Wind Characteristics of Mesquite Streets in the Northern Chihuahuan Desert, New Mexico, USA

Past research has shown that the most important areas for active sand movement in the northern part of the Chihuahuan Desert are mesquite-dominated desert ecosystems possessing sandy soil texture. The most active sand movement in the mesquite-dominated ecosystems has been shown to take place on elongated bare soil patches referred to as “streets”. Aerodynamic properties of mesquite streets eroded by wind should be included in explaining how mesquite streets are more emissive sand sources than surrounding desert land. To understand the effects of wind properties, we measured them at two flat mesquite sites having highly similar soil textures but very different configurations of mesquite. The differences in wind properties at the two sites were caused by differences of size, orientation, and porosity of the mesquite, along with the presence of mesquite coppice dunes (sand dunes stabilized by mesquites growing in the dune and on its surface) found only at one of the two sites. Wind direction, u_* (friction velocity), z₀ (aerodynamic roughness height) and D (zero plane displacement height) were estimated for 15-m tower and 3-m mast data. These aerodynamic data allowed us to distinguish five categories with differing potentials for sediment transport. Sediment transport for the five categories varied from unrestricted, free transport to virtually no transport caused by vegetation protection from wind forces. In addition, “steering” of winds below the level of the tops of mesquite bushes and coppice dunes allowed longer parallel wind durations and increased wind erosion for streets that aligned roughly SW–NE. U.S. Government right to retain a non-exclusive royalty-free licence in and to any copyright is acknowledged.     

Atmospheric Sulfur Deposition onto Different Ecosystems Over China

The regional acid deposition model system (RegADMS) was applied to simulate the air sulfur deposition onto different landuse types over China, in which the dry deposition velocities of SO₂ and sulfate aerosol (SO ₄ ^2– ) were estimated by use of a big leaf resistance analogy model and the wet scavenging coefficients were parameterized in terms of precipitation rate. Investigations show that the annual total sulfur deposition over mainland China is 7.24 mt (1 mt = 10⁶ ton) , in which dry deposition and wet deposition accounts for 56 and 44%, respectively. The sulfur deposition onto agriculture land, grass land, and forest land is 1.09, 3.6 and 1.41 mt, respectively, which sums 6.1 mt and accounts for 84% of the total sulfur deposition. The modeled sulfur deposition was in agreement with the measurement conducted at farmland in Yingtan, a typical read soil region in Jiangxi province of China, during the period of November 1998–October 1999. The total sulfur deposition at the Yingtan site is about 10.3 gm^–2 year^–1 of which 83% is dry deposition. The modeling sulfur deposition at the same site is 8.4 gm^–2 year^–1. Furthermore, the comparison between RegADMS and RAINS-ASIA on modeling regional sulfur deposition shows the consistence of the two models. The correlation coefficient between the simulated sulfur deposition at the medium-large cities reaches 0.72.     

Effects of ovarian fluid on sperm velocity in Arctic charr (Salvelinus alpinus)

Numbers of studies in externally fertilizing fish species provide evidence for an effect of ovarian fluid on sperm motility characteristics such as duration of forward mobility, velocity or percent motile sperm cells. Yet, because of variations among females in the quality of their ovarian fluid, such effects might differ between individuals. Additionally, ovarian fluid from different females could also be expected to affect each ejaculate differently, resulting in cryptic female choice. In this study on Artic charr (Salvelnius alpinus), sperm velocity from several males was measured in the diluted ovarian fluid of several females according to a fully balanced crossing design. This design allowed us to estimate variations among females in the effect of their ovarian fluid on the velocity of sperm from different males, and to detect variations among males in the ability of their sperm to swim in ovarian fluid. Sperm velocity was estimated by computer-assisted sperm analysis. Average velocity was found to vary among females, with some females having constantly higher velocity measurements in their ovarian fluid, and among males, indicating that some males had overall faster sperm in ovarian fluid than others. Moreover, variation in sperm velocity was shown to depend on individual female-male interactions. Our results document that females vary in the effect of their ovarian fluid on sperm velocity and that their ovarian fluid may stimulate sperm velocity according to individual characteristics of males. This latter result suggests a potential mechanism for cryptic female choice.

光降解制药废水的试验研究

研究了紫外光催化氧化法对制药废水的降解机理。考察了 Ti O2 投加量与污染物初始浓度的关系 ,并经初步估算其量子效率为 6.1 %     

MULTICRITERION ANALYSIS OF GROUNDWATER CONTAMINATION MANAGEMENT1

ABSTRACT: Multicriterion decision making (MCDM) techniques were used to analyze a groundwater contamination management problem from the viewpoint of conflicting multiple objectives. The groundwater management model was used to find a compromise strategy for trading off fresh water supply, containment of the waste, and total pumping cost in a hypothetical confined aquifer affected by previous waste disposal action. A groundwater flow model was used to formulate the hydraulic constraints. A linear system model was used to describe drawdown and velocity as functions of the decision variables which were pumping rates. The model determines the pumping location and rates. A modified c-constraint method was used to generate the set of nondominated solutions which were the alternative compromise strategies. Three different MCDM techniques, Compromise programming (CP), ELECTRA II and MCQA II, were used to select a “satisficing” alternative. Analysis of the results showed that, although these techniques follow different principles, the same preferred strategies were reached. Also, it was noticed that maintaining high groundwater velocities is expensive and difficult. In order to meet a two year target date, large amounts of water had to be pumped. Therefore, rapid restoration results in large pumping volumes and high costs.     

有风条件下火灾自然排烟的临界失效风速分析

采用双区模拟思想对有风条件下室内火灾自然补气、自然排烟过程进行分析。引入"总风压系数"和"临界失效风速"的概念,并将其作为评价外界环境风对自然排烟过程影响程度的判定参数。总风压系数非负时,外界风的存在将提高自然排烟的效果;总风压系数为负时,外界风的存在将降低自然排烟的效果,甚至使自然排烟失效。通过对排烟口内外压差以及气体流动进行分析,发现临界失效风速正比于总风压系数绝对值的-1/2次幂,并给出了不同条件下自然排烟临界失效风速的计算方法。实际采用自然排烟方式进行火灾排烟时,应尽量避免出现总风压系数为负的情形,以防止自然排烟的失效。     

由微振动记录用剥层法研究浅层S波速度结构

根据江苏华电句容发电一期2×1000 MW发电机组场地情况,布设了三角形嵌套和同心圆台阵进行微振动观测,采用空间自相关法计算频散曲线,并用剥层法反演得到该工程场地浅部的S波速度结构。反演结果与钻孔探测结果吻合较好,表明用微振动台阵记录反演浅部地壳S波速度结构在工程上是可行的。该方法具有不需要人工源,对避开噪声要求不苛刻、成本低且精度可满足工程要求等优点,故有良好的应用前景。     

RELATIONSHIPS BETWEEN WIND VELOCITY AND UNDERWATER IRRADIANCE IN A SHALLOW LAKE (LAKE OKEECHOBEE,FLORIDA, USA)1

ABSTRACT: Relationships between wind velocity and the vertical light attenuation coefficient (K₀) were determined at two locations in a large, shallow lake (Lake Okeechobee, Florida, USA). K₀ was significantly correlated with antecedent wind conditions, which explained as much as 90 percent of the daily variation in K₀. Sub-surface irradiance began to change within 60 to 90 minutes of the time when wind velocity exceeded or dropped below a threshold value. Maximum one hour changes in K₀ were > 50 percent, however, 20 to 30 percent changes were more common. The magnitude of change in K₀ varied spatially based on differences in sediment type. K₀ never exceeded 2.8 at a location where bottom sediments were dominated by a mixture of coarse sand and shells. In comparison, K₀ exceeded 9 during episodic wind events where the bottom sediment was comprised of fine grain mud. Underwater irradiance data can be used to determine threshold wind velocity and account for the influence sediment type has on K₀. Once a threshold velocity has been established, the frequency, rate, and duration of expected change in underwater irradiance can be evaluated. This is critical information for scientists who are studying algal productivity or other light-related phenomena.     

大型游乐设施运行状态测试系统及关键技术研究

系统分析游乐设施当前的测试水平,指出游乐设施运行状态测试是当前迫切需要解决的问题,并确定了加速度测试、速度测试、应力应变测试作为游乐设施运行状态测试系统的核心。结合游乐设施运行的特点,分别对以上3种核心测试技术从理论分析、设备选择、测试方法上进行了深入的研究。测试案例表明:基于以上技术测试的游乐设施运行状态测试系统是可行的,并为游乐设施检测提供了有力的技术支持。