Evaluating Visitor-Monitoring Techniques: A Comparison of Counting and Video Observation Data

Two visitor-monitoring methods, video monitoring and counts by human observers, were compared in order to identify and evaluate their respective advantages and disadvantages. The analysis considered user numbers, user type (walkers, dog walkers, bicyclists, and joggers) and group size of visitors. Remarkable differences were found between the two methods for user type and use levels. At low use levels, evaluations based on video monitoring resulted in fewer single bicyclists compared to counts by human observers, whereas at high use levels, human observers counted fewer walkers and bikers than video-interpreters. Based on this comparative analysis, we derive recommendations for more effective visitor-monitoring approaches. All data were collected during a visitor-monitoring project in the Danube Floodplains National Park in Austria between 1998 and 1999.     

脱硫粉的粒度评述

阐述了脱硫粉剂粒度组成的内涵，确定粒度配比的必要性和3种粒度配比（曲线）的比较，为正确选用脱硫粉粒度提供基础资料。     

Ecological Integrity Assessment of Lakes Using Fish Communities: An Example from Traunsee Exposed to Intensive Fishing and to Effluents from the Soda Industry

In order to analyse potential influences of soda industryeffluents on the ecological integrity of Traunsee (TS) weinvestigated the fish community of the lake in comparison witha reference lake (Hallstättersee HS) and used a reconstructionfrom the (older) literature concerning the original speciescomposition of Traunsee. Published `Index of Biotic Integrity(IBI)' metrics were considered to be of limited value due tothe relatively low species number in the oligotrophic, Alpinelake. Therefore we included, in addition to speciescomposition, studies on egg distribution, larval fishdensities, life-history parameters (i.e. growth, maturity,fecundity, age and size composition), stress levels and heavymetal content of the dominant whitefish (Coregonuslavaretus), as well as overall fish density and biomass (usinghydroacoustics) to assess the ecological status of the fishcommunity. Two of the original 18 species have disappearedfrom the lake, presumably in connection with the introductionof non-native eel (Anguilla anguilla) and theconstruction of a power plant in the outflow. Silt from grindedlimestone together with highly alkaline pore waters is emittedvia industrial wastewater from Sodaworks and covers part of thelake bottom. We observed that eggs of whitefish were spawnedmainly in the main inflowing river and close to the shore, thusavoiding the silty areas and making the anticipated damage tothe reproductive potential of whitefish neglectable. This wascorroborated by larval surveys done weekly on both lakes fromJanuary to May, which showed halve the density of whitefishlarvae in TS compared to HS. Estimates of potentially spawningfish from hydroacoustic surveys resulted in a ratio of 1(TS) :3 (HS). Analysis of whitefish revealed that they are growingfaster in TS and have higher fecundity leading to somecompensation of lower abundance. High levels of fishing in TSmight have led to this pattern and to depressed yields asindicated by the age composition. Level of oxidative stress andheavy metal content were not discernible from the referencelake. Therefore we concluded that negative impacts on theecological status of the fish community resulted from fisheriesmismanagement and a power plant situated in the outflow of thelake, considered to have damaged spawning places for somespecies, but not from soda industry effluents.     

The influence of personal protection equipment,occupant body size,and restraint system on the frontal impact responses of Hybrid III ATDs in tactical vehicles

Objective: Although advanced restraint systems, such as seat belt pretensioners and load limiters, can provide improved occupant protection in crashes, such technologies are currently not utilized in military vehicles. The design and use of military vehicles presents unique challenges to occupant safety—including differences in compartment geometry and occupant clothing and gear—that make direct application of optimal civilian restraint systems to military vehicles inappropriate. For military vehicle environments, finite element (FE) modeling can be used to assess various configurations of restraint systems and determine the optimal configuration that minimizes injury risk to the occupant. The models must, however, be validated against physical tests before implementation. The objective of this study was therefore to provide the data necessary for FE model validation by conducting sled tests using anthropomorphic test devices (ATDs). A secondary objective of this test series was to examine the influence of occupant body size (5th percentile female, 50th percentile male, and 95th percentile male), military gear (helmet/vest/tactical assault panels), seat belt type (3-point and 5-point), and advanced seat belt technologies (pretensioner and load limiter) on occupant kinematics and injury risk in frontal crashes.

Methods: In total, 20 frontal sled tests were conducted using a custom sled buck that was reconfigurable to represent both the driver and passenger compartments of a light tactical military vehicle. Tests were performed at a delta-V of 30 mph and a peak acceleration of 25 g. The sled tests used the Hybrid III 5th percentile female, 50th percentile male, and 95th percentile male ATDs outfitted with standard combat boots and advanced combat helmets. In some tests, the ATDs were outfitted with additional military gear, which included an improved outer tactical vest (IOTV), IOTV and squad automatic weapon (SAW) gunner with a tactical assault panel (TAP), or IOTV and rifleman with TAP. ATD kinematics and injury outcomes were determined for each test.

Results: Maximum excursions were generally greater in the 95th percentile male compared to the 50th percentile male ATD and in ATDs wearing TAP compared to ATDs without TAP. Pretensioners and load limiters were effective in decreasing excursions and injury measures, even when the ATD was outfitted in military gear.

Conclusions: ATD injury response and kinematics are influenced by the size of the ATD, military gear, and restraint system. This study has provided important data for validating FE models of military occupants, which can be used for design optimization of military vehicle restraint systems.     

“后桥”专机流水线排风除尘系统设计

通过治理某厂差动齿轮箱壳体流水线中各类机床在生产过程中产生的金属粉尘，介绍了排风除尘系统的吸尘罩设计，排风量计算，风管管路布置以及除尘器和风机的选用等，系统运行结果表明，达到设计要求。     

Chemical composition of aerosols in winter/spring in Beijing

In 1999 aerosol samples were collected by cascade at Meteorological Tower in Beijing.The 12 group aerosol samples obtained were analyzed using PIXE method,which resulted in 20 elemental concentrations and size distribution of elemental concentrations.From the observation,the elemental concentrations,size distribution of elemental concentrations and their variations are analyzed.It shows that concentrations of most elements in aerosols increase greatly compared with those in the past except that the concentrations of V,K,Sr,and the source of aerosols has changed greatly in the past decade.Fine mode aerosols increase more rapidly in the past decade,which may be due to the contribution of coal combustion and automobile exhaust.Pb contait in aerosol is much higher than that at the beginning of 1980s,and has a decreasing trend in recent years because of using non-leaded gasoling.     

Ti-Nb微合金钢焊接粗晶热影响区组织及韧性

喷锌、喷铝、喷锌铝合金三种保护层材料在青海格尔木盐水湖进行1年暴露试验，采用电化学方法研究了该金属喷涂层材料的腐蚀情况，并将其与碳钢的实验结果相对照，初步探讨了其耐蚀机理。     

Cation exchange capacities of soil organic matter fractions in a Ferric Lixisol with different organic matter inputs

Soil organic matter (SOM) has an important effect on the physicochemical status of highly weathered soils in the tropics. This work was conducted to determine the contribution of different SOM fractions to the cation exchange capacity (CEC) of a tropical soil and to study the effect of organic matter inputs of different biochemical composition on the CEC of SOM. Soil samples were collected from a 20-year-old arboretum established on a Ferric Lixisol, under seven multipurpose tree species: Afzelia africana, Dactyladenia barteri, Gliricidia sepium, Gmelina arborea, Leucaena leucocephala, Pterocarpus santalinoides, and Treculia africana. Fractions were obtained by wet sieving and sedimentation after ultrasonic dispersion. Relationships between CEC and pH were determined using the silver thiourea-method and were described by linear regression. The CEC of the fractions smaller than 0.053 mm was inversely related to their particle size: clay (<0.002 mm)>fine silt (0.002–0.02 mm)>coarse silt (0.02–0.053 mm), except for the soils under T. africana, D. barteri, and L. leucocephala, where the CEC of the fine silt fraction was highest or comparable to the CEC of the clay fraction. The clay and fine silt fractions were responsible for 76–90% of the soil CEC at pH 5.8. The contribution of the fine silt fraction to the CEC at pH 5.8 ranged from 35 to 50%, which stressed the importance of the fine silt fraction for the physicochemical properties of the soil. Differences in CEC between treatments for the whole soil and the fractions could be explained by the differences in carbon content. Except for the intercept for the clay fraction, SOM had a significant (P<0.001) contribution to both the intercepts (=estimated CEC at pH 0) and slopes (=pH-dependent charge) of the CEC–pH relationships for the whole soil and the fractions. The CEC of SOM at pH 5.8 varied between 283 cmol_c kg⁻¹ C for particulate organic matter, and 563 cmol_c kg⁻¹ C for the fine silt fraction. The biochemical composition of the organic inputs did not have an important effect on the CEC of SOM. In total, SOM was responsible for 75–85% of the CEC of these soils.     

冲裁模刃口尺寸及公差的自动标注与修改

根据冲裁模刃口尺寸及公差的确定原则和计算公式 ,提出了切实可行的人机交互式的自动标注和修改冲裁模刃口尺寸及公差的方法     

普通旋风除尘器结构尺寸优化设计

以Ｌｅｉｔｈ设计法为基础，考虑除尘效率和压降等因素的影响，以除尘效率为理想目标，以一些流体力学特性和实际限制、经验值为约束，建立数学模型，用数学规划论的方法进行旋风除尘器结构尺寸的优化，以此设计的旋风除尘器应用到现场既可节约投资，又可降低能耗，设计方法通用性好．