主要气候因素与云南松天然林生长率的关系研究

依据森林资源连续清查获得的云南松天然林样地调查数据及气象数据,研究了年均温、年均降水量与云南松天然林平均胸径生长率的关系。结果表明,不同年均温区域云南松天然林样木平均胸径生长率总体上呈现出温度越高生长率越大的趋势,但趋势在年均温为16℃时出现了拐点,当年均温>16℃时,随着年均温的升高,云南松天然林生长率反而开始降低。在不同降水量区域的云南松天然林平均胸径生长率总体上与年均降水量呈正相关,降水量越大,生长越快。但在降水量为900~1099mm区域,6~16径阶云南松天然林的生长率却超过了降水量≥1100mm区域。文中对上述现象进行了讨论,认为其原因涉及云南松的适生区、生态稳定性以及林木的生物学与生态学机制等。     

AR凸函数的Hermite-Hadamard型不等式

建立AR凸函数的积分不等式,特别是Hermite-Hadamard型不等式.利用通常凸函数与AR凸函数的关系,证明了AR凸函数的单侧导数的存在性和单调性,并通过不等式建立了AR凸函数与其单侧导数的关系.从AR凸函数的定义出发,得到了AR凸函数的Hermite-Hadamard型不等式.利用AR凸函数与其单侧导数的关系,使用数学分析的方法,研究了由AR凸函数的Hermite-Hadamard型不等式生成的差值.利用AR凸函数与其单侧导数的关系,构造了与AR凸函数有关的单调函数,从而给出AR凸函数的定积分的上界和下界.另外,利用AR凸函数与其单侧导数的关系,还建立了AR凸函数的其他的积分不等式.     

基于微波反射法的谷物含水率在线检测装置研制

针对稻麦联合收割机在收获作业时难以对小麦、水稻等谷物的含水率进行准确在线测量的问题,该文基于微波反射法研究了谷物含水率在线检测方法,建立了稻麦含水率检测模型,研发了一种稻麦联合收割机谷物含水率在线检测装置。该装置采用微波测量模块对稻麦含水率进行非接触式测量,设计了电压转换电路将微波参数转换成电压信号,采用滑动平均滤波算法进行信号滤波,最后通过标定试验所建立的含水率检测模型进行稻麦含水率计算,计算结果经CAN总线通讯在显示器上实时显示。基于上述理论研究、技术开发和结构设计对所研制的谷物含水率在线检测装置分别进行了室内静态试验和田间收割试验研究,试验结果表明:检测装置的对稻麦含水率的测量范围为14%～34%,在室内静态试验和田间收割试验中的性能标准差分别为0.458 3%和1.078 0%,相对误差分别在2.5%和5%左右,具有良好的准确性与实用性。     

最优控制问题的Tikhonov正则化

主要研究了约束线性二次最优控制问题.通过一阶最优性条件将它等价地转化为单调变分不等式问题,并利用变分不等式的Tikhonov正则化方法研究了约束线性二次最优控制问题的正则化,证明了扰动问题的解收敛到原问题的最小范数解.     

基于自适应ARMA模型的区域农业总产值构成研究与应用

由于噪声的存在并随时间累积,传统的自回归滑动平均模型(ARMA模型)不能直接应用于时间序列的中期预测.该文针对这种情况,提出了一种自适应的自回归滑动平均模型,将模型状态划分为无噪声的迭代模型和有噪声的观察模型,并根据迭代模型的特点,详细推导并完整给出了它的迭代求解公式,以便使其可以用于时间序列的中期预测,同时研究1985～2001年黄淮海平原农业、牧业与渔业产值预测模型,得到较理想的预测结果.并用所建模型对2001年产值进行外延预测,以期为区域农业结构调整提供理论依据.     

劳动力配置对农户收入及收入不均等的影响——基于要素市场发育的视角

为厘清外部市场环境对农户收入增长以及收入分配的影响,本研究利用分位数回归,基于2020年南京农业大学中国土地经济调查数据库(CLES),从要素市场发育的视角探究农户家庭劳动力配置对收入及收入不均等的影响。结果表明：相对于完备的要素市场,市场发育不完备造成的劳动力配置扭曲会对农户收入有显著负向影响;同时将农户分为不同收入组后发现,要素市场发育不完备造成的劳动力配置扭曲对低收入和中等收入组农户的影响更为显著,在一定程度上加剧了农户收入不均等。由此提出以下建议,应当进一步加强农村要素市场建设,优化农户家庭劳动力配置,实现农民收入增长的同时,努力缩小农户内部收入差距。     

Evidence of sedimentation inequality along riparian areas colonised by Impatiens glandulifera (Himalayan balsam)

Soil loss from riparian areas supporting the annual invasive weed, Impatiens glandulifera (Himalayan balsam), was measured and compared with equivalent values recorded at nearby, topographically similar areas supporting perennial vegetation over a cumulative seven-year period, along sections of two separate river systems; one in Switzerland, and one in the UK. Soil loss from colonised locations was significantly greater than from reference locations in four of the seven measurement periods. Despite contrasting results, standard deviations, based on soil losses and gains, were predominantly higher for colonised areas at both rivers over most monitoring periods. These findings indicated that areas colonised by Himalayan balsam experience higher sediment flux in comparison with areas free of invasion. Here, we test those original interpretations by reinterrogating the datasets using a more robust analysis of inequality. Nine datasets were tested, five of which (i.e. 56%) showed that sediment flux was significantly greater at Himalayan balsam-invaded areas than at reference areas. Three datasets showed no difference in sediment flux between invaded and reference areas (33%), and one (11%) showed higher sediment flux at reference areas. Most results uphold our original interpretations and support our hypothesis that hydrochory probably dictates where colonisation initially occurs, by depositing Himalayan balsam seeds in slack or depressional areas along river margins. Once Himalayan balsam becomes established and sufficient perennial vegetation is displaced, seasonal die-off and depleted vegetation cover may increase the risk that some areas will experience significantly higher sediment flux.     

千年桐苗木生长规律研究

以千年桐1年生播种苗为研究对象,对其苗高、地径的生长规律和苗高、地径与气象因子的关系等进行研究。试验结果表明：Logistic方程可较好地反映1年生千年桐的苗高、地径生长规律;日平均气温是影响苗高生长的主要气象因子,气象因子与地径生长关系不大。     

Organic additives used in beef cattle feedlot: Effects on metabolic parameters and animal performance

Organic additives are recently being used in animal diets owing to their ability to control metabolic issues and result in better animal performance. Specifically, the organic additive Fator P^® presents an additional advantage that is to cause a lesser greenhouse gas emission. This study evaluated whether Fator P^® intake changes ruminal parameters or animal performance of beef cattle. Evaluations were carried out in a feedlot experiment divided into growing (46 days; two diets [control mix—CM and standard mix—SM] and finishing (lasted 83 days; four diets: CM, SM, Fator P^® + virginiamycin, and Fator P^® alone [FP]) trials. Animal performance study involved 48 animals allocated to 12 collective pens in completely randomized experimental design. Ruminal parameters were evaluated in separate metabolism study developed carried out using individual pen with four steers. During growing trial, FP diet resulted in higher (p < 0.05) dry matter intake (DMI) and ruminating time. In the finishing trial, diets containing Fator P^® resulted in higher DMI than obtained with CM. Most of the ruminal parameters did not differ (p > 0.05) among dietary treatments. Therefore, Fator P^® represents a viable and safe strategy for supplementation to beef cattle finished using high‐concentrate diet in feedlot systems.