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Let δ be a (d-1)-dimensional simplicial complex and let h(δ)=(h0,h1,...,hd) be its h-vector. A recent result of Murai and Terai guarantees that if δ satisfies Serre's condition (Sr), then (h0,h1,...,hr) is an M-vector and hr+hr+1+...+hd is nonnegative. In this article, we extend the result of Murai and Terai by giving r extra necessary conditions. More precisely, we prove that if δ satisfies Serre's condition (Sr), then iihr+i+1ihr+1+...+i+d-rihd, 0≤i≤r≤d, are all nonnegative  

The one-pot synthesis of several secondary amines and secondary amino esters are reported. Treatment of aldehydes (aliphatic or aromatic) with (trimethylsilyl)alkylamines, in the presence of 5 M lithium perchlorate in diethyl ether gives intermediate imines. Reaction of these intermediate imines with different nucleophiles and functionalized organozinc reagents, BrZnCH2COOR, produce a variety of secondary amines and N-alkyl- or N-arylamino esters in good yields. © 2001 Elsevier Science Ltd. All rights reserved  

Malaysian secondary schools are facing a shortage of male teachers. Almost 70% of the teaching profession is dominated by female teachers. There is an obvious gap in the reason why teaching is not preferred by the male gender. This study intends to find the determinants of career success among male teachers with the hope of revealing the career success factors that are associated with male teachers. A survey was done among 140 male teachers in secondary schools in the state of Malacca, Malaysia. Results showed that 4out of 5 of the determinants factors are significantly explaining career success among the teachers (Emotional Intelligence, Person-Job-Fit, Career Adaptability & Work-Life... 

In this investigation, changes in γ′ characteristics in superalloy IN-738LC during aging are presented. The SEM studies revealed that coarsening kinetics of γ′ follows a linear law at different aging time for different temperatures. Whereas when coarsening of secondary γ′ is studied, it was found that at the early stage of aging, volume fraction of secondary γ′ is high, leading to short inter-particle distances. In this condition interfacial energy is dominant and variation of [r3-r03] as a function of aging time is linear. As the coarsening proceeds, volume fraction of secondary γ′ decreases and elastic interaction energy becomes dominant. In such case a deviation in variation of [r3-r03]... 

Let G be a group of invertible linear transformations on a finite-dimensional vector space over an algebraically closed field. We show that if G = H V K, where H is a normal subgroup consisting of singleton spectrum operators and K is a triangularizable subgroup, then G is triangularizable  

Mixing is an essential operation in many microfluidic devices. Droplet-based micromixers utilize droplets for mixing enhancement. In the present study, a novel three-dimensional simulation is conducted which has the ability to capture not only the mixing process, but also the chemical reactions inside liquid droplets. This two-phase model is used for simulating the reacting flow inside a serpentine microchannel and explores the effects of droplet size and reaction rate on the production and consumption of species in droplets. It is observed that the chemical reaction in each droplet, begins from its front area. Furthermore, it is shown that the production of species does not depend on water... 

This article aims to present a geometric interpretation of the simplicity of the rotation group of three-dimensional Euclidean space. Some historical remarks on the subject and an overview of a collection of different proofs of this result are also given  

Aryl schiff bases were efficiently reduced to the corresponding secondry amines by triethylammonium formate/formic acid system under microwave irradiation in solvent-free condition  

The dependency of amino acid chemical shifts on φ and ψ torsion angle is, independently, studied using a five-residue fragment of ubiquitin and ONIOM(DFT:HF) approach. The variation of absolute deviation of 13Cα chemical shifts relative to φ dihedral angle is specifically dependent on secondary structure of protein not on amino acid type and fragment sequence. This dependency is observed neither on any of 13Cβ, and 1Hα chemical shifts nor on the variation of absolute deviation of 13Cα chemical shifts relative to ψ dihedral angle. The 13Cα absolute deviation chemical shifts (ADCC) plots are found as a suitable and simple tool to predict secondary structure of protein with no requirement of... 

In an ac microgrid, a common frequency exists for coordinating active power sharing among droop-controlled sources. A common frequency is absent in a dc microgrid, leaving only the dc source voltages for coordinating active power sharing. That causes sharing error and poorer voltage regulation in dc microgrids, which in most cases, are solved by a secondary control layer reinforced by an extensive communication network. To avoid such an infrastructure and its accompanied complications, this paper proposes an alternative droop scheme for low-voltage dc microgrid with both primary power sharing and secondary voltage regulation merged. The main idea is to introduce a non-zero unifying frequency... 

In this paper, we study the impact of sensing error and channel fading on the decision process of a multiple secondary user network in a primary network whose channel occupancy states are modelled as a Bernoulli process. We present a randomized access strategy to maximize total secondary network throughput. The proposed method guarantees that the probability of collision between primary and secondary users in each channel is less than the predefined value of P c = ξ. To find the optimal access strategy, we formulate secondary network throughput as an optimization problem. Then, using the KKT method to find the solution, we break the original problem into multiple sub-problems. Then, we... 

Lysozyme loaded niosomes containing various molar ratios of two kinds of surfactants were prepared and the properties of these niosomal formulations were studied. The results revealed that the size of niosomes varied between 240.06 ± 32.41 and 895.2 ± 20.84 nm. Formulations with the lowest size and no precipitation had entrapment efficiencies ranging from 60.644 ± 3.310 to 66.333 ± 1.98%. Their controlled release profiles after 48 h were 15.67, 20.67 and 31.50%. After 2 months, the most stable formulation in terms of size, PDI, zeta potential, and entrapment efficiency was used to study the secondary structures of lysozyme in niosomal and free forms. Lysozyme loaded niosome and lysozyme... 

The feasibility of using fluidic thrust-vectoring system, as a control technique for the longitudinal and lateral trim purpose was investigated in this study. For this purpose, integration of a Co-flow method into the propulsion unit of a conceptual aerial vehicle was assumed. The focus of the research presented was to estimate the required thrust vector angle in order to trim the aerial vehicle in different flight phases. Since the fluidic thrust vectoring requires secondary air flow to deflect the engine exhaust gas, this research also provides an analytical toolset for preliminary sizing of a suitable secondary air supply. It was found that thrust vectoring could be an effective mean of... 

In this paper, we study the impact of sensing error and channel fading on the decision process of a multiple secondary user network in a primary network whose channel occupancy states are modelled as a Bernoulli process. We present a randomized access strategy to maximize total secondary network throughput. The proposed method guarantees that the probability of collision between primary and secondary users in each channel is less than the predefined value of Pc = ξ. To find the optimal access strategy, we formulate secondary network throughput as an optimization problem. Then, using the KKT method to find the solution, we break the original problem into multiple sub-problems. Then, we employ... 

Because of the advances in power electronics, DC-based power systems, have been used in industrial applications such as data centers [. 18], space applications [. 10], aircraft [. 12], offshore wind farms, electric vehicles [. 56], DC home systems [. 5, 20], and high-voltage DC transmission systems. To provide such sensitive loads with more reliability, efficiency, and controllability for future power systems, AC microgrid and more recently DC microgrid and smart-grid technologies have been employed [. 5-9].To obtain stable and optimal operation in DC power systems (microgrids), proper load sharing among different energy units and acceptable voltage regulation across the microgrid is... 

In this paper, a 2D shuffle-exchange based mesh topology, or 2D SEM (Shuffle-exchange Mesh) for short, is presented for network-on-chips. The proposed two-dimensional topology applies the conventional well-known shuffle-exchange structure in each row and each column of the network. Compared to an equal sized mesh which is the most common topology in on-chip networks, the proposed shuffle-exchange based mesh network has smaller diameter but for an equal cost. Simulation results show that the 2D SEM effectively reduces the power consumption and improves performance metrics of the on-chip networks with regard to the conventional mesh topology. ©2008 IEEE  

This paper proposes a frequency control strategy for an islanded inverter-based microgrid which based on the priority of supply, has got two distinct types of loads, namely sensitive and deferrable. The proposed strategy consists of primary and secondary levels of generation control supported by a loadshedding scheme. The primary control regulates the output power of the distributed generator (DG) units to be proportional to their ratings while secondary control has got the duty of frequency restoration after each load change. Functionality of these two levels is demonstrated to be independent of each other. Both controls are in distributed forms which have no need of communication... 

Effective spectrum sensing strategies enable cognitive radios (CRs) to identify and opportunistically transmit on under-utilized spectral resources. In this paper, sequential channel sensing problems for single and multiple secondary users (SUs) networks are effectively modeled through finite state Markovian processes. More specifically, a model for single user case is introduced and its performance is validated through analytical analysis. Then, in order to address multiple SUs case, this model is extended to include the modified p-persistent access (MPPA) protocol. Since the scheme utilized experiences a high level of collision among the SUs, to mitigate the problem appropriately,... 

In this paper, we propose a new scenario in order to increase the total throughput of a WLAN. In this scenario, some secondary users (SUs) are considered in a primary WLAN such that SUs cooperate with primary users (PUs) in transmitting the primary packets. Each SU sends its packets as well as the primary packets collided at the access point, but overheard successfully at the SU, by random access the primary WLAN. We show that SUs cooperation is able to compensate their adverse effect in the WLAN, so total throughput in the WLAN increases without a significant degrading effect for the stability region of PUs. To this end, we use an analytical model based on open queueing networks. By solving... 

To investigate the effects of flow rate, diameter and offset of secondary fuel injection on combustor noise level, pressure fluctuation and NOx emission, four types of injectors were examined in a swirl-stabilized combustor for overall equivalence ratio (Ø) of 0.7 ~ 0.9 and flow rate of secondary fuel (Qsec) from 0.6 to 4.2 L/min. As for the reference injector used in previous related studies, secondary fuel injection of 3.0 L/min is the best condition for the reduction of pressure fluctuation and combustion noise with tolerable NOx emission. For lower secondary fuel rate of 1.8 L/min, reduction of the injection diameter of reference injector results in a better performance in terms of...