （SOFC） is considered, which refers to constant chemical potentials of incoming hydrogen fuel and oxidant. Lowering of the cell voltage below its reversible value is attributed to polarizations and imperfect conversions of reactions. An imperfect power formula summarizes the effect of transport laws, irreversible polarizations and efficiency of power yield. Reversible electrochemical theory is extended to the case with dissipative chemical reactions; this case includes systems with incomplete conversions, characterized by ＂reduced affinities＂ and an idle run voltage. Efficiency drop is linked with thermodynamic and electrochemical irreversibilities expressed in terms of polarizations （activation, concentration and ohmic）. Effect of incomplete conversions is modeled by assuming that substrates can be remained after the reaction and that side reactions may occur. Optimum and feasibility conditions are discussed for basic input parameters of the cell. Calculations of maximum power show that the data differ for power generated and consumed and depend on current intensity, number of mass transfer units, polarizations, electrode surface area, average chemical rate, etc.. These data provide bounds for SOFC energy generators, which are more exact and informative than reversible bounds for electrochemical transformation.

江苏省教育行政干校拼音字母学习班教学小结

《汉语拼音方案草案》公布以后,我厅决定组织各市县部分中、小学教育干部(包括中、小学校长,教导主任,科局督学,科员)学习一次拼音方案。学员246人,共编四个班,平均每班60人。一月十二日上午全体学员听取了周总理、胡乔木同志的录音报告和胡愈之同志的传达报告。下午,我厅领导上又向全休学员进行了一次动员。十三日正式上课,十七日结束。

Artemisinin mimics calorie restriction to extend yeast lifespan via a dual-phase mode: a conclusion drawn from global transcriptome profiling

Calorie restriction(CR) promotes longevity among distinct organisms from yeast to mammals. Although CR-prolonged lifespan is believed to associate with enhanced respiratory activity, it is apparently controversial for accelerated energy consumption regardless of insufficient nutrient intake. In reconciling the contradiction of less food supply versus much metabolite dispense, we revealed a CR-based mode of dual-phase responses that encompass a phase of mitochondrial enhancement(ME) and a phase of post-mitochondrial enhancement(PME), which can be distinguished by the expression patterns and activity dynamics of mitochondrial signatures. ME is characterized by global antioxidative activation, and PME is denoted by systemic metabolic modulation. CR-mediated aging-delaying effects are replicated by artesunate, a semi-synthetic derivative of the antimalarial artemisinin that can alkylate heme-containing proteins, suggesting artesunate-heme conjugation functionally resembles nitric oxide-heme interaction. A correlation of artesunate-heme conjugation with cytochrome c oxidase activation has been established from adduct formation and activity alteration. Exogenous hydrogen peroxide also mimics CR to trigger antioxidant responses, affect signaling cascades, and alter respiratory rhythms, implying hydrogen peroxide is engaged in lifespan extension. Conclusively, artesunate mimics CR-triggered nitric oxide and hydrogen peroxide to induce antioxidative networks for scavenging reactive oxygen species and mitigating oxidative stress, thereby directing metabolic conversion from anabolism to catabolism, maintaining essential metabolic functionality, and extending life expectancy in yeast.

Effect of Linguizhugan decoction on hyperlipidemia rats with intermittent fasting

OBJECTIVE:To explore the effect of Linguizhugan decoction on hyperlipidemia rats with caloric restriction.METHODS:The hyperlipidemia model of rat was induced by high fat diet for 8 weeks.After the model was established,26 rats were randomly divided into 4 groups:the control group(n=6),the model group(n=6),the intermittent fasting(IF) group(n= 8),and the IF and herbal medicine(IFH) group(n= 6).IF group was applied intermittent fasting every other day.The IFH group was given Linguizhugan decoction every day and intermittent fasting every other day.Blood samples were taken at the end of 16 weeks,and serum ghrelin and lipid was tested.RESULTS:Serum ghrelin in the IF group significantly increased(P<0.01).Serum ghrelin in IFH group was lower than the IF group(P<0.05),but higher than the model group(P<0.01).CONCLUSION:Linguizhugan decoction may play a part in regulation of energy and appetite in hyperlipidemia rats with IF.

Intermittent protein restriction protects isletβcells and improves glucose homeostasis in diabetic mice

Diabetes is caused by the interplay between genetics and environmental factors, tightly linked to lifestyle and dietary patterns. In this study, we explored the effectiveness of intermittent protein restriction(IPR)in diabetes control. IPR drastically reduced hyperglycemia in both streptozotocin-treated and leptin receptor-deficient db/db mouse models. IPR improved the number, proliferation, and function of β cells in pancreatic islets. IPR reduced glucose production in the liver and elevated insulin signaling in the skeletal muscle. IPR elevated serum level of FGF21, and deletion of the Fgf21 gene in the liver abrogated the hypoglycemic effect of IPR without affecting β cells. IPR caused less lipid accumulation and damage in the liver than that caused by continuous protein restriction in streptozotocin-treated mice. Single-cell RNA sequencing using mouse islets revealed that IPR reversed diabetes-associated β cell reduction and immune cell accumulation. As IPR is not based on calorie restriction and is highly effective in glycemic control and β cell protection, it has promising translational potential in the future.

Effect of a combination of calorie-restriction therapy and Lingguizhugan decoction on levels of fasting blood lipid and inflammatory cytokines in a high-fat diet induced hyperlipidemia rat model

OBJECTIVE:To combine calorie-restriction therapy(CRT) with Traditional Chinese Medicine(TCM) using Lingguizhugan Decoction and note the effects on expression of inflammatory cytokines[tumor necrosis factor(TNF)-α,high-sensitivity C-reactive protein(hs-CRP),interleukin(IL)-6]in high-fat-diet induced hyperlipidemia in rats.METHODS:Forty rats were divided randomly and equally into four groups:control group A(regular feeding for 5 weeks);model group B(high-fat diet for 5 weeks),calorie-limited group C(high-fat diet for 5 weeks) and TCM calorie-limit group D(high-fat diet for 5 weeks).After modeling,groups C and D were fasted for 3 days:group C with simple fasting,and group D with TCM fasting.The motion as well as changes in color,body weight,food intake,plasma lipids[low-density lipoprotein-cholesterol(LDL-C),high-density lipoprotein-cholesterol,total cholesterol(TC) and triglyceride(TG) along with TNF-α,hs-CRP and IL-6]were measured before and after intervention.RESULTS:Modeled rats were established after five weeks.After 3 days of fasting,compared with group B,blood lipid levels(TG,TC,LDL-C) of groups C and D decreased dramatically.Those of group D decreased more obviously than those of group C.However,the values of TNF-α,hs-CRP and IL-6 showed no obvious difference between each of the three treatment groups.CONCLUSION:CRT can reduce fasting blood lipid levels in rats,but not by reducing the levels of inflammatory cytokines.

Mechanistic perspectives of calorie restriction on vascular homeostasis

Calorie restriction(CR)is a dietary regime based on low calorie intake.CR without malnutrition extends lifespan in a wide range of organisms from yeast to rodents,and CR can prevent and delay the onset of age-related functional decline and diseases in human and non-human primates.CR is a safe and effective intervention to reduce vascular risk factors in humans.In recent years,studies in rodents have provided mechanistic insights into the beneficial effects of CR on vascular homeostasis,including reduced oxidative stress,enhanced nitric oxide(NO)bioactivity,and decreased inflammation.A number of important molecules,including sirtuins,AMP-activated protein kinase,mammalian targets of rapamycin,endothelial nitric oxidase and their regulatory pathways are involved in the maintenance of vascular homeostasis.Evidence has shown that these pathways are responsible for many aspects of CR’s effects,and that they may also mediate the effects of CR on vasculature.

拿破仑法典初步批判

一拿破仑法典就是一八○四年三月二十一日公布的法国民法典。它是在法国一七八九年资产阶级大革命以后,于拿破仑执政期间内,在拿破仑亲自领导起草之下制定的,因此曾经取得『拿破仑法典』的名称。它是资产阶级国家在时间上占着最先、在影响上最为远大的一部民法典。