Effects of block shape and inclination on the stability of melange bimrocks

Bulletin of Engineering Geology and the Environment - A wide range of heterogeneous geological units composed of strong rock blocks enclosed in a bonded matrix of fine texture exists worldwide....     

Optimal classification methods for diagnosing latent skills and misconceptions for option-scored multiple-choice item quizzes

Behaviormetrika - The paper’s extended Diagnostic Classification Modeling setting assumes (a) nominal item (question) coding, thus including multiple-choice (MC) items, and (b)...     

A short term −12° head down tilt does not mimic microgravity in terms of human gonadal function

A significant reversible decrease in testosterone (T) has been associated with microgravity in male rodents and humans. Urinary T excretion increases in primates under hypergravity. Hypogonadism is somehow related to abnormally high levels of leptin (L), a hormone produced by the adipose tissue which has been found to increase under microgravity simulation conditions like head down bed rest (HDBR). The aim of this study was to assess hemodynamic and pituitary-adrenal and -gonadal adaptation to an acute HDBR test to be eventually used on a routine basis to get better prepared to next space flights. The Authors performed a 1 hour ?12° HDBR in 6 male and 6 female volunteers who underwent heart rate and blood pressure measurement together with a blood draw three times at 30 min intervals from the start to the end of the test for L, T, estradiol (E₂), LH, androstenedione (A), cortisol (F), ACTH. 12 age- and sexmatched control subjects followed the same protocol except for keeping the sitting position all the time. According to the ANOVA for repeated measures, no changes occurred in L, T, E₂ or LH whereas A, F and ACTH significantly decreased independently of gender. During HDBR systolic blood pressure decreased in both genders, diastolic blood pressure decreased significantly only in men and HR showed a more clear-cut decrease in women than in men. As a conclusion, such an acute steep-slope HDBR protocol may be efficiently used to testing immediate individual haemodynamic or adrenal response to microgravity but is not suitable for studies concerning gonadal adaptation.     

几种铜带轧制润滑剂的性能评价与研究

对收集到的７种国内外铜带轧制润滑剂进行了基础性能测试，并对其工艺使用性能进行了评价研究，其结果将为有关工厂润滑剂的选用与研制提供一些依据。     

Load modeling at electric power distribution substations using dynamic load parameters estimation

This paper is focused on electric power distribution substations load modeling using dynamic load parameters estimation. The load parameters are estimated using two models: the exponential and the ZIP load models. Since the load bus voltage and parameters are known one can determine the active and reactive power injections of this bus and include these pseudo-measurements in the state estimation in order to improve observability and estimation accuracy. The dynamic parameter estimation is developed using the weighted least squares method in a recursive form and the tests are carried out based on actual measurements. It is shown that the estimated parameters (for both load models) at a distribution substation are valid, since the obtained active and reactive power residuals are very close to zero.     

Effect of chitosan and Dysphania ambrosioides on the bone regeneration process: A randomized controlled trial in an animal model

The focus of this triple‐blind study was on evaluating the effect of chitosan combined with Dysphania ambrosioides (A) extract on the bone repair process in vivo. In total, 60 male Wistar rats (Rattus norvegicus albinus) weighing between 260 and 270 g were randomly selected for this study and distributed into four groups (n = 15). Group C (chitosan), Group CA5 (chitosan + 5% of D. ambrosioides), Group CA20 (chitosan + 20% of D. ambrosioides), and Group CO (Control‐Blood clot). In each animal, bone defects measuring 2 mm in diameter were performed in both tibias for placement of the substances. After 7, 15, and 30 days, the animals were sedated and sacrificed using the cervical dislocation technique and the tissues were analyzed under optical microscope relative to the following events: inflammatory infiltrate, necrosis, osteoclasts, osteoblasts, fibroblasts, periosteal, and endosteal bone formation. The data were evaluated to verify distribution using the Kolmogorov–Smirnov test, and variance, using the Levene test; as distribution was not normal, data were subjected to the Kruskal–Wallis and Dunn nonparametric tests (p < .05). A significant inflammatory infiltrate was observed in Group CA5 (p = .008) in the time interval of 7 days, and in Group C at 15 (p = .009) and 30 (p = .017) days. Osteoblastic activity was more significant in Group CA20 (p = .027) compared with CA5 in the time interval of 7 days. Group CA20 demonstrated a significantly higher endosteal and periosteal bone formation value in the time interval of 7 (p = .013), 15 (p = .004), and 30 days (p = .008) compared with the other groups. The null hypothesis was refuted, bone regeneration was faster in spheres with an association of chitosan and 20% extract, and complete bone repair occurred clinically at 15 days and histologically at 30 days. The spheres proved to be a promising method for the biostimulation of alveolar bone repair and bone fractures.     

基于弯曲板波的延迟线振荡器的ANSYS仿真

针对复合板结构中弯曲板波谐振频率计算相对复杂的问题,建立并分析了基于弯曲板波延迟线振荡器的理论模型,计算得到A0(0阶反对称)模式板波的谐振频率为41 MHz;为了验证理论分析的结果,利用有限元软件ANSYS建立了基于弯曲板波的延迟线振荡器的3D有限元模型,并对其进行了谐响应分析以及瞬态动力学分析。谐响应分析得到A0模式的谐振频率为37.2 MHz,与理论计算结果的相对误差为9.3%;瞬态动力学分析得到A0模式的谐振频率为39.1 MHz,与理论计算结果的相对误差为4.6%。计算和仿真为基于弯曲板波的延迟线振荡器的结构设计提供了重要的依据。     

Performance of direct carbon fuel cell

A direct carbon fuel cell (DCFC) is a variation of the molten carbonate fuel cell (MCFC) which converts the chemical energy of carbon directly into electrical energy. Thus, the energy conversion efficiency is very high and correspondingly CO₂ emission is very low for given power output. DCFC as a high temperature fuel cell performs better at elevated temperatures (>800 °C) but because of the corrosive nature of the molten carbonates at elevated temperatures the degradation of cell components becomes an issue when DCFC is operated for an extended period of time.We explored the DCFC performance at lower temperatures (at 700 °C and less) using different sources of carbon, different compositions of electrolytes and some additives on the cathode surface to increase catalytic activity. Experiments showed that with petroleum coke as a fuel at low temperatures the ternary eutectic (43.4 mol % Li₂CO₃ - 31.2 mol% Na₂CO₃ - 25.4 mol % K₂CO₃) spiked by 20 wt % Cs₂CO₃ performed better than any binary or ternary eutectics described in the published work by other researchers. Maximum power output achieved at 700 °C was 49 mW/cm² at a current density of 78 mA/cm² when modified cathode was fed with O₂/CO₂ gases.     

The Creation of Play Spaces in Twentieth-century Amsterdam: From an Intervention of Civil Actors to a Public Policy

This case study uncovers a turning point in the production of play space in Amsterdam. Whereas over the first half of the twentieth century the creation of play spaces used to be the primary responsibility of the Amsterdam civil society, this situation started to change after the Second World War. Between 1947 and 1970, the Amsterdam Urban Planning Department created over 700 public play spaces. These spaces were little niches in the urban public domain, specifically designed and constructed to enable city children's play. This remarkable change from a predominantly private to a public intervention, is explained through a rapid increase of the number of children (the post-war baby-boom), the existence of the General Extension Plan (AUP) with its detailed age specific approach and the fruitful collaboration between powerful urban planners and politically dominant socialist politicians.