中国草地农业气候分区及其饲草栽培适宜性

为了草地农业区域优化发展,依W Koppen世界气候分类途径,进行了中国气候分类及草地农业气候分区,依据相应途径,制作了中国饲草寒冷度分区图和中国饲草炎热度分区图,分析了各饲草气候区适宜的饲草作物种类及管理对策。中国气候及草地农业气候有17个类型,归并为6个饲草气候系统,中国饲草寒冷度分11个区,中国饲草炎热度分8个区。每个气候系统及寒冷度分区和炎热度分区内,分别有适宜的饲草作物,其评价标准为:生态适应、生长状态正常、发挥潜在遗传产量、有经济效益。干旱饲草气候系统发展低密度放牧饲养,湿润饲草气候系统发展规模化集约饲养,为中国草地畜牧业生产模式的基本理论选择。

广西异常霜冻天气过程特征指数研究

根据1957～2002年45个冬季的广西逐日霜冻天气图资料,按农业区划对气候要素保证率要求原则选择出45个冬季的异常霜冻天气过程共9次,计算它们的寒冷度、冰冻度和持续性指数,对入选过程进行排序分析,确定1954～1955年冬天发生的霜冻天气过程是1950年以来最严重的一次异常霜冻天气过程。这一结果与实际影响较一致,设置特征指数以量化的方式综合评判广西异常霜冻天气的气象学特征,具有明晰的物理意义,可操作性强。

Impact of cold indoor thermal environmental conditions on human thermal response

To explore the thermal responses under the non-thermal equilibrium cold environmental conditions,a laboratory study was conducted in climate chamber.The local skin temperatures and thermal sensation of 20 subjects were recorded at 10 min intervals for 90 min under air temperatures of 7.4,9.1,11 and 15 °C.The results show that both local skin temperatures and mean skin temperature decrease not only with the drop of ambient air temperature but also with the exposure time.Local thermal sensation and overall the thermal sensation have the similar temperature-varying and time-varying characteristics.Predicted mean vote(PMV) model cannot correctly predict the thermal sensation under non-thermal equilibrium cold environment.The correlation between local thermal sensation and local skin temperatures shows that thermal sensation is closely related to skin temperature.Skin temperature is an effective indicator of thermal sensation.A linear relationship model between overall thermal sensation and mean skin temperature,considering both ambient temperature and exposure time,was established in the non-thermal equilibrium cold environment,which makes the evaluation of thermal sensation more objective.

Skin Sensitive Difference of Human Body Sections under Clothing - Multiple Analysis of Skin Surface Temperature Changes

A new researching method on clothing comfort perception is developed.By it the skin surface temperature changes and subjective psychological perception of human body sections stimulated by the same cold stimulation are studied.With the multiple comparison analysis method the changing laws of skin temperature of main human body sections is obtained.

Skin Sensitive Difference of Human Body Sections under Clothing — Comparative Judging of Body Sections' Cold Sensitivity Sequence

Skin seasitive difference of human body sections under clothing is the theoretic foundation of thermal insulation clothing design. By a new psychological ＆ physical researching method, the subjective psychological perception of human body sections affected by the same cold stimulus are studied, and with Thurstone comparative judgement the main human body sections＇ cold sensitivity sequences are obtained. Furthermore the physiological causes for skin sensitive difference of human body sections under clothing are suggested.

Seismic analysis of long-span continuous rigid frame bridges in cold regions:a case study of Bridge 1 in north of international tourism resort in Changbai Mountain

It is helpful to improve the seismic design theory of long-span continuous bridges for studying the seismic performance of each cantilever construction state.Taking the Bridge 1 in the north of Changbai-Mountain international tourism resort as an example,the authors studied it in shutdown phase and the cantilever construction process,established the simulation model by using Midas / civil,and analyzed time-history of each construction stage for the bridge.The study shows that long-span bridge cantilever construction in northeastern China can be divided into two-year tasks for construction(suspending in winter).It is needed to think about seismic stability of the cantilever position in shut-down phase of winter.The effect of longitudinal vibration is the most disadvantageous influence to bridge,and its calculation results can provide reference for seismic design of similar bridges in the future.

Simulation analysis of temperature control calculation of RCC gravity dam in the cold region

In this paper, regarding the actual conditions of a roller compacted concrete dam, three-dimensional finite element relocating mesh method is utilized to simulate and calculate the temperature field of the RCC dam during the construction stage and operating period. The calculation is well consistent with the actual construction process, the thin-layer pouring process the pouring temperature and all kinds of external loads involved being taken into account, By comparing and analyzing of the impact of the cold wave on the dam stress, important references are provided for the RCCD design and the temperature control during construction.

Study on mechanism of circumferential cracks in cold-region tunnels

There exists frost damage in cold-region tunnels. The circumferential cracks affect the function of tunnels. Using three-dimensional finite element method, the authors analyzed the mechanism of circumferential cracks in cold-region tunnels It is proved that the internal thermal stress in lining exceeds the tensile strength of concrete, which is the direct cause for circumferential cracks occurring. The laws of thermal stress in lining induced by parameters such as temperature drop, horizontal drag coefficient and length of lining are analyzed. The conclusions are valuable to the design and construction of cold-region tunnels considering the thermal stress.

Influence of water flow on gas hydrate accumulation at cold vents

A cold vent is an area where methane-rich fluid seepage occurs. This seepage may alter the local temperature, salinity, and subsequent accumulation of the gas hydrate. Using a kinetic gas hydrate formation model and in situ measurement of tempera- ture, salinity and fluid flux at the southern summit of Hydrate Ridge, we simuIate the gas hydrate accumulation at three distinct fluid sites： clam, bacterial mat, and gas discharge sites. At the clam sites （pore water flux 〈 20 kg m-2 yr-1）, pore water advec- tion has little influence on temperature and salinity. However, the salinity and temperature are increased （peak salinity 〉 0.8 tool kg-1） by the formation of gas hydrate causing the base of the hydrate stability zone to move gradually from -115 to -70 meters below seafloor （mbsf）. The gas hydrate saturation at the clam sites is relatively high. The water flux at the bacterial mat sites ranges from 100 to 2500 kg m-2 yr-1. The water flow suppresses the increase in salinity resulting in a salinity close to or slightly higher than that of seawater （〈 0.65 mol kg-l）. Heat advection by water flow increases temperature significantly, shifting the base of the hydrate stability zone to above 50 or even 3 mbsf. The gas hydrate saturation is relatively low at the bacterial mat site. At the gas discharge sites, the pore water flux could reach 10^10 kg m-2 yr-1, and the temperature could reach that of the source area in 9 min. There is no gas hydrate formation at the gas discharge sites. Our simulative analysis therefore reveals that a lower pore water flux would result in lower salinity, higher temperature, and a shallower base of the hydrate sta- bility zone. This in turn induces a lower gas hydrate formation rate, lower hydrate saturation, and eventually less gas hydrate resources.

An elevational trend of body size variation in a cold-climate agamid lizard, Phrynocephalus theobaldi

The pattern that many ectotherms have smaller body sizes in coM environments follows the converse to Bergmann＇s rule and is most frequently found in lizards. Allen＇s rule predicts animals from warm climates usually have longer tails and limbs, while these traits tend to be shorter in individuals from cold climates. We examined body size variation in an endemic Chinese lizard Phrynocephalus theobaldi along a broad elevational gradient （3,600-5,000 m on the Qinghai-Tibetan Plateau）. Female body size showed a U-shaped cline, decreasing with increased elevation within the range 3,600-4,200 m, but increasing at eleva- tions 〉 4200 m. Male body size continued to increase with increasing elevations. Both sexes showed an increased pattern of ex- tremity length with elevation that does not conform to Allen＇s rule. Limb length and tail length increased along the elevational gradients. In terms of color pattern, an abdominal black speckled area appears at elevations 〉4,200 m. This trait increases in size with increased elevation. Unlike most studies, our results indicated that annual sunshine hours corresponding to the activity pe- riod of the lizards could play an important role on the positive body size cline in environments at very high elevations 〉 4200 m

Microstructural characteristics of cold-rolled Zr-2.5Nb alloy annealed near the monotectoid temperature

A dual-phase Zr-2.5 Nb alloy was rolled at room temperature to 50% reduction and then annealed at two temperatures(560 and580°C) near the monotectoid temperature. X-ray diffraction, electron channeling contrast imaging and electron backscatter diffraction techniques were jointly used to characterize microstructural characteristics developed in the as-rolled and annealed specimens. Results show that plastic deformation occurs in both bulk α-Zr grains and thin β-Zr films during rolling, allowing large lattice strains to be accumulated in β-Zr and active dislocation slip(especially the prismatic áa?slip) to be initiated in α-Zr. During subsequent annealing at 580°C, the prior β-Zr films are transformed into submicron β-Zr particles, which lose coherency(the Burgers orientation relationship) with surrounding α grains. In the specimen annealed at 560°C, however, the prior β-Zr films are found to be decomposed into nanoscale β-Nb particles. In both the annealed specimens, the β-Zr and the β-Nb particles appeared to be linearly distributed along the rolling direction. Two types of α structures, i.e., small equiaxed crystallites formed by recovery of dislocation structures and coarse bamboo-like recrystallized grains, are revealed in the annealed specimens. Effective boundary pinning due to the dense β-phase particles is demonstrated to play a key role in forming such unusual bamboo-like grains.