3,651 research outputs found
Exploring the factors influencing the success of UK service sector SMEs: an owner/manager perspective
Small and Medium-sized Enterprises (SMEs) are an important part of any economy
consistently contributing over 90% of businesses, 60% of employment and over 50%
of GDP. They are regarded as a key source of innovation and business growth, and so
governments globally attempt to support SMEs.
Given the SME sector is very diverse, covering almost all industrial sectors, the
focus of this research is on the service sector. Whilst there has been considerable
research on âsuccessâ, this has been driven by external views, while in this research
the focus will be on how SMEs view success. The research explores SMEsâ definitions
of success from the SMEsâ viewpoint using qualitative research methods based on
interviews and a survey. Using SMEsâ opinions, this research determines the attributes
that SMEs believe create success. This approach takes a broad perspective and
includes the ecological context in which SMEs exist.
Firms define themselves as SMEs in relation to their own industrial sector. They
view themselves as successful if they are financially sustainable and often attach
importance to achieving non-financial goals. They widely interact with their
environment to acquire knowledge, skills, employees and customers. Start-ups in
particular attempt to gain visibility. Their interaction with others includes competitors
when there is mutual benefit, primarily through referrals.
The contribution of the thesis is an enhanced understanding of SMEsâ views of
success and how they see themselves as achieving success. This is based on their stage
of development and their self-identification within the market place. At an early stage
of development, they seek visibility and market penetration through personality. In
later stages, they either develop their business further or maintain a stable position.
This research makes some theoretical contributions in terms of developing the
perception of SMEs, giving definition to success, modifying the 5 stages of
development model, enriching the factors influencing SMEs in achieving success, and
extending the scope of competitive advantages. This research also develops an
adaptive framework by combining the discussion of SMEsâ stage development,
dynamic capability and adaptive capability in terms of resource-based theory and
competitive advantage theory. The methodological contribution is that, rather than
previewing SME within the 5 stage development model, the findings suggest that
potentially SMEs form into two groups: young and mature. The practical contribution
is that it offers insight into SMEsâ views of success and how to achieve it
An optimal full frequency control strategy for the modular multilevel matrix converter based on predictive control
The modular multilevel matrix converter (M3C) is a promising topology for high-voltage high-power applications. Recent researches have proved its significant advantages for adjustable-speed motor drives compared with the back-to-back modular multilevel converter (MMC). However, the branch energy balancing in the M3C presents great challenge especially at critical-frequency points where the output frequency is close to zero or grid-side frequency. Generally, this balancing control depends on the appropriate injection of inner circulating currents and the common-mode voltage (CMV) whereas their values are hard to determine and optimize. In this paper, an optimization based predictive control method is proposed to calculate the required circulating currents and the CMV. The proposed method features a broad-frequency range balancing of capacitor-voltages and no reactive power in the grid side. For operation at critical-frequency points, there is no increase on branch voltage stresses and limited increase on branch current stresses. A downscaled M3C system with 27 cells is designed and experiment results with the R-L load and induction motor load are presented to verify the proposed control method
A branch current reallocation based energy balancing strategy for the modular multilevel matrix converter operating around equal frequency
The Modular multilevel matrix converter (M3C) is a promising topology for medium-voltage, high-power applications. Due to the modular structure, it is scalable, produces high quality output waveforms and can be fault tolerant. However, the M3C suffers from capacitor-voltage fluctuation if the output frequency is similar to the input frequency. This problem could limit the circuitâs application in the adjustable speed drives (ASD). This paper introduces a theoretical analysis in the phasor-domain to find the branch energy equilibrium point of the M3C when operating with equal input and output frequencies. On the basis of this equilibrium point, a branch current reallocation based energy balancing control method is proposed to equalize the energy stored in the nine converter branches. With this novel control method, the M3C can effectively overcome the capacitor voltage fluctuation without using balancing techniques based on common mode voltage or applying reactive power at the input side
Sums of Powers of Primes in Arithmetic Progression
Gerard and Washington proved that, for k > -1, the number of primes less than xk+1 can be well approximated by summing the kth powers of all primes up to x. We extend this result to primes in arithmetic progressions: we prove that the number of primes p congruent to n modulo m less than xk+1 is asymptotic to the sum of kth powers of all primes p congruent to n modulo m up to x. We prove that the prime power sum approximation tends to be an underestimate for positive k and an overestimate for negative k, and quantify for different values of k how well the approximation works for x between 104 and 108
Sums of Powers of Primes in Arithmetic Progression
Gerard and Washington proved that, for , the number of primes less
than can be well approximated by summing the -th powers of all
primes up to . We extend this result to primes in arithmetic progressions:
we prove that the number of primes less than is
asymptotic to the sum of -th powers of all primes up to
. We prove that the prime power sum approximation tends to be an
underestimate for positive and an overestimate for negative , and
quantify for different values of how well the approximation works for
between and Comment: 19 pages, 16 table
PreDiff: Precipitation Nowcasting with Latent Diffusion Models
Earth system forecasting has traditionally relied on complex physical models
that are computationally expensive and require significant domain expertise. In
the past decade, the unprecedented increase in spatiotemporal Earth observation
data has enabled data-driven forecasting models using deep learning techniques.
These models have shown promise for diverse Earth system forecasting tasks but
either struggle with handling uncertainty or neglect domain-specific prior
knowledge, resulting in averaging possible futures to blurred forecasts or
generating physically implausible predictions. To address these limitations, we
propose a two-stage pipeline for probabilistic spatiotemporal forecasting: 1)
We develop PreDiff, a conditional latent diffusion model capable of
probabilistic forecasts. 2) We incorporate an explicit knowledge control
mechanism to align forecasts with domain-specific physical constraints. This is
achieved by estimating the deviation from imposed constraints at each denoising
step and adjusting the transition distribution accordingly. We conduct
empirical studies on two datasets: N-body MNIST, a synthetic dataset with
chaotic behavior, and SEVIR, a real-world precipitation nowcasting dataset.
Specifically, we impose the law of conservation of energy in N-body MNIST and
anticipated precipitation intensity in SEVIR. Experiments demonstrate the
effectiveness of PreDiff in handling uncertainty, incorporating domain-specific
prior knowledge, and generating forecasts that exhibit high operational
utility.Comment: Technical repor
A branch current reallocation based energy balancing strategy for the modular multilevel matrix converter operating around equal frequency
Modular multilevel matrix converter (M3C) is a promising topology for medium-voltage high-power applications. Due to the modular structure, it features easy scalability, high quality output waveforms and superior fault tolerance. However, M3C suffers serious capacitor-voltage fluctuation if the output frequency gets closer to the input frequency. This limits its use in the adjustable-speed-drive (ASD) applications. This paper introduces a theoretical analysis in phasor-domain to find the branch energy equilibrium point of M3C when operating around equal frequency. On the basis of this equilibrium point, a branch current reallocation based energy balancing control method is proposed to equalize the energy stored in the nine converter branches. With this novel control method, M3C can effectively overcome the capacitor voltage fluctuation with neither using common voltage nor applying reactive power at the input side
A Hybrid 3D/2D Field Response Calculation for Liquid Argon Detectors with PCB Based Anode Plane
Liquid Argon Time Projection Chamber (LArTPC) technology is commonly utilized
in neutrino detector designs. It enables detailed reconstruction of neutrino
events with high spatial precision and low energy threshold. Its field response
(FR) model describes the time-dependent electric currents induced in the
anode-plane electrodes when ionization electrons drift nearby. An accurate and
precise FR is a crucial input to LArTPC detector simulations and charge
reconstruction. Established LArTPC designs have been based on parallel wire
planes. It allows accurate and computationally economic two-dimensional (2D) FR
models utilizing the translational symmetry along the direction of the wires.
Recently, novel LArTPC designs utilize electrodes formed on printed circuit
board (PCB) in the shape of strips with through holes. The translational
symmetry is no longer a good approximation near the electrodes and a new FR
calculation that employs regions with three dimensions (3D) has been developed.
Extending the 2D models to 3D would be computationally expensive. Fortuitously,
the nature of strips with through holes allows for a computationally economic
approach based on the finite-difference method (FDM). In this paper, we present
a new software package "pochoir" that calculates LArTPC field response for
these new strip-based anode designs. This package combines 3D calculations in
the volume near the electrodes with 2D far-field solutions to achieve fast and
precise field response computation. We apply the resulting FR to simulate and
reconstruct samples of cosmic-ray muons and Ar decays from a Vertical
Drift (VD) detector prototype operated at CERN. We find the difference between
real and simulated data within 5 %. Current state-of-the-art LArTPC software
requires a 2D FR which we provide by averaging over one dimension and estimate
that variations lost in this average are smaller than 7 %.Comment: 16 pages, 12 figure
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