11,199 research outputs found
Growing Pains or Opportunities? A Customer Survey of Three Farmers\u27 Markets in One Rural Community
The continued growth of farmers\u27 markets is presenting new challenges to Extension. As the number of markets expands, how can Extension help those in the same community work together for mutual benefit? The study reported here examined similarities and differences among customers attending three different farmers\u27 markets within a single locality in Gettysburg, Pennsylvania. Based on 370 customer surveys, study results underscore the diversity of markets operating within the same community and provide insights into ways Extension might assist markets to work together to expand their shared customer base, increase revenues, and better serve local residents
Recommended from our members
Simplex basis function based sparse least squares support vector regression
In this paper, a novel sparse least squares support vector regression algorithm, referred to as LSSVR-SBF, is
introduced which uses a new low rank kernel based on simplex basis function, which has a set of nonlinear parameters.
It is shown that the proposed model can be represented as a sparse linear regression model based on simplex basis
functions. We propose a fast algorithm for least squares support vector regression solution at the cost of O(N) by
avoiding direct kernel matrix inversion. An iterative estimation algorithm has been proposed to optimize the nonlinear parameters associated with the simplex basis functions with the aim of minimizing model mean square errors using the gradient descent algorithm. The proposed fast least square solution and the gradient descent algorithm are alternatively applied. Finally it is shown that the model has a dual representation as a piecewise linear model with respect to the
system input. Numerical experiments are carried out to demonstrate the effectiveness of the proposed approaches
Analysis of some global optimization algorithms for space trajectory design
In this paper, we analyze the performance of some global search algorithms on a number of space trajectory design problems. A rigorous testing procedure is introduced to measure the ability of an algorithm to identify the set of ²-optimal solutions. From the analysis of the test results, a novel algorithm is derived. The development of the novel algorithm starts from the redefinition of some evolutionary heuristics in the form of a discrete dynamical system. The convergence properties of this discrete dynamical system are used to derive a hybrid evolutionary algorithm that displays very good performance on the particular class of problems presented in this paper
Point regular groups of automorphisms of generalised quadrangles
We study the point regular groups of automorphisms of some of the known
generalised quadrangles. In particular we determine all point regular groups of
automorphisms of the thick classical generalised quadrangles. We also construct
point regular groups of automorphisms of the generalised quadrangle of order
obtained by Payne derivation from the classical symplectic
quadrangle . For with we obtain at least two
nonisomorphic groups when and at least three nonisomorphic groups
when or . Our groups include nonabelian 2-groups, groups of exponent 9
and nonspecial -groups. We also enumerate all point regular groups of
automorphisms of some small generalised quadrangles.Comment: some minor changes (including to title) after referee's comment
What works to boost social relations and community wellbeing? A scoping review of the evidence
Background: Social relations are recognized as an important determinant of individual & community wellbeing. The UK What Works Wellbeing Centre chose “boosting social relations” as a priority topic for systematic review. First, a scoping review was undertaken to identify evidence gaps. Methods: We searched: Cochrane database of systematic reviews, DARE, Campbell Library, DoPHER (EPPI-Centre), Joanne Briggs Institute, MEDLINE, IDOX, CINAHL, PsycINFO, Social Policy & Practice, Social Care Online; relevant websites. Inclusion criteria: Population – communities in OECD countries; Intervention - Any community-based intervention, change in policy, organisation or environment that were designed to boost social relations within the community; Outcomes – social relations, community wellbeing or related synonyms; Study design – systematic & non-systematic reviews published between 2005 and 2016. Studies were selected & data extracted by 3 reviewers, and summarised narratively. Results: 11,257 titles and abstracts were screened, 182 obtained in full & 29 included. Existing evidence tells us: Targeted group interventions that foster social networks & provide meaningful roles can reduce social isolation and/ or loneliness in older people; Volunteering can improve physical & mental health & wellbeing in older people; Effective community engagement produces sustainable improvements in community health & individual wellbeing. Evidence gaps: Interventions for social isolation &/ or loneliness in adults aged up to 65 years; Volunteering in people aged up to 65 years; Social network analyses; Community infrastructure (places & spaces). Stakeholder consultations identified community infrastructure (places & spaces) as the most useful topic for systematic review. Conclusions: A systematic scoping review of reviews, with stakeholder consultation, identified community infrastructure (places & spaces) as an evidence gap. Early findings from the resulting systematic review will be presented
A Detailed Investigation into Low-Level Feature Detection in Spectrogram Images
Being the first stage of analysis within an image, low-level feature detection is a crucial step in the image analysis process and, as such, deserves suitable attention. This paper presents a systematic investigation into low-level feature detection in spectrogram images. The result of which is the identification of frequency tracks. Analysis of the literature identifies different strategies for accomplishing low-level feature detection. Nevertheless, the advantages and disadvantages of each are not explicitly investigated. Three model-based detection strategies are outlined, each extracting an increasing amount of information from the spectrogram, and, through ROC analysis, it is shown that at increasing levels of extraction the detection rates increase. Nevertheless, further investigation suggests that model-based detection has a limitation—it is not computationally feasible to fully evaluate the model of even a simple sinusoidal track. Therefore, alternative approaches, such as dimensionality reduction, are investigated to reduce the complex search space. It is shown that, if carefully selected, these techniques can approach the detection rates of model-based strategies that perform the same level of information extraction. The implementations used to derive the results presented within this paper are available online from http://stdetect.googlecode.com
On testing global optimization algorithms for space trajectory design
In this paper we discuss the procedures to test a global search algorithm applied to a space trajectory design problem. Then, we present some performance indexes that can
be used to evaluate the effectiveness of global optimization algorithms. The performance
indexes are then compared highlighting the actual significance of each one of them. A number of global optimization algorithms are tested on four typical space trajectory design problems. From the results of the proposed testing procedure we infer for each pair
algorithm-problem the relation between the heuristics implemented in the solution algorithm and the main characteristics of the problem under investigation. From this analysis we derive a novel interpretation of some evolutionary heuristics, based on dynamical system
theory and we significantly improve the performance of one of the tested algorithms
Influence of effective stress and pore‐fluid pressure on fault strength and slip localization in carbonate slip zones
The presence of pressurized fluids influences the mechanical behaviour of faults. To test the roles of normal stress and fluid pressure on shear strength and localization behaviour of calcite gouges, we conducted a series of rotary‐shear experiments with pore‐fluid pressures up to 10.5 MPa and difference between normal stress and fluid pressure up to 11.2 MPa. Calcite gouges were sheared for displacements of 0.3 m to several meters at slip rates of 1 mm/s and 1 m/s. Drainage conditions in experiments were constrained from estimates of the hydraulic diffusivity. Gouges were found to be drained at 1 mm/s, but possibly partially undrained during sliding at 1 m/s. Shear strength obeys an effective‐stress law with an effective‐stress coefficient close to unity with a friction coefficient of c. 0.7 that decreases to 0.19 due to dynamic weakening. The degree of comminution and slip localization constrained from experimental microstructures depends on the effective normal stress. Slip localization in calcite gouges does not occur at low effective normal stress. The presence of pore fluids lowers the shear strength of gouges sheared at 1 mm/s and causes an accelerated weakening at 1 m/s compared to dry gouges, possibly due to enhanced subcritical crack growth and intergranular lubrication. Thermal pressurization occurs only after dynamic weakening when friction is generally low and relatively independent of normal stress and therefore unaffected by thermal pressurization. The experimental results are consistent with the view that the presence of pressurized fluid in carbonate‐bearing faults can facilitate earthquake nucleation
- …