Effect of Shear Rate Distribution on Particle Aggregation in a Stirred Vessel

The modeling of particle aggregation under a simple shear flow and the extension of the model to a stirred vessel is described. The model quantitatively demonstrates the change of the number of aggregates with time for each shear rate. This number increased with higher shear rate and, conversely, the aggregate size became small when raising the shear rate. This was because aggregates were broken by the stronger shear force. The number of aggregates for different impellers was determined. The shear rate was back‐calculated from the experimentally obtained aggregate size and the model equation. This shear rate was different from that estimated from the Metzner‐Otto method, consequently, some revisions of the Metzner‐Otto equation might be necessary for its application to particle aggregation.     

A classification control strategy for energy storage system in microgrid

Storage devices are indispensable elements in a microgrid to compensate for the power imbalance between loads and the distributed generator (DG) output. Different storage strategies give diverse performances in adjustment speed and capacity. Based on the performance of different storage devices and the features of power imbalance curve in different periods, a classification control strategy is proposed in this paper. First, storage devices are given priorities according to the adjusting speed, and the power imbalance curve is divided into two periods according to the changing speed. During an emergency, all the storages are employed to compensate the rapidly increasing power imbalance; during the steady period, storage device with higher priority is employed to track the instantaneous component of power imbalance, while storage device with lower priority is used to replace the kWh output of higher priority storage. The proposed strategy is tested in a microgrid within the subdistribution network of IEEE RBTS Bus6 system using Monte Carlo methods. Simulation results indicate that the classification control strategy could endow the system with fast adjusting ability through coordination between storages. Reliability indices of the testing system are utilized to demonstrate that the classification control strategy could improve the stability of the microgrid and reliability of the distribution network. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Ether lipids based on the glyceryl ether skeleton: Present state,future potential

Lipids from natural sources consist mainly of saponifiable substances, such as glycerides, along with some unsaponifiable lipids, some of which are ether lipids. Typical ether lipids are monoalkyl ethers of glycerin, also called alkyl/alkenyl glyceryl ethers. Alkyl/alkenyl glyceryl ethers have also been reported in marine organisms and in human feces. Several chemical syntheses of such ether lipids have been reported. Typical examples are alkyl glyceryl ether formation by the addition reaction of alkyl glycidyl ether and the telomerization reaction of butadiene with glycerin and a transition metal catalyst. Characteristic chemical structures, such as terpene alkyl glyceryl ethers, archaebacterial macrocyclic ether lipids, and glyceryl ethers of condensed cyclic planar molecules, have been obtained as well. Over the past few decades, industry has shown much interest in the chemistry and application of highly branched fatty acids. For example, isostearyl glyceryl ether (GE-IS) with methyl branching in the middle chain was already known, but it is now prepared at an industrial scale by proprietary alkyl glycidyl ether methods. The characteristic behavior of GE-IS toward water, such as formation of water-in-oil emulsions containing large amounts of water and of liquid crystals, has made it applicable for use in hair and skin-care cosmetics. Based on these studies and considerations, glyceryl ether lipids, which are rarely investigated, may become one of the most important and useful lipids in the industry.     

Contact and friction between catheter and blood vessel

Therapeutic vascular catheterization techniques are sometimes hampered by the frictional forces between the blood vessel and the catheter, when contact points of the vessel are changing and deforming during the movement of the catheter. The goal of the present study was to characterize frictional interactions between the blood vessel wall and the catheter using experimental and numerical analysis. First, the frictional force was measured with an experimental apparatus that uses a ball and flattened porcine aorta to simulate frictional forces between the catheter and the vessel. Second, catheter motion was characterized by two-dimensional numerical calculations based on the experimental results. Experimental analysis demonstrated that slip occurred and that friction coefficient between the vessel and the catheter and the deformation of the specimen were small when the contact between the ball and the aorta occurred at a small angle. The compliance of the specimen in the normal direction obtained by the experiment was by far larger than that calculated according to the Hertzian contact theory. Numerical analysis shows that this difference of the parameter of the vessel, which must be determined accurately in surgical simulator, could affect the trajectory of the catheter.     

On Robust Stability And Sensitivity Of Circadian Rhythms

We develop an approach to robustness analysis of circadian rhythms from the viewpoints of (local) robust stability of periodic trajectories and their period‐sensitivity, based on mathematical models. Our attention is directed to the core molecular model generating circadian rhythms in Drosophila, proposed by Goldbeter [1], for our approach to be illustrated. We consider two cases when the circadian rhythms are subjected to periodic forcing by light/dark (LD) cycles and when the circadian rhythms are under continuous darkness (DD). First, we propose conditions/algorithms for (local) robust stability, and show that the circadian rhythms generated by the core molecular model are (locally) robustly stable, in both LD and DD cases. Second, in DD case, we derive a formula of period sensitivity, and assess effects of (infinitesimal) parameter‐variations on the period of the circadian rhythms.     

Numerical prediction of sound generated from flows with a low Mach number

Numerical computations of sound generated from flows with a low Mach number are presented based on Lighthill’s acoustic analogy with an assumption that sound does not alter the flow field from which it is generated. The source fluctuations of the flow field are computed by a large-eddy simulation (LES) with Dynamic Smagorinsky Model (DSM) and they are fed to the following acoustical computation as input data. An explicit/implicit finite element method with second order accuracy both in time and space is used for flow field discretization. The method is applied to the prediction of sound in three different classes of problems: far-field sound generated from flow around a bluff body, sound resulting from blade-stator interaction of turbomachinery and sound due to a turbulent boundary layer on an aerofoil. The computed frequency spectra of the sound show a fairly good agreement with the measured spectra for all the cases.     

A 250-Mb/s/pin, 1-Gb double-data-rate SDRAM with a bidirectionaldelay and an interbank shared redundancy scheme

This paper describes three circuit technologies indispensable for high-bandwidth multibank DRAM's. (1) A clock generator based on a bidirectional delay (BDD) eliminates the output skew. The BDD measures the cycle time as the quantity charged or discharged of an analog quantity, and replicates it in the next cycle. This achieves a 0.18-mm ², two-cycle-lock clock generator operating from 25 to 167 MHz with a 30-ps resolution. (2) A quad-coupled receiver eliminates the internal skew caused by the difference between a rise input and a fall input by 40%. (3) An interbank shared redundancy scheme (ISR) with a variable unit redundancy (VUR) efficiently increases yield in multibank DRAM's. The ISR allows redundancy match circuits to be shared with two or more banks. The VUR allows the number of units replaced to be variable. These circuit technologies achieved a 250-Mb/s/pin, 8-bank, 1-Gb double-data-rate synchronous DRAM     

Magnetically Ordered State of Cold Fermions on a Decorated Square Lattice

We study two-component ultracold fermions with repulsive interactions, which are loaded into a decorated square lattice. By combining the real-space dynamical mean-field theory with the numerical renormalization group method, we discuss magnetic properties in the system. It is clarified how the ferromagnetically ordered ground state, which is stabilized by a flat band mechanism, is adiabatically connected to the ferrimagnetically ordered state expected in the strong coupling limit.     

Expression of 5-lipoxygenase and 5-lipoxygenase-activating protein mRNAs in the peripheral blood leukocytes of asthmatics

Hormone-sensitive lipase (HSL) catalyzes the rate-limiting step in adipocyte lipolysis. We have studied the effect of glucose and long chain fatty acids on the HSL mRNA content of 3T3-F442A adipocytes. Exposure of the cells for 32 h to a medium without glucose led to a decrease by a factor of 2.5-3 in the HSL mRNA without a change in C/EBP alpha mRNA or triglyceride content of the adipocytes. The reduction in HSL mRNA level was accompanied by a decrease in HSL total activity. The effect of glucose exposure was observed after 24 h of exposure and was reversible. Treatment of the adipocytes with oleate did not affect HSL expression. These data show that glucose modulates HSL gene expression and hence could participate in the regulation of adipose tissue lipolysis.