Some effects of cyclic induced deformation in rocket thrust chambers

A test program to investigate the deformation process observed in the hot gas wall of rocket thrust chambers was conducted using three different liner materials. Five thrust chambers were cycled to failure using hydrogen and oxygen as propellants at a chamber pressure of 4.14 MN/m square (600 psia). The deformation was observed nondestructively at midlife points and destructively after failure occurred. The cyclic life results are presented with an accompanying discussion about the types of failure encountered. Data indicating the deformation of the thrust chamber liner as cycles are accumulated are presented for each of the test thrust chambers

Some effects of thermal-cycle-induced deformation in rocket thrust chambers

The deformation process observed in the hot gas side wall of rocket combustion chambers was investigaged for three different liner materials. Five thrust chambers were cycled to failure by using hydrogen and oxygen as propellants at a chamber pressure of 4.14 MN/cu m. The deformation was observed nondestructively at midlife points and destructively after failure occurred. The cyclic life results are presented with an accompanying discussion about the problems of life prediction associated with the types of failures encountered in the present work. Data indicating the deformation of the thrust chamber liner as cycles are accumulated are presented for each of the test thrust chambers. From these deformation data and observation of the failure sites it is evident that modeling the failure process as classic low cycle thermal fatigue is inadequate as a life prediction method

An evaluation of oxygen-hydrogen propulsion systems for the Space Station

Conceptual designs for O2/H2 chemical and resistojet propulsion systems for the space station was developed and evaluated. The evolution of propulsion requirements was considered as the space station configuration and its utilization as a space transportation node change over the first decade of operation. The characteristics of candidate O2/H2 auxiliary propulsion systems are determined, and opportunities for integration with the OTV tank farm and the space station life support, power and thermal control subsystems are investigated. OTV tank farm boiloff can provide a major portion of the growth station impulse requirements and CO2 from the life support system can be a significant propellant resource, provided it is not denied by closure of that subsystem. Waste heat from the thermal control system is sufficient for many propellant conditioning requirements. It is concluded that the optimum level of subsystem integration must be based on higher level space station studies

Space station propulsion analysis study

This paper summarizes the impacts on the weight, volume and power usage of a manned space station and its 90-day resupply for three integrated, auxiliary propulsion subsystems. The study was performed in coordination with activities of the Space Staton Concept Development Group (CDG). The study focused on three space station propulsion high-low thrust options that make use of fluids that will be available on the manned space station. Specific uses of carbon dioxide, water and cryogen boiloff were considered. For each of the options the increase in station hardware mass and volume to accommodate the dual thrust option is offset by the resupply savings, relative to the reference hydrazine system, after one to several resupplies. Over the life of the station the savings in cost of logistics could be substantial. The three options are examples of alternative technology paths that, because of the opportunity they provide for integration with the environmental control life support system (ECLSS) and OTV propellant storage systems, may reduce the scarring which is required on the early station to meet the increasing propulsion requirements of the growth station

Same Environment, Stratified Impacts? Air Pollution, Extreme Temperatures, and Birth Weight in South China

This paper investigates whether associations between birth weight and prenatal ambient environmental conditions—pollution and extreme temperatures—differ by 1) maternal education; 2) children’s innate health; and 3) interactions between these two. We link birth records from Guangzhou, China, during a period of high pollution, to ambient air pollution (PM10 and a composite measure) and extreme temperature data. We first use mean regressions to test whether, overall, maternal education is an “effect modifier” in the relationships between ambient air pollution, extreme temperature, and birth weight. We then use conditional quantile regressions to test for effect heterogeneity according to the unobserved innate vulnerability of babies after conditioning on other confounders. Results show that 1) the negative association between ambient exposures and birth weight is twice as large at lower conditional quantiles of birth weights as at the median; 2) the protection associated with college-educated mothers with respect to pollution and extreme heat is heterogeneous and potentially substantial: between 0.02 and 0.34 standard deviations of birth weights, depending on the conditional quantiles; 3) this protection is amplified under more extreme ambient conditions and for infants with greater unobserved innate vulnerabilities

Teaching Nonsexist Language to College Students

Although psychologists have noted the importance of avoiding sexist language because of its potential role in transmitting sexism, little attention has been given to methods of teaching students of psychology to use nonsexist language. Two experiments were conducted to measure the effectiveness of teaching general Psychology students to use nonsexist language. In a pilot study (Experiment 1), undergraduates were exposed to a 20-minute lecture either on use of nonsexist language (experimental group) or on an unrelated topic (control group). No changes in use of sexist language in short essay responses were noted on the posttest or in a 2-week follow-up. In Experiment 2, the method of measuring sexist language was expanded by using three essay responses, and the procedure was repeated except that a second independent variable was added: Students were instructed either in lecture format or with an interactive computer program. The method of presentation showed no effect, but the group receiving training about nonsexist language used less sexist language on one of the three essay questions. Interpretations and implications of the findings are discussed

Does Sexist Language Reflect Personal Characteristics?

We investigated whether or not sexist language in written form can be linked to traditional views of sex roles, assertiveness, psychological androgyny, Christian beliefs, or sexist language in oral form. In Experiment 1, undergraduates were given an essay designed to test written sexist language and several pencil-and-paper personality inventories. No relationship between sexist language and interpersonal assertiveness or psychological androgyny was found. However, those who avoided sexist language were less traditional in their sex role perceptions scored lower on a scale of Christian beliefs. In Experient 2, the method of measuring sexist language was expanded by using three essay responses and a brief oral interview. Those who used sexist language in written form were more likely than others to use sexist language in oral form on some responses. Interpretations and implications of the fmdings are discussed

An Empirical Study of Scoring Methods for the Conover Driving Attitude Inventory

The measurement of driving attitudes has followed in the wake of various studies and statistical data indicating that improper attitudes are responsible for an unduly high percentage of accidents. Certain of these tests have limitations, one of which is an economical method of scoring. Conover (Conover, 1947) used a scoring method such that the values 0, 1, 2, 3, 4, are assigned respectively to the responses designated as; most displeasing, displeasing, indifferent, pleasing, and most pleasing, for the positive items, and to avoid negative scores the values 4, 3, 2, 1, 0, are assigned respectively to the same responses; most displeasing, displeasing, indifferent, pleasing, and very pleasing, on the negative items. Summing the positive items according to the values given and the negative items by the reverse scoring system, the score for an individual is obtained. The Conover Driving Attitude Inventory is designed to measure the attitudes of individuals toward factors shown to be important in safe driving. An individual\u27s attitude toward specific factors, as indicated by his response to the items of the scale may be considered to constitute his attitude toward safe driving in general. In other words it is a test of one\u27s reactions to everyday driving experiences while behind the wheel. One-hundred fifty items make up the scale, thirty-five of which are considered positive items, thirty negative, and the remaining eighty-five are considered as fillers

Aplikasi Marka Ssr Pada Keanekaragaman Genetik Durian (Durio Zibethinus Murr.) Di Kabupaten Deli Serdang, Sumatra Utara

Kabupaten Deli Serdang merupakan salah satu kontributor untuk produksi durian (Durio zibethinus Murr.) Provinsi Sumatra Utara. Durian Deli Serdang memiliki varietas yang banyak dikenal di pasar buah domestik, diantaranya; Bintana, Ginting, dan Sikapal. Pada penelitian ini, dilakukan analisis keanekaragaman genetik pada durian asal Deli Serdang untuk memperoleh informasi keragaman genetik dan hubungan antar aksesi dengan menggunakan 6 lokus Simple Sequence Repeats (SSR). Hasil menunjukkan bahwa 9 aksesi durian yang dikoleksi dari Kabupaten Deli Serdang berhasil diamplifikasi dan bersifat polimorfik. Hal ini dibuktikan dengan hasil visualisasi lokus SSR yang menghasilkan 23 fragmen DNA berukuran 72-255 bp yang didapat melalui bantuan piranti lunak GeneMarker V2.6.7. Hasil penelitian juga menampilkan konstruksi dendogram yang menunjukkan kemiripan antar aksesi durian Deli Serdang yang didapat melalui bantuan perangkat lunak NTSYSpc V2.0.2. Susunan antar aksesi pada pohon dendogram terlihat menyerupai pohon filogenetik, aksesi terpisah dan menyebar pada koefisien 0,54-0,95 yang tidak dipengaruhi oleh sebaran geografis. Data ini dapat menjadi dasar penelitian budidaya dan konservasi buah durian di Indonesia khususnya di Sumatra Utara

The Asian Games, Air Pollution and Birth Outcomes in South China: An Instrumental Variable Approach

We estimate the causal effects of air pollution exposure on low birthweight, birthweight, and prematurity risk in South China, for all expectant mothers and by maternal age group and child sex. We do so by exploiting exogenous improvement in air quality during the 2010 Guangzhou Asian Games, when strict regulations were mandated to assure better air quality. We use daily air pollution levels collected from monitoring stations in Guangzhou, the Asian Games host city, and Shenzhen, a nearby control city, between 2009 and 2011. We first show that air quality during the Asian Games significantly improved in Guangzhou, relative to Shenzhen. Further, using birth-certificate data for both cities for 2009 to 2011 and using expected pregnancy overlap with the Asian Games as an instrumental variable, we study the effects of three pollutants (PM10, SO2, NO2) on birth outcomes. Results show that 1) air pollutants significantly reduced average birthweight and increased preterm risk; 2) for birthweight, late pregnancy is most sensitive to PM10 exposure, but there is not consistent evidence of a sensitive period for other pollutants and outcomes; 3) for birthweight, babies of mothers who are at least 35 years old show more vulnerability to all three air pollutants; and 4) male babies show more vulnerability than female babies to PM10 and SO2, but birthweights of female babies are more sensitive than those of male babies to NO2