Does sand content in spawning substrate result in early larval emergence? Evidence from a lithophilic cyprinid fish

The spawning success of lithophilic salmonids is strongly influenced by the fine sediment content (“fines”) of spawning substrates, yet knowledge on the impacts of fines on the spawning of non‐salmonid lithophiles remains limited, despite their ecological and socio‐economic importance in European rivers. Consequently, the aim here was to use an ex‐situ experiment to investigate the impact of sand content on egg survival and timing of larval emergence of the surface‐spawning cyprinid European barbel Barbus barbus. Thirty incubator boxes within a recirculating system were filled with one of five experimental sediment mixtures (0%–40% sand by mass) that each contained 300 fertilised eggs at a depth of 50 mm. Emerged, free‐swimming larvae were captured and counted daily to assess grain‐size effects on larval survival and emergence. Specifically, total proportion of emerged larvae, cumulative daily proportion of emerged larvae and time required to reach 50% emergence were measured during the study. Whilst the proportion of sand in the sediments did not have a significant impact on egg‐to‐emergence survival (mean survival per treatment 75%–79%), it significantly affected the timing of larval emergence to the water column; early emergence was detected in treatments with elevated sand content (on average, 50% emergence after 12–13 days versus 19 days in the control). Similar to findings from salmonid studies, these results suggest high sand content in spawning gravels can influence timing of larval emergence and potentially cyprinid lithophilic fish survival.     

Adjusted method of penis fixation during boar semi-automatic semen collection aiming to reduce bacterial contamination

Semen collection has an essential role in the initial bacterial load in boar ejaculates and extended semen. The study aimed to explore the efficacy of an adjusted penis fixation in a semi-automatic collection system on reducing bacterial contamination of ejaculates in two-boar studs with different scenarios. Historically, stud A had low levels of bacterial load in raw semen, while stud B had a high level of contamination. A total of 56 mature boars had their semen collected using two methods of penis fixation: (a) Traditional: The penis was fixed directly with the artificial cervix and transferred to the adjustable clamp; (b) Adjusted: The fixation was performed with one gloved-hand, and after exteriorization, the penis was gripped using the artificial cervix with the other gloved-hand and transferred to the adjustable clamp. The bacterial load (p = .0045) and the occurrence of ejaculates >231 CFU/ml (p = .0101) were reduced in the Adjusted compared to the Traditional method. Bacterial load was reduced when using the Adjusted method in stud B (p = .0011), which showed a greater occurrence of critical factors for bacterial contamination (p ≤ .0034). The Adjusted method reduced the occurrence of ejaculates >231 CFU/ml when the preputial ostium was dirty (p = .016) and the duration of semen collection was >7 min (p = .022) compared to the Traditional method. In conclusion, the Adjusted penis fixation was efficient in reducing bacterial load of ejaculates, mainly in boar stud B, which had high contamination challenges.     

Estimation of Runoff,Peak Discharge and Sediment Load at the Event Scale in a Medium‐Size Mediterranean Watershed Using the Annagnps Model

In this paper, the Annualized Agricultural Non‐Point Source (AnnAGNPS) model has been used to estimate runoff, peak discharge and sediment load at the event scale in a Mediterranean watershed. The study area is the Carapelle torrent, Southern Italy (area = 506 km²), where continuous rainfall, streamflow and sediment load data are available. Nineteen flood events have been registered in the period 2007–2009 and were used for the application of the model. The aim of the paper is to evaluate the predictive accuracy of the model at the event scale, in a medium‐size watershed, given the specific conditions of the semi‐arid environments. A sensitivity analysis has been carried out to assign the correct parameterization: the mean normalized output variation of the most meaningful input parameters pointed out the influence of the curve number on runoff, peak discharge and sediment load predictions (values greater than 1); the MN Manning's roughness coefficient and K, C and P factors of the universal soil loss equation showed a moderate influence on sediment load simulations (values between 0·5 and 1). The selection of the Soil Conservation Service synthetic storm types has been based on the observed storm events analysis to improve the peak discharge simulations. The model prediction has proved to be good for runoff (R² = 0·74, NSE = 0·75, W = 0·92) and peak discharge (R² = 0·85, NSE = 0·70, W = 0·94), and satisfactory for sediment yield (R² = 0·70, NSE = 0·63, W = 0·91). The relative error is lower for high events; this result is quite interesting in semi‐arid environments, where most of the annual sediment yield is concentrated in a few, severe events. Copyright © 2013 John Wiley & Sons, Ltd.     

卷盘式喷灌机卷盘驱动负载计算与分析

为优化卷盘式喷灌机驱动结构,研制高效卷盘喷灌机驱动器,需要对卷盘式喷灌机的卷盘负载情况进行计算和分析。为此,以软管牵引式卷盘喷灌机为对象,建立了卷盘负载转矩计算的物理模型,理论推导了在运行时的卷盘负载转矩数学计算模型。以JP50和JP75型卷盘式喷灌机为例,按推导所得数学模型进行计算,得到了运行时卷盘负载转矩随已回卷PE管长度的变化规律和估计值。计算结果表明:JP50型卷盘式喷灌机运行时最大负载转矩约为960N·m,JP75型为6 001N·m;卷盘负载转矩随已回卷长度的增加而减小,且当卷盘回卷半径变化时,负载转矩将突然变大;负载转矩的大小和变化规律只与喷灌机的参数和运行条件有关,与运行时的速度无关。     

Analysis of the Sediment Development and Trend In Jinshajiang River Drainage Area

Jinshajiang River, which has a drainage area of 485,100 Km 2, average flux of 142.9 billion m 3, and soil conveyance of 247 million t/a, is the largest branch of Changjiang river. It is also the largest soil resource of the Three Gorges reservoir and upper reach of Changjiang River. To research the development and trend of Jinshajiang sediment not only has a relation to Jinshajiang water resource strategy, but also has important meaning to control the silt in Three Gorges reservoir and the Changjiang water resource development. The paper statistically analyses the flux and sediment conveyance of the Pingshan station, which is the primary hydrological station in the Jinshajiang River Drainage Area. Through several non-parameter statistical methods such as Spearman order correlativity check, Kendell order correlativity check, and linear regression check, the paper concludes that the sediment evolvement trend of Pingshan station is not distinct.     

ANALYTIC SOLUTION OF CYLINDRICAL SHELL ROOF UNDER GENERAL TRANSVERSE LOCAL LOADINGS

This paper uses the method of mixed-type series to derive the analyticsolution of cylindrical shell roof,being simply supported transversely,arbitra-rily restrained longitudinally and subjected to gereral transverse local loads.This paper also presents the analytic expressions of the solutions for somekinds of local load.Some examples of this kind of shell roof subjected to ainlined single force near the middle of it with free lorgitudinal edges aregiven.The computation shows that the convergence of the solution is woll     

Application of Attribute Reduct Method in Spatial Load Forecasting

Spatial load forecasting is a process distributing the total forecasted load to all partitioned area, and involving more spatial information and more factor influencing application of the future small area, which need a great deal of memory space and longer operation time. Rough set is new method of data analysis. It need not be provided with any advanced information except data set. But attribute reduct is its main algorithms. Division matrix approach on rough set used to reduce the attribute related to land - use decision in order to remove redundancy attribute and then the rules of small area land - use decision is distilled. The method obtained better effect and enhanced the total load forecasting efficiency.     

Analysis of Load-bearing Characteristics of Concrete Pile Composite Foundation

Some conclusions were drawn from two groups of in-site tests on concrete pile composite foundations. In the tests, it was found that the pressure under the rigid loading slab is different, in which the pressure under the center of the slab is the less and under the edge of the slab is the biggest. The pile-soil stress ratio is not a constant; it increases with the adding of the load. Most of the pile-soil ratio vary from 9 to 13 in these tests and the load that the piles share can be more than seventy percent of the whole load. It was proved that the bearing capacity of the concrete pile composite foundation is high with a little settlement, so it will be used more and more in the future.