浅谈《热学》中几个问题的对立统一关系

恩格斯在《自然辩证法)的《导言》中指出,哲学与自然科学自古以来就处于密切的相互影响的关系中.自然科学,尤其是物理字的发现,就涉及到许多重要的哲学问题.在物理教学中贯彻以哲学思想为指导,对于加深物理概念的理解,培养学生的辩证唯物主义世界观,都是有益的.

易燃物质受热自燃的可能因素及预防

随着市场经济的不断发展和现代化建设进程的推进,集中供热、集中供气几乎成为城市、乡村现代文明发展的一个标准,它极大地提高了居民的生活水准。无论是设计者,还是使用者,对安全及防爆等都予以足够的关注,然而在日常生活中,对防范物质因受热自燃,以免造成巨大的灾害所采取的措施,却显得力不从心了。

发热贴致老年患者低温烫伤合并感染7例的护理体会

低温烫伤是指皮肤长时间接触高于体温的低热物体而造成的烫伤[1]。低温烫伤的特点是真皮浅层向真皮深层及皮下各层组织渐进性损害,往往表面看只是一个小水疱,其实可能已伤及皮下组织,甚至肌肉、神经和血管[2]。近年来,发热贴(又称一次性热宝)以其使用方便、保暖时间长而成为冬季老年人的新宠,但其引起的低温烫伤也屡见报道。2012年11月~2013年4月,作者使用湿润烧伤膏加庆大霉素的换药方法对7例老年患者因发热贴引起的低温烫伤合并感染进行伤口护理,取得良好效果。现报道如下。

机械构造专用内部媒体播放控制的一种简易实现

本文从机械构造结构展示所需的内部专用媒体播放的实际功能需求出发,应用Authorware 6.x讨论如何制作一种专用的媒体播放器程序,并对Authorware 6.x内部交互与媒体播放有关的系统变量之间的关系进行了探讨。

在Authorware中实现对CAI课件音频的控制

介绍了利用Authorware 设计多媒体课件时,实现对音频控制的方法和程序等问题.

Preparation of Cetyl-Chitosan Nanoparticles as Carriers for Paracetamol

Cetyl-chitosan, prepared by reacting chitosan with chlorocetane under alkaline condition, is soluble and spontaneously forms nanoparticles about 100 nm in diameter. Infrared spectra (IR) revealed that there was a substitution reaction mainly on the amine groups of chitosan (CS). By using paracetamol (PCTM) as a model drug, the balanced release concentration of PCTM in phosphate buffer solution (pH=7.4) can be decreased with the increase of degree of substitution alkyl and can be reduced effectively even under a lower PCTM loading.

熵与企业行为

引言在自然界中存在着各种现象。有的现象能自动进行,有的现象则不能自动进行。例如,冷物体和热物体碰在一起,那末热量能自动地从热物体传递到冷物体,而不能自动地从冷物体传递到热物体,温度高→温度低。水能自动地从高处流向低处,而不能自动地从低处流向高处,压力高→压力低。为了判别在自然界中由物体组成的孤立系统中各种自然现象能否自动进行,十九世纪德国物理学家克劳修斯提出了热力学第二定律。

3D topographic correction of the BSR heat flow and detection of focused fluid flow

The bottom-simulating reflector（BSR） is a seismic indicator of the bottom of a gas hydrate stability zone. Its depth can be used to calculate the seafloor surface heat flow. The calculated BSR heat flow variations include disturbances from two important factors：（1） seafloor topography, which focuses the heat flow over regions of concave topography and defocuses it over regions of convex topography, and（2） the focused warm fluid flow within the accretionary prism coming from depths deeper than BSR. The focused fluid flow can be detected if the contribution of the topography to the BSR heat flow is removed. However, the analytical equation cannot solve the topographic effect at complex seafloor regions. We prove that 3D finite element method can model the topographic effect on the regional background heat flow with high accuracy, which can then be used to correct the topographic effect and obtain the BSR heat flow under the condition of perfectly flat topography. By comparing the corrected BSR heat flow with the regional background heat flow, focused fluid flow regions can be detected that are originally too small and cannot be detected using present-day equipment. This method was successfully applied to the midslope region of northern Cascadia subducting margin. The results suggest that the Cucumber Ridge and its neighboring area are positive heat flow anomalies, about 10%–20% higher than the background heat flow after 3D topographic correction. Moreover, the seismic imaging associated the positive heat flow anomaly areas with seabed fracture–cavity systems. This suggests flow of warm gas-carrying fluids along these high-permeability pathways, which could result in higher gas hydrate concentrations.

Single Polar Compound Bioelectret Material and Its Influence on the Cell Growth

To explore the influence of compound bioelectret material′s dielectric property on the cell growth,several kinds of compound bioelectret materials of collagen/chitosan were developed Their TSDC(thermally stimulated depolarization current)spectra were analyzed,and the compound bioelectret collagen/chitosan whose t α and I α were 37℃ and 2×10 -9 A respectively at polarized state was selected The cell culture study showed that the compound bioelectret material could promote normal cell growth when singly negatively polarized,and could inhibit cancer cell growth when singly positively polarized It proves that the rational designation of compound bioelectret has a broad application for clinical medicine

Studying creation of bulk elementary excitation by heaters in superfluid helium-II at low temperatures

In this paper, the obtained experimental results concerning creation of bulk elementary excitations （BEEs） in isotopically pure liquid ^4He at low temperatures -60 mK are discussed. Positive rotons＇ （R^＋-rotons） creation by a pulsed heater was studied. Signals were recorded for the following quantum processes： quantum evaporation of ^4He-atoms from the free liquid-helium surface by the BEEs of the liquid helium-Ⅱ, and BEEs reflection from the free surface back into the bulk liquid. Typical signals are shown, and ratios of signal amplitudes are evaluated. For long heater pulses from 5 to 10 μs, appearance of the second atomic cloud consisting of evaporated ^4He-atoms was observed in addition to the first atomic cloud. It is thought that the first atomic cloud of the evaporated helium atoms consists of very fast ^4He-atoms with energies ～35 K evaporated by positive rotons with the special energies ～17 K （～2ER～2×8.6 K with ER representing the roton minimum energy） corresponding to the third non-dispersive Zakharenko wave. The second cloud of slower ^4He-atoms was created by surface elementary excitations （SEEs or ripplons） possessing the special energies ～7.15 K representing the binding energy. It was assumed that such SEEs can be created by phonons incoming to the liquid surface with special energies ～6.2 K corresponding to the first non-dispersive Zakharenko wave which can interact at the liquid surface with the same phonons already reflected from the surface for long heater pulses. Also, some pulsed-heater characteristics were studied in order to better understand the features of such heaters in low temperature experiments.

Calculation of Transport Properties of CF4＋Noble Gas Mixtures

The present work is concerned with determining the viscosity,diffusion,thermal diffusion factor and thermal conductivity of five equimolar binary gas mixtures including:CF4-He,CF4-Ne,CF4-Ar,CF4-Kr,CF4-Xe from the principle of corresponding states of viscosity by the inversion technique.The Lennard-Jones (12-6) model potential is used as the initial model potential.The calculated interaction potential energies obtained from the inversion procedure is employed to reproduce the viscosities,diffusions,thermal diffusion factors,and thermal conductivities.The accuracies of the calculated viscosity and diffusion coefficients were 1% and 4%,respectively.

Hydrothermal Synthesis and Structure Characterization of Compound Zn(Hpydc)_2(H_2O) (pydc=pyridine-2,5-dicarboxylate)

The hydrothermal reaction of ZnO, H3PO4(85%), (H2NCH2CH2)2NH and H2pydc results in the formation of a discrete mononuclear zinc(II) complex Zn(Hpydc)2(H2O). It crystallizes in monoclinic space group C2/c with a = 17.9947(8), b = 7.1875(3), c = 12.5895(4) , b = 110.802(2), V = 1522.14(10) 3, Z = 4, Mr = 415.61, (C14H10N2O9Zn), Dc = 1.814g/cm3, = 16.71cm-1, F(000) = 840, R = 0.0505, wR = 0.1144. Each zinc(II) is coordinated to two nitrogen and three oxygen atoms of which two nitrogen and two oxygen atoms are from two pydc ligands, and one oxygen atom from the coordinated water molecule to form an irregular polyhedral geometry. The complex is linked further into a three-dimensional structure through the weak interactions of hydrogen bonds between the two oxygen atoms. IR spectrum of the complex is also discussed.

Reaction mechanism between“memory effect”and induction time of gas hydrate formation

Abstract Using visual experimental apparatus, one system （T40, 1×10^-3 mol/L, nonadded with coal） and another system （T40, 2×10^-3 mol/L, added with coal） were experimented with for three times and two times, respectively. Five groups of P-T experimental parameters were obtained using the data logger system and analyzed combined with the video information of the experiments. Major conclustions show that the induction time is shortened by 10-20 times in the experimental system containing residual pentahedral ring structures; ＂memory effect＂ can accelerate the dynamic progress and improve the thermodynamic conditions of gas hydrate formation.

Thermal conductivity modeling of water containing metal oxide nanoparticles

The nano particles have demonstrated great potential to improve the heat transfer characteristics of heat transfer fluids.Possible parameters responsible for this increase were studied. The heat transfer profile in the nanolayer region was combined with other parameters such as volume fraction, particle radius thermal conductivity of the fluid, particle and nanolayer, to formulate a thermal conductivity model. Results predicting the thermal conductivity of nanofluids using the model were compared with experimental results as well as studies by other researchers. The comparison of the results obtained for the Cu O/water and Ti O2/water nanofluids studied shows that the correlation proposed is in closest proximity in predicting the experimental results for the thermal conductivity of a nanofluid. Also, a parametric study was performed to understand how a number of factors affect the thermal conductivity of nanofluids using the developed correlation.

Indirect heat integration across plants using hot water circles

Total site heat integration(TSHI) provides more opportunities for energy saving in industry clusters. Some design methods including direct integration using process streams and indirect integration using intermediate-fluid circuits, i.e., steam, dowtherms and hot water, have been proposed during last few decades. Indirect heat integration is preferred when the heat sources and sinks are separated in independent plants with rather long distance. This improves energy efficiency by adaption of intermediate fluid circle which acts as a utility provider for plants in a symbiotic network. However, there are some significant factors ignored in conventional TSHI, i.e. the investment of pipeline, cost of pumping and heat loss. These factors simultaneously determine the possibility and performance of heat integration. This work presents a new methodology for indirect heat integration in low temperature range using hot water circuit as intermediate-fluid medium. The new methodology enables the targeting of indirect heat integration across plants considering the factors mentioned earlier. An MINLP model with economic objective is established and solved. The optimization results give the mass flow rate of intermediate-fluid, diameter of pipeline, the temperature of the circuits and the matches of heat exchanger networks(HENS) automatically. Finally, the application of this proposed methodology is illustrated with a case study.

Practical Paths towards Lowering Black Carbon Emissions

Black carbon （BC） aerosol, accounting for a minor fraction of atmospheric aerosols, is attracting increased attentio1 due to its impact on air quality, human health, and climate change. Focusing on BC emission reduction, this paper give1 a brief introduction to the sources and global distribution of BC. Along with the decrease of BC emissions from sue1 actions as the reduction of global greenhouse gases （GHGs） and regulating local air quality, it also highlights othet BC reduction approaches such as control and improvement of combustion conditions, the elimination of open biomas burning, and the sequestration of BC by biomass pyrolysis. Finally, it is stressed that at this moment there is no enougt reason to push BC reduction into any climate change related negotiations, although BC has been included in some o so-called win-win reduction targets for the quick response to both climate and non-climate appeals.

Electromotive Force for Solid Oxide Fuel Cells Using Biomass Produced Gas as Fuel

The electromotive force （e.m.f.） of solid oxide fuel cells using biomass produced gas （BPG） as the fuels is calculated at 700-1,200 K using an in-house computer program, based on thermodynamic equilibrium analysis. Tour program also predicts the concentration of oxygen in the fuel chamber as well as the concentration of equilibrium species such as H2, CO, CO2 and CH4. Compared with using hydrogen as a fuel, the e.m.f. for cells using BPG as the fuels is relative low and strongly influenced by carbon deposition. To remove carbon deposition, the optimum amount of H2O to add is determined at various operating temperatures. Further the e.m.f, for cells based on yttria stabilized zirconia and doped ceria as electrolytes are compared. The study reveals that when using BPG as fuel, the depression of e.m.f, for a SOFC using doped ceria as electrolyte is relatively small when compared with that using Yttria stabilized zirconia.

Heat Transfer Validation and Comparative Evaluation of Biochar Yield from Pyrolysis Cook Stove

The developing world still largely depends on biomass, such as wood, animal dung and agricultural waste for domestic fuel sources that are typically burned in traditional stoves. Ethiopia has different biomass resource for biochar production, through pyrolysis cook stove co-producing biochar. Coffee husks are the major solid residues from the handling and processing of coffee in the study area. This study was to evaluate the biochar co-producing pyrolysis cook stove with respect to heat transfer through the bed and biochar yield. From allothermal type of pyrolysis cook stove, the stove design was selected for both the computational fluid dynamic （CFD） simulation and experimental measurements. ANSYS 14.5 was used for CFD simulation of the wood combustion. The production of biochar from coffee husk, corncob and sawdust at different heating times, bed and stove surface temperature were undertaken. Bulk density, pH and surface area of the biochar were measured. While good agreement between simulation and experimental result was obtained in the conduction phase during pyrolysis, deviation between the two on account of the effect of volatile gas in changing the temperature trend within the biomass bed was noticed. Within the biomass type, the maximum mean biochar yield （38.91%） was seen from coffee husk. In the case of different stove designs, the minimum mean biochar yield （27.11%） was found from normal Anila stove. The pH of biochar is found to be significantly affected by the type of biomass （9.83 mean for corncob and coffee husk, 6.43 mean for sawdust）, heating time （9.19 mean for 90 min and 8.01 mean for 30 min） and stove type （9.52 mean for normal Anila and 8.01 mean for flangeless Anila continuous feeding type）. In fact, the type of biomass is observed to significantly affect the bulk density and surface area ofbiochar.