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131.
复眼照明系统利用复眼透镜,可实现高亮度和较好的亮度均匀性,并且有较成熟的偏振处理方法,在投影系统特别是基于偏振光的投影系统中能提供比光棒照明系统更加高的亮度和好的均匀性的画面,使得光能利用率和图像均匀性有了较大的提高。在对复眼照明系统的原理进行分析的基础上,设计了一种用于投影光机的复眼照明系统,并用Matlab对该系统进行了光线追迹的仿真程序设计。对复眼照明系统的光线追迹进行了仿真。实际应用证明,在LCoS中采用本方案设计的照明系统比光棒照明系统具有更高的亮度和更好的均匀性。  相似文献   
132.
The symmetries and non-Noether conservation laws of Birkhoffian system with unilateral constraints are studied. The differential equations of motion of the system are established, and the criterions of Noether symmetry, Lie symmetry and Mei symmetry of the system are given. Two types of new conservation laws, called the Hojman conservation law and the Mei conservation law respectively, are obtained, and the intrinsic relations among the symmetries and the new conservation laws are researched. At the end of the paper, an example is given to illustrate the application of the results.  相似文献   
133.
Noether-Mei Symmetry of Mechanical System in Phase Space   总被引:1,自引:0,他引:1  
In this paper, a new kind of symmetry and its conserved quantities of a mechanical system in phase space are studied. The definition of this new symmetry, i.e., a Noether-Mei symmetry, is presented, and the criterion of this symmetry is also given. The Noether conserved quantity and the Mei conserved quantity deduced from the Noether-Mei symmetry of the system are obtained. Finally, two examples are given to illustrate the application of the results.  相似文献   
134.
The relation between the total variation of classical field theory and the multisymplectic structure is shown. Then the multisymplectic structure and the corresponding multisymplectic conservation of the coupled nonlinear Schrodinger system are obtained directly from the variational principle.  相似文献   
135.
In this paper, we improve the method for deriving Jacobi elliptic function solutions of nonlinear evolution equations given in Ref. [12] and apply it to the integrable higher-order Broer-Kaup system in (2 1)-dimensional spaces.Some new elliptic function solutions are obtained.  相似文献   
136.
以处理后的脱硫石膏为原料,在H2SO4-H2O体系中以Cu(NO3)2为晶形控制剂采用水热法制备脱硫石膏晶须,探讨了Cu(NO3)2对脱硫石膏晶须生长的影响机理。结果表明:Cu(NO3)2对脱硫石膏有明显促溶作用,其中Cu2+可减小溶液中各离子的活度系数,使溶液中的Ca2+浓度增大。NO-3通过静电作用在Ca2+周围聚集并对SO2-4产生屏蔽作用,导致脱硫石膏继续溶解并使Ca2+和SO2-4的浓度处于相对稳定状态,有利于半水脱硫石膏晶体的形核与生长。此外,Cu2+还可在晶须的生长过程中选择性吸附在晶须表面,生成CuSO4,促进了脱硫石膏的结晶生长,最终在Cu(NO3)2用量为2.0%(质量分数)时制备的脱硫石膏晶须长径比约为73。  相似文献   
137.
采用弧过滤离子沉积系统(arc filtered deposition,AFD)在纯硅表面制备铁纳米薄膜。研究了750℃下铁纳米薄膜在氢气氛围以及氨气氛围中重凝核的规律。研究表明,在氢气氛围中,铁纳米薄膜重凝核以后形成的铁纳米颗粒随薄膜的厚度增加以及保温时间的延长而增大;但在氨气氛围中,铁纳米薄膜重凝核后形成的纳米颗粒的尺寸随保温时间的变化更为复杂:在氨气作用的初始阶段,铁颗粒的尺寸随氨气作用时间的延长而逐渐变大,但一段时间以后,铁颗粒的尺寸又随氨气作用时间的延长而变小,直到铁颗粒平均直径达到一个最小值(大约在氨气介入后的12min),随后铁颗粒的尺寸又逐渐变大,并最终达到一稳定值。  相似文献   
138.
Biopolymers, especially polysaccharides (e.g., gum Arabic), are widely applied as drug carriers in drug delivery systems due to their advantages. Curcumin, with high antioxidant ability but limited solubility and bioavailability in the body, can be encapsulated in gum Arabic to improve its solubility and bioavailability. When curcumin is encapsulated in gum Arabic, it is essential to understand how it works in various conditions. As a result, in Simulated Intestinal Fluid and Simulated Gastric Fluid conditions, we investigated the potential of gum Arabic as the drug carrier of curcumin. This study was conducted by varying the gum Arabic concentrations, i.e., 5, 10, 15, 20, 30, and 40%, to encapsulate 0.1 mg/mL of curcumin. Under both conditions, the greater the gum Arabic concentration, the greater the encapsulation efficiency and antioxidant activity of curcumin, but the worse the gum Arabic loading capacity. To achieve excellent encapsulation efficiency, loading capacity, and antioxidant activity, the data advises that 10% is the best feasible gum Arabic concentration. Regarding the antioxidant activity of curcumin, the findings imply that a high concentration of gum Arabic was effective, and the Simulated Intestinal Fluid brought an excellent surrounding compared to the Simulated Gastric Fluid solution. Moreover, the gum Arabic releases curcumin faster in the Simulated Gastric Fluid condition.  相似文献   
139.
The age of information (AoI) metric was proposed to measure the freshness of messages obtained at the terminal node of a status updating system. In this paper, the AoI of a discrete time status updating system with probabilistic packet preemption is investigated by analyzing the steady state of a three-dimensional discrete stochastic process. We assume that the queue used in the system is Ber/Geo/1/2*/η, which represents that the system size is 2 and the packet in the buffer can be preempted by a fresher packet with probability η. Instead of considering the system’s AoI separately, we use a three-dimensional state vector (n,m,l) to simultaneously track the real-time changes of the AoI, the age of a packet in the server, and the age of a packet waiting in the buffer. We give the explicit expression of the system’s average AoI and show that the average AoI of the system without packet preemption is obtained by letting η=0. When η is set to 1, the mean of the AoI of the system with a Ber/Geo/1/2* queue is obtained as well. Combining the results we have obtained and comparing them with corresponding average continuous AoIs, we propose a possible relationship between the average discrete AoI with the Ber/Geo/1/c queue and the average continuous AoI with the M/M/1/c queue. For each of two extreme cases where η=0 and η=1, we also determine the stationary distribution of AoI using the probability generation function (PGF) method. The relations between the average AoI and the packet preemption probability η, as well as the AoI’s distribution curves in two extreme cases, are illustrated by numerical simulations. Notice that the probabilistic packet preemption may occur, for example, in an energy harvest (EH) node of a wireless sensor network, where the packet in the buffer can be replaced only when the node collects enough energy. In particular, to exhibit the usefulness of our idea and methods and highlight the merits of considering discrete time systems, in this paper, we provide detailed discussions showing how the results about continuous AoI are derived by analyzing the corresponding discrete time system and how the discrete age analysis is generalized to the system with multiple sources. In terms of packet service process, we also propose an idea to analyze the AoI of a system when the service time distribution is arbitrary.  相似文献   
140.
设计了江西省萍乡市兰坡村“猪-沼-粮”循环经济系统工程的流率入树模型,并利用流率入树枝向量行列式算法得到了系统的反馈环,在反馈环基础上,构造了系统增长基模,得到结论,以沼气工程(沼肥)为纽带,发展养殖业能实现生猪养殖、稻谷种植和蔬菜种植之间的良性循环,能够达到稻谷增产和收入增长,在微观层面上实现粮食安全和农民增收双赢。  相似文献   
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