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Ahstract- With the rapid development of network equipment, single-port capacity becomes larger. The traditional Quality of Service applications based on single level queue and single level port become the bottleneck of the development of Software Defined Network switching equipment. Therefore, a five-level queue scheduling model based on Software Defined Network is proposed. Through five-level pipeline scheduling, this model can reduce the number of queue which every level scheduler maintenance. By choosing the appropriate scheduling algorithm and flow control algorithm, the multiple users, various flows and different types of network traffic can be uniformly managed and hierarchically scheduled. The simulation result shows that the five-level queue scheduling model reduces the weighted packet loss rate on the premise of guaranteeing the output bandwidth. It can support multiple types of traffic scheduling and flow control, and can ensure the Quality of Service of different business to some extent.

Burst traffic is a common traffic pattern in modern communication networks, and this traffic is the main cause of the unfairness problem in shared memory switch. In this paper, a shared-private buffer management (SPBM) scheme is proposed, which can efficiently utilize the switch buffer and reduce overall packet loss rate under burst traffic. The key idea of SPBM is to partition the total memory space into shared area and private area. Each output port has a private memory area that cannot be used by other ports. The shared area is completely shared among all output ports. A theoretical queuing model of the proposed scheme is formulated and closed-form formula for the overall packet loss rate is derived. By analyzing the numerical results, the optimal partition of the switch buffer is obtained. Besides, simulation result shows that the proposed scheme can reduce the overall packet loss rate by about 20% on average compared with existing buffer management schemes.

The OpenFlow protocol specifies a variety of match fields, including exact fields, prefix fields, and range fields. Existing hardware-implemented packet classification causes prefix expansion when searching for a range field, resulting in large memory requirement. In order to reduce the cost and energy consumption, the high speed packet classification supporting multi-field for flow tables in OpenFlow is proposed. The solution is based on bit-vector method. Firstly, divide fields into two groups according to the matching type of fields. Then, select suitable matching methods for each match field to get intermediate results. Finally, a bit-wise logical AND operation among all intermediate results is performed to get the final matching result. The hardware implementation structure is a two-dimensional pipeline structure. According to theoretical analysis and simulation results, the solution can sustain a throughput of 100 Gigabit Per Second (Gbps).

IEEE 1588 is a standard for a precision clock synchronization protocol for networked measurement and control systems. IEEE 1588 protocol can provide sub-microsecond accuracy. However, most synchronous systems generate timestamps using software-generated methods or proprietary chips. Thus, the accuracy and portability of synchronous systems cannot be balanced. Based on the analysis of IEEE 1588 standard and current Ethernet time synchronization scheme, this study presented a scheme using FPGA and ARM. In order to improve the universality and portability of synchronous system, this research adopted the method of generating hardware timestamps in Media Access Control(MAC) layer. Verified by experiment in Gigabit Ethernet environments, this design is correct and the marking accuracy is better than 20ns. The portability of synchronous system is improved on the premise of ensuring the accuracy of synchronization.

Network flow classification is a key function in high-speed switches and routers. It directly determines the performance of network devices. With the development of the Internet and various kinds of applications, the flow classification needs to support multi-dimensional fields, large rule sets, and sustain a high throughput. Software-based classification cannot meet the performance requirement as high as 100 Gbps. FPGA-based flow classification methods can achieve a very high throughput. However, the range matching is still challenging. For this, this paper proposes a range supported bit vector (RSBV) method. First, the characteristic of range matching is analyzed, then the rules are pre-encoded and stored in memory. Second, the fields of an input packet header are used as addresses to read the memory, and the result of range matching is derived through pipelined Boolean operations. On this basis, bit vector for any types of fields (AFBV) is further proposed, which supports the flow classification for multi-dimensional fields efficiently, including exact matching, longest prefix matching, range matching, and arbitrary wildcard matching. The proposed methods are implemented in FPGA platform. Through a two-dimensional pipeline architecture, the AFBV can operate at a high clock frequency and can achieve a processing speed of more than 100 Gbps. Simulation results show that for a rule set of 512-bit width and 1[Formula: see text]k rules, the AFBV can achieve a throughput of 520 million packets per second (MPPS). The performance is improved by 44% compared with FSBV and 30% compared with Stride BV. The power consumption is reduced by about 43% compared with TCAM solution.

A contracted ring degradation product, WYE-120318 (compound 2), was discovered during the development phase for methylnaltrexone bromide (compound 1) drug substance. The compound was isolated by high-performance liquid chromatography fractionation, and its structure was determined by spectroscopic data analyses. WYE-120318 is formed from methylnaltrexone through a benzyl-benzilic acid type rearrangement reaction to yield an α-hydroxy-cyclopentanecarboxylic acid substructure. The proposed structure and the formation mechanism are confirmed by the synthesis of WYE-120318 from methylnaltrexone (compound 1). A similar benzyl-benzilic acid type rearrangement reaction can be envisioned as the biological origin of remisporine A (compound 3), a naturally occurring cyclopentadienyl compound that autocatalytically dimerizes to remisporine B (compound 4). The structure of remisporine A was deduced from its dimer 4. Coniothyione (compound 5) can be considered as the first example of a stable natural product bearing the remisporine A skeleton. However, the regiochemistry of the chlorosubstitution in the coniothyrione structure needs to be revised to compound 6 on the basis of the nuclear magnetic resonance data and biogenesis analysis. Copyright © 2012 John Wiley & Sons, Ltd.

Differential reactivity of the amine functionality in a number of common 1,2-diamine starting materials is exploited to undertake an expedient synthesis of unsymmetrical 2,3,6-trisubstituted quinoxaline and unsymmetrical 2,3,7-trisubstituted pyridopyrazine derivatives.

An improved route for the preparation of highly functionalized 5,6‐dihydro‐pyrimido[4,5‐b][1,4]oxazepine 1a in multigram quantities was developed. This new methodology was highlighted by the proper methoxy disposition via a regioselective methylation of 2,4,5‐trihydroxy‐benzaldehyde followed by a magnesium sulfate–promoted cyclization.

Novel synthetic approaches toward 5,6-dihydro-pyrimido[4,5-b][1,4]oxazepines were reported that led to successful introduction of poorly reactive anilines and various 2-hydroxybenzaldehydes to this therapeutically relevant scaffold. More extensive SAR studies on this scaffold hence became possible.

[reaction: see text] The geometrical isomers of 6-ethylidenedioxadisilacyclohexane were prepared by intramolecular hydrosilylation of an unsymmetrical disiloxane by the use of Pt (syn) and Ru (anti) catalysts. This new class organosilicon reagents underwent cross-coupling reactions with a range of aryl iodides to afford (E)- and (Z)-trisubstituted allylic alcohols in a highly stereospecific fashion.

Highly substituted alkenylsilanols (1), readily prepared from commercially available simple starting materials, are efficiently coupled with aryl or alkenyl halides in the presence of tetrabutylammonium fluoride (TBAF) and a palladium(0) catalyst. Yields are generally high and the reactions are highly stereoselective and compatible with a wide range of functional groups.

The formation mechanism of TiC particles in a Ni-Ti-C system were revealed by using differential thermal analysis (DTA), XRD, and SEM to identify the reaction products in different temperature ranges. The results indicated that the synthesis mechanism of TiC in Ni-Ti-C system was complex; several reactions were involved in the combustion synthesis of TiC-Ni composite. The Ni-Ti intermediate phases play important roles during the formation of TiC. Moreover, the influence of heating rate on the size range of TiC was also discussed.

Cyclohept-1-en-3-yne rearranges thermally to toluene via cycloheptatriene, and to a mixture of 1- and 2-vinylcyclopentadiene an intermediate allene, 1-ethenylidenecyclo-2-pentene.

The benzophenone-photosensitized decomposition of ethyl diazomalonate in 1,3-cyclooctadiene led to trans -bicyclo[6.1.0]non- cis -2-ene, a new strained ring system. The function of the photosensitizer is to convert Z,Z -1,3-cyclooctadiene into the E,Z -isomer.

Almost thirty years after the first (and only) description of 1,4-addition of a carbene to cyclooctatetraene, we report that direct photolysis of ethyl diazomalonate in cyclooctatetraene leads to 13% of the product of 1,4-addition. When the decomposition of the diazo compound is photosensitized by benzophenone, 1,4-addition becomes virtually the sole reaction pathway.

Generation of benzocyclohex-1-en-3-yne in two ways leads to naphthalene and methyleneindene (benzofulvene). Labeling studies favor a multistep mechanism involving an initial electrocyclic ring opening, and carbene−alkene interconversions.

Photolysis of naphtho[b]cyclopropene in hydrocarbons leads to products derived from hydrogen abstraction by a diradical. Photolysis in a cryogenic matrix allows ESR detection of this diradical, which has zero field spliting parameters D/hc = 0.057, E/hc −1 .

The reaction of atomic carbon with N-methylpyrrole, 5b, at 77 K generates the N-methyl-3-dehydropyridinium ylid, 6b, which can be trapped with added hydrogen halides or CO2. The addition of CO2 is strong evidence for the ylid 6b rather than cumulene 7. Deuterium and 13C labeling studies demonstrate that 6b rapidly rearranges to the N-methyl-2-dehydropyridinium ylid, 13, by an intermolecular mechanism. Ylid 13 can be trapped with added acids or with O2 to form 1-methyl-2-pyridone.

Thermolysis of ethynyl(phenyl)iodonium triflate, 1, in the presence of cyclooctatetraene generates naphthalene in a reaction involving free C2 or in which 1 acts as a C2 donor.

The union of HCV-796, a potent selective HCV NS5B polymerase inhibitor, and Ribavirin, a molecule with activities against a wide spectrum of viruses, resulted in a class of new anti-HCV agents with a sequential triple inhibitory mechanism.

Highly substituted alkenylsilanols (1), readily prepared from commercially available simple starting materials, are efficiently coupled with aryl or alkenyl halides in the presence of tetrabutylammonium fluoride (TBAF) and a palladium(0) catalyst. Yields are generally high and the reactions are highly stereoselective and compatible with a wide range of functional groups.

In this paper, a simple delay model for manual analysis of DCVSPG logic is built to evaluate the delay of the circuit. The delay obtained by the model is very close to that obtained by HSPICE Also the model can be used to optimize the size of NMOS transistors in DCVSPG logic under specific constraints. At last, the technique how to use this model is displayed1.

A novel class of pyrimido[4,5-b]-1,4-benzoxazepines is described as inhibitors of epidermal growth factor receptor (EGFR) tyrosine kinase. Two compounds display potent EGFR inhibitory activity of less than 1 microM in cellular phosphorylation assays (IC(50) 0.47-0.69 microM) and are highly selective against a small kinase panel. Such compounds demonstrate anti-EGFR activity within a class that is different from any known EGFR inhibitor scaffolds. They also provide a basis for the design of kinase inhibitors with the desired selectivity profile.

Pyrimido-oxazepine based sub-micromolar inhibitors (2–4) for Aurora and FLT-3 were designed and synthesized. These preliminary results supported the potential use of pyrimido-oxazepines as a versatile template for developing specific kinase inhibitors.

A novel class of N-(4-{[4-(1H-benzoimidazol-2-yl)-arylamino]-methyl}-phenyl)-benzamides are described as inhibitors of the endo-beta-glucuronidase heparanase. Among them are N-(4-{[4-(1H-benzoimidazol-2-yl)-phenylamino]-methyl}-phenyl)-3-bromo-4-methoxy-benzamide (15h), and N-(4-{[5-(1H-benzoimidazol-2-yl)-pyridin-2-ylamino]-methyl}- phenyl)-3-bromo-4-methoxy-benzamide (23) which displayed good heparanase inhibitory activity (IC(50) 0.23-0.29 microM), with the latter showing oral exposure in mice.

A novel class of 1-[4-(1H-benzoimidazol-2-yl)-phenyl]-3-[4-(1H-benzoimidazol-2-yl)-phenyl]-ureas are described as potent inhibitors of heparanase. Among them are 1,3-bis-[4-(1H-benzoimidazol-2-yl)-phenyl]-urea (7a) and 1,3-bis-[4-(5,6-dimethyl-1H-benzoimidazol-2-yl)-phenyl]-urea (7d), which displayed good heparanase inhibitory activity (IC(50) 0.075-0.27 microM). Compound 7a showed good efficacy in a B16 metastasis model.

A highly regio- and stereoselective anti-intramolecular hydrosilylation of alkynyl silyl ethers catalyzed by a ruthenium arene complex has been developed. The resultant (Z)-alkylidenesilacyclopentanes are efficiently coupled with aryl or alkenyl halides in the presence of tetrabutylammonium fluoride and a palladium(0) catalyst. The yields are generally good, and the reaction is compatible with a wide range of functional groups. The overall transformation achieves the stereoselective conversion of homopropargyl alcohols to trisubstituted homoallylic alcohols. [reaction: see text]

[figure: see text] Alkylidenesilacyclopentanes (formed by intramolecular hydrosilylation of homopropargyl alcohols) are efficiently coupled with aryl or alkenyl halides in the presence of tetrabutylammonium fluoride and a palladium(0) catalyst. Yields of cross-coupling were generally high, and the reaction is compatible with a wide range of functional groups. The overall transformation achieves the conversion of homopropargyl alcohols to trisubstituted homoallylic alcohols in a highly stereoselective fashion.

Alkylidenesilacyclopentanes (formed by intramolecular hydrosilylation of homopropargyl alcohols) are efficiently coupled with aryl or alkenyl halides in the presence of tetrabutylammonium fluoride and a palladium(0) catalyst. Yields of cross-coupling were generally high, and the reaction is compatible with a wide range of functional groups. The overall transformation achieves the conversion of homopropargyl alcohols to trisubstituted homoallylic alcohols in a highly stereoselective fashion.

Thermolysis of ethynyl(phenyl)iodonium triflate, 1, in the presence of cyclooctatetraene generates naphthalene in a reaction involving free C2 or in which 1 acts as a C2 donor.