解决电话“热装冷用”问题的十条对策

解决电话“热装冷用”问题的十条对策董苏敏，叶玫随着住宅电话的日益增多，电话＂热装冷用＂的问题亦随之出现了。内陆省份尤其明显。如何解决电话＂热装冷用＂问题，已成为电信经营管理者的一大课题。笔者认为，应从以下十个方面采取措施。第一，针对当地的经济特点和风...

对电话“热装冷用”对策的探讨——电话计费实行分段制的思考

近年来,全国掀起了装电话的热潮,电话业务撑起了邮电业务的半边天,但随后出现的电话“热装冷用”一定程度上影响了业务的进一步发展,已经成为全国具有一定普遍性的问题。以江苏省海门市为例,据抽样调查,目前市区66％的住宅电话日均使用不足2次,市镇尚且如此,在农村这一现象更为突出。改革现行电话计费,试行分段、分类计费,不仅是社会广大客户的企盼,也是电信部门发展业务、改善服务的有效手段。

冷用接蜡配制方法

冷用接蜡配制方法果树嫁接用的接蜡，随着嫁接技术的发展也在改进。现介绍冷用接蜡配制方法如下；冷用接蜡，即配制后用时不加热，可直接涂抹。配合量是松蚝１６份、动物油１份（或松香８份、动物油８份）、酒精３份、松节油０．５份。先把松香、动物油放在小锅内加热，待...

Comparison of two schemes for district cooling system utilizing cold energy of liquefied natural gas

Two schemes（scheme Ⅰ and scheme Ⅱ）for designing a district cooling system（DCS）utilizing cold energy of liquefied natural gas（LNG）are presented.In scheme Ⅰ,LNG cold energy is used to produce ice,and then ice is transported to the central cooling plant of the DCS.In scheme Ⅱ,return water from the DCS is directly chilled by LNG cold energy,and the chilled water is then sent back to the central plant.The heat transportation loss is the main negative impact in the DCS and is emphatically analyzed when evaluating the efficiency of each scheme.The results show that the DCS utilizing LNG cold energy is feasible and valuable.The cooling supply distance of scheme Ⅱ is limited within 13 km while scheme Ⅰ has no distance limit.When the distance is between 6 and 13 km,scheme Ⅱ is more practical and effective.Contrarily,scheme Ⅰ has a better economic performance when the distance is shorter than 6 km or longer than 13 km.

未雨绸缪话冬防

进入冬季风高物燥,人们为抵御寒冷用火用电量明显增加。从连年火灾统计看,冬季火灾四项指数明显高于其它季节,重、特大火灾也往往发生在冬季。如何搞好冬季防火就成为消防工作的一个重要环节。 坚强的组织领导是实现消防安全目标管理的关键所在。

HBP—160热镦机备用水箱水位自控装置改造

当电网停电时,HBP—160热镦机加热炉水冷用供水泵停止供水,造成炉温急剧上升、感应圈表面绝缘层损坏。针对以上问题,设计了备用水箱自动控制装置,使问题得到解决。

Role of the Nocturnal Low-level Jet in the Formation of the Morning Precipitation Peak over the Dabie Mountains

The diurnal variation of precipitation over the Dabie Mountains(DBM) in eastern China during the 2013 mei-yu season is investigated with forecasts of a regional convection-permitting model. Simulated precipitation is verified against surface rain-gauge observations. The observed morning precipitation peak on the windward(relative to the prevailing synoptic-scale wind) side of the DBM is reproduced with good spatial and temporal accuracy. The interaction between the DBM and a nocturnal boundary layer low-level jet(BLJ) due to the inertial oscillation mechanism is shown to be responsible for this precipitation peak. The BLJ is aligned with the lower-level southwesterly synoptic-scale flow that carries abundant moisture.The BLJ core is established at around 0200 LST upwind of the mountains. It moves towards the DBM and reaches maximum intensity at about 70 km ahead of the mountains. When the BLJ impinges upon the windward side of the DBM in the early morning, mechanical lifting of moist air leads to condensation and subsequent precipitation.

Integration of Low-level Waste Heat Recovery and Liquefied Nature Gas Cold Energy Utilization

Two novel thermal cycles based on Brayton cycle and Rankine cycle are proposed, respectively, which integrate the recovery of low-level waste heat and Liquefied Nature Gas （LNG） cold energy utilization for power generation. Cascade utilization of energy is realized in the two thermal cycles, where low-level waste heat,low-temperature exergy and pressure exergy of LNG are utilized efficiently through the system synthesis. The simulations are carried out using the commercial Aspen Plus 10.2, and the results are analyzed. Compared with the conventional Brayton cycle and Rankine cycle, the two novel cycles bring 60.94% and 60% in exergy efficiency, respectively and 53.08% and 52.31% in thermal efficiency, respectively.

Kerosene-alumina nanofluid flow and heat transfer for cooling application

Kerosene-alumina nanofluid flow and heat transfer in the presence of magnetic field are studied. The basic partial differential equations are reduced to ordinary differential equations which are solved semi analytically using differential transformation method. Velocity and temperature profiles as well as the skin friction coefficient and the Nusselt number are determined analytically. The influence of pertinent parameters such as magnetic parameter, nanofluid volume fraction, viscosity parameter and Eckert number on the flow and heat transfer characteristics is discussed. Results indicate that skin friction coefficient decreases with increase of magnetic parameter, nanofluid volume fraction and viscosity parameter. Nusselt number increases with increase of magnetic parameter and nanofluid volume fraction while it decreases with increase of Eckert number and viscosity parameter.

Effect of temperature on soil respiration in a Chinese fir forest

Soil samples collected from the surface soil （0-10 cm） in an 88-year-old Chinese fir （Cunninghamia lanceolata） forest in Nanping Fujian, China were incubated for 90 days at the temperatures of 15℃, 25℃ and 35℃ in laboratory. The soil CO2 evolution rates were measured at the incubation time of 2, 5, 10, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80 and 90 days. The results showed that CO2 evolution rates of soil samples varied significantly with incubation time and temperature during the incubation period. Mean CO2 evolution rate and cumulative amount of CO2 evolution from soil were highest at 35℃, followed by those at 25℃, and 15℃. Substantial differences in CO2 evolution rate were found in Q10 values calculated for the 2nd and 90th day of incubation. The Q10 value for the average CO2 evolution rate was 2.0 at the temperature range of 15-25℃, but it decreased to 1.2 at 25 35℃. Soil CO2 evolution rates decreased with the incubation time. The cumulative mineralized C at the end of incubation period （on the 90th day） was less than 10% of the initial C amounts prior to incubation.

A Novel Process for Natural Gas Liquids Recovery from Oil Field Associated Gas with Liquefied Natural Gas Cryogenic Energy Utilization

A novel process to recovery natural gas liquids from oil field associated gas with liquefied natural gas (LNG)cryogenic energy utilization is proposed.Compared to the current electric refrigeration process,the proposed process uses the cryogenic energy of LNG and saves 62.6%of electricity.The proposed process recovers ethane, liquid petroleum gas(propane and butane)and heavier hydrocarbons,with total recovery rate of natural gas liquids up to 96.8%.In this paper,exergy analysis and the energy utilization diagram method(EUD)are used to assess the new process and identify the key operation units with large exergy loss.The results show that exergy efficiency of the new process is 44.3%.Compared to the electric refrigeration process,exergy efficiency of the new process is improved by 16%.The proposed process has been applied and implemented in a conceptual design scheme of the cryogenic energy utilization for a 300 million tons/yr LNG receiving terminal in a northern Chinese harbor.

Ecological Status and Uses of Juniper Species in the Cold Desert Environment of the Lahaul Valley, North-western Himalaya, India

The juniper species Juniperus polycarpos C. Koch, J. indica Bertol. and J. communis L. var. saxatilis （Pallas） are important elements of the forest vegetation in Lahaul valley in the north-western Himalaya. Their ability to grow under the barren and xeric conditions of cold deserts makes them particularly suited for afforestation programmes under these eeologieal conditions. In the Lahaul valley, juniper species are used as subsistence resources and for religious purposes. Excessive removal of juniper wood and leaves by the local population, overgrazing, habitat fragmentation and low regeneration potential are the main obstacles to eonservation of juniper forests in this region. The present study was carried out to assess density, basal area and importance value index （WI） of the local vegetation as well as uses and amounts of juniper wood and leaves removed from the local forests. Pressure on relict juniper forests due to grazing animals and intensive removal of wood and leaves by the loeal population was found to be greater at an altitude above 3,00o m. The results of the study demonstrated that the different juniper speeies were adapted to specific altitude ranges. A higher species density was recorded at lower altitude except for J. indica which was only present at high altitude （〉3,200 m） on south-facing slopes. Density, basal area and IVI of J. polycarpos were higher at Hinsa （2,7oo m） than at Jahlma （3,000 m）. The rapid loss of vegetation due to overuse and habitat degradation has made the eonservation of juniper forests an important priority in the Lahaul valley. J. polycarpos at loweraltitude and J. indica at higher altitude are ecologically the more suitable species for the successful implementation of conservation programmes. The support of rehabilitation programmes by regional authorities is essential for the reestablishment of the local juniper forests.

Dynamic model of saturator based on a global heat and mass transfer coefficient

Saturator is one of the core components of humid air turbine （HAT） and is the main feature of HAT making it different from other gas turbine cycles. Due to the lack of sufficient experience in commercial plant operation, HAT cycle has a great demand for modeling and simulation of the system and its components, especially the saturator, to provide reference for system design and optimization. The conventional saturator models are usually based on the theory of heat and mass transfer, which need two accurate coefficients to ensure convincing results. This work proposes a global heat and mass transfer coefficient based on cooling tower technology to model the saturator in small-scale HAT cycle. Compared with the experimental data, the simulation results show that the proposed model well predicts the dynamic humidity and temperature distribution characteristics of saturator at low air pressure and temperature.

EFFECTS OF THE ATMOSPHERIC COLD SOURCE OVER THE TIBETAN PLATEAU ON THE QUASI 4-YEAR OSCILLATION OF OCEAN-ATMOSPHERIC-LAND INTERACTION

Using correlation analyses, composite analyses, and singular value decomposition, the relationship between the atmospheric cold source over the eastern Tibetan Plateau and atmospheric/ocean circulation is discussed. In winter, the anomaly of the strong (weak) atmospheric cold source over the eastern plateau causes low-level anomalous north (south) winds to appear in eastern China and low-level anomaly zonal west (east) winds to prevail in the equatorial Pacific from spring to autumn. This contributes to the anomalous warm (cold) sea surface temperature the following autumn and winter. In addition, the anomalous variation of sea surface temperature over the equatorial middle and eastern Pacific in winter can influence the snow depth and intensity of the cold source over the plateau in the following winter due to variation of the summer west Pacific subtropical high.

Study on Application of Mixed-Refrigerant Refrigeration in Ethylene Plant

This paper focuses on the mixed-refrigerant refrigeration process flows which are applied in the cryogenic separation section of ethylene plant. Based on a 120 kt/a ethylene plant which employs a sequence separation process flow and lowpressure demethanization system, the energy consumption of three refrigeration process flows（typical cascade refrigeration, binary refrigeration and tertiary refrigeration） was calculated by means of the ASPEN PLUS simulation software. An optimized mixed-refrigerant composition which achieved the minimum energy consumption of refrigeration systems was found out and the exergy loss was analyzed and compared. Results indicated that the energy consumption of typical cascade refrigeration and binary refrigeration systems was almost equal and that of tertiary refrigeration system was higher than the other two systems. Based on the current situation of production, the suggestions on production optimization and refrigeration process flow selection were put forward.

Isothermal Crystallization Behavior of Biodegradable Poly (butylene succinate-co-terephthalate) (PBST) Copolyesters at High Undercoolings

Poly （butylene succinatc-co-terephthalate） （PBST） copolycsters were prepared by polycondensation. The crystallization behavior of the as-prepared copolyesters was investigated by depolarized light intensity （DLI） at high undercoolings. According to Avrami equation, the exponent n, independent of the crystallization temperature, is at a range of 2. 5 to 3. 4, which probably corresponds to the heterogeneous mucleation and a 3-dimensional spherulitic growth. The maximum crystallization rate, very useful to polymer processing, was found at about 90℃ based on the half-crystallization time t1/2 analysis.

Coupling effect of evaporation and condensation processes of organic Rankine cycle for geothermal power generation improvement

Organic Rankine cycle(ORC)is widely used for the low grade geothermal power generation.However,a large amount of irreversible loss results in poor technical and economic performance due to its poor matching between the heat source/sink and the working medium in the condenser and the evaporator.The condensing temperature,cooling water temperature difference and pinch point temperature difference are often fixed according to engineering experience.In order to optimize the ORC system comprehensively,the coupling effect of evaporation and condensation process was proposed in this paper.Based on the laws of thermodynamics,the energy analysis,exergy analysis and entropy analysis were adopted to investigate the ORC performance including net output power,thermal efficiency,exergy efficiency,thermal conductivity,irreversible loss,etc.,using geothermal water at a temperature of 120℃as the heat source and isobutane as the working fluid.The results show that there exists a pair of optimal evaporating temperature and condensing temperatures to maximize the system performance.The net power output and the system comprehensive performance achieve their highest values at the same evaporating temperature,but the system comprehensive performance corresponds to a lower condensing temperature than the net power output.

Nonmonotonic Trust Region Algorithm via the Conjugate Gradient Path for Unconstrained Generalized Geometric Programming

In this paper,on the basis of making full use of the characteristics of unconstrained generalized geometric programming（GGP）,we establish a nonmonotonic trust region algorithm via the conjugate path for solving unconstrained GGP problem.A new type of condensation problem is presented,then a particular conjugate path is constructed for the problem,along which we get the approximate solution of the problem by nonmonotonic trust region algorithm,and further prove that the algorithm has global convergence and quadratic convergence properties.

Application of Liquid Nitrogen Cold Trap for Purification of Hydrogen Gas Stream Generated from NaBH4

The feasibility of using liquid nitrogen cold trap （LNCT） for the removal of water vapour and alkaline mist from the hydrogen gas stream which is generated from the catalytic and acidic decomposition of sodium borohydride is investigated. Practically, the target application is mobile fuel cells based on hydrogen production from storage in chemical hydrides. The LNCT would be used as a one step purification method with less cost and space requirements instead of applying the conventional purification techniques. Two catalysts were investigated for the production of hydrogen from the aqueous solution of NaBH4 in a small scale packed bed reaction column. The hydrogen generated from the catalytic decomposition of NaBH4 was accompanied by limited quantity of water vapour and alkaline mist. Nonetheless, higher quantities were generated when applying the acidic decomposition of NaBH4 and consequently the utilization of LNCT for H2 purification has proved useful and lead to a reduction in the content of these impurities; thereby the concentration of hydrogen in the outlet stream has increased.

A Rotating Bose-Einstein Condensation in a Toroidal Trap

We have studied the ground state configurations of a rotating Bose-Einstein condensation in a toroidal trap as the radius of the central Ganssian potentiaJ expands adiabatically. Firstly, we observe that the vortices are devoured successively into the central hole of the condensate to form a giant vortex as the radius of the trap expands. When all the pre-existing vortices are absorbed, the angular momentum of the system still increase as the radius of the ganssian potential enlarges. When increasing the interaction strength, we find that more singly quantized vortices are squeezed into the condensate, but the giant vortex does not change.