Time to live of identifier‐to‐locator mappings: with‐reset or no‐reset

In networks with identifier/locator separation, border routers often cache recently used identifier‐to‐locator mappings of remote hosts and set a time to live (TTL) for each mapping. We consider two options to update the TTL of a mapping, designated as no‐reset (NR) and with‐reset (WR) modes. In the NR mode, once a mapping is cached, its TTL is set to a default value called cache timeout, and the mapping is removed when the TTL expires. By contrast, in the WR mode, whenever the mapping is queried, its TTL is reset to the cache timeout. Although it is not difficult to intuitively observe that the WR mode performs better than the NR mode in terms of cache hit rate, it is still of interest to evaluate what is the benefit gained by using the WR mode rather than the NR mode and what is the cost incurred to achieve this gain. Another equivalent question is what is the additional cost incurred in terms of resources for the NR mode to perform similarly to the WR mode. We model the cache hit rate and compare the performance of the WR and NR modes for flat and aggregatable identifiers by analysis and simulation, and estimate how much more cache size the NR mode requires to achieve similar cache hit rate and communication interruptions to the WR mode. The comparison results provide rational to use the WR mode, rather than the NR mode, for identifier‐to‐locator mapping caches. Copyright © 2012 John Wiley & Sons, Ltd.     

高架桥,拆除还是保留?

目前在中国的规划理论界有一种声音,认为高架桥是城市发展的一个过程产物,它终将被拆除和消失,并以清溪川复原工程等案例作为这一结论的佐证。同时,在美国纽约的高线公园案例中,出现了另一种对待废弃高架桥的方式,保留高架桥作为步行公园使用,而不是单纯暴力地拆除。在案例研究的基础上,作者尝试提出了五个方面的因素,希望可以作为未来高架桥发展的参考与借鉴。     

莲子中不同蛋白的结构及理化特性对比分析

该研究分别制备了莲子分离蛋白与莲子分级蛋白（清蛋白、球蛋白、醇溶蛋白、谷蛋白）,并对比研究了不同莲子蛋白的溶解性、乳化性、分子特性等结构变化。研究结果表明,莲子中蛋白质约占干基总量的16.14%,4种分级蛋白所占比例依次约为55:6:0.1:25。对比5种不同莲子蛋白,清蛋白溶解性最高,Zeta电位最低值为-21.3 mV,粒径最小值为75.47 μm,分离蛋白乳化性最好,五种不同蛋白的等电点均在4.9附近。光谱研究表明,醇溶蛋白和谷蛋白荧光更强,清蛋白和球蛋白α-螺旋含量更低,醇溶蛋白和谷蛋白β-转角含量更高。光谱研究表明,分离蛋白、清蛋白（球蛋白）的波长蓝移,清蛋白和球蛋白的α-螺旋含量更低,且α-螺旋、β-折叠、β-转角含量也发生不同变化。这些研究结果也表明清蛋白和球蛋白分子柔性相对更高,与其溶解性、乳化性、疏水性密切相关。通过实验有助于揭示莲子分离蛋白和分级蛋白理化特性与分子结构间的构效关系,并为深入研究莲子蛋白的功能特性提供理论依据。     

Empagliflozin Treatment Attenuates Hepatic Steatosis by Promoting White Adipose Expansion in Obese TallyHo Mice

Sodium-glucose co-transporters (SGLTs) serve to reabsorb glucose in the kidney. Recently, these transporters, mainly SGLT2, have emerged as new therapeutic targets for patients with diabetes and kidney disease; by inhibiting glucose reabsorption, they promote glycosuria, weight loss, and improve glucose tolerance. They have also been linked to cardiac protection and mitigation of liver injury. However, to date, the mechanism(s) by which SGLT2 inhibition promotes systemic improvements is not fully appreciated. Using an obese TallyHo mouse model which recapitulates the human condition of diabetes and nonalcoholic fatty liver disease (NAFLD), we sought to determine how modulation of renal glucose handling impacts liver structure and function. Apart from an attenuation of hyperglycemia, Empagliflozin was found to decrease circulating triglycerides and lipid accumulation in the liver in male TallyHo mice. This correlated with lowered hepatic cholesterol esters. Using in vivo MRI analysis, we further determined that the reduction in hepatic steatosis in male TallyHo mice was associated with an increase in nuchal white fat indicative of “healthy adipose expansion”. Notably, this whitening of the adipose came at the expense of brown adipose tissue. Collectively, these data indicate that the modulation of renal glucose handling has systemic effects and may be useful as a treatment option for NAFLD and steatohepatitis.     

75 m/s simulation and experiment of two-stage reluctance coilgun

Magnetic launchers are divided into three main techniques, with one of them being the reluctance coilgun. The projectile in this method is rather simple and the obtained velocity is relatively low, which is its main disadvantage. Also, theoretical simulations for high velocity usually predict much higher velocities than that of the experiments. The aim of this work is to demonstrate an accurate simulation of a two-stage coilgun and show experimental validation of high launching velocity. A two-stage coilgun was designed and optimized by numerical simulations. Accordingly, it was implemented and tested experimentally. As an outcome, the highest reported velocity of 75 m/s was obtained both in the simulation and experiment. This outcome contributes to the understanding that adding stages can increase the launching velocity by carefull implementation of the initial position of the projectile, together with proper timing of the second stage. It is concluded that with this approach a multi-stage coilgun can reach even higher velocity.

     

Obtaining small photovoltaic array operational curves for arbitrary cell temperatures and solar irradiation densities from standard conditions data

The paper presents a simple approach to deriving I–V curves of photovoltaic panels and small arrays for arbitrary environmental conditions on the basis of three points of a single operating curve data and short current temperature coefficient only. The proposed method does not employ fitting of any type and is solely based on a numerical solution of a system of transcendental equations. The equations are expressed in a dimensionless form, simplifying both the solution and photovoltaic panel parameters' representation. The solution is used to find the values of normalized equivalent circuit elements for the available data and then perform an appropriate adjustment to obtain the operating curves for arbitrary conditions. The proposed method was applied to monocrystalline and polycrystalline commercial solar panels and was compared with both manufacturer‐provided and experimentally measured operating curves to analyze the approach applicability and accuracy. Copyright © 2012 John Wiley & Sons, Ltd.     

Classification of spatio-temporal patterns in charging and discharging of Li-ion batteries

We classify the dynamic patterns that emerge in charging or discharging of Li-ion batteries, under galvanostatic conditions, using simulations of the two-phase one-dimensional (1D) porous electrode model. This work examines the effect of the exchange current function, R₀(X), which expresses the nature of kinetics. This extends our previous study with R₀ = 1 where the same pattern emerges in charging or discharging, whether as a homogeneous or a step-wise process made of multiple symmetry breaking events. With commonly-used asymmetric R₀(X), the emerging patterns may be one of the two above or as fronts that follow single SB event and the lithiation/delithiation behaviors are different. These effects are clear when parameters are uniform; nonuniformity leads to noise that mask the behavior. The full four-variable model exhibits SB, even in absence of noise, since the liquid potential gradient (${\varphi }_l$) works like a perturbation. This similarity allows us to derive approximations to the full model behavior.     

Particulate multi‐phase polymeric nanocomposites

The present research focuses on a model system of a blend of two immiscible polymers containing an inorganic nanofiller, exploring the effect of various melt processing procedures on structuring and on the resulting properties. Binary polypropylene/alumina and ternary polypropylene/nylon/alumina composites were produced by batch compounding under various processing conditions and compositions. Several types of polypropylene and alumina grades were examined. The alumina nanoparticles vary primarily in their mean particle size (13, 50, 500 nm). The morphology of the nanocomposites produced and their thermal, and rheological properties were studied. It was found that under certain processing conditions the nanoparticles significantly affect the morphology of the polypropylene/nylon polymer blend causing compatibilization. Also, the alumina nanoparticles affect the melt viscosity of the polypropylene/nylon blends, whereas their effect on either polypropylene or nylon melts was found insignificant. POLYM. COMPOS., 27:425–430, 2006. © 2006 Society of Plastics Engineers