Muna E. Raypah, Mutharasu Devarajan and Fauziah Sulaiman
Proper thermal management is a key to improve the efficiency and reliability of light-emitting diodes (LEDs). This paper aims to report the influence of applying thermally…
Abstract
Purpose
Proper thermal management is a key to improve the efficiency and reliability of light-emitting diodes (LEDs). This paper aims to report the influence of applying thermally conductive materials on thermal performance of indium gallium aluminum phosphide (InGaAlP)-based thin-film surface-mounted device (SMD) LED.
Design/methodology/approach
The LED thermal and optical parameters were determined using the combination of thermal transient tester (T3Ster) and thermal and radiometric characterization of power LEDs (TeraLED) instruments. The LED was mounted on FR4, 2W and 5W aluminum (Al) package substrates. Measurements were carried out by setting different boundary conditions: air between LED package and substrate and using thermally conductive epoxy (TIM A) and adhesive (TIM B) of thermal conductivity 1.67 and 1.78 W/mK, respectively.
Findings
For LED mounted on FR4 package, the total real thermal resistance is improved because of TIM B by 6 and 9 per cent at 50 and 100 mA, respectively. Likewise, the relative decrease in total thermal resistance of LED on 2W Al package is about 9 and 11 per cent. As well, for LED mounted on 5W Al package, the total real thermal resistance is reduced by 2 and 4 per cent.
Originality/value
No much work can be found in the literature on thermal interface material effects on thermal performance of low-power SMD LED. This work can assist in thermal management of low-power LEDs.
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It is argued that government is not really interested in trainingin some important areas, especially information technology. The need forunions to influence this attitude with…
Abstract
It is argued that government is not really interested in training in some important areas, especially information technology. The need for unions to influence this attitude with individual employers through a contractual individual training agreement is set out.
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Contingency planning in cases of computer failure, for whatever reason, is not undertaken by many companies. They then risk direct financial losses and the integrity of the data…
Abstract
Contingency planning in cases of computer failure, for whatever reason, is not undertaken by many companies. They then risk direct financial losses and the integrity of the data. The author discusses means of insuring against such disasters.
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Muna E. Raypah, Mutharasu Devarajan and Shahrom Mahmud
One major problem in the lighting industry is the thermal management of the devices. Handling of thermal resistance from solder point to the ambiance of the light-emitting diode…
Abstract
Purpose
One major problem in the lighting industry is the thermal management of the devices. Handling of thermal resistance from solder point to the ambiance of the light-emitting diode (LED) package is linked to the external thermal management that includes a selection of the cooling mode, design of heatsink/substrate and thermal interface material (TIM). Among the significant factors that increase the light output of the of the LED system are efficient substrate and TIM. In this work, the influence of TIM on the luminous flux performance of commercial indium gallium aluminium phosphide (InGaAlP) low-power (LP) LEDs was investigated.
Design/methodology/approach
One batch of LEDs was mounted directly onto substrates which were glass-reinforced epoxy (FR4) and aluminium-based metal-core printed circuit boards (MCPCBs) with a dielectric layer of different thermal conductivities. Another batch of LEDs was prepared in a similar way, but a layer of TIM was embedded between the LED package and substrate. The TIMs were thermally conductive epoxy (TCE) and thermally conductive adhesive (TCA). The LED parameters were measured by using the integrated system of thermal transient tester (T3Ster) and thermal-radiometric characterization of LEDs at various input currents.
Findings
With the employment of TIM, the authors found that the LED’s maximum luminous flux was significantly higher than the value mentioned in the LED datasheet, and that a significant reduction in thermal resistance and junction temperature was revealed. The results showed that for a system with low thermal resistance, the maximum luminous flux appeared to occur at a higher power level. It was found that the maximum luminous flux was 24.10, 28.40 and 36.00 lm for the LEDs mounted on the FR4 and two MCPCBs, respectively. After TCA application on the LEDs, the maximum luminous flux values were 32.70, 36.60 and 37.60 lm for the FR4 and MCPCBs, respectively. Moreover, the findings demonstrated that the performance of the LED mounted on the FR4 substrate was more affected by the employment of the TIM than that of MCPCBs.
Research limitations/implications
One of the major problems in the lighting industry is the thermal management of the device. In many low-power LED applications, the air gap between the two solder pads is not filled up. Heat flow is restricted by the air gap leading to thermal build-up and higher thermal resistance resulting in lower maximum luminous flux. Among the significant factors that increase the light output of the LED system are efficient substrate and TIM.
Practical implications
The findings in this work can be used as a method to improve thermal management of LP LEDs by applying thermal interface materials that can offer more efficient and brighter LP LEDs. Using aluminium-based substrates can also offer similar benefits.
Social implications
Users of LP LEDs can benefit from the findings in this work. Brighter automotive lighting (signalling and backlighting) can be achieved, and better automotive lighting can offer better safety for the people on the street, especially during raining and foggy weather. User can also use a lower LED power rating to achieve similar brightness level with LED with higher power rating.
Originality/value
Better thermal management of commercial LP LEDs was achieved with the employment of thermal interface materials resulting in lower thermal resistance, lower junction temperature and brighter LEDs.
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Presents a special issue, enlisting the help of the author’s students and colleagues, focusing on age, sex, colour and disability discrimination in America. Breaks the evidence…
Abstract
Presents a special issue, enlisting the help of the author’s students and colleagues, focusing on age, sex, colour and disability discrimination in America. Breaks the evidence down into manageable chunks, covering: age discrimination in the workplace; discrimination against African‐Americans; sex discrimination in the workplace; same sex sexual harassment; how to investigate and prove disability discrimination; sexual harassment in the military; when the main US job‐discrimination law applies to small companies; how to investigate and prove racial discrimination; developments concerning race discrimination in the workplace; developments concerning the Equal Pay Act; developments concerning discrimination against workers with HIV or AIDS; developments concerning discrimination based on refusal of family care leave; developments concerning discrimination against gay or lesbian employees; developments concerning discrimination based on colour; how to investigate and prove discrimination concerning based on colour; developments concerning the Equal Pay Act; using statistics in employment discrimination cases; race discrimination in the workplace; developments concerning gender discrimination in the workplace; discrimination in Japanese organizations in America; discrimination in the entertainment industry; discrimination in the utility industry; understanding and effectively managing national origin discrimination; how to investigate and prove hiring discrimination based on colour; and, finally, how to investigate sexual harassment in the workplace.
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This article presents a compelling case study of a workers’ cooperative in the cultural sector. It offers a unique opportunity to delve into the tensions between managerial and…
Abstract
Purpose
This article presents a compelling case study of a workers’ cooperative in the cultural sector. It offers a unique opportunity to delve into the tensions between managerial and democratic control, particularly in the context of heightened artistic claims. The pivotal role of an accountant in management for nearly two decades sparks a thought-provoking question about the potential for cooperative degeneration.
Design/methodology/approach
Our research employs a rigorous qualitative method, utilizing semi-structured interviews of six key members and a comprehensive analysis of legal, accounting and other media documents.
Findings
Our findings offer a significant perspective, refuting any indications of organizational degeneration. The decision-making processes continue to uphold democratic principles. While the manager and his administrative staff wield substantial authority, this is justified by their duty to preserve the collective. This duty is executed under democratic control, facilitated by information transparency. The low level of democratic participation poses a challenge, but the manager’s initiatives are aimed at addressing this. The effectiveness of this control, however, relies on the active participation of the members, which acts as a strong deterrent against organizational degeneration.
Originality/value
The originality of our contribution lies in our reference to Chester Barnard whose reflections on industrial democracy have been forgotten, reflections linked to his conception of managerial authority. We also highlight the importance of empowering individual members, which leads them to consider the consequences of their actions. As a result, the manager is not placed in a situation where he has to decide alone, as the scope of his unilateral powers is de facto delimited.
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Andrew R. Timming, Chris Baumann and Paul Gollan
The paper aims to examine the effect of employees' perceived physical attractiveness on the extent to which their voices are “listened to” by management.
Abstract
Purpose
The paper aims to examine the effect of employees' perceived physical attractiveness on the extent to which their voices are “listened to” by management.
Design/methodology/approach
Using an experimental research design, the paper estimates main effects of employee attractiveness and possible moderating effects of employee race and gender as well as the gender of their “managers.”
Findings
The results suggest that, with few exceptions, more physically attractive employees are significantly more likely to have their suggestions acted upon by managers than less attractive employees, pointing to a powerful form of workplace discrimination. This finding holds across races, with more attractive white, black, and Asian employees exerting a more impactful voice than their less attractive counterparts, although the moderation appears to be stronger for whites than ethnic minorities.
Research limitations/implications
The results have important implications for the extant literatures on employee voice, diversity and discrimination.
Originality/value
This is among the first studies to demonstrate that less attractive employees suffer from an “employee voice deficit” vis-à-vis their more attractive counterparts.
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The purpose of this paper is to report on a search of criminology and related databases to identify fraud prevention intervention projects that showed promising achievements in…
Abstract
Purpose
The purpose of this paper is to report on a search of criminology and related databases to identify fraud prevention intervention projects that showed promising achievements in reducing offences.
Design/methodology/approach
A keyword search of Criminal Justice Abstracts was supplemented by searches of related databases and case study repositories – conducted up to 31 May 2019. The paper includes some attention to indicators of “what doesn’t work” as well as “what might work” or “what should work”. Selection criteria were open about evidence, rather than exclusively applying strict scientific standards.
Findings
Overall, the literature is marked by inferences regarding what should work, based on diagnostics about opportunity factors in fraud and victim characteristics. In terms of evaluated intervention projects, only two were identified that met best practice scientific standards. However, a further 17 projects were included where there was some evidence of a likely benefit.
Research limitations/implications
Available evaluations of intervention projects are predominantly within-in group studies. Pre- and post-intervention time frames are often short, limited to one year or less; with only one follow-up study.
Practical implications
The findings demonstrate the need for applied experiments to build knowledge about effective fraud reduction strategies. The main lesson from the content of the 19 projects concerns the value of a situational crime prevention framework for designing and testing interventions, especially through enhancing rule setting, reducing anonymity, extending guardianship and formal surveillance, and facilitating compliance.
Originality/value
This appears to be the first systematic literature review of applied counter-fraud intervention projects.
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Tim Prenzler, Tyler Cawthray, Louise E. Porter and Geoffrey P. Alpert
From 2002 to 2014, the Portland Police Bureau reported large reductions in complaints against officers and use of force indicators. The purpose of this paper is to develop a case…
Abstract
Purpose
From 2002 to 2014, the Portland Police Bureau reported large reductions in complaints against officers and use of force indicators. The purpose of this paper is to develop a case study to document these changes and explore possible influences.
Design/methodology/approach
The paper maps the changes in conduct indicators against the developing relationship between the Bureau and the Portland Independent Police Review Division, and changes in policies and procedures.
Findings
Public complaints reduced by 54.4 per cent, while the rate of specific allegations per officer fell by 70.1 per cent. Quarterly use of force incident reports were reduced by 65.4 per cent between 2008 and 2014. Annual average shootings decreased from a high of nine per year across 1997-2002 to just below four per year in 2009-2014. Fatal shootings also trended downward but remained two per year in the last three years on record. Reforms instituted during this period that may have influenced these trends include a more rigorous complaints process, an early intervention system (EIS), enhanced external and internal review mechanisms, policy changes and training initiatives.
Research limitations/implications
The researchers were unable to control for a range of additional variables that may have influenced the findings, including police deployments and changes in officer demographics.
Practical implications
The study provides support for strategies to improve police conduct including external oversight, diagnostic research, training focussed on de-escalation and minimal force, and complaint profiling and EISs.
Originality/value
There are very few studies available showing large long-term reductions in adverse police conduct indicators.