Solvent-drop assisted mechanochemical synthesis of the black and green polymorphs of the tetrathiafulvalene–chloranil charge transfer salt

This work describes the synthesis of the green and black polymorphic forms of the tetrathiafulvalene–chloranil (TTF–CA) charge transfer salt as pure phases, by solvent-assisted mechanochemistry. Both materials were characterized using laboratory and high-resolution X-ray powder diffraction (XRPD), elemental analysis and scanning electron microscopy (SEM). The high-resolution XRPD pattern of the TTF–CA black polymorph was indexed with a triclinic lattice a = 10.756(5) Å, b = 11.057(4) Å, c = 6.614(2) Å, α = 101.36(2)°, β = 93.69(3)°, γ = 89.37(3)°, V = 769.6(5) Å³. The chemical stability of these phases upon heating was investigated using thermogravimetric analysis (TGA), elemental analysis and X-ray powder diffraction (XRPD), indicating that both polymorphs undergo chemical decomposition, and ruling out the transition to an air-stable high temperature polymorph.     

Dynamic hybrid model of an electro-pneumatic clutch system

This paper deals with modelling an electro-pneumatic clutch system, which is used for medium- and heavy duty commercial vehicles. The mathematical model is built up for dynamic simulation, parameter estimation and control design/validation purposes, which is a phase of the design process of a new clutch system. These intended applications define the modelling goals and determine the modelling assumptions, which let one to reduce the model complexity. Since the model shows discrete–continuous behaviour, i.e. the model has hybrid properties, a nominal state domain or hybrid mode has been chosen for the sake of simplicity, where the model is continuous. In addition all the cases are given systematically, where the model has discrete transients. The model is constructed on the basis of the conservation principles such as mass, energy, momentum and magnetic linkage conservation and it is provided with constitutive equations to get a solvable set of equations. This final collection is then transformed into state space form for the given applications above. The verification of the developed model is carried out using extensive simulations against engineering perception and operation experience on the qualitative behaviour. Then for validation purposes the outputs of the model are compared to measurements on the real system to give a quantitative performance index about the model accuracy. Since for model-based controller design the developed model is too complex it should be simplified. Hence possible model reduction methods are proposed, which omit all details that are weakly represented in the state variables/outputs and not coupled with the control aims.     

安全仪表系统的网络安全考虑：最先还是最后？

对于完整的控制和安全系统，建立强大的防护体系是否是一项可以确保安全仪表系统商业连续性的必要投资？     

Performance measures,performance limits and optimal PI control for the IPDT plant

This paper considers PI controller tuning for the Integral Plus Dead Time (IPDT) plant subject to constraints on tolerable deviations from ideal shapes and guaranteeing minimal combined IAE (Integral of Absolute Error) measure composed of weighted IAE values of the setpoint and disturbance step responses. As the ideal responses at the plant output, monotonic (MO) transients are chosen. This implies one-pulse (1P) responses consisting of two monotonic intervals at the plant input. Optimal nominal tunings for the most important situations regarding the servo/regulation trade-off are determined by the newly developed Matlab/Simulink tool based on the performance portrait (PP) method. Generated results confirm Pareto-like limits of performance achievable under PI control and are used in classifying traditional tuning approaches into the setpoint and disturbance oriented ones. Principles of robust PP based tuning are briefly illustrated and conditions of invariance of the closed loop performance against the dead time uncertainty are formulated and checked by simulation.     

Determinants of sexual and dating behaviors among adolescents.

Data on sexual behavior were obtained from 183 male and 193 female 12–18 yr olds, selected from 3 birth cohorts using a stratified random sample. Eight latent constructs—sexual and dating involvement, self-acceptance, feminist sex-role attitudes, deviant social network, importance of dating, lack of heterosexual competence, sexually active social network, and stressful change events—were hypothesized to explain the variance in 26 observed variables. Several causal models were tested that specified structural relationships among the latent constructs. A theoretically meaningful model was arrived at that linked the 8 error-free factors. This model indicates that dating and sexual involvement was a direct function only of the importance of dating, which in turn was positively related to self-acceptance and stressful changes and negatively related to lack of heterosexual competence. (52 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive motivations for drug use among adolescents: Longitudinal tests of gender differences and predictors of change in drug use.

Four factors were found to reflect 15 reasons for drug use, Enhance Positive Affect and Creativity, Reduce Negative Affect, Social Cohesion, and Addiction. These factors were found to reflect second-order latent factors of Alcohol Motivations as well as Cannabis Motivations and to be invariant by sex. All Alcohol and Cannabis Motivation scales were significantly correlated with actual use of alcohol, cannabis, cocaine, and hard drugs. In both bivariate and latent variable longitudinal analyses over a 1-yr period, motivations for alcohol use increased actual use of alcohol, whereas motivations for cannabis use increased all types of drug use. Very similar patterns of effects were noted for boys and girls. We conclude that self-acknowledged cognitive motivations or reasons for drug use are important etiological factors in understanding actual drug-use behavior and discuss the counseling and prevention implications of these results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Simple minitheories of love.

Developed 2 causal models of love as alternatives to the A. Tesser and D. L. Paulhus (see record 1978-21448-001) theory. These models were tested for adequacy of fit using maximum-likelihood methods. While the Tesser-Paulhus models can be rejected empirically, the alternate models provide acceptable statistical representations of 4 variables measuring love at 2 times separated by 2 wks. One formulation is based on the idea of unidimensionality of interpersonal attraction. The 2nd formulation represents a refinement of the Tesser-Paulhus view of love. The formulation based on the idea that interpersonal attraction is primarily a unidimensional construct provides the more parsimonious and interpretable theory. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the usefulness of latent variable causal modeling in testing theories of naturally occurring events (including adolescent drug use): A rejoinder to Martin.

Replies to J. A. Martin's (see record 1983-06984-001) criticism of the present authors' (see record 1981-32589-001) methodology and conclusions. It is stated that Martin's criticisms are the result of misreading the present authors' paper and citations, whereas other criticisms were discussed in the original paper and resolved through alternate forms of data analysis. Further analyses are presented to address issues raised by Martin, and arguments against latent variable models are refuted. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Depression, alcohol use, and smoking over one year: A four-wave longitudinal causal model.

Longitudinal data collected at 4 periods from an adult community sample (N?=?742) were used to study the relationships between depression (Center for Epidemiologic Studies—Depression Scale), alcohol use, and smoking in a latent-variable causal model. Over a 1 yr period, current levels of depression were dependent upon depression levels at all previously measured times. In the short term, alcohol use led to decreased levels of depression, but the long-term causal effects—taking 1 yr to unfold—were that alcohol use led to slightly heightened depression levels. The effects of depression on increased alcohol use was relatively short term. Smoking level was very stable and neither influenced nor was changed by depression. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)