改进YOLOv5识别复杂环境下棉花顶芽

为提高复杂环境下棉花顶芽识别的精确率,提出了一种基于YOLOv5s的改进顶芽识别模型。建立了田间复杂环境下棉花顶芽数据集,在原有模型结构上增加目标检测层,提高了浅层与深层的特征融合率,避免信息丢失。同时加入CPP-CBAM注意力机制与SIOU边界框回归损失函数,进一步加快模型预测框回归,提升棉花顶芽检测准确率。将改进后的目标检测模型部署在Jetson nano开发板上,并使用TensorRT对检测模型加速,测试结果显示,改进后的模型对棉花顶芽识别平均准确率达到了92.8%。与Fast R-CNN、YOLOv3、YOLOv5s、YOLOv6等算法相比,平均准确率分别提升了2.1、3.3、2、2.4个百分点,该检测模型适用于复杂环境下棉花顶芽的精准识别,为后续棉花机械化精准打顶作业提供技术理论支持。     

不同仓库条件对粮食储藏损耗的影响

对３种隔热、密封条件不同的房式仓储粮时的粮温变化、杂质增量、水分减量、储藏损耗、费用投入及储粮品质变化情况进行了对比性实验。结果表明：一般房式仓的８水分减量最大，标准化房式仓的储粮性能最好，保管损耗也最小。     

金刚石涂层木工刀片耐腐蚀性试验

本文主要研究屑末溶液和酸溶液对金刚石涂层刀片的腐蚀作用。试验表明：金刚石涂层抑制了屑末溶液和酸溶液对高速钢（W18Cr4V）或硬质合金（YGS）刀片的腐蚀作用；未涂层的高速钢（W18Cr4V）或硬质合金（YG8）刀片，其表面在酸溶液或屑末溶液的作用下，都存在程度不同的腐蚀。     

A comparison of mineral-magnetic and distributed RUSLE modeling in the assessment of soil loss on a southeastern U.S. cropland

As geospatial technologies increasingly figure into resource management activities, there is a corresponding need to provide commensurately detailed high resolution spatial data. This study addresses the capacity of rapidly and cheaply acquired mineral-magnetic data to provide detailed spatially distributed assessments of long-term cumulative soil loss from agricultural fields. Model output from a simple distributed implementation of the Revised Universal Soil Loss Equation (RUSLE) and from a field-data-oriented soil magnetism-based erosion model are compared for a small Alabama (USA) farm lot. An undisturbed reference soil toposequence is used as input to the magnetism model, in contrast with earlier studies that relied on a single reference soil profile. Results from this procedure, while likely to be more dependable, proved primarily to further emphasize spatial patterns noted in prior studies. In addition, the use of a toposequence decreased the area over which RUSLE and magnetism models were in agreement. RUSLE underpredicted denudation relative to magnetism-model results over upper slopes, and overpredicted it on lower slopes. The locations of former access roads may explain underprediction on the upper slopes. The differences between the two method outcomes are discussed with regard to the potential for spatial variability in parent materials, the efficacies of non-fluvial soil redistribution processes, and the availability of detailed land use records for the 100+ years of agricultural activities at the site.     

二氧化硅/木材复合材料的动态黏弹性

为弄清二氧化硅/木材复合材料的动态黏弹性,通过动态热机械分析仪研究不同增重率的二氧化硅/木材复合材料松弛过程的转变温度及力学损耗角正切的变化.结果表明:二氧化硅/木材复合材料的松弛过程数量减少,直接溶胶-凝胶法制备的二氧化硅/木材复合材料,α松弛过程的转变温度随着增重率的增加而向高温方向移动.增重率为0,5.10%和28.00%的α松弛过程的转变温度分别为75.2,76.8和93.6℃;α松弛峰的峰值减小,增重率为0,5.10%,12.63%和28.00%的α松弛过程的损耗角正切值分别为0.043,0.041,0.033和0.03.加硅烷偶联剂法制备的二氧化硅/木材复合材料,随着增重率的增加,α松弛过程的起始温度向低温方向移动,增重率为6.61%,8.08%和10.58%的α松弛过程的起始温度分别为44.9,41.0和32.2℃.     

麦田泽漆生态经济阈值的研究

麦田泽漆对小麦危害造成产量损失，通过试验得到麦田泽漆密度（x）与小麦产量损失率（y）之间为双曲线关系，即：^y=x/(8.9920 0.0181x）。根据生态经济阈值的定义，建立了麦田泽漆的生态经济阈值模型，按目前淮北麦区的小麦产量、价格及除草成本、效果等，计算得出高、中、低产麦田泽漆的化学防除指标分别为30株/m^2、40株/m^2、65株m^2。     

草原蝗虫防治指标的研究

作者测定了4种蝗虫从孵化至成虫期的食量,把草原蝗虫划分为以红翅皱膝蝗、邱氏异爪蝗和狭翅雏蝗为代表的大、中、小三种食量类型,混合种群虫口密度(x)与其对牧草取食量(y)的模型为y=16.4732x。通过野外混合种群不同密度下对牧草产量损失的测定,回归式为(ŷ)=-20.8070+14.4143x±15.56(r=0.9993,F>F_0.01),两种方法计算的防治指标分别为21.7、26.2头/m²,其经济允许损失均为8.8%。大、中、小三种食料类型的防治指标分别为5.2、17.6和32.3头/m²。     

稻茬烟田杂草为害损失及经济阈值研究

对稻茬烟田杂草定点调查发现，草害参数与烟叶产量损失率呈ｙ＝Ａ＋Ｂｘ直线回归关系，并求出当地生产水平下杂草经济防除阈值模型：     

Water balance,respiration and immobilisation in relation to deltamethrin poisoning and physical conditions in the epigeal spider Oedothorax apicatus

The effect of a pyrethroid insecticide, deltamethrin, on water loss, metabolic rate and immobilisation was studied, using the epigeal spider Oedothorax apicatus (Blackwall) (Linyphiidae) as a test species. Water loss was measured gravimetrically at different temperatures, air humidities, and doses of deltamethrin. Metabolic rate and immobilisation were measured at different temperatures and doses. Immobilisation was measured at different relative humidities and temperatures. Water loss due to evaporation increased linearly with vapour pressure deficit. The slope of the latter relationship increased with temperature, indicating an increase in cuticle permeability with temperature. In addition to water loss by evaporation, deltamethrin treatment induced water excretion. This was positively related to dose and temperature, but independent of air humidity. Metabolic rate increased with temperature and dose. Immobilisation was highest at low temperatures in combination with low air humidity. The consequences of pesticide-induced water excretion are discussed with respect to field- and laboratory-based dose-effect relationships for pyrethroids presented in the literature. The present results seem to offer an explanation for hitherto unexplained minima in temperature-response curves in pyrethroid toxicity in some arthropod species. It is concluded that simultaneous measurements of metabolic rate, water-loss rate and pesticide effects are a prerequisite for an understanding of the effects of pesticides on arthropods.     

Effects of chronic obesity and weight loss on plasma ghrelin and leptin concentrations in dogs

The objective of this study was to evaluate, in dogs, the effects of obesity and weight loss on plasma total ghrelin and leptin concentrations. Twenty-four Beagle dogs, 12 control lean and 12 obese dogs of both genders and aged between 1 and 9 years, were used for the experiments. Mean body weight was 12.7+/-0.7 kg for the lean group and 21.9+/-0.8 kg for the obese group. The trial was divided into three phases. During phase 1, all 24 Beagle dogs were fed a maintenance diet. During phase 2, the obese dogs were submitted to a weight loss protocol with a high protein-low energy diet. The weight loss protocol ended once dogs reached optimal body weight. During phase 3, the dogs that were submitted to the weight loss protocol were maintained at their optimal body weight for 6 months. Plasma total ghrelin, leptin, insulin and glucose concentrations were measured to evaluate the effects of obesity and weight loss on these parameters in dogs. Body weight, body condition score, thoracic and pelvic perimeters, and ingested food amounts were also recorded during the study. Obese dogs demonstrated a significant decrease in plasma ghrelin and a significant increase in plasma leptin and insulin concentrations when compared with control dogs. During weight loss, significant increases in plasma total ghrelin and glucose and significant decreases in plasma leptin and insulin were observed. The increase in plasma ghrelin concentrations seemed to be transient. Body weight and the morphometric parameters correlated positively with leptin concentrations and negatively with total ghrelin concentrations. These results suggest that ghrelin and leptin could play a role in dogs in the adaptation to a positive or negative energy balance, as observed in humans.