真理想存在性的一个判定方法

本文主要通过极大理想空间与乘法线性泛函的核空间的关系,给出了真理想存在性的一个判别方法.     

Bilateral deficit in power production during multi-joint leg extensions

Abstract

The purpose of this study was to determine the presence of the bilateral deficit both as a function of overall and individual joint power. Most studies addressing the deficit have assessed force; however, in most sporting events maximal power is more important than maximal force production. To address this, in the current study we assessed the bilateral deficit for multi-joint movements as measured by overall lower extremity and individual joint power. We assessed power production using an isokinetic machine permitting both unilateral and bilateral leg extensions. Several significant effects and interactions between the contraction type (unilateral, bilateral, alternating unilateral), side of the body, lower extremity joint, and percentage of a 1-RM load were revealed. All interactions were between the lower extremity joints (hip, knee, ankle) and involved the contraction protocol (P=0.001), the percentage of 1-RM load (P=0.0002), and the side of the body (P=0.0003). Taken together, the results indicate that the bilateral deficit is manifested using a measure of power, but more importantly, the deficit has differential implications based on the overall resistance, and various joints involved in the movement. In conclusion, a reduction in power generation was evidenced for both simultaneous contractions of the leg extensors as well as reciprocal contractions. With reduced contributions from the knee joint during bilateral and reciprocal contractions, combined with past research demonstrating differential activation of mono-articular knee joint muscles, evidence for reduced contributions from the peripheral nervous system are suggested based on the results of this study.     

Resultant muscle torque and electromyographic activity during high intensity elastic resistance and free weight exercises

Abstract

The purpose of this study was to quantify and compare Resultant Muscle Torque (RMT) and muscle activation (EMG) pattern, during resistance exercise comprising eight repetitions maximum (8 RM) biceps curl with elastic resistance and free weight exercise. Sixteen male and female recreationally active subjects completed 8 RM biceps curl by each of three modalities of resistance exercise: (i) dumbbell (DB), (ii) elastic tubing with original un-stretched length at the commencement of contraction (E0), and (iii) elastic tubing with 30% decrement of original length (E30) at the commencement of contraction. The magnitude of muscle activation, external force, acceleration as well as range of motion (ROM) were quantified and synchronised by specific software. The data were collected from all eight repetitions but the first (initial), the fifth (middle) and the eighth (last) repetitions were selected for further data analysis. Each selected repetition was partitioned into a concentric and eccentric phase and then each phase was further divided into three equal segments (3 concentric and 3 eccentric = 6 segments per repetition). The EMG and RMT data demonstrated a bell-shaped muscle activation and muscle torque production pattern for the three modes of exercise. The E30 resulted in 15.40% and 14.89% higher total EMG (µV) as well as 36.85% and 17.71% higher RMT (N · m) than E0 and DB, respectively (all P <0.05). These findings support the contention that an elastic resistance device (E30) has the capacity to provide an appropriate high resistance stimulus to meet the training requirement of elite athletes.     

勾股逆定理的推广

用导数方法对勾股逆定理进行了推广，得到了如下结果：在△ABC中，若△a~x＋b~x＝c~x，其中x∈R－［0，1」，则1）当x∈（－∞，0）∪（1，2］时，Cmax＝；2）当x∈［2，＋∞）时，Cmin＝．此外，给出了上述结果的两个推论及其应用．     

最优停止规则在多种选择中的应用

众所周知,在n种物品中选择k种优秀物品是常发生的事。问题是按怎样的选择方式才能使选到的优秀物品的可能性最大。本文应用最优停时定理给出了在n种物品中选择k种物品的一般数学模型及最优选择规则的求解方程;本文还就k等于2给出了最优规则τ_1~α,n及按此规则进行选择所能得到的概率P~2——在n种物品中选择2种优秀物品的最大概率。     

太阳电池发电系统的最佳功率流控制

本文提出一种实现太阳电池输出最大功率的跟踪控制方法,给出实验结果,证实这一控制方法的可行性和有效性。文中还讨论了太阳电池发电系统最佳功率流控制的实现方法以及补偿无功功率和谐波失真等问题.     

最大模原则的推广及应用

主要讨论了Phragmen-Lindelof原则在有界区域边界上有不解析点的函数;在无界区域上满足适当条件函数的最大模的状态;对在有界区域上的解析函数f(z),其实部或虚部有界,则在该区域内|f(z)|有界.     

矩法估计与极大似然估计的比较

以二项分布为例,讨论了其分布参数的矩法估计与极大似然估计,并比较了两种估计的优良性质,主要讨论它们的一致性、无偏性和有效性．     

两种Zipf定律拟合方法的对比实证研究

采用普通最小二乘法和最大似然估计两种方法分别对Zipf定律的分布进行拟合比较研究。普通最小二乘法是目前曲线拟合中普遍采用的方法,而最大似然估计是曲线拟合更为合理的方法。分别利用三组中文和三组英文语料,对两种方法进行对比实证研究,结果发现最大似然估计方法的拟合更合理,对Zipf定律的拟合比普通最小二乘法好,同时发现英文词汇比中文更好地符合Zipf定律分布,即中文语料不严格符合经典的Zipf定律分布。本研究可以为幂律拟合的研究提供一些参考。     

一类捕食与被捕食系统的最优可持续收获策略

运用最优控制理论,对一类具有HollingⅢ类功能反应的捕食与被捕食模型进行了进一步研究,找到了其最优可持续收获策略。