Influence of Non-Natural Ageing Temperature on the Microstructural Characteristics and Mechanical Properties of Cast Aluminum 6063 Alloy

This research considered the effect of non-natural aging on the microstructural characteristics and mechanical properties of as-cast aluminum 6063 alloys. The samples were developed through a sand casting process and machined into tensile and impact test samples before carrying out solution heat treatment at 550?C (0.83 Tm) on two parts of the samples while retaining one part as the control. The two parts were further divided into sets denoted A and B and were aged at 180?C (0.27 Tm) and 160?C (0.24 Tm), respectively, for 12 hours. The results showed that sample A has the optimal yield strength and ultimate tensile strength of 192 and 206 MPa, respectively. Likewise, the sample gave the highest impact strength value of about 9.63 J/mm2. The observed results were supported by the optical micrograph, which revealed that the sample has evenly dispersed precipitates in its microstructure. This is deemed responsible for the observed increase in strength of the sample.

Non-use value assessment for wetland ecosystem service of Hongxing National Nature Reserve in northeast China

By the contingent value method, we studied the non-use value of wetland ecosystem service of Hongxing National Nature Reserve （HNNR） in Heilongjiang Pro- vince, northeast China. The proportion of respondents willing to pay （WTP） for protection of HNNR was 63 %. The WTP ratio was affected by geographical area, contact nature, personal preferences, and familiar degree of the respondents. The WTP value was affected by age, education level and career of the respondents. The mainly reasons for people rejecting to pay for protecting HNNR were ＂I am not familiar to HNNR＂ and ＂I had no capacity for additional spending because of low income＂. Weighted average individual WTP value was CNY 59.26 Yuan ind.^-1 year^-1 for all the respondents with WTP. The total non-use ecosystem service value of HNNR was CNY 1430 million Yuan in 2013. The heritage value was highest followed by existence value and option value. From the high ecosystem service value in HNNR, it is very important to construct nature reserve for protecting natural ecosystems and human sustainable use of natural resources.

Path Integral Quantization of Non-Natural Lagrangian

Path integral technique is discussed using Hamilton Jacobi method. The Hamilton Jacobi function of non-natural Lagrangian is obtained using separation of variables method. This function makes an important role in path integral quantization. The path integral is obtained as integration over the canonical phase space coordinates, which contains the generalized coordinate q and the generalized momentum p. One illustrative example is considered to explain the application of our formalism.

Entropy Production in a Non-Isolated Thermodynamic System Taking into Account Regular Factors of Nonrandom Nature

The work illustrates the impossibility of decreasing entropy in a strictly random thermodynamic process in a non-isolated system using the example of heating a planet by solar radiation flux without and taking into account its rotation around its own axis. That is, the second law of thermodynamics formulated for isolated systems continues to govern such systems. We have shown that in order to achieve a stationary state at lower values of temperature and entropy far from thermodynamic equilibrium at a maximum of temperature and entropy, it is necessary to have regular factors of nonrandom nature, one of which in this example is the rotation of the planet around its own axis. This means that the reason for the appearance of ordered structured objects in non-isolated thermodynamic systems is not the random process itself, but the action of dynamic control mechanisms, such as periodic external influences, nonlinear elements with positive feedback, catalysts for chemical reactions, etc. We present the plots with dependences of temperature and entropy versus time in non-isolated systems with purely random processes and in the presence of a control factor of non-random nature-rotation.

Natural convection of an alumina-water nanofluid inside an inclined wavy-walled cavity with a non-uniform heating using Tiwari and Das' nanofluid model

The present study is devoted to numerical analysis of natural convective heat transfer and fluid flow of alumina-water nanofluid in an inclined wavy-walled cavity under the effect of non-uniform heating. A single-phase nanofluid model with experimental correlations for the nanofluid viscosity and thermal conductivity has been included in the mathematical model. The considered governing equations formulated in dimensionless stream function, vorticity, and temperature have been solved by the finite difference method. The cavity inclination angle and irregular walls(wavy and undulation numbers)are very good control parameters for the heat transfer and fluid flow. Nowadays, optimal parameters are necessary for the heat transfer enhancement in different practical applications. The effects of the involved parameters on the streamlines and isotherms as well as on the average Nusselt number and nanofluid flow rate have been analyzed. It has been found that the heat transfer rate and fluid flow rate are non-monotonic functions of the cavity inclination angle and undulation number.

On the combined heat transfer of natural convection, radiation and conduction in the non-gray semitransparent thermal fibrous insulation

A detailed numerical modeling is performed to investigate heat transfer in high-porous, high-temperature non-gray semitransparent silica insulation materials. Radiation between fibers, conduction within fibers and convection from the fibers to the surrounding fluid are considered. Macroscopic (porous media) modeling is used to determine the velocity, pressure and temperatures fields for fibrous insulation with a random packing geometry under natural convection. Based on a non-gray application of the solution to the radiative transfer equation, the value of the refractive index(n,m)is used to generate macroscopic average radiative properties such as extinction coefficient, scattering albedo and phase function. Key features of the macroscopic model include two-dimensional effects,non-gray radiative exchange, and the relaxation of the local thermodynamic non-equilibrium. The effectiveness of this numerical model is validated by the previous experimental data.

NONLINEAR NATURAL FREQUENCY OF SHALLOW CONICAL SHELLS WITH VARIABLE THICKNESS

The nonlinear dynamical variation equation and compatible equation of the shallow conical shell with variable thickness are obtained by the theory of nonlinear dynamical variation equation and compatible equation of the circular thin plate with variable thickness. Assuming the thin film tension is composed of two items. The compatible equation is transformed into two independent equations. Selecting the maximum amplitude in the center of the shallow conical shells with variable thickness as the perturbation parameter, the variation equation and the differential equation are transformed into linear expression by theory of perturbation variation method. The nonlinear natural frequency of shallow conical shells with circular bottom and variable thickness under the fixed boundary conditions is solved. In the first approximate equation, the linear natural frequency of shallow conical shells with variable thickness is obtained. In the third approximate equation, the nonlinear natural frequency of it is obtained. The figures of the characteristic curves of the natural frequency varying with stationary loads, large amplitude, and variable thickness coefficient are plotted. A valuable reference is given for dynamic engineering.

Non-dimensional analysis of static bifurcation in a natural circulation loop

The steady-state characteristics of a two-phase natural circulation loop were investigated based on the homogenous model. Transcendental equations of non-dimensional loop mass flow rate under various conditions were also derived. The static bifurcation diagram of a two-phase natural circulation described with non-dimensional vari-ables Npch-m + was obtained. In addition, various steady-state characteristics of a natural circulation loop were ana-lyzed and discussed. These characteristics include the existence of multiple solutions under certain conditions, and the maximum mass flow rate. The authors also examined the effects of important parameters such as sub-cooling number, riser-to-heated-region length ratio, and riser-to-heated-region diameter ratio.

Mechanism of ONB based on nonequilibrium thermodynamics of natural circulation in narrow channels

Based on the experiment of onset of nucleate boiling(ONB)in natural circulation and the nonequilibrium thermodynamics dissipative theory,the mechanism of ONB in narrow rectangle channels of natural circulation is proposed.It points out that the onset of nucleate boiling is influenced by the degree of superheat and the special conditions of narrow channels.Under the conditions of both density difference in natural circulation and narrow rectangle channels,the prediction model of ONB in natural circulation of narrow channels based on fluctuating is established.The experimental results show that the present model can be used to predict the heat flux of ONB in narrow rectangle channels.Features of ONB in natural circulation narrow rectangle channels are as follows:heating power is the incentive of the happen of ONB;the higher the heating power is,the higher the degree of superheat is,and the earlier the ONB will appear.With the pressurizing,the appearance of ONB will be delayed.The higher the degree of supercooling is,the later the ONB appears.The ONB will happen easier when there are noncondensable gases and roughness in the channels.

医学伦理学发展新阶段的历史使命

每个时代都有每个时代伦理学的主轴。当今医学伦理学面临崭新的境遇,资本、技术、权力和全民健康等问题,已经构成医学伦理学应对和挑战的主要课题。新形势向医学伦理学提出了种种新任务,探索完成这些新任务的政策建议和伦理举措;适应新形势医学伦理学如何加强自身理念的充实、创新和提高;在新情境下如何促进医学伦理学在医学领域内的全面覆盖,让医学伦理学在医学中深深扎根,促进医学技术更好地服务于人民大众的健康,都是开启医学伦理学新征程面临的担当。

地震事件分类识别软件

非天然地震事件分类是地震监测业务部门的日常工作之一。本研究主要针对地震、爆炸和矿震的分类问题,在地震波数据处理、特征提取和人工智能综合分类的研究基础上,基于Qt开发框架,结合Python、 Matlab等多种编程语言,开发了一个具有良好的可移植性和可扩展性、具有自主知识产权的地震分类识别软件。该软件可以部署在不同操作系统上,由七个模块组成:地震数据导入模块、数据处理模块、特征提取模块、综合分类模块、特征分析模块、当量估算模块和结果分析模块。软件集成了多种时频特征提取技术和人工智能分类方法,形成了较为完整的地震类型判定流程。软件内置的地震事件分类模型准确率高于90%,适用范围较广,已推广应用于多个地震监测部门,并取得了较好的应用成果,提高了对非天然地震的快速分析能力。

基于分层分区域虚拟材料方法的丝杠螺母结合部精确建模研究

为了建立精确的滚珠丝杠螺母结合部模型,基于多目标优化方法获取其结合部虚拟材料模型的参数,构建了精确的结合部虚拟梯度材料模型,从而建立了准确的滚珠丝杠螺母结合部动力学模型,并通过实验对此方法建立的动力学模型进行了实验验证。结果表明:基于虚拟梯度材料法建立的结合部模型具有较高的精度,梯度结构材料层的宏观材料特性在空间上呈现与接触应力随滚珠相位角分布相同的变化,据此能够充分表征滚珠轴承中滚珠和滚道接触面间接触应力分布不均匀的特性。

一种新型绿色汞清洗剂的应用研究

主要研究了一种二烷基二硫代次膦酸盐和乙醇组成的汞清洗剂,利用二烷基二硫代次膦酸盐与汞形成配位化合物、采用乙醇作为溶剂体系,在溶剂和配位体作用下,可以让大汞珠转变为细微的配位体颗粒物,分散于乙醇中,无搅拌情况下剥离沉积在壁面的汞,并实现了对沉积于设备内壁的汞的清洗。该工艺的含汞配位体通过简单过滤实现与清洗剂分离,汞清洗剂可循环利用,含汞物可作固废处理,而且所用的清洗剂不腐蚀设备,是一种绿色汞清洗剂。分析了影响洗汞效果的各种因素,得到了最优的洗汞工艺:2%的浓度,保持中性或弱碱性,室温处理,漫灌浸泡不少于6hr。

非小细胞肺癌患者血清CA211水平和NK细胞数与预后相关

目的 探究非小细胞肺癌(NSCLC)患者血清糖类抗原211(CA211)表达水平和自然杀伤(NK)细胞数与预后的相关性。方法 选取杭州师范大学附属医院2019年6月至2022年7月收治的132例NSCLC患者作为实验组,另选取同期收治的132例肺部良性病变患者作为对照组。从检验科收集数据分析NSCLC患者血清CA211表达水平和NK细胞数与患者预后关系以及影响NSCLC患者预后的相关因素。结果 实验组中性粒细胞/淋巴细胞值(NLR值)和血清CA211表达水平高于对照组(P<0.05),NK细胞数低于对照组(P<0.05);实验组血清CA211表达水平和NK细胞数呈负相关(r=-0.405,P<0.001);不同血清CA211表达水平和NK细胞数的患者淋巴结转移情况以及TNM分期存在显著性差异(P<0.05);CA211低表达者1年生存率高于CA211高表达者(P<0.05),NK细胞高水平者1年生存率高于NK细胞低水平者(P<0.05);淋巴结转移、TNM分期、CA211是影响NSCLC患者预后的危险因素(P<0.05),NK细胞是NSCLC患者预后的保护因素(P<0.05)。结论 NSCLC患者血清CA211表达水平及NK细胞数与临床病理特征及预后有密切联系。

不同坏死病灶位置对非创伤性股骨头坏死自然病程的影响

背景:非创伤性股骨头坏死若股骨头发生塌陷将会显著影响患者的正常生活,因此需要使用恰当方式去评估股骨头塌陷风险,进而采取针对性措施延缓股骨头塌陷进程。目的:分析不同坏死病灶位置下早期股骨头坏死(未塌陷时)的自然病程发展规律。方法:选择2016年10月至2017年10月在西安交通大学附属红会医院门诊确诊的早期非创伤性股骨头坏死患者121例(191髋),门诊随访5年后,观察在不同JIC分型下股骨头坏死塌陷情况及各分型之间的股骨头塌陷风险系数,计算随访期间股骨头坏死塌陷率。结果与结论:(1)纳入191髋,随访期间股骨头塌陷86髋,股骨头总塌陷率为45.0%;在影响因素里,年龄、ARCO分期、JIC分型为股骨头塌陷的主要影响因素(P<0.05),体质量指数值、性别、发病侧别、致病因素不是股骨头塌陷的主要影响因素(P>0.05);(2)纳入的191髋中,随访期间JIC分型A型、B型、C1型、C2型的股骨头总塌陷率分别为11.1%(2/18),30.2%(16/53),52.4%(43/82),65.8%(25/38),各分型间股骨头总塌陷率比较差异有显著性意义(P<0.05);塌陷风险结果显示,B型、C1型、C2型股骨头塌陷风险分别是A型的2.41,5.22,7.89倍;(3)JIC分型及ARCO分期均与股骨头塌陷具有相关性(P<0.01),在ARCOⅠ期患髋中,各JIC分型股骨头塌陷率比较差异无显著性意义(P>0.05);在ARCOⅡ期患髋中,JIC A型、B型、C1型及C2型的股骨头塌陷率分别为1.2%,19.5%,50.0%,29.3%,各分型间股骨头塌陷率比较差异有显著性意义(P<0.05);(4)随访期间,第1-5年内的股骨头塌陷率分别为29.3%,7.9%,4.7%,2.6%,0.5%;(5)结果显示,对于早期非创伤性股骨头坏死,1年内股骨头塌陷的风险大,骨坏死病灶位置影响着股骨头塌陷的风险,临床治疗中应考虑到病灶位置对疾病预后的影响。

数字经济对农业生产性服务业的影响——基于非农就业和要素供给视角

基于2003—2019年213个地级市面板数据,将智慧城市试点作为一项衡量数字经济发展的准自然实验,构建多时点双重差分模型,实证检验数字经济对农业生产性服务业的影响效应和作用机制。研究表明:(1)数字经济显著促进了农业生产性服务业发展,且这一结论在经过平行趋势、安慰剂等多种方法检验后依然稳健。(2)“需求-供给”两端分析表明,促进非农就业和资本、技术和信息等要素供给是数字经济推动农业生产性服务业发展的重要路径。(3)数字经济对农业生产性服务业的促进作用,在东部地区以及传统基础设施和规模化种植较为完善的城市更明显。(4)城镇化在数字经济与农业生产性服务业之间具有显著“单一”门槛效应,只有在人口、产业和土地城镇化达到一定水平时,数字经济才能发挥出对农业生产性服务业发展的促进作用。

鲜胶乳熟化时间对天然橡胶组成及性能的影响

采用复合保存剂HY/NH 3保存鲜胶乳1~5 d,定期取样凝固制备成天然生胶,以胶乳熟化时间为1 d的样品作对照样,探究鲜胶乳熟化时间对天然橡胶组成、性能的影响。分别采用红外光谱仪、核磁共振交联密度仪、拉力试验机等仪器对天然橡胶进行表征。结果表明,鲜胶乳熟化可以减少天然生胶中杂质、灰分、挥发物的含量,提高塑性保持率及交联密度;混炼胶的焦烧时间、正硫化时间、扭矩差值以及硫化胶的拉伸强度、撕裂强度、定伸应力等均有提高;胶乳熟化3 d制备的天然橡胶综合性能最好,其硫化胶的拉伸强度、撕裂强度分别达到20.47 MPa、30.38 kN/m,比对照样提高了3.5%和7.0%。

基于四元驱动的非平稳水文干旱评估方法

为了科学评估自然-社会系统影响下非平稳水文干旱,考虑气候变化(降水、气温)和人类活动(取用水、水库)四元要素的影响,通过基于四元驱动的GAMLSS模型构建非平稳标准化径流指数(NSRI),提出了基于四元驱动的非平稳水文干旱评估方法。黄河流域非平稳水文干旱实例评估结果表明:黄河流域花园口站径流序列呈现出明显的非平稳特征,径流量1961—2020年发生显著下降,并在1990年发生突变;基于四元驱动的非平稳水文干旱评估方法能够更好地对径流数据进行非平稳概率分布拟合;对于历史干旱事件的识别,NSRI识别的干旱过程与实际更加接近,NSRI比标准化径流指数(SRI)识别效果更好,可以更好地反映变化环境下的水文干旱演变趋势。

乳化剂对冰淇淋抗融性影响的研究进展

冰淇淋因其独特的口感日益受到消费者的喜爱,而抗融性作为一项重要的指标可以直接反映冰淇淋品质的好坏。在冰淇淋的运输、储存和销售过程中,由于环境温度的波动,使得抗融性差的冰淇淋容易产生变形的现象,进而影响冰淇淋品质,甚至会对消费者体验、产品销售乃至品牌声誉产生影响。因此,提高冰淇淋的抗融性是保证冰淇淋品质的关键,而乳化剂作为冰淇淋中常用的食品添加剂对冰淇淋的抗融性具有十分重要的作用。该文主要综述冰淇淋中最常用的两种乳化剂,包括非离子型乳化剂及天然型乳化剂,对冰淇淋抗融性的影响及其特点,以期为提高冰淇淋的抗融性提供理论依据,为改善冰淇淋品质提供参考。