10,583 research outputs found
Positive Solutions for the Eigenvalue Problem of Semipositone Fractional Order Differential Equation with Multipoint Boundary Conditions
We study the existence of positive solution for the eigenvalue problem of semipositone
fractional order differential equation with multipoint boundary conditions by using known Krasnosel'skii's
fixed point theorem. Some sufficient conditions that guarantee the existence of at least one positive solution
for eigenvalues λ>0 sufficiently small and λ>0 sufficiently large are established
Networking, Resource Acquisition, and the Performance of Small and Medium-Sized Enterprises: An Empirical Study of Three Major Cities in China
Previously, resource-based view (RBV) research has focused on the characteristics of resources, paying less attention to the relationship between resource acquisition and the acquisition method. In addition, entrepreneurship research has focused a lot on the firm’s entrepreneurial network to explain performance. This network is critical not only to resource acquisition but also to overall firm performance. The results of a study of small and medium-sized firms in three major Chinese cities support these notions. The results differ when dividing the sample into two groups (young vs. old).resource acquisition, networking, performance, SMEs, entrepreneurship
Distributed Opportunistic Scheduling for MIMO Ad-Hoc Networks
Distributed opportunistic scheduling (DOS) protocols are proposed for
multiple-input multiple-output (MIMO) ad-hoc networks with contention-based
medium access. The proposed scheduling protocols distinguish themselves from
other existing works by their explicit design for system throughput improvement
through exploiting spatial multiplexing and diversity in a {\em distributed}
manner. As a result, multiple links can be scheduled to simultaneously transmit
over the spatial channels formed by transmit/receiver antennas. Taking into
account the tradeoff between feedback requirements and system throughput, we
propose and compare protocols with different levels of feedback information.
Furthermore, in contrast to the conventional random access protocols that
ignore the physical channel conditions of contending links, the proposed
protocols implement a pure threshold policy derived from optimal stopping
theory, i.e. only links with threshold-exceeding channel conditions are allowed
for data transmission. Simulation results confirm that the proposed protocols
can achieve impressive throughput performance by exploiting spatial
multiplexing and diversity.Comment: Proceedings of the 2008 IEEE International Conference on
Communications, Beijing, May 19-23, 200
Distributed Opportunistic Scheduling For Ad-Hoc Communications Under Noisy Channel Estimation
Distributed opportunistic scheduling is studied for wireless ad-hoc networks,
where many links contend for one channel using random access. In such networks,
distributed opportunistic scheduling (DOS) involves a process of joint channel
probing and distributed scheduling. It has been shown that under perfect
channel estimation, the optimal DOS for maximizing the network throughput is a
pure threshold policy. In this paper, this formalism is generalized to explore
DOS under noisy channel estimation, where the transmission rate needs to be
backed off from the estimated rate to reduce the outage. It is shown that the
optimal scheduling policy remains to be threshold-based, and that the rate
threshold turns out to be a function of the variance of the estimation error
and be a functional of the backoff rate function. Since the optimal backoff
rate is intractable, a suboptimal linear backoff scheme that backs off the
estimated signal-to-noise ratio (SNR) and hence the rate is proposed. The
corresponding optimal backoff ratio and rate threshold can be obtained via an
iterative algorithm. Finally, simulation results are provided to illustrate the
tradeoff caused by increasing training time to improve channel estimation at
the cost of probing efficiency.Comment: Proceedings of the 2008 IEEE International Conference on
Communications, Beijing, May 19-23, 200
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The demands of improving energy efficiency for high performance scientific applications arise crucially nowadays. Software-controlled hardware solutions directed by Dynamic Voltage and Frequency Scaling (DVFS) have shown their effectiveness extensively. Although DVFS is beneficial to green computing, introducing DVFS itself can incur non-negligible overhead, if there exist a large number of frequency switches issued by DVFS. In this paper, we propose a strategy to achieve the optimal energy savings for distributed matrix multiplication via algorithmically trading more computation and communication at a time adaptively with user-specified memory costs for less DVFS switches, which saves 7.5% more energy on average than a classic strategy. Moreover, we leverage a high performance communication scheme for fully exploiting network bandwidth via pipeline broadcast. Overall, the integrated approach achieves substantial energy savings (up to 51.4%) and performance gain (28.6% on average) compared to ScaLAPACK pdgemm() on a cluster with an Ethernet switch, and outperforms ScaLAPACK and DPLASMA pdgemm() respectively by 33.3% and 32.7% on average on a cluster with an Infiniband switch
The New Paradigm of Ethnic Minority Educational Research: Mixed Methods Research
Qualitative research and quantitative research have their own advantages, so mixed use both to improve scientific research. Too many Chinese Ethnic Minority Educational Research in qualitative research, and few use quantitative research, leading the results with many subjective factors. The reason is that selecting ethnic minority educational research paradigm is based on the subject property-oriented, rather than a problem-oriented research, and the selection of ethnic minority educational research paradigms was too concern about minority culture, ignored its educational attribute. Mixed methods research as the "third methodological movement", it can not only integrate the advantages of qualitative research and quantitative research, and enhance the consciousness of problem-oriented of researchers, but also to improve the science of ethnic minority educational research and promote the development of this discipline. Keywords: ethnic minority educational research; mixed method research; minority culture; research paradigm Ethnic minority educational research, sharing dual natures of education and minority, people and culture have become an important factor in ethnic minority educational research, however, in the dispute of qualitative research and quantitative research, the ethnic minority educational research prefer the former. Causing it is difficult to go into the vision of ethnic minority educational researchers for the latter paradigm. Currently, the international education research be in a major shift in paradigm, the estrangement of qualitative research and quantitative research gradually digestion. Instead, the mixed methods research is rising in educational research as “The Third Paradigm" and affecting it in a large part
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