Preventing TCP performance interference on asymmetric links using ACKs-first variable-size queuing

In developing network-enabled embedded systems, developers are often forced to spend a great deal of time and effort analyzing and solving network performance problems. In this paper, we address one such problem: TCP performance interference on an asymmetric link. The upload or download throughput abruptly degrades if there is simultaneously upload and download TCP traffic on the link. While the problem has been addressed by many researchers, their solutions are incomplete as they only improve throughput in one direction, require TCP protocol modifications in end-user devices or are effective for a limited range of network configurations.In order to overcome such limitations, we propose ACKs-first variable-size queuing (AFVQ) for a gateway. In doing so, we have derived an analytic model of the steady-state TCP performance with bidirectional traffic to clearly identify the two sources of the problem: the excessive queuing delay of ACK packets and the excessive number of ACK packets in the queue. Our AFVQ mechanism is designed to directly eliminate the two causes. Specifically, we have based AFVQ on two policies. First, ACKs-first scheduling is used to shorten the queuing delay of ACK packets. Second, the queue size for ACK packets is dynamically adjusted depending on the number of data packets queued in the gateway so that the number of ACK packets is reduced when packets are congested in the gateway. By applying the two policies simultaneously at the uplink and downlink output queue in the gateway, AFVQ achieves balanced TCP throughput improvements in both directions. In this way, it breaks circular dependencies between upload and download traffic.We have implemented AFVQ in our ADSL-based residential gateway using the traffic control module of the Linux kernel. Our gateway yields 95.2% and 93.8% of the maximum download and upload bandwidth, respectively. We have also evaluated the proposed mechanism using the ns-2 simulator over a wide range of network configurations and have shown that AFVQ achieves better upload and download throughput than other representative gateway-based mechanisms such as ACQ, ACKs-first scheduling and ACK Filtering.     

Single-atom Pd catalyst anchored on Zr-based metal-organic polyhedra for Suzuki-Miyaura cross coupling reactions in aqueous media

The challenge for single-atom catalysts in various C-C cross coupling reaction exists in the development of solid supporting materials.It has been desired tofind a supporting material designed in molecular level to anchor a single-atom catalyst and provide high degree of dispersion and substrate access in aqueous media.Here,we prepared discrete cages of metal-organic polyhedra anchoring single Pd atom(MOP-BPY(Pd))and successfully performed a Suzuki-Miyaura cross coupling reaction with various substrates in aqueous media.It was revealed that each tetrahedral cage of MOP-BPY(Pd)has 4.5 Pd atoms on average and retained its high degree of dispersion up to 3 months in water.The coupling efficiencies of the Suzuki-Miyaura cross coupling reaction exhibited more than 90.0%for various substrates we have tested in the aqueous media,which is superior to those of the molecular Pd complex and metal-organic framework(MOF)anchoring Pd atoms.Moreover,MOP-BPY(Pd)was successfully recovered and recycled without performance degradation.     

English course E-learning system based on relative item difficulty using web component composition

Many researches about e-learning system have been applied item difficulty to increase learning effectiveness. And development environment was changed the internet based learning media contents into the more various technology such as component, web 2.0, service oriented development and so on. Especially, service-oriented development is one of new trend in web based system and has become mainstream in software development. In the development, web components aims at providing support to service-oriented technique by enabling automatic discovery, composition, invocation and interoperation of the services. In this paper, we aimed the implementation of English e-learning system including the item guessing parameter and considering the relative correction of item difficulty. In the system, a learner was given to choose the learning step by the relative difficulty. In order to process and combine, all the learning contents are based on Sharable Content Object Reference Model (SCORM) with Learning Management System (LMS). Also, each learning contents are belong to Sharable Content Objects (SCOs).     

Effect of grinding aids on the kinetics of fine grinding energy consumed of calcite powders by a stirred ball mill

An experimental investigation was carried out on the ultra-fine grinding of inorganic powders using a stirred ball mill. The power consumed in the grinding process was measured, and the comminution coefficient, K, in the grinding kinetics equation was examined, based on an analysis of the relationship between the experimental specific surface area and the particle-size distribution of ground products. The effect of grinding aids on the comminution coefficient, K, was also investigated. It was demonstrated that the grinding rate for calcite could be improved by the addition of grinding aids. When using grinding aids, K improved by 16.0% and 34.2% for 60 wt% and 70 wt% slurry concentrations, respectively. Thus grinding aids are very effective in the submicron range grinding process.     

Compiling real-time programs with timing constraint refinement andstructural code motion

We present a programming language called TCEL (Time-Constrained Event Language), whose semantics are based on time-constrained relationships between observable events. Such a semantics infers only those timing constraints necessary to achieve real-time correctness, without overconstraining the system. Moreover, an optimizing compiler can exploit this looser semantics to help tune the code, so that its worst-case execution time is consistent with its real-time requirements. In this paper we describe such a transformation system, which works in two phases. First, the TCEL source code is translated into an intermediate representation. Then an instruction-scheduling algorithm rearranges selected unobservable operations and synthesizes tasks guaranteed to respect the original event-based constraints     

Far-infrared drying characteristics and quality assessment of Ligularia fischeri

The purpose of this study was to investigate drying models and drying characteristics of Ligularia fischeri by using far-infrared drying. The far-infrared drying tests on L. fischeri were performed at air velocities of 0.6 and 0.8 m/s, and drying chamber temperatures of 40, 45, and 50°C. Four thin layer drying models were used to estimate drying curves. Drying characteristics were analyzed on the basis of drying rate, color, antioxidant activity, and contents of polyphenolics and flavonoids. The goodness of the models was estimated using the coefficient of determination, the root mean square error, and the reduced chi-square. The results revealed that increases in drying temperature and air velocity caused a decrease in drying time. The Page and Thompson models were considered suitable for the far-infrared drying of L. fischeri. After drying, the antioxidant properties of L. fischeri were decreased under all drying conditions.

     

Analysis of Grinding Rate Constant on a Stirred Ball Mill Using Discrete Element Method Simulation

The results of discrete element method simulation were compared with actual grinding experimental results. The grinding rate constant K can be expressed as K = a exp( bn ), where n is the rotation speed. To investigate the correlation between K and the simulation results, a new factor, the calculated force, was defined as F _cal=average force acting on a ball coordination number. K could then be expressed as K = a ' F _cal+ b ' and is thus one-dimensionally proportional to F _cal K was found to be correlated with the forces acting on a ball and its contact points. Experimental results confirmed that F _cal is suitable for use as a factor for expression of K .     

Intra-task voltage scheduling for low-energy hard real-timeapplications

A novel intra-task voltage-scheduling algorithm controls the supply voltage within an individual task boundary. By fully exploiting slack time, it achieves a high-energy reduction ratio. Using this algorithm, a software tool automatically converts an application into a low energy version     

An efficient VLSI implementation of H.264/AVC entropy decoder

<正>This paper proposes an efficient H.264/AVC entropy decoder.It requires no ROM/RAM fabrication process that decreases fabrication cost and increases operation speed.It was achieved by optimizing lookup tables and internal buffers,which significantly improves area,speed,and power.The proposed entropy decoder does not exploit embedded processor for bitstream manipulation, which also improves area,speed,and power.Its gate counts and maximum operation frequency are 77515 gates and 175MHz in 0.18um fabrication process,respectively.The proposed entropy decoder needs 2303 cycles in average for one macroblock decoding.It can run at 28MHz to meet the real-time processing requirement for CIF format video decoding on mobile applications.     

Differential Expressions of G0/G1 Switch Gene 2 and Comparative Gene Identification-58 are Associated with Fat Content in Bovine Muscle

Regulation of lipolysis in muscle is a potential mechanism affecting marbling in beef carcasses and fat accumulation in muscles of humans, which is a known risk factor for type 2 diabetes. Adipose triglyceride lipase-mediated lipolysis is inhibited by G0/G1 switch gene 2 (G0S2) and co-activated by comparative gene identification-58 (CGI-58). In this study, bovine G0S2 and CGI-58 were sequenced, and expressions of these genes were compared among various tissues and in muscles between bulls and steers with different degrees of marbling. The protein coding sequences of bovine G0S2 and CGI-58 revealed breed-specific SNPs, causing two amino acid variations for each protein. Bovine CGI-58 mRNA showed two isoforms from alternative splicing. The G0S2 gene was preferentially expressed in fat and, to a lesser degree, in the liver; whereas, CGI-58 was highly expressed in the muscle and fat (P < 0.05), suggesting their association with lipid metabolism in those tissues. The longissimus dorsi muscle (LM) of steers showed higher FABP4, G0S2 and CGI-58 mRNA expression levels than the LM of bulls, implying the roles of those genes more in marbling of steers than in that of bulls. The G0S2 expression was markedly higher in the intramuscular fat (IMF) (P < 0.001); whereas, the CGI-58 expression was significantly higher in the pure muscle portion of the LM of steers (P < 0.01), suggesting that G0S2 and CGI-58 may regulate IMF and intramyocellular triglycerides, respectively. Taken together, our data suggest that G0S2 and CGI-58 are associated with fat content in bovine species.