P. Regenfuss, A. Streek, L. Hartwig, S. Klötzer, Th. Brabant, M. Horn, R. Ebert and H. Exner
The purpose of the paper is the elucidation of certain mechanisms of laser material processing in general and laser micro sintering in particular. One major intention is to…
Abstract
Purpose
The purpose of the paper is the elucidation of certain mechanisms of laser material processing in general and laser micro sintering in particular. One major intention is to emphasize the synergism of the various effects of q‐switched laser pulses upon metal and ceramic powder material and to point out the non‐equilibrium character of reaction steps.
Design/methodology/approach
Recent results and observations, obtained in development of “laser micro sintering,” are surveyed and analyzed. By breaking down the overall process into relevant steps and considering their possible kinetics, an approach is made towards interpreting specific phenomena of laser micro sintering. Thermodynamics upon heating of the material as well as its photo‐electronic response to the incident radiation are considered.
Findings
The findings corroborate a model whereby short pulses of high intensity provide non‐equilibrium pressure conditions at the location of incidence, that allow for the melting of metal powder with an almost immediate expansion of a plasma and/or vapor bulb. Thereby the molten material is condensed and propelled towards the substrate. A final boiling eruption after each pulse is the reason for the morphology of the laser micro‐sintered surfaces and can prevent oxidation when the process is conducted under normal atmosphere. In sintering of ceramics, the short pulsed and intensive radiation increases the chance to excite the material even with photon energies below the bandgap value and it lowers the risk of running into a destructive avalanche.
Research limitations/implications
Owing to the stochastic character of the respective sintering event, that is initiated by each individual pulse, the gathered data are not suitable yet for the formulation of an exact quantitative function between sintering behavior and laser parameters.
Practical implications
The qualitative findings yield a good rule of thumb for the choice of parameters in laser sintering on a micrometer scale and the model is conducive for advanced interpretation of other phenomena in laser material processing besides sintering.
Originality/value
The kinetics and thermodynamics of laser sintering with q‐switched pulses are approached by a qualitative explanation. The heterogeneous and non‐equilibrium character of the processes is taken into account; this character is often neglected by researchers in the area.
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P. Regenfuss, L. Hartwig, S. Klötzer, R. Ebert, Th. Brabant, T. Petsch and H. Exner
Examples are given for the technical applicability of a novel development of selective laser sintering called “laser micro sintering”.
Abstract
Purpose
Examples are given for the technical applicability of a novel development of selective laser sintering called “laser micro sintering”.
Design/methodology/approach
Together with a specific method to produce powder layers, the controlled application of pulsed radiation for the processing of sub‐μm grained metal powders was exploited to produce micro‐tools with a heretofore unattained structural resolution.
Findings
High resolution micro bodies are displayed. Instruments could be generated which proved to fulfil their designation as grip bits for micro manipulators. The micro‐bodies can be generated detachably from or firmly fixed to the construction substrate. The material of the generated bodies withstands the traction forces when used as an injection mold for polymer casts.
Research limitations/implications
Densities and structural resolutions can still be improved especially with a newly updated version of the equipment. Laser micro sintering of materials, other than metal (e.g. ceramics), has still to be developed. The introduction of the equipment and the technique into the market is on its way.
Practical implications
Micro‐tools can be generated with an overall structural resolution of 30 μm and with all the advantages of a freedom technique.
Originality/value
The paper informs the technical community on a new novel modification of the freeform technique selective laser sintering, demonstrating the solution of some problems that have hampered the progress of metal laser into resolution ranges below 100 μm. It also supplies evidence for the technical applicability.
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Claudio Cruz-Cázares, Cristina Bayona-Sáez, Teresa García-Marco, Hans Berends, Armand Smits and Isabelle Reymen
The purpose of this paper is to analyse a firm’s internal and external drivers of formal and informal open innovation (OI) practices. To enrich the analysis and to obtain more…
Abstract
Purpose
The purpose of this paper is to analyse a firm’s internal and external drivers of formal and informal open innovation (OI) practices. To enrich the analysis and to obtain more robust results, the authors checked the study’s hypotheses using samples from two European regions, Navarre (Spain), classified an innovator follower, and Noord-Brabant (Netherlands), an innovator leader.
Design/methodology/approach
The sample selected includes manufacturing and service firms that completed the Community Innovation Survey for the year 2008 in both regions. The final sample had 1,288 observations from Navarre and 623 observations from Noord-Brabant. The authors consider two OI dimensions, breadth of information sources for informal OI practices and breadth of cooperation agreement for formal OI practices. Finally, the estimates were performed by means of a negative binomial regression.
Findings
Results indicate that for the internal drivers, product-related motives to innovate and in-house R&D intensity are strong drivers for both formal and informal OI engagement in general, while the influence of process- and environmental-related motives are context dependence.
Originality/value
This study distinguishes between formal (i.e. cooperation activities) and informal (i.e. external sources of information used for new ideas) inbound OI practices, while most of the literature has focussed on one single type of OI practice. The use of two samples coming from two different European regions allows observe whether the adoption motives of the OI practices are robust independently from the firms’ location or if they vary across regions owing to context dependence.
Objetivo
La innovación abierta (IA) ha demostrado ser crucial para aumentar la innovación y el desempeño económico de las empresas. Sin embargo todavía existe una comprensión limitada de los factores que impulsan realizar esta IA. El principal objetivo de este artículo es arrojar luz en esta dirección al analizar simultáneamente los determinantes internos y externos que llevan a las empresas a realizar prácticas formales e informales de IA.
Diseño
Las hipótesis son contratadas con muestras de dos regiones europeas, Navarra (España), calificada como región seguidora en innovación, y Noord Brabant (Países Bajos), líder innovador. La muestra seleccionada incluye empresas manufactureras y de servicios que completaron la Community Innovation Survey (CIS) 2008.
Resultados
Los resultados indican que, para los determinantes internos, los motivos relacionados con la búsqueda de innovaciones en producto y la intensidad interna de I + D son fuertes impulsores para todas las prácticas de IA, mientras que la importancia de los motivos relacionados con la obtención de innovaciones en proceso y medioambientales dependen del contexto regional. En cuanto a los factores externos, la política pública influye en la adopción de IA tanto formal como informal, pero estos resultados varían entre las regiones dependiendo del origen de los fondos.
Originalidad/valor
El estudio presenta importantes implicaciones para la literatura en IA. En primer lugar, mientras la mayoría de la literatura analiza un único tipo de prácticas de IA, este estudio distingue prácticas formales e informales de IA y estudia sus determinantes internos y externos simultáneamente. Segundo, las hipótesis son contrastadas en dos regiones europeas diferentes. Esto permite observar si los resultados obtenidos son robustos independientemente de la localización de las empresas o si varían dependiendo del contexto de ambas regiones.
Objetivo
A inovação aberta (IA) provou ser crucial para aumentar a inovação e o desempenho económico das empresas. No entanto, ainda há uma compreensão limitada dos fatores que conduzem essa IA. O principal objetivo deste artigo é lançar luz nessa direção, analisando simultaneamente os determinantes internos e externos que levam as empresas a realizar práticas de IA formais e informais.
Desenho
As hipóteses são contratadas com amostras de duas regiões européias, Navarra (Espanha), classificada como uma região de inovação, e Noord Brabant (Holanda), um líder inovador. A amostra selecionada inclui empresas de fabricação e serviços que completaram o Community Innovation Survey (CIS) 2008.
Resultados
Os resultados indicam que, para os determinantes internos, os motivos relacionados à busca de inovações no produto e na intensidade interna de P & D são fortes impulsionadores para todas as práticas de IA, enquanto a importância dos motivos relacionados à obtenção Inovações em processo e ambientes dependem do contexto regional. Em relação aos fatores externos, observamos que a política pública influencia a adoção de IA formal e informal, mas esses resultados variam de acordo com as origens dos fundos.
Originalidade/valor
O estudo apresenta implicações importantes para a literatura em IA. Primeiro, enquanto a maioria da literatura analisa um único tipo de práticas de IA, este estudo distingue práticas formais e informais de IA e simultaneamente estuda seus determinantes internos e externos. Em segundo lugar, as hipóteses são contrastadas em duas regiões européias diferentes. Isso permite verificar se os resultados obtidos são robustos independentemente da localização das empresas ou se variam de acordo com o contexto de ambas as regiões.
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Dai Cheng, Haihong Zhu and Linda Ke
This paper aimed to investigate the plasma characteristics of selective laser micro sintering Cu‐based metal powder using spectra method.
Abstract
Purpose
This paper aimed to investigate the plasma characteristics of selective laser micro sintering Cu‐based metal powder using spectra method.
Design/methodology/approach
Temporal and time integrating plasma induced during selective laser micro sintering Cu‐based metal powder with a Q‐switched pulsed YAG laser have been detected and analyzed. Boltzmann plot and Stark broadening of the spectra line are utilized to analyze the electron temperature and density, respectively. The influences of the Q‐switching rate and duration on the plasma temperature and electron density have been investigated.
Findings
The results show that the plasma temperature decreases from 9,600 to 9,000 K with the increase of the Q‐switching rate from 5 to 35 kHz if Q‐switching duration of laser is kept at a constant value. The plots of temporal temperature and electron density show that the electron density varies in a faster speed than plasma temperature and the entire expansion process takes about 700 ns‐1 μs in this experiment. Evolutional images of the plasma plume using Q‐switching rate of 5 kHz and 5 μs have been registered by the ICCD with a 10 ns exposure time, which shows that the plasma plume takes about 100 ns to get to the maximum size and 600 ns to disperse.
Originality/value
The plasma spectra of selective laser micro sintering Cu‐based metal powder have been diagnosed experimentally. The plasma characteristics of selective laser micro sintering Cu‐based metal powder have been analyzed.
Details
Keywords
Aerospatiale has just been granted from the Brazilian Council for Industrial Development an agreement for the manufacture of its helicopters in Brazil.
It is an ill wind that blows nobody good, and the British public may be congratulated on the salutary, if rude, awakening which the gale raised in Chicago has given them…
Abstract
It is an ill wind that blows nobody good, and the British public may be congratulated on the salutary, if rude, awakening which the gale raised in Chicago has given them. Peacefully slumbering, and content for years to accept as gospel truths the asseverations of all sorts and conditions of food‐fakers, both of home and foreign growth, the “Britisher” has suddenly received a shock from which it will take him a long time to recover. The abominable crime of milk‐adulteration—striking as it does at helpless infancy and at the vitality of the infirm and the weak; the “doctoring” of food products with a variety of pernicious drugs on the pleas of “preservation” and of meeting “public wants,” but in reality done for the sake of sordid gain; the gigantic meat and butter frauds, whereby largely the agricultural interest of this country has been brought to its present pass; the faking of beer and the wholesale arsenical poisoning which was one of its direct consequences; the denaturing of other foods by abstraction, substitution, and sophistication—all these things have been regarded by the “man in the street” with a sort of languid interest; have, at most, called forth passing comment from the lay press, and cheap sneers about faddery and faddists from various ignorant scribblers; while a succession of lethargic and feeble administrations have shelved the reports of their own Committees and Commissions, and, except under rare and abnormal pressure, have been content to adopt a policy of laissez faire.
Ilkan Sarigol, Rifat Gurcan Ozdemir and Erkan Bayraktar
This paper focuses on multi-objective order allocation with product substitution for the vaccine supply chain under uncertainty.
Abstract
Purpose
This paper focuses on multi-objective order allocation with product substitution for the vaccine supply chain under uncertainty.
Design/methodology/approach
The weighted-sum minimization approach is used to find a compromised solution between three objectives of minimizing inefficiently vaccinated people, postponed vaccinations, and purchasing costs. A mixed-integer formulation with substitution quantities is proposed, subject to capacity and demand constraints. The substitution ratios between vaccines are assumed to be exogenous. Besides, uncertainty in supplier reliability is formulated using optimistic, most likely, and pessimistic scenarios in the proposed optimization model.
Findings
Covid-19 vaccine supply chain process is studied for one government and three vaccine suppliers as an illustrative example. The results provide essential insights for the governments to have proper vaccine allocation and support governments to manage the Covid-19 pandemic.
Originality/value
This paper considers the minimization of postponement in vaccination plans and inefficient vaccination and purchasing costs for order allocation among different vaccine types. To the best of the authors’ knowledge, there is no study in the literature on order allocation of vaccine types with substitution. The analytical hierarchy process structure of the Covid-19 pandemic also contributes to the literature.
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Mario Becerra, Matteo Balliauw, Peter Goos, Bruno De Borger, Benjamin Huyghe and Thomas Truyts
Ticket sales are an essential source of income for football clubs and federations. Analyzing the determinants of fans' willingness-to-pay for tickets is therefore an important…
Abstract
Purpose
Ticket sales are an essential source of income for football clubs and federations. Analyzing the determinants of fans' willingness-to-pay for tickets is therefore an important exercise. By knowing the match- and fan-related characteristics that influence how much a fan wants to pay for a ticket, as well as to what extent, football clubs and federations can modify their ticket offering and targeting in order to optimize this revenue stream.
Design/methodology/approach
Using a detailed discrete choice experiment, based on McFadden's random utility theory, this paper formulates a Bayesian hierarchical multinomial logit model. Such models are very common in the discrete choice modeling literature. The analysis identifies to what extent match and personal attributes influence fans' willingness-to-pay for games of the Belgian men's and women's football national teams.
Findings
The results show that the strength of the opponent, the type of competition, the location of the seats in the stadium, the day and kick-off time of the match and the ticket price exert an influence on the choice of the respondent. Fans are attracted most by competitive games against strong opponents. They prefer to sit along the sideline, and they have clear preferences for specific kick-off days and times. The authors also find substantial variation between socio-demographic groups, defined in terms of factors such as age, gender and family composition.
Practical implications
The authors use the results to estimate the willingness-to-pay for match tickets for different socio-demographic groups. Their findings are useful for football clubs and federations interested in optimizing the prices of their match tickets.
Originality/value
To the best of the authors' knowledge, no stated preference methods, such as discrete choice analysis, have been used to analyze the willingness-to-pay of sports fans. The advantage of discrete choice analysis is that options and variations in tickets that are not yet available in practice can be studied, allowing football organizations to increase revenues from new ticketing instruments.