Narrow Results

The method of characteristics is a key tool for studying consistency of equations of motion; it allows issues such as predictability, maximal propagation speed, superluminality, unitarity and acausality to be addressed without requiring explicit solutions. We review this method and its application to massive gravity (mGR) theories to show the limitations of these models' physical viability: Among their problems are loss of unique evolution, superluminal signals, matter coupling inconsistencies and micro-acausality (propagation of signals around local closed time-like curves (CTCs)/closed causal curves (CCCs)). We extend previous no-go results to the entire three-parameter range of mGR theories. It is also argued that bimetric models suffer a similar fate.

The star images obtained through the CCD camera can visually display the star structure. In order to get the wide starry image, we need to extract the characteristics of star images to achieve the star image stitching. In the star images, star points, whose characteristics are limited, are easily influenced by noise and are also difficult to extract. The number of stars is too large to stitch accurately. Thus, we propose a stitching algorithm based on blocking star images. First, we establish the maximum intensity projection model based on time sequence to locate the star points accurately. Then, according to the relative positions of star points, the block model is introduced to realize the establishment of the characteristics. Finally, the star image stitching is achieved from the perspective of the characteristic similarity. The experiments illustrate that CM (combination measure) reaches 0.87, and the proposed algorithm has better anti-noise performance and robustness.

This paper has summarized five surface strengthening methods, and these methods could to improve the surface properties of materials. The selection of mechanical parts materials has determined according to their working conditions. The work-piece in using cannot avoid defects in the material. This paper has introduced surface deformation enhancement, surface phase transformation enhancement, ion implantation technology, surface diffusion and infiltration technology, chemical transformation technology and surface coating technology. And has also included the principle of every surface technology, various technologies, parameters, strengthening characteristics, as well as strengthening effect and matters needing attention. The hardness, residual stress and corrosion resistance off mechanical parts could be improved through these surface strengthening methods. It is convenient to find the strengthening method and parameters in this paper when strengthening mechanical parts.

In this article, we show that, in high-tech industries, there are significant differences in the Habitual Domains (HD) of technologists/researchers (T/R) and managers/leaders (M/L). The differences are measured specifically in the following: characteristics, attitudes toward career and life, perception of business problems, business competences and resources. We then describe how a T/R can effectively transform himself/herself into a successful M/L, by transforming his/her HD closer to that of a successful M/L.

Many physical systems are described by partial differential equations (PDEs). Determinism then requires the Cauchy problem to be well-posed. Even when the Cauchy problem is well-posed for generic Cauchy data, there may exist characteristic Cauchy data. Characteristics of PDEs play an important role both in Mathematics and in Physics. I will review the theory of characteristics and bicharacteristics of PDEs, with a special emphasis on intrinsic aspects, i.e. those aspects which are invariant under general changes of coordinates. After a basically analytic introduction, I will pass to a modern, geometric point of view, presenting characteristics within the jet space approach to PDEs. In particular, I will discuss the relationship between characteristics and singularities of solutions and observe that: "wave-fronts are characteristic surfaces and propagate along bicharacteristics". This remark may be understood as a mathematical formulation of the wave/particle duality in optics and/or quantum mechanics. The content of the paper reflects the three-hour mini-course that I gave at the XXII International Fall Workshop on Geometry and Physics, September 2–5, 2013, Évora, Portugal.

I will consider how there are FOSH formulations and associated results in relativistic cosmology expressed in 1+3 tetrad form. The characteristics of scalar and vector perturbations are timelike, hence the real domains of dependence in cosmology are much smaller than implied by the light cone, associated with gravitational wave perturbations.

Contemporary national development policy in many parts of the world is focused on the promotion of entrepreneurship. This is because policy makers see entrepreneurship as an important driver of economic development. Drawing on in-depth research in Ghana and Uganda, this paper provides a comparative analysis of the characteristics of entrepreneurs and their enterprises, their motives for choosing self-employment and the constraints to their businesses in Ghana and Uganda. Using a sample of over 1,000 micro and small entrepreneurs in each country, we found that Ghanaian entrepreneurs are much more motivated by necessity-driven motives while Ugandans are motivated by a combination of opportunity- and necessity-driven motives. Specifically, the factor analysis indicated that whereas Ghanaian entrepreneurs are significantly motived by “Work-family consideration” and “Low opportunity,” entrepreneurs in Uganda rated “Career consideration” and “Survival consideration” as their main motives for engaging in self-employment activities. On success, a much higher fraction of Ugandan entrepreneurs are found to be more successful than their Ghanaian counterparts. Comparatively, we found that Ghanaian businesses are significantly challenged with access to finance or credit; however, their counterparts in Uganda significantly face problems related to institutional weaknesses. Thus, from the factor analysis, “Financial problem” and “Institutional problem” were found to be significantly higher for Ghana and Uganda respectively. Hence, among others, Ghanaian policy makers can stimulate entrepreneurship by taking steps to reduce the level of financial constraints facing its entrepreneurs while in Uganda, much effort should be geared toward improving the business institutional environment.

The characteristics of effective teamwork in construction are examined. From the general management literature, the most common of these are expected to be clear objectives, trust, cohesiveness, interdependency, and enthusiasm of the team members. This is confirmed by an empirical questionnaire survey of a sample of 57 Singapore construction industry personnel where, in terms of correlation, the highest characteristics are trust and cohesiveness, followed by clear objectives, enthusiasm and interdependency. In terms of respondents' views, the most necessary was clear objectives, followed by interdependency, enthusiasm, trust and cohesiveness.

This paper presents an experimental work, which studies the performance of a counter-flow type cooling tower. The experimental trials have been carried out in a counter-flow type cooling tower test rig with mechanical draft. Expanded Wire Mesh type of film packing has been used for experimentation. The packing is made of mild steel with height ranging from 800 to 1255 mm. This study investigates the effect of the air and water flow on the cooling tower range, as well as the tower characteristics for different air flow and water flow quantities. The variation of temperature along the height of pack is measured by means of suitable thermocouples at five different places. The results show that the mass flow rate has adverse effect on the number of transfer unit. Also tower range would be increased by decreasing the inlet wet bulb air temperature.

Background: The carpometacarpal (CMC) joint of the thumb is the second most common site of osteoarthritis in the hand. Clinical severity stage of CMC joint arthritis has not been correlated with the pain level of the patient. Recently, the association of joint pain with patient psychological factor, such as depression or case-specific personality, has been investigated. This study was designed to determine the impact of psychological factors to residual pain after treatment of CMC joint arthritis, using pain catastrophizing scale (PCS) and the Yatabe–Guilford (YG) personality test.

Methods: Twenty-six patients (7 males and 19 females) with 26 hands were included. Thirteen patients classified as Eaton stage 3 underwent suspension arthroplasty and 13 patients as Eaton stage 2 underwent conservative treatment using a custom fitted orthosis. Clinical evaluation was assessed using Visual Analogue Scale (VAS) and the quick Disabilities of the Arm, Shoulder and Hand Questionnaire Score (QuickDASH) at initial evaluation, at 1 month and at 3 months after treatment. We compared both groups using the PCS and YG test.

Results: The PCS showed significant difference in the VAS scores only at initial evaluation in both surgical and conservative treatment. There was a significant difference in VAS at 3 months between the two groups in both surgical and conservative treatment and in QuickDASH at 3 months in conservative treatment.

Conclusions: The YG test has been used mainly in psychiatry. Although this test has not yet been used worldwide, its usefulness has been recognised and applied clinically, especially in Asia. Patient characteristics are strongly associated with residual pain of the CMC joint arthritis of the thumb. The YG test is a useful tool to analyse pain-related patient characteristics and can be utilised to determine the therapeutic modalities and most effective rehabilitation programme for pain control.

Level of Evidence: Level III (Therapeutic)

The mechanical properties of nanocomposites depend on the interfacial characteristics between the reinforcements and the matrix, but these interfacial behaviours and the associated molecular structures need more understanding. This study investigates the impact of diameter and chirality of carbon nanotube (CNT) and temperature on the interfacial interaction, bonding, and pullout energy, as well as the shear strength between CNT and epoxy, using molecular dynamics (MD) and molecular mechanics (MM). The modelling technique utilised a reactive force field (ReaxFF) and a new high-throughput approach to pullout energy calculations that provide an understanding of the interfacial behaviours of CNT/epoxy composites. The analyses showed that these interfacial energies and the shear strength increase with temperature. In addition, the smaller the diameter of CNT, which is a function of chirality, the greater is the interfacial bonding and shear strength. While interfacial interaction and pullout energy increase with CNT diameter.

A paper with special properties that can be used for specialized applications is termed as “specialty paper”. The basic features of specialty paper include the specific performance, specialized application-based features, low quantity demand, small-scale production, low-cost input equipment, narrow application, and high value-added and technical threshold; it should demonstrate uniform structure and good appearance. It has been developed rapidly in the domestic paper market, which is putting a great impact on the domestic paper, design, and printing industry. The specialty paper could be classified according to performance and applications in different fields. This chapter provides a comprehensive overview of the concept, properties, and classification of specialty paper. It discusses the potential of nanocellulose, the smallest physical structural unit of cellulose possessing nanometer network structure and excellent properties, to be replaced with wood pulp in making the specialty paper. Nanocellulose can add more fillers and reduce the overall production cost of specialty paper, which can further impart stability and strength and improve the printing quality of specialty paper. It further summarizes various applications of nanocellulose-based specialty paper in developing energy storage and electronic devices as well as in nanomedicine and water cleaning.

China’s women table tennis players are front-runners in the global table tennis scene and are supported a strong development program. However, recent defeats in competitions such as the 1-3 loss to Singapore in the 50th World Table Tennis Championship finals have raised some concerns. Moreover, the International Assistance and Development Plan implemented by the Chinese Table Tennis Association have allowed for the sharing of table tennis tactics and techniques and this has bridged the gap between other countries and China. Therefore this paper analyzes the characteristics of the tactical ability and technical skill of the Chinese women table tennis rising star Zhu Yuling, to identify and provide solutions to her problems and weaknesses in order to provide full preparation for the 2016 Rio Olympic Games.

In the study of multidimensional systems of conservation laws people confront more difficulties than that for one-dimensional systems. The difficulties include characteristic boundary, free boundary associated with unknown nonlinear waves, various nonlinear wave structure, mixed type equations, strong singularities, etc. Most of them come from the complexity of characteristics. We will give a survey on the progress obtained in the study of this topics with the applications in various physical problems, and will also emphasize some crucial points for the further development of this theory in future.

Non-quenched and tempered steel (NQTS) has attracted wide attention and application due to its excellent performance, energy saving, low cost, green environmental protection and other advantages. This paper reviews the classification and characteristics of NQTS at home and abroad. On this basis, it explores the research direction and development of NQTS. Furthermore, this review studied the problem in the application of NQTS in our country and puts forward some suggestions on the development of NQTS.

Though many new energy like nuclear power and wind power have been emerged and utilized, coal is still occupy an important position in energy field. The reserve of biomass is abundant in almost every country, which takes up 10-14% of the world's total fuel stream and is recognized as one of the most largest energy resource in the world, and its neutrality in CO₂ emissions, low NO_x and SO₂ emissions, therefore, biomass tend to become suitable feedstock, especially in the field of mixing biomass with coal nowadays. Co-combustion of coal and biomass is a good way to improve the combustion performance and the pollutants produced. The co-combustion characteristics and the pollutants are reviewed, such as ignition behavior, flame stability, burnout behavior and NOx emission etc., and some issues exist in researches are proposed in this article, it is expected to provide valuable reference for the further study.

It is the special structure to make the porous materials have the unique performance and application. As new structural and functional material, porous materials are being paid much more attention in the world and found application in many industrial fields. Classifications, properties, fabrication methods and application are summarized in this paper. Finally, we indicate the developing tendency of porous materials.