130 research outputs found
Hidden and surreptitious adoption of organizational information technology solutions
"Despite a broad literature on organizational adoption of technological innovations, the extant research has paid very little attention to a particular adoption scenario corresponding to user-initiated, surreptitious acceptance of information technology (IT) solutions that have been rejected at the organizational level. This lack of attention is surprising considering the strong anecdotal evidence pointing to various examples of user initiated organizational adoption of IT solutions. For example, in spite of formal organizational policies, procedures and guidelines sanctioning only a small subset of ""pre-approved"" and mostly vendor-bound organizational IT solutions, illegitimate, surreptitious, or hidden adoption of free and open source systems and applications by technical users has become increasingly prevalent in today's organizations. While we have learned a great deal about the legitimate adoption of systems by people and organizations, we know very little about this growing category of organizational systems. Indeed, the antecedents and consequences of these forms of hidden and surreptitious adoption are likely to be multifaceted and complex. The concept of hidden and surreptitious adoption marks an important organizational occurrence where organizational hierarchy fails. The departure from ""the routine, established and sanctioned"" approaches provide an opportunity to drill down into the organizational logic behind this unexplored occurrence. Drawing on concepts from institutional theory as well as on technology adoption literature this dissertation creates a careful synthesis of two previously separate streams of research and brings together two distinct sets of factors under the umbrella concept of social influence. In an empirical study the concept of hidden and surreptitious adoption was then analyzed and a causal network was proposed to help create a better understanding of hidden and surreptitious adoption of IT systems in organizations today. The findings confirmed wide-spread organizational occurrence of hidden adoption. Four complementary causal streams were found to contribute towards the materialization and magnitude of hidden and surreptitious adoption of IT solutions. Three of these streams; normative pressures, identification pressures, and performance induced awareness were confirmed to contribute positively towards hidden adoption whereas the remaining stream, compliance pressures were found to have an inverse relationship. In turn, each stream was further evaluated in detail to uncover various factors that positively or negatively contributed to that particular stream. The empirical findings were then discussed in light of theory to identify their theoretical as well as practical implications.
A Comprehensive Review and Synthesis of Open Source Research
The open source movement has grown steadily and matured in recent years, and this growth has been mirrored by a rise in open source related research. The objective of this paper is to pause and reflect on the state of the field. We start by conducting a comprehensive literature review of open source research, and organize the resulting 618 peer-reviewed articles into a taxonomy. Elements of this taxonomy are defined and described. We then draw on a number of existing categorization schemes to develop a framework to situate open source research within a wider nomological network. Building on concepts from systems theory, we propose a holistic framework of open source research. This framework incorporates current research, as represented by the taxonomy, identifies gaps and areas of overlap, and charts a path for future work
Poliamid 6'nın aşınmasında karşı yüzey pürüzlülüğünün etkisi
In this study, effect of counterface roughness on the wear of extruded PA 6 is investigated in dry sliding against stainless steel discs. In a pad on disc wear machine, PA 6 pins were tested against stainless steel discs which had various roughness values. Disc material is AISI 416 C stainless steel (0.15% C, 1.25% Mn, 1% Si, 13% Cr, 0.04% P, 0.03% S). Hardness is 52 HRC. Cylindrical surfaces of discs in 60 mm diameter were used as wearing surfaces. Polymer specimens were produced as cylindrical pins in 10 mm diameter. One of end faces of each pin was formed in the same radius with the discs. In all experiments, normal force and sliding speed is constant. The variable parameter is the surface roughness of the discs. Roughness of the discs were produced by cylindrical grinding. Four different grinding wheels were used. The grain sizes of wheels were 36, 46, 60 and 120. Grain size, diamond dressing rate, grinding time and circumferential speed of the wheel were varied in order to obtain verious counterface roughness values. Circumferential speed was varied using wheels with different diameters without changing the rotational speed. Very high roughness values (mean of profile deviations Ra = 3 mm) were generated by using grinding wheels with smallest possible diameters. Very low roughness values (Ra 1 mm) it was investigated whether wear rate increases with the parameter (1+4m2)1/2/s or not. It was seen that wear rates of PA 6 increase with this parameter. According to the results of experiments it was seen that steady state wear rates increase in the range of axial Ra = 0 - 1.5 mm and decrease in the range of 1.5 - 3 mm, generating a maximum for almost Ra = 1.5 mm. It is estimated that the decrease in wear rate is caused by the continuous transfer film formation on the counterface. Coefficient of friction generally decreases with increasing counterface roughness. In our experiments, when counterface roughness increased coefficient of friction decreased slowly. It is estimated that the observed slow decrease was caused by high coefficient of friction and high temperature. Keywords: Wear, polymer, roughness, fatigue, abrasive wear. Polimerlerin metal karşı yüzeyle eş çalışmasında, aşınmayı etkileyen en önemli faktörlerden biri karşı yüzeyin pürüzlülüğüdür. Bu çalışmada ekstrüzyon PA 6'nın, paslanmaz çelikten disklerle kuru sürtünmesinde, karşı yüzey pürüzlülüğünün polimerin aşınmasına etkisi incelenmektedir. Pürüzlülük silindirik taşlamayla oluşturulmuştur. Çok küçük pürüzlülük değerleri ise (profil sapmalarının aritmetik ortalaması Ra £ 0.15 mm) taşlamanın ardından 280-320 numaralı SiC zımpara kağıdı kullanılarak elde edilmiştir. Disklerin eksenel yöndeki Ra değeri yaklaşık olarak 0.08 mm'den 3 mm'ye kadar değişmektedir. PA 6 papuç-disk aşınma cihazında, farklı yüzey pürüzlülüğüne sahip paslanmaz çelikten disklerle (AISI 416 C, 52 HRC) aşınma deneyine tabi tutulmuştur. Disk malzemesinin alaşımı % 0.15 C, % 1.25 Mn, % 1 Si, % 13 Cr, % 0.04 P, % 0.03 S şeklindedir. Disklerin yüzeyinde pürüzlülük ölçümleri yapılarak standart pürüzlülük parametreleri elde edilmiştir. Pürüzlülük profillerinden ortalama tepe yuvarlaklık yarıçapı Rav sayısal analizle hesaplanmıştır. Disk yüzeylerinin optik mikrofotoğrafları çekilmiştir. Deneyler sonucunda, ekstrüzyon PA 6'nın karşı yüzeyde sürekli bir transfer filmi oluşturduğu, eksenel Ra = 0-1.5 mm aralığında aşınma hızının arttığı, 1.5-3 mm aralığında ise aşınma hızının azaldığı görülmüştür. Ayrıca karşı yüzeyin Ra = 0-1 μm aralığında, transfer filmi oluşumu sebebiyle, aşınma hızının Rav ile değişiminin Hollander ve Lancaster'in yorulma aşınması modeline uymadığı tespit edilmiştir. Deney sonuçlarının, eksenel Ra = 1-3 mm aralığında, polimerin kopma mukavemeti, sürtünme katsayısı ile abrazif aşınma hızı arasında bir bağıntı veren abrazif aşınma modeline uyduğu görülmüştür. Anahtar Kelimeler: Aşınma, polimer, yüzey pürüzlülüğü, yorulma, abraziv aşınma. 
A new approach to modelling gamma-ray burst afterglows: using Gaussian processes to account for the systematics
A new approach to modelling γ-ray burst afterglows: Using Gaussian processes to account for the systematics
The afterglow emission from gamma-ray bursts (GRBs) is a valuable source of
information to understand the physics of these energetic explosions. The blast
wave model has become the standard to describe the evolution of the afterglow
emission over time and frequency. Thanks to recent developments in the theory
of afterglows and numerical simulations of relativistic outflows, we are able
to model the afterglow emission with realistic dynamics and radiative
processes. Although the models agree with observations remarkably well, the
afterglow emission still contains additional physics, instrumental systematics,
and propagation effects which make the modelling of these events challenging.
In this work, we present a new approach to modelling GRB afterglows, using
Gaussian processes (GPs) to take into account systematics in the afterglow
data. We show that, using this new approach, it is possible to obtain more
reliable estimates of the explosion and microphysical parameters of GRBs. We
present fit results for 5 long GRBs and find a preliminary correlation between
the isotropic energetics and opening angles of GRBs, which confirms the idea of
a common energy reservoir for the kinetic energy of long GRBs.Comment: Accepted to MNRAS. 10 pages, 5 figure
Laboratory performance of x-ray detector on 2U cubesat beeaglesat
A CdZnTe based semiconductor X-ray detector (XRD) and its associated readout electronics has been developed by the Space Systems Design and Testing Laboratory of Istanbul Technical University and the High Energy Astrophysics Detector Laboratory of Sabanci University along with an SME partner. The XRD will be the secondary science mission on board BeEagleSat, which is developed as one of the double CubeSats for the QB50 project. QB50 is a European Framework 7 project carried out by a number of international organizations led by the von Karman Institute of Belgium.
The heart of the XRD is a 2.5 mm thick, 15 mm x 15 mm CdZnTe crystal with orthogonal electrode strips on top and bottom for position resolution on the crystal. There are 3 sets of steering electrodes in between anodes. A
commercial off the shelf (COTS) high voltage source provides necessary potential difference to transport electrons and holes towards electrodes. The signals from each strip are read by a COTS ASIC, RENA-3b, controlled my MSP
430. The XRD board (single ~10 cm x 10 cm board) also carries the necessary power regulators and 7 COTS batteries. In a previous paper presented at the IAC 2014, we discussed the main design of the XRD and provided results from some of the early vibration tests of the mechanical design. At the time, the CdZnTe crystal has not been attached, and the readout electronics and software were still in development phase. In this paper, we present the laboratory performance of the electronic readout system and discuss the current phase of the XRD development
Infection dynamics of Theileria annulata over a disease season following cell line vaccination
Tropical theileriosis is a tick-borne haemoparasitic disease of cattle caused by the protozoan parasite Theileria annulata. Globally, the economic impact of the disease is immense and enhanced control measures would improve livestock production in endemic regions. Immunisation with a live attenuated vaccine is an effective and widely used control method, however, the repeated use of live vaccines may have an impact on the field parasite population at a genetic level. Additionally, there has been an increasing number of reports of vaccine breakthrough cases in recent years. Thus, the present study was designed to evaluate the genetic composition of a parasite population over a disease season in a locality where live cell line vaccination is practised. A diverse range of parasite genotypes was identified and every T. annulata positive cattle blood sample harboured multiple parasite genotypes. An alteration in the major genotype and an increasing multiplicity of infection in individual animals was observed over the course of the disease season. Vaccination status was found not to effect within-host multiplicity of infection, while a significantly higher number of genotypes was detected in grazed cattle compared to non-grazed ones. A degree of genetic isolation was evident between parasite populations on a micro-geographic scale, which has not been reported previously for T. annulata. Analysis of parasite genotypes in vaccinated animals suggested only a transient effect of the vaccine genotype on the genetic diversity of the T. annulata population. The vaccine genotype was not detected among clones of two vaccine ‘breakthrough’ isolates and there is no suggestion that it was responsible for disease. The obtained data indicated that in the system studied there is no apparent risk of introducing the vaccine genotype into the population with only a transient effect on the genetic diversity of the parasite population during the disease season
Development and in orbit testing of an x ray detector within a 2U cubesat
A CdZnTe based semiconductor X-ray detector (XRD) and its associated readout electronics is developed by the Space Systems Design Laboratory of Istanbul Technical University and High Energy Astrophysics Detector Laboratory of Sabanci University along with an SME partner. The detector will utilize 30 orthogonal cross strip electrodes (and 3 steering electrodes in between anodes) whose geometry is optimized by an extensive set of simulations and energy resolution measurements. The signals will be read by RENA 3b ASIC controlled by MSP 430 microcontroller. The system will have its own battery and will be turned on intermittently due to power constraints. CdZnTe based X-ray detectors have been utilized in space, but they are either pixellated (NuStar), or they consist of many individual crystal pieces (BAT in Swift satellite). The aim of the XRD is to show that large volume crystals with orthogonal strips are viable alternatives, especially for small satellite systems with medium energy resolution requirement. XRD will also characterize the hard X-ray background in 20-200 keV at low Earth orbit conditions as a function of altitude. Due to power and telemetry constraints, the individual events will be corrected for hole trapping on-board, histogrammed, and only the X-ray spectra will be transmitted to the ground station along with a small set of raw data for diagnostic purposes.
The XRD is planned to travel into space, as a secondary science mission, on board BeEaglesat which is a 2U CubeSat developed as one of the possible double (2U) CubeSats for the QB50 project. QB50 is a European Framework 7 (FP7) project carried out by a number of international organizations led by the von Karman Institute of Belgium. Its main scientific objective is to study in situ the temporal and spatial variations of a number of key constituents and parameters in the lower thermosphere with a network of about 50 double and triple CubeSats, separated by few hundred kilometers and carrying a determined set of sensors
Soil fertility evaluation based on the sugeno fuzzy logical model
With the improvement of soils, the productivity of agricultural crops and the efficiency of mineral fertilizers increase;though for individual types of fertilizers the changes take different ways. In different types of soil, different interactions between soil and fertilizersare observed;variouscrop varieties react differently to them, because each variety was bred under one of these interaction conditions, and its influence is phenotypically fixed in it. It was established that the fertility of different types of soils is quantitatively best characterized bystored soil moisture, bulk density, and it is closely related to such generally recognized fertility components as the amount of humus, nitrogen, phosphorus, etc. The main aim of the article is to build a Sugeno fuzzy logical model for assessing soil fertility
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