Effect of limited statistics on higher order cumulants measurement in heavy-ion collision experiments

We have studied the effect of limited statistics of data on measurement of the different order of cumulants of net-proton distribution assuming that the proton and antiproton distributions follow Possionian and Binomial distributions with initial parameters determined from experimental results for two top center of mass energies ($\sqrt{s_{\mathrm{NN}}}=200$ and $62.4$ GeV) in most central ($0-5$%) Au$+$Au collisions at Relativistic Heavy Ion Collider (RHIC). In this simulation, we observe that the central values for higher order cumulants have a strong dependence on event sample size and due to statistical randomness the central values of higher order cumulants could become negative. We also present a study on the determination of the statistical error on cumulants using delta theorem, bootstrap and sub-group methods and verified their suitability by employing a Monte Carlo procedure. Based on our study we find that the bootstrap method provides a robust way for statistical error estimation on high order cumulants. We also present the exclusion limits on the minimum event statistics needed for determination of cumulants if the signal strength (phase transition or critical point) is at a level of $5$% and $10$% above the statistical level. This study will help the experiments to arrive at the minimum required event statistics and choice of proper method for statistical error estimation for high order cumulant measurements.Comment: 14 pages, 16 figure

Shock-Induced Failure of Protection Materials using Laser-Driven Micro-Flyers

Protection materials in defense applications must withstand impacts that produce incredible forces and high strain rate deformations, yet remain light enough for use in personal or vehicle armor applications. Understanding the failure processes of these materials is crucial to improving their protection capacity, but experiments to probe these processes are complex. The conventional methods using explosive, gas or gunpowder-driven experiments are dangerous, expensive, and difficult, requiring large-scale facilities where experimental throughput is low. In this thesis, we attempt to achieve similar loading conditions (e.g. strain rates, shock stresses, energy density, etc.) with a high throughput apparatus: a laser-driven micro-flyer plate launcher.   Laser-driven micro-flyer plate (LDMFP) facilities use a short duration pulsed laser with high peak power to launch small metal foil flyers at velocities of several km/s by generating an ablation pressure behind the flyer. Here we describe the Hopkins Extreme Materials Institute LDMFP facility, including the launcher configuration, expected velocity envelope, and photon Doppler velocimetry (PDV) diagnostics. We interrogate the failure of magnesium alloys and boron carbide using the facility.   The widely available AZ31B Mg alloy has a potential application as a low-weight vehicle protection material. We use the LDMFP facility to drive incipient spall failure in AZ31B foils. In spall, shockwave interactions from the impact loading generate high tensile stresses within the target specimen, leading to failure through void growth, coalescence and fracture. Our experiments show an increase in spall strength when compared to lower strain rate spall experiments on the same alloy, and also show differences in strength based on the level of deformation in the as-received microstructure. The LDMFP apparatus facilitates specimen recovery by imparting little kinetic energy, so we perform micro-computed tomography scans of the preserved shocked specimens to learn the void distribution within.   Next, we demonstrate the LDMFP facility capability for high experimental throughput to learn the orientation dependent strength of a Mg-9 wt. % Al binary alloy. The binary alloy is prepared without second phase particles when fully solutionized, and with lath precipitates when warm-aged. The large number of experiments, coupled with numerical simulations, indicate a lack of orientation dependent strength in the solutionized sample, and significant orientation dependent strength in the precipitate-laden microstructure.    Finally, we use the LDMFP facility to examine brittle fragmentation of boron carbide, a lightweight ceramic used in personal body armor. We design the micro-flyer experiment to have a similar energy density as conventional ballistic experiments, and compare the resulting fragmentation statistics. The results suggest that fragment sizes from projectile impact are related to microstructural length scales for both ballistic and laser-driven loading conditions

Evaluating Product-Centric Continuous Improvements: Impact on Competitive Capabilities and Business Performance

Product-centric continuous improvements (CIs) are actions via which firms modify the design of a product after the start of its production and release into the market. Product-centric CIs are initiated to help build competitive capabilities and sustain competitive advantage throughout the product life cycle. This study complements the perspective pervasive in the extant literature that actions related to product-centric CIs can be disruptive to firms and be associated with negative performance consequences. It investigates a topic that is relatively much less researched, namely the upside potential of product-centric CIs. The empirical analysis is based on data collected from 144 plants in the United States representing process and discrete part manufacturing industries. Specifically, the study analyzes the impact of product-centric CIs on competitive capabilities and business performance. The results of the empirical analysis indicate the following: First, there exist two categories of product-centric CIs: (1) actions for quality improvement and (2) actions for cost reduction. Second, while there is a positive association between each type of CI and the intended competitive capability, there also is a trade-off—i.e., actions for quality improvement increase quality capability but reduce cost capability, and vice versa. Third, there is a strong linkage between business performance and quality capability, but not cost capability. All in all, the study presents empirical evidence that product-centric CIs have a significant impact on competitive capabilities related to quality and cost, and, in turn, have an impact on business performance. From the standpoint of practice, the study suggests that product-centric CIs should be managed to develop competitive capabilities and improve business performance

New Product Development: Impact of Project Characteristics and Development Practices on Performance

Concurrent product development process and integrated product development teams have emerged as the two dominant new product development (NPD) “best practices” in the literature. Yet empirical evidence of their impact on product development succes

Antecedents and Consequences of New Product Development Practices and Software Tools: An Exploratory Study

Many development practices and software tools enable new product development (NPD), yet few empirical studies shed light on the project characteristics and project contexts driving their use. Using a cross-sectional sample of NPD projects, this study examines how project characteristics and availability of information technology (IT) infrastructure relate to the use of NPD practices and software tools. We also examine how the extent of their use is associated with NPD project performance. The results indicate that different project characteristics influence the use of NPD practices and software tools, with project complexity associated with software tool use, but project uncertainty associated with NPD practice use. Also, customer facing IT infrastructure is associated with the use of NPD practices, while manufacturing plant IT infrastructure is associated with the use of design/validation software tools. Moreover, use of NPD practices has a positive association with all project-level performance metrics examined in this study, and as a result, a greater impact on overall market success. In comparison, the performance impacts of software tools appear relatively limited, with only design/validation software tools exhibiting a strong positive association with product performance quality and a weak positive association with time-to-market and responsiveness. Communication/teamwork software tools exhibit no such impact

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

A novel approach of high-voltage low-current electric energy input to synthesise cost-effective ultra-strong ductile material

Adopting a unique electrical circuit design, here we treat a significant low-cost engineering material (eutectoid steel not containing costly alloying elements) with a high-voltage (100 kV) low-current (150 mA) energy input (energy level exceeding cohesive energy). A distinctive structural evolution is ascertained with treatment duration of only 5 min as an outcome of lamellar fragmentation and matrix supersaturation. This envisages an origin of dispersed nano-sized hard cementite spheroids embedded in nano-thick martensite crystals of stratified-tile-morphology along with distributed α-ferrite regions containing sub-microscopic cementite particles of various shapes. Apart from the conjoint effect of nano-scale dispersion strengthening and martensitic strengthening overhauling the effect of conventional lamellar strengthening on a gross scale; high dislocation density and systematically arranged dislocations of similar sign at incoherent cementite particle-matrix interface provides a unique combination of ultra-high strength (UTS ∼ 1.5 GPa), significantly high specific strength (188 MPa/g cm−3) and large ductility (%Elongation = 20). Therefore, in terms of the adopted synthesis route, structural evolution and mechanical property achieved, a new dimension is hereby added to the next-generation material development so as to meet the ever increasing demand for low-cost structural application. In turn, we elucidate a fundamental conceptualization for the first time which exemplifies disproportionate atomic migration at highly incoherent nano-sized cementite particle-martensite matrix interface in steel under high-voltage low-current energy input, resulting in accumulation of dislocations of similar sign so as to significantly enhance strength along with retention of substantial ductility

Can Ego Defense Mechanism Help Explain IS Security Dysfunctional Behavior

IS security behavior studies are becoming popular. To date, much of the research has been based on theories such as the Theory of Planned Behavior, Technology Adoption Model, Rational Choice theory and Theory of Reasoned Action. They view users as rational individuals making conscious utilitarian decisions when there is increasing evidence that security breaches are the result of human behavior such as carelessness, malicious intent, bad habits, and hostility. We propose the ego defense mechanism model, taken from the psychoanalytical world. This model makes no assumption of rationality and has been developed to help understand the roots of dysfunctional behavior such as fear, phobias, anger, forgetfulness, indifference and hostility. Our model shows that security threats trigger anxiety among users and the ego react by both functional and dysfunctional behavior. This could be the earliest if not the first paper to explore user behavior in IS security situations using this framework