Inherent stability of central element coaxial liquid-liquid injectors

Most TRW liquid bi-propellant rocket engines built over the past thirty-plus years have employed a central element coaxial pintle injector and have operated with liquid/liquid propellant injection. This injector is a patented design exclusive to TRW and has unique features that make the rocket engine combustion characteristics different from those of other types of injector engine designs. Its many benefits include excellent combustion performance, efficient deep throttling, adaptability to low cost manufacturing, and high reliability. Approximately 200 pintle injector engines of various sizes and operating on a variety of propellants have been flown without a single inflight failure. An especially important feature of the pintle injector engine is its apparent inherent combustion stability. In over thirty years of development, testing, and production, TRW has never experienced combustion instability in any of its pintle injector engine designs. This has been true of engines operating over a range of thrust from 5 to 250,000 lbs. on earth-storable hypergolic propellants and a large number of smaller engines operating on a variety of propellants (21 combinations) in long duration-firing, pulsing (down to 2 msec), and deep throttling (as much as 19:1) modes. Operating chamber pressures have ranged from 10 to 3,500 psia. This record is particularly impressive given that typical TRW design practice does not consider combustion instability as an issue and no pintle engine has ever employed stability-enhancing features, such as baffles or acoustically resonant chambers. In spite of this, TRW engines have operated stably in regimes not possible with other types of injectors. Various physical explanations and combustion process models for this favorable stability characteristic have been postulated. However, a definitive study that unequivocally establishes the important stabilizing mechanisms still remains to be conducted

Utilizing Structure Property Correlations to Predict and Analyze Two Derivatives of an Ampicillin Homologous Series

Structure Property Correlation methods such as regression analysis and pattern recognition are applied to predict the molecular properties of two members of an ampicillin homologous series. The pentyl and hexyl esters of ampicillin are also evaluated for their similarity to other penicillins by use of multiple regression, contingency tables, cluster analysis, correspondence analysis, self organizing tree algorithms, factor analysis, principal component analysis, box plots, and other graphing methods. Other members of the homologous series include methyl, ethyl, propyl, and butyl esters of ampicillin which have been previously synthesized and tested in tissue culture against Escherichia coli. All of the tested esters of ampicillin significantly inhibited penicillin susceptible and ampicillin resistant bacteria, as well as streptomycin resistant bacteria. Drug homologous series has been observed with other antibiotics and medicinal compounds. Homologous series activity is a trend observed for ampicillin by graphing the reciprocal equi-effective concentrations versus the number of carbons comprising the ester group. Regression analysis and contingency tables predict the molecular properties of the hexyl and pentyl esters, while cluster analysis, factor analysis, correspondence analysis, principal component analysis, and tree algorithms correlate them to the parent ampicillin and other members of the ß - lactam class of antibiotics. This work demonstrates the effectiveness of applying numerical analysis methods to drug design and development

Incentivized Torts: An Empirical Analysis

Courts and scholars assume that group causation theories deter wrongdoers. This Article empirically tests, and rejects, this assumption, using a series of incentivized laboratory experiments. Contrary to common belief and theory, data from over 200 subjects show that group liability can encourage tortious behavior and incentivize individuals to act with as many tortfeasors as possible. We find that subjects can be just as likely to commit a tort under a liability regime as they would be when facing no tort liability. Group liability can also incentivize a tort by making subjects perceive it as fairer to victims and society. These findings are consistent across a series of robustness checks, including both regression analyses and nonparametric tests. We also test courts’ and scholars’ insistence that the but-for test fails in cases subject to group causation. We use a novel experimental design that allows us to test whether, and to what extent, each individual’s decision to engage in a tortious activity is influenced by the decisions of others. Upending conventional belief, we find strong evidence that the but-for test operates in group causation settings (e.g., concurrent causes). Moreover, across our experiments, subjects’ reliance on but-for causation produced the very tort that group liability attempted to discourage. A major function of liability in torts, criminal law, and other areas of the law is to deter actors from engaging in socially undesirable activities. The same is said about doctrines that result in group liability. Our empirical results challenge this basic logic

Using Focus Groups and Correspondence Analysis to Explore the Relationship Between Millennials\u27 Online Behavior and Their Opinions of Online Reviews

Consumer decision-making regarding a purchase is usually influenced by feedback received from other people in addition to prior experiences/beliefs/attitudes and marketer dominated information. Such diverse sources of influence are collectively referred to as the influence mix (Simonson and Rosen 2014). Of the different sources in the influence mix, word-of-mouth (i.e., feedback received from other people) is one of the most impactful sources of information (Duan, Gu, and Whinston 2008). With the advent of e-tailers on the Internet, the influence of word-of-mouth communication has grown significantly in the form of online consumer reviews (Schindler ad Bickart 2012). Research has shown that online reviews significantly influence consumer purchase decisions (see, for example, Chevalier and Mayzlin 2006; Senecal and Nantel 2004). Further, according to Zhu and Zhan (2010), 24% of Internet consumers avail themselves of online reviews before buying an offering offline; additionally, the authors note that an increasing number of firms persuade consumers to spread word of their offerings online

Processing and Transmission of Information

Contains reports on three research projects

Do Social Connections and Hope Matter in Predicting Early Adolescent Violence?

We tested relationships between social connections, hope, and violence among young adolescents from socially distressed urban neighborhoods, and examined whether relationships between adolescents' family and school connectedness and violence involvement were mediated by hopefulness. Data were from middle school students involved in the Lead Peace demonstration study. The sample (N = 164) was 51.8% female; 42% African American, 28% Asian, 13% Hispanic, and 17% mixed race or other race; average age was 12.1 years; 46% reported physical fighting in the past year. In multivariate models, parent‐family connectedness was protective against violence; school connectedness was marginally protective. Hopefulness was related to lower levels of violence. The relationship between school connectedness and violence was mediated by hopefulness; some evidence for mediation also existed in the family‐parent connectedness and violence relationship. Findings warrant continued exploration of hopefulness as an important protective factor against violence involvement, and as a mediator in relationships between social connections and violence involvement.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116982/1/ajcp9387.pd

Energy cost reduction opportunities

Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; in conjunction with the Leaders for Global Operations Program at MIT, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 46-48).Company X uses large amounts of electricity in its manufacturing operations. Electricity prices at selected plants in the company's Region 1 territory rose by over 350% between 2000 and 2011, in part due to increasing reliance on high-cost fossil fuels. A focus on reducing these costs has identified numerous energy-saving projects in recent years, but with mixed implementation and performance results between the different plants in the region. Consequently, there is both a need to reduce exposure to high electricity prices and an opportunity to better share best-use practices between plants. This paper has two focuses: identifying and quantifying energy cost-reduction opportunities, and mapping the value-streams for the decision-making and implementation process for energy savings projects. From this Value Stream Map, recommendations are made for a new process that can be standardized and rolled out to other sites in the region. During the first phase of the project, data gathered from utility bills, power meters, and production records are used to identify the best opportunities for energy reduction within the plants. Using this technique, 7 GWh/year of potential energy cost savings are identified via reduced downtime, lighting motion detectors, high-efficiency lighting, and negotiable changes to energy contracts. For the benchmarking phase, the historical record of identified energy projects is compared with the number of projects actually implemented. An observational study of the local LEAN team from one plant is combined with interviews of engineers, managers, and financial analysts to build a process map of both the current and former processes for energy project identification, evaluation, and implementation. The results show a reduction in process steps and a step-change increase in the number of energy projects implemented. A key feature of the new approach is the creation of a dedicated energy team within the existing LEAN program. It is believed that emulating this integration of energy and LEAN at other sites will yield cost reductions as well. To follow up this work, a pilot study modeling this program at another site is recommended before further expansion to the rest of the region.by Steven J. Stoddard.S.M.M.B.A

Impaired object tracking in children with chromosome 22q11.2 deletion syndrome

Background: Chromosome 22q11.2 Deletion Syndrome (22q11.2DS) occurs in approximately 1:4,000 live births with a complex and variable presentation that includes medical, socioemotional and psychological symptoms with intellectual impairment. Cognitive impairments in spatiotemporal and visuospatial attention have also been reported. However, maintenance of selective attention to dynamic and interacting objects has not been systematically investigated in children with 22q11.2DS. Methods: We used a multiple object tracking task to assay capacity and resolution performance of children with 22q11.2DS aged 7 to 14 years versus age-matched typically developing (TD) peers. Results: Children with 22q11.2DS but not TD children demonstrated impaired performance when task demands increased due to an increase in the number of targets presented, but not from an increase in object speed. Task performance in children with 22q11.2DS was also unrelated to intelligence or measures of attention deficit hyperactivity disorder. Conclusions: These findings suggest that children with 22q11.2DS may be particularly susceptible to dynamic crowding of objects with increasing cognitive demands related to monitoring multiple targets reflecting a reduced acuity in spatiotemporal cognitive representation