An overview of forestry journals in the period 2006–2010 as basis for ascertaining research trends

Articles published between January 1, 2006 and December 31, 2010 in 42 forestry journals (N = 16,258) were collected and, depending on their content and key words, classified in one of 22 sub-disciplines. Among the forestry sub-disciplines, the following are currently dominant: Mensuration and inventories, Forest management, Plant ecophysiology and Wood science. PCA ordination was used to visualize grouping tendencies and data separation. For each component, a number of characteristics contributed to the total variation, and significant importance was attached to those with the highest loading factors. The first component included Mensuration and inventories, Plant ecophysiology, Vegetation ecology and Forest management, as the highest loading factors. The second components comprised Sociological aspects, Plant ecophysiology, Wood science and Forest management. The most pronounced increase trend over the five-year period is noted for Genetics and breeding, Vegetation ecology, Fuels and energy, while the most pronounced decrease trend is visible in Forest health, Forest fire, Sociological aspects and Forest products. PCA suggests the existence of three groups of journals: the first group comprises Forest Ecology and Management and Canadian Journal of Forest Research, the dominating two, the second group comprises Annals of Forest Science, Plant Ecology, Tree Physiology and Trees-Structure and Function, while the rest of the journals belong to the third group. The Canadian Journal of Forest Research is the most diversified, while Tree Genetics and Genomes, Silvae Genetica and Tree-ring Research are narrowly specialized.     

Fractions of fatal crashes attributable to speeding: Evolution for the period 2001–2010 in France

Road safety is a major concern in the West, especially in France. Among all the established risk factors for fatal crashes, speed is specific in two ways: every road-user is exposed to it, and it increases not only crash rates but also the severity of crashes. Thus, speed regulation is of primary importance in road-safety policy and has also generated much public debate. To contribute to this debate, we constructed a power-model which relates the number of fatal crashes to speed raised to the power four. Despite its simplicity, this model fitted the data well. Notably, it enabled the fractions of fatal crashes attributable to various levels of speeding to be estimated. Data for secondary roads over the period 2001–2010 showed that the fraction of fatal crashes attributable to high-level speeding (>20 kph over the speed limit) decreased from 25% to 6% and that attributable to medium-level speeding (10–20 kph over the speed limit) decreased from 13% to 9%, whereas that attributable to low-level speeding progressively increased from 7% to 13%. Similar trends were observed on main roads. These results highlight the effectiveness of the speed regulation policies introduced during the study period with respect to high-level speeding. They also suggest that future policy should focus on low and medium-level speeding in order further to reduce road deaths significantly, since these levels now correspond to the major fraction of fatal crashes.     

Growth in the number of references in engineering journal papers during the 1972–2013 period

The number of references per paper, perhaps the best single index of a journal’s scholarliness, has been studied in different disciplines and periods. In this paper we present a four decade study of eight engineering journals. A data set of over 70,000 references was generated after automatic data gathering and manual inspection for errors. Results show a significant increase in the number of references per paper, the average rises from 8 in 1972 to 25 in 2013. This growth presents an acceleration around the year 2000, consistent with a much easier access to search engines and documents produced by the generalization of the Internet.     

Mapping research collaborations in the business and management field in Malaysia, 1980–2010

This paper examines research collaborations in the field of business and management in Malaysia, a fast-developing economy in Southeast Asia. The country aims to become a developed nation by the year 2020, guided by its well-charted Wawasan 2020 or Vision 2020 program. Research and development are important agenda items within this program. Rarely, however, have studies investigated the research collaborations of researchers based in Malaysia from the network perspective. After a manual author disambiguation process, we examined the network of 285 business and management researchers at the individual, institutional, and international levels. Author collaborations per paper almost doubled between 2001 and 2010 compared to the period 1980–1990. The popularity of researchers and the strength and diversity of their ties with other researchers had significant effects on their research performance. Furthermore, geographical proximity still mattered in intra-national collaborations. Malaysian institutions more often collaborated intra-institutionally or with foreign partners than with other institutions within Malaysia. The country’s five research universities are among the top-most productive of all institutions in Malaysia. Malaysia’s top international partners are all developed countries, including the US, Australia, Japan, the UK, and Canada. Surprisingly, Malaysia has had relatively little collaboration with ASEAN nations, of which it is a prominent member and which has an important agenda of educational cooperation within its member states. Internationally co-authored articles have been cited almost three times more than locally co-authored articles. Based on these results, we suggest an effective co-authorship strategy.     

Contributions of Turkish academicians supervising PhD dissertations and their universities to economics: an evaluation of the 1990–2011 period

In this study, doctoral dissertations conducted at the Turkish Universities for the period of 1990–2011 and the scientifically indexed publications of the professors supervising these dissertations were investigated. In the evaluations, the publications scores of the Google Scholar, Web of Science, and Scopus as well as the citations belonging to the publications in these indexes were included. During the relevant period, 617 professors supervised all the 1,906 doctoral dissertations in the field of economics. The first three universities with the highest number of doctoral dissertations were determined to be Istanbul University, Marmara University, and Dokuz Eylül University whereas the first three universities with the highest scientific indexes were Ihsan Do?ramaci Bilkent University, Middle East Technical University, and Bo?aziçi University. The academicians of the last three universities also outperformed those at the other universities regarding the scientific publications they produced and the citations they received. Overall, there is a low correlation between the dissertations conducted and scientific citations. Finally, academicians with publications and/or citations in Web of Science or Scopus were researched further via logistic regressions. The results indicate that there is positive and meaningful relation with PhD degrees earned abroad and number of publication in the Web of Science.     

Structural analysis of the interrelationship between economic activities and water pollution in Vietnam in the period of 2000–2011

Clean Technologies and Environmental Policy - Rapid economic growth and poor waste management have left Vietnam with severe water pollution problems. It is thus important to develop a model to...     

Evolution of the publications in clinical neurology: scientific impact of different countries during the 2000–2009 period

We analyzed the productivity and visibility of publications on the subject category of Clinical Neurology by countries in the period 2000–2009. We used the Science Citation Index Expanded database of the ISI Web of Knowledge. The analysis was restricted to the citable documents. Bibliometric indicators included the number of publications, the number of citations, the median and interquartile range of the citations, and the h-index. We identified 170,483 publications (84.9 % original articles) with a relative increase of 28.5 % throughout the decade. Fourteen countries published over 2,000 documents in the decade and received more than 50,000 citations. The average of citations received per publication was 8 (interquartile range: 3–20) and the h-index was 261. USA was the country with the highest number of publications, followed by Germany, Japan, the UK and Italy. Moreover, USA publications had the largest number of citations received (44.5 % of total), followed by the UK, Germany, Canada, and Italy. On the other hand, Sweden, the Netherlands and the UK had the highest median citations for their total publications. During the period 2000–2009 there was a significant increase in Clinical Neurology publications. Most of the publications and citations comprised 14 countries, with the USA in the first position. Interestingly, most of the publications and citations originated from only 14 countries, with European countries with relatively low population, such as Switzerland, Austria, Sweden, Belgium, and the Netherlands, in this top group.     

Improving the performance of small Joule–Thomson cryocooler

This paper presents a new cycle for improving the performance of small Joule–Thomson (JT) cryocooler by applying an additional ejector in cycle system. Based on the presented JT cycle with an additional ejector (JTE), the performance of small JT cryocooler operating with pure N₂ and the mixture N₂?CH₄ for cryogenic applications in a temperature range of 80–130 K is investigated by theoretical calculations. It can be found that the refrigeration efficiency of the JTE cryocooler operating with pure N₂ increase by 55.6–25.1%, and the refrigeration capacity increase by a factor of 4.9–1.5 compared to a conventional JT cryocooler. Similar performance improvements are also obtained when the mixture N₂?CH₄ is used as the working gas. The refrigeration efficiency increase by 46.6–17.7% and the refrigeration capacity increase by a factor of 3.8–1.3. It is concluded that the performance of small JT cryocooler can be significantly improved based on the presented JTE cycle.     

The effect of Ca on the in vitro corrosion performance of biodegradable Mg–Nd–Y–Zr alloy

The effect of 0.4% Ca on the in vitro corrosion behavior of Mg–1.2% Nd–0.5% Y–0.5% Zr was evaluated in a simulated physiological environment in the form of 0.9% NaCl solution saturated with Mg(OH)₂ at ambient temperature and at 37 °C. The microstructure examination was carried out using optical microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction analysis. The corrosion behavior was evaluated by immersion test, salt spray testing, and potentiodynamic polarization analysis. The stress corrosion behavior was examined using slow strain rate testing analysis in different strain rates. The results obtained have shown that the addition of 0.4% Ca has a beneficial effect on the corrosion resistance of the tested alloy. This was mainly attributed to the effect of calcium, which reduces oxidation in the molten condition and consequently improves the soundness of the obtained casting. Hence, it is believed that the reduction in the extent of inherent casting defects in the alloy containing calcium overcomes the detrimental micro-galvanic effect of the Mg₂Ca phase that was formed in the tested alloy. Contrary to the beneficial effect of calcium on the corrosion performance, the addition of calcium has a damaging effect on the stress corrosion behavior in terms of reduced ultimate tensile strength and ductility. This was mainly due to the embrittlement effect of calcium that was generated by the formation and distribution of Mg₂Ca phase at grain boundaries.     

Analysis of the scientific productivity of researchers from the Republic of Croatia for the period 1990–1992

The scientific production of researchers from the Republic of Croatia, consisting of the published papers with addresses of the institutions from Croatia only, was analyzed for the period 1990–1992, covering 2047SCI, SSCI, andA&HCI registered papers. The source index ofSCI has registered 1912 (92.50% of total number of published articles) papers,SSCI 118 (5,71%), andA&HCI 37 (1.79%) papers, respectively. The papers were published in more than 700 different journals, covering 122 scientific subfields. The most frequently used journals are the nationalPeriodicum Biologorum, Croatica Chemica Acta andCollegium Antropologicum with 236 published papers or 11.5%. The largest number of papers have been published in scientific subfields:Biology (146 papers),Chemistry (107), andPhysics of Condensed Matter (102). The average paper was published by 3.57 researchers, but subfields ofNuclear Physics (7.40 authors per paper),Immunology (5.67), andHematology (5.60) were with the highest authorship. The partial contributions of institutions were also determined, and the most productive were Ruder Bokovi Institute with 645.0, the Faculty of Medicine with 396.7, and the Faculty of Science and Mathematics with 201.7 published papers, respectively. The average quality of the used journals were estimated; Institute of Physics, Ruder Bokovi Institute, and the Faculty of Science and Mathematics published their papers in journals with bigger impact factor (higher quality) than average institutions. Publications were divided by the type of papers, most frequent being articles (1778 publications, 86.85%), notes (117, 5.71%) and letters (56, 2.74%), respectively. Scientific subfield distribution of papers published by the most productive institutions were also analyzed.     

Research or management? An investigation of the impact of leadership roles on the research performance of academic administrators

This study quantitatively investigated whether the research performance of academic administrators (leaders) was affected by their administrative services. We sampled 111 academic administrators, including 90 department deans and 21 university presidents, from 26 universities. These leaders’ research performance was determined by the number of their publications and citations in the Web of Science databases. To compare the effect on their research performance by their administrative roles, we proposed four periods: the pre-position period, the latest position period, the reference period, and the in-position period. Statistical methods were applied to compare the research performance of the sampled administrators before and after they accepted the current administrative roles. The results suggest that 80% of academic leaders’ productivity and citation have fallen by 42 and 62% averagely. The extent of such impact varied in different disciplines. Leaders’ performance in medicine fields has declined the most (60%). The impact on research productivity appeared to be stronger for administrators serving in higher-ranking universities. In addition, the research performance of both university presidents and department deans were substantially influenced by their administrative services.     

Characterization of lubricating oil effects on the performance of reciprocating compressors in air–water heat pumps

Lubricating oils play several key roles in compressors, such as lubrication of the parts exposed to friction, prevention of gas leakage at the compression chamber, and cooling of the pieces heated by friction. Oil viscosity and possibility of mixing with refrigerant are the significant factors that should be considered in choosing compatible lubricants. Generally, high viscosity lubricants reduce the efficiency and lubricants with low viscosity cause to direct contact between the metal parts in the compressor. In this study, an experimental procedure has been carried out to investigate the influences of oil circulation in the compressor working with R-404a refrigerant. Although this study has been devoted to a detailed attempt to identify the effects of oil viscosity on energy consumption, an innovative way to analyze this critical parameter has been carried out in parallel with other parameters including refrigerant charge amount, condenser water flow rate and air temperature in the evaporator. The sample oils selected for experiments are SL22, SL68 and SL220. The basic nature of the lubricants and their mixtures with refrigerant, COP value, compressor efficiency and exergetic efficiency of the system has been analyzed under different working conditions.     

On the beat of the drum: improving the flow shop performance of the Drum–Buffer–Rope scheduling mechanism

One of the main elements of the theory of constraints is its Drum–Buffer–Rope (DBR) scheduling (or release) mechanism that controls the release of jobs to the system. Jobs are not released directly to the shop floor – they are withheld in a backlog and released in accordance with the output rate of the bottleneck (i.e. the drum). The sequence in which jobs are considered for release from the backlog is determined by the schedule of the drum, which also determines in which order jobs are processed or dispatched on the shop floor. In the DBR literature, the focus is on the urgency of jobs and the same procedure is used both for backlog sequencing and dispatching. In this study, we explore the potential of using different combinations of rules for sequencing and dispatching to improve DBR performance. Based on controlled simulation experiments in a pure and general flow shop we demonstrate that, although the original procedure works well in a pure flow shop, it becomes dysfunctional in a general flow shop where job routings vary. Performance can be significantly enhanced by switching from a focus on urgency to a focus on the shortest bottleneck processing time during periods of high load.     

Lotka's law and productivity patterns of entomological research in Nigeria for the period, 1900–1973

A bibliography of entomological research in Nigeria, 1900–1973 totally 1720 publications was analysed to study the author productivity patterns and to test the applicability of Lotka's law for the obtained distributions. Four different files were generated, one for the publications of all the authors, second for the publications by first authors, third for single authors and fourth for coauthors. Lotka's law in its original form as inverse square law does not apply to any of the four data sets. However, it does apply in its generalised form with the calculated values of characteristic exponent . The values of were found to be 1.9, 1.8, 2.2 and 2.4 for the four different data sets. K-S statistical test was aplied to test the applicability of generalised form of Lotka's law. The maximum difference in the observed and estimated values of the proportions of authors was found to be highly insignificant at 0.01 level of significance in each of the four cases.     

Impact of insulator layer thickness on the performance of metal–MgO–ZnO tunneling diodes

The performance of metal–insulator–semiconductor (MIS) type tunneling diodes based on ZnO nanostructures is investigated through modeling. The framework used in this work is the Schrödinger equation with an effective-mass approximation. The working mechanism of the MIS type tunneling diode is investigated by examining the electron density, electric field, electrostatic potential, and conduction band edge of the device. We show that a valley in the electrostatic potential is formed at the ZnO/MgO interface, which induces an energy barrier at the ZnO side of this interface. Therefore, electrons need to overcome two barriers: the high and narrow MgO barrier, and the barrier from the depletion region induced at the ZnO side of the ZnO/MgO interface. As the MgO layer becomes thicker, the valley in electrostatic potential becomes deeper. At the same time, the barrier induced at the ZnO/MgO interface becomes higher and wider. This leads to a fast decrease in the current passing through the MIS diode. We optimize the thickness of the MgO insulating layer, sandwiched between a ZnO film (in this work we use a single ZnO nanowire) and a metal contact, to achieve maximum performance of the diode, in terms of rectification ratio. An optimal MgO layer thickness of 1.5 nm is found to yield the highest rectification ratio, of approximately 169 times that of a conventional metal–semiconductor–metal Schottky diode. These simulated results can be useful in the design and optimization of ZnO nanodevices, such as light emitting diodes and UV photodetectors.

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