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This research aims to characterize the tribological behavior of polybutylene terephthalate (PBT) and PBT composites with micro glass beads (MGB) on steel, in dry conditions and on a block-on-ring tester, pointing out the influence of sliding distance and speed. The tribology of PBT and its composites is still in an early stage because this thermoplastic polyester requires accurate technological and thermal treatment.

The composites were produced by ICEFS Savinesti Romania and contain PBT grade Crastin6130NC010 (as supplied by Du Pont), 0.5 […] 1.0 per cent (weight) Relamyd B-2Nf (polyamide grade produced by ICEFS, for a better dispersion of MGB), 1 per cent (weight) black carbon for technological and tribological reasons and different micro glass beads (MGB) concentrations (10.0 and 20.0 per cent weight). Tests were done for different sliding distances (2,500, 5,000 and 7,500 m) and speeds (0.5, 1.0 and 1.5 m/s) and a normal load of 5 N.

The friction coefficient and the wear parameter (as mass loss of polymeric blocks) pointed out a good tribological behavior for these composites. Scanning electron microscope (SEM) images revealed particular aspects of PBT local transfer on steel. Also, 10 per cent MGB in PBT reduces wear, especially for longer distances (75,000 m) and higher speeds (0.5 and 0.75 m/s); the friction coefficient is only slightly increased up to 0.23, being less influenced by the speed and the sliding distance as compared to neat polymer.

PBT and PBT composites could become challengers for replacing materials in applications similar to tested ones. Even the neat polymer exhibits a good tribological behavior. The composites have a lower sensibility to higher speeds and sliding distances for the applied load.

The purpose of this paper is to find a real-time parking location for a four-wheeler.

Real-time parking availability using specific infrastructure requires a high cost of installation and maintenance cost, which is not affordable to all urban cities. The authors present statistical block matching algorithm (SBMA) for real-time parking management in small-town cities such as Bhavnagar using an in-built surveillance CCTV system, which is not installed for parking application. In particular, data from a camera situated in a mall was used to detect the parking status of some specific parking places using a region of interest (ROI). The method proposed computes the mean value of the pixels inside the ROI using blocks of different sizes (8 × 10 and 20 × 35), and the values were compared among different frames. When the difference between frames is more significant than a threshold, the process generates “no parking space for that place.” Otherwise, the method yields “parking place available.” Then, this information is used to print a bounding box on the parking places with the color green/red to show the availability of the parking place.

The real-time feedback loop (car parking positions) helps the presented model and dynamically refines the parking strategy and parking position to the users. A whole-day experiment/validation is shown in this paper, where the evaluation of the method is performed using pattern recognition metrics for classification: precision, recall and F1 score.

The authors found real-time parking availability for Himalaya Mall situated in Bhavnagar, Gujarat, for 18th June 2018 video using the SBMA method with accountable computational time for finding parking slots. The limitations of the presented method with future implementation are discussed at the end of this paper.

The transpiration has been recognized as one of the most effective thermal protection methods for future hypersonic vehicles. To improve efficiency and safety, it is urgent to optimize the design of the transpiration system for heat and drag reduction. The purpose of this paper is to investigate the effects of transpiration on heat and drag reduction.

A chemical nonequilibrium flow model with the transpiration is established by using Navier–Stokes equations, the shear-stress transport turbulence model, thermodynamic properties and the Gupta chemical kinetics model. The solver programmed for this model is verified by comparing with experimental results in the literature. Effects of air injection on the flow field, the aerodynamic resistance and the surface heat flux are calculated with the hypersonic flow past a blunt body. Furthermore, a modified blocking coefficient formula is proposed.

Numerical results show that the transpiration can reduce the aerodynamic resistance and the surface heat flux observably and increase the shock wave standoff distance slightly. It is also manifested that the modified formula is in better agreement with the wind tunnel test results than the original formula.

The modified formula can expand the application range of the engineering method for the blocking coefficient. This study will be beneficial to carry out the optimal design of the transpiration system.

Amides made from animal and vegetable oil fatty acids and the fatty acids of fats, by reaction with ammonia or various amines, have several uses in the processing and production of many polymers, e.g. anti‐static agents, anti‐blocking agents, slip agents, and mould release agents etc., and this article reviews the various amides available for these outlets.

This paper aims to present a modeling and analysis approach for multi-station aircraft assembly to predict assembly variation. The variation accumulated in the assembly process will influence the dimensional accuracy and fatigue life of airframes. However, in digital large aircraft assembly, variation propagation analysis and modeling are still unresolved issues.

Based on an elastic structure model and variation model of multistage assembly in one station, the propagation of key characteristics, assembly reference and measurement errors are introduced. Moreover, the reposition and posture coordination are considered as major aspects. The reposition of assembly objects in a different assembly station is described using transformation and blocking of coefficient matrix in finite element equation. The posture coordination of the objects is described using homogeneous matrix multiplication. Then, the variation propagation model and analysis of large aircraft assembly are established using a discrete system diagram.

This modeling and analysis approach for multi-station aircraft assembly reveals the basic rule of variation propagation between adjacent assembly stations and can be used to predict assembly variation or potential dimension problems at a preliminary assembly phase.

The modeling and analysis approaches have been used in a transport aircraft project, and the calculated results were shown to be a good prediction of variation in the actual assembly.

Although certain simplifications and assumptions have been imposed, the proposed method provides a better understanding of the multi-station assembly process and creates an analytical foundation for further work on variation control and tolerance optimization.

The purpose of this paper is to develop multilayer clothing assemblies consisting of fibrous battings and reflective nano-fibrous thin layers for cold protective clothing for improved thermal insulation.

Thermal insulation values of totally 20 assemblies made of varying layers of a thick polyester batting and four different types of thin interlayers were measured using a guarded hot-plate to investigate the effect of the properties of thin interlayers and construction of multilayer assemblies on thermal insulation. Cold protective jackets filled with polyester battings sandwiched with or without interlayers were also made and tested on the sweating fabric manikin-Walter.

Results show that the Rosseland mean extinction coefficients of the thin interlayer and the associated radiative thermal conductivity of the interlayers have significant influence on thermal insulation of the assembly when more than one reflective nano-fibrous interlayers are sandwiched in the assembly. The cold protective jacket filled with multilayer polyester battings and reflective nano-fibrous interlayers have better thermal insulation and moisture permeability index (i_m) than those filled with the same multilayer polyester battings, but with non-reflective nonwoven interlayers or without interlayers.

This paper clearly demonstrates the advantages of reflective nano-fibrous thin material for interlayers in the cold projective jacket.

This paper tests whether employers responded particularly negatively to African American job applicants during the deep U.S. recession that began in 2007. Theories of labor queuing and social closure posit that members of privileged groups will act to minimize labor market competition in times of economic turbulence, which could advantage Whites relative to African Americans. Although social closure should be weakest in the less desirable, low-wage job market, it may extend downward during recessions, pushing minority groups further down the labor queue and exacerbating racial inequalities in hiring. We consider two complementary data sources: (1) a field experiment with a randomized block design and (2) the nationally representative NLSY97 sample. Contrary to expectations, both analyses reveal a comparable recession-based decline in job prospects for White and African American male applicants, implying that hiring managers did not adapt new forms of social closure and demonstrating the durability of inequality even in times of structural change. Despite this proportionate drop, however, the recession left African Americans in an extremely disadvantaged position. Whites during the recession obtained favorable responses from employers at rates similar to African Americans prior to the recession. The combination of experimental methods and nationally representative longitudinal data yields strong evidence on how race and recession affect job prospects in the low-wage labor market.

Rotating stall is an unsteady flow phenomenon that causes instabilities and low efficiency in pumps. The purpose of this paper is to investigate the rotating stall characteristics and unsteady behavior of stall cells in a centrifugal pump impeller at low flow rates.

A developed large eddy simulation with dynamic mixed nonlinear model is performed to evaluate the unsteady flow in a centrifugal pump impeller. The rotating stall flow field through the centrifugal pump impeller is analyzed under three typical flow rates. Frequency spectrum analysis are carried out on the series of pressure fluctuation to get the rotating stall characteristics. The size and intensity of stall cells are also analyzed using time-averaged vorticity and static pressure.

The rotating stall cell first occurs in the suction side of the blade and exhibits an obvious life cycle including decay mergence, shedding, growing and development with a low frequency. With the decrease of flow rate, the amplitude of pressure fluctuations in the impeller tends to be larger, the propagated speed of stall cells and rotating stall frequency tends to be smaller, but the number of cells remains unchanged. The size of stall cells increases as the flow rate decreases, but intensity changes is very little.

The rotating stall characteristics in a centrifugal pump impeller under low flow rates are presented first using a developed large eddy simulation approach.

The purpose of this study is to examine whether the influence of block ownership on firm performance depends on the identity of the largest investor.

The authors analyse the data for New Zealand companies for the period from 2002 to 2007 and develop multiple regression models which test the influence of block ownership on firm performance subject to the identity of the investor. A two‐stage least square approach is employed to test the effect of possible reverse causality between block ownership and firm performance on the relationship found in multiple regression models.

The authors find that the concentrated ownership has a positive, albeit decreasing, association with firm performance. This relationship is conditioned on the identity of the largest investor. Those companies whose block investors were financial institutions performed better than their peers. The superior influence of financial investors on corporate performance did not disappear even when the endogeneity of this relationship was accounted for.

The main contribution of this paper is the finding of a differential influence of various identities of block investors on firm performance. It questions the role that some domestic block investors play in the governance of New Zealand companies and the reason why the financial system has allowed corporate entities to be the main shareholders of the majority of firms when they underperform relative to their peers.

This paper aims to examine the factors influencing the level of disclosures of sustainability (SR) and integrated report (IR) information in a developing country context, with particular reference to Kenya.

The study uses a panel data set of 419 firm-year observations of listed companies in Kenya covering the period 2010 through 2018. Data are collected from the annual reports and analysed using a generalized estimations equation model.

The results reveal that there is momentum towards newer reporting frameworks in Kenya with substantial IR and SR disclosures in their annual reports. The results also show that level of SR and IR disclosures is influenced by both agency-related factors (board gender diversity, audit committee independence, block ownership and the presence of foreign ownership). Additionally, institutional-related factors (regulatory pressure and promotional efforts of regulatory and professional bodies [reporting excellence awards]) influence the disclosures.

The results highlight that initiatives such as those led by the regulatory and professional bodies in Kenya are effective in motivating companies to enhance disclosures. Thus, regulators and professional bodies might need to continue and even intensify their efforts. These results have implications for further research as they show that SR and IR disclosures are influenced by similar factors.

The study has the potential to contribute to the ongoing initiatives and discussions on the adoption of IR by firms in Africa as spearheaded by the African Integrated Reporting Council.

To the best of the knowledge, the study is, perhaps, the first to examine both SR and IR disclosures at the same study allowing comparison of the extent and drivers of the two disclosures. Moreover, examining the institutional-related factors in a single country has not been done in prior literature, and so this is an innovation.