Theoretical study of γ-hexachlorocyclohexane and β-hexachlorocyclohexane isomers interaction with surface groups of activated carbon model

Activated carbon (AC) is employed in drinking water purification without almost any knowledge about the adsorption mechanism of persistent organic pollutants (POPs) onto it. Hexachlorocyclohexane (HCH) is an organochlorinated contaminant present in water and soils of banana crops production zones of the Caribbean. The most relevant isomers of HCH are γ-HCH and β-HCH, both with great environmental persistence. A theoretical study of the influence of AC surface groups (SGs) on HCH adsorption is done in order to help to understand the process and may lead to improve the AC selection process. A simplified AC model consisting of naphthalene with a functional group was used to assess the influence of SGs over the adsorption process. The Multiple Minima Hypersurface (MMH) methodology was employed to study γ-HCH and β-HCH interactions with different AC SGs (hydroxyl and carboxyl) under different hydration and pH conditions. The results obtained showed that association of HCH with SGs preferentially occurs between the axial protons of HCH and SG's oxygen atom, and the most favorable interactions occurring with charged SGs. An increase in carboxylic SGs content is proposed to enhance HCH adsorption onto AC under neutral pH conditions. Finally, this work presents an inexpensive computer aided methodology for preselecting activated carbon SGs content for the removal of a given compound.     

Preparation and characterisation of a planar pre-concentrator for benzene based on different activated carbon materials deposited by air-brushing

A high area planar pre-concentrator based on various microporous activated carbons of different origins, granularities and preparation conditions, is studied. The adsorbing layer of different thicknesses was deposited on a self-heated planar substrate using the air-brushing technique. By coupling the pre-concentrator to a mass spectrometer, the thermo-desorption of benzene induced by application of a heat pulse was monitored with time. The effects of adsorbent layer thickness, grain size, origin, and activation conditions on the adsorption capacity and pre-concentration of the device are examined and discussed. Suggestions are given for preparing a planar pre-concentrator presenting the highest performances for the detection of benzene present as traces in a carrier gas.     

Interactions of the surface heat and moisture transfer from the human body under varying climatic conditions and walking speeds

The surface heat and moisture transfer from the human body are normally characterized by the thermal insulation and moisture vapor resistance, which are important parameters in environmental engineering. In the past, due to the limitation of measurement technology, simultaneous measurement of these two parameters was not possible and hence there is a lack of clear understanding on the interaction of surface heat and moisture transfer. In this paper, through the experimental measurements on a newly developed sweating/non-sweating fabric manikin (named WALTER) under varying climatic conditions and "walking" speeds, we show that the surface thermal insulation is little affected by moisture transfer. The surface moisture vapor resistances measured under isothermal conditions tend to be greater than those measured under non-isothermal conditions, especially when the wind velocity is less than 2.0m/s. The Lewis Relation holds under non-isothermal conditions, but should be corrected under isothermal condition when the wind velocity is small.     

Groupware support as a moderator of interdepartmental knowledge communication in process improvement groups: an action research study

This paper presents a review of the organizational learning literature that points to process improvement (PI) groups as an appropriate too for organizational knowledge communication. Based on this review, the impact of support provided by a class of groupware systems, email conferencing (EC) on knowledge dissemination in organizations is examined in the context of PI groups. Data were collected through an action research project, in which the researcher facilitated seven PI groups in two organizations with the support of an EC system implemented with Novel/ Groupwise and using a group methodology for PI called MetaProi. The study suggests that, overall, EC support seems to have a positive impact on knowledge dissemination in organizations when used in combination with a group methodology for PI. EC support effects on PI groups can be summarized as: (a) a reduction in, first, the influence of distance and other physical obstacles to the participation of members from different departments in PI groups, and, second, in the disruption that group discussions are likely to cause for individual group members, particularly when these members are from different departments; (b) a reduction in interdepartmental conflict obstacles to the formation of PI groups; and (c) an increase or decrease in individual learning in PI groups, depending on the complexity of the issues being discussed and the clarity of electronic contributions by members. Organizational implications of these research findings are discussed.     

活性炭酚羟基和羧基对二苯并噻吩吸附作用的分子模拟研究

采用密度泛函理论计算酚羟基、羧基和二苯并噻吩的结构以及酚羟基和羧基吸附二苯并噻吩后的结构;用分子内原子理论计算酚羟基和羧基吸附二苯并噻吩后体系的电荷密度及其拉普拉斯值;用自然键轨道理论计算酚羟基与二苯并噻吩之间的电荷转移。结果表明:酚羟基与二苯并噻吩之间形成了O-H…π芳香氢键,其结合能为7.97 kJ·mol~(-1);成键路径为从酚羟基的H_(34)开始,指向二苯并噻吩的C_1=C_2;酚羟基与二苯并噻吩形成芳香氢键的原因是其反键轨道σ_(O33-H34)~*与二苯并噻吩的π体系π_(C1=C2)存在交互作用;约有5.29×10~(-22) C的电荷从二苯并噻吩的C_1=C_2转移至酚羟基的σ_(O33-H34)~*;羧基未与二苯并噻吩形成氢键。增加活性炭表面酚羟基含量,将有利于提高活性炭对DBT的吸附容量。     

Assessment of the impacts of surface topography, off-nadir pointing and vegetation structure on vegetation lidar waveforms using an extended geometric optical and radiative transfer model

In order to prioritize the measurement requirements and accuracies of the two new lidar missions, a physical model is required for a fundamental understanding of the impact of surface topography, footprint size and off-nadir pointing on vegetation lidar waveforms and vegetation height retrieval. In this study, we extended a well developed Geometric Optical and Radiative Transfer (GORT) vegetation lidar model to take into account for the impacts of surface topography and off-nadir pointing on vegetation lidar waveforms and vegetation height retrieval and applied this extended model to assess the aforementioned impacts on vegetation lidar waveforms and height retrieval.Model simulation shows that surface topography and off-nadir pointing angle stretch waveforms and the stretching effect magnifies with footprint size, slope and off-nadir pointing angle. For an off-nadir pointing laser penetrating vegetation over a slope terrain, the waveform is either stretched or compressed based on the relative angle. The stretching effect also results in a disappearing ground peak return when slope or off-nadir pointing angle is larger than the “critical slope angle”, which is closely related to various vegetation structures and footprint size. Model simulation indicates that waveform shapes are affected by surface topography, off-nadir pointing angle and vegetation structure and it is difficult to remove topography effects from waveform extent based only on the shapes of waveform without knowing any surface topography information.Height error without correction of surface topography and off-nadir pointing angle is the smallest when the laser beams at the toward-slope direction and the largest from the opposite direction. Further simulation reveals within 20° of slope and off-nadir pointing angle, given the canopy height as roughly 25 m and the footprint size as 25 m, the error for vegetation height (RH100) ranges from − 2 m to greater than 12 m, and the error for the height at the medium energy return (RH50) from − 1 m to 4 m. The RH100 error caused by unknown surface topography and without correction of off-nadir pointing effect can be explained by an analytical formula as a function of vegetation height, surface topography, off-nadir pointing angle and footprint size as a first order approximation. RH50 is not much affected by topography, off-nadir pointing and footprint size. This forward model simulation can provide scientific guidance on prioritizing future lidar mission measurement requirements and accuracies.     

A comparison of traditional geometrical models and mass triangle model in calculating the surface tensions of ternary sulphide melts

Surface tension of the Ni₃S₂–FeS–Cu₂S ternary mattes has been calculated using a mass triangle model as well as six traditional geometrical models based on the same calculation data to investigate the difference between mass triangle model and other kinds of geometrical models. From the calculated results, it might be seen that, the mass triangle model, irrespective of the method of selection of the binary data, would give the best results compared with other traditional geometrical models. The mean square root errors of the mass triangle method only range from 1.09% to 2.8%, which are almost within the experimental error of 2.5%.     

A theoretical study on the characteristics of the intermolecular interactions in the active site of human androsterone sulphotransferase: DFT calculations of NQR and NMR parameters and QTAIM analysis

A theoretical study at the level of density functional theory (DFT) was performed to characterize noncovalent intermolecular interactions, especially hydrogen bond interactions, in the active site of enzyme human androsterone sulphotransferase (SULT2A1/ADT). Geometry optimization, interaction energy, ²H, ¹⁴N, and ¹⁷O electric field gradient (EFG) tensors, ¹H, ¹³C, ¹⁷O, and ¹⁵N chemical shielding (CS) tensors, Natural Bonding Orbital (NBO) analysis, and quantum theory of atoms in molecules (QTAIM) analysis of this active site were investigated. It was found that androsterone (ADT) is able to form hydrogen bonds with residues Ser80, Ile82, and His99 of the active site. The interaction energy calculations and NBO analysis revealed that the ADT molecule forms the strongest hydrogen bond with Ser80. Results revealed that ADT interacts with the other residues through electrostatic and Van der Waals interactions. Results showed that these hydrogen bonds influence on the calculated ²H, ¹⁴N, and ¹⁷O quadrupole coupling constants (QCCs), as well as ¹H, ¹³C, ¹⁷O, and ¹⁵N CS tensors. The magnitude of the QCC and CS changes at each nucleus depends directly on its amount of contribution to the hydrogen bond interaction.     

不同竞争结构下闭环供应链碳减排和低碳推广决策

为了研究闭环供应链的竞争减排和竞争低碳推广问题,分别构建了两个制造商和一个零售商分散决策结构(模型HR)、一个制造商和两个零售商分散决策结构(模型MH),两个制造商和两个零售商分散决策结构(模型HH)和两个制造商和两个零售商纵向合作结构(模型CC),通过对比前三种结构(模型HR、MH和HH)的决策结果,研究制造商竞争和零售商竞争对不同供应链结构决策的影响。通过对比后两种结构(模型HH和CC)的决策结果,研究供应链企业纵向合作对供应链竞争决策的影响。研究表明：零售商之间的横向竞争能够提高制造商的废旧产品回收水平。两个制造商和两个零售商纵向合作结构的回收水平和低碳推广努力程度最高以及市场需求最大,该结构的减排水平高低受到制造商的竞争强度和零售商的竞争强度影响。最后,结合算例分析,进一步对比四种不同供应链结构的决策结果和利润。     

林木固碳释氧量预测的BP神经网络模型研究

为了实现林木固碳释氧量的数字化估算,针对现有估算方法的不足,提出了基于BP神经网络的林木固碳释氧量的预测模型。基于对神经网络理论和固碳释氧量估算模型的研究,分析了林木在生长季节的CO2通量变化趋势,采用规范化方法对训练样本预处理,进行BP神经网络训练,并结合弛豫涡旋积累法和箱式法,建立了CO2通量神经网络模型。实验结果表明,所建模型具有较好的泛化性能,能够比较准确地估算出林木的固碳释氧量。     

The EPQ model under conditions of two levels of trade credit and limited storage capacity in supply chain management

An inventory problem involves a lot of factors influencing inventory decisions. To understand it, the traditional economic production quantity (EPQ) model plays rather important role for inventory analysis. Although the traditional EPQ models are still widely used in industry, practitioners frequently question validities of assumptions of these models such that their use encounters challenges and difficulties. So, this article tries to present a new inventory model by considering two levels of trade credit, finite replenishment rate and limited storage capacity together to relax the basic assumptions of the traditional EPQ model to improve the environment of the use of it. Keeping in mind cost-minimisation strategy, four easy-to-use theorems are developed to characterise the optimal solution. Finally, the sensitivity analyses are executed to investigate the effects of the various parameters on ordering policies and the annual total relevant costs of the inventory system.     

A new hyperbolic model and an experimental study for the flow of polymer melts in Multi-Pass Rheometer

A new mathematical model and an experimental study are presented for polymeric liquids. The main advantage of the proposed model over the existing models is its hyperbolic nature, which overcomes some of the drawbacks of the available models. One of the advantages of the proposed model is that the boundary conditions can be determined without ambiguity for all variables including the stresses, which may not be the situation for other mixed type systems. The modified Tait equation is used to describe the polymer compressibility and to keep a real set of characteristics for the resulting system of equations. The Giesekus model is used to model the polymer viscoelasticity. A hybrid finite element/finite difference scheme coupled with Newton–Raphson’s linearization scheme is used to solve the governing system of equations. Numerical and experimental studies for the flow of polymer melts in a Multi-Pass Rheometer (MPR) are presented. Despite using a one-mode Giesekus model, the predicted shear-rate dependent viscosity curve is in good agreement with the experimental results.     

Design of agile supply chain assessment model and its case study in an Indian automotive components manufacturing organization

Agile Manufacturing (AM) paradigm is fast instilled in modern organizations. AM enables an organization to evolve products and services quickly and economically in response to the customers’ dynamic demands. The effectiveness of AM is largely determined by the performance of Agile Supply Chains (ASC). In order to assess their performance, an ASC assessment model was reported in this research paper. This model is encompassed with agile supply chain attributes whose performance levels need to be determined for assessing the overall ASC performance of the organization. The computation was performed using fuzzy logic approach. The working of this model was examined by conducting a case study in an Indian automotive components manufacturing organization. The experience gained by conducting this case study favored the use of a computerized system which will ensure accuracy of computations involving fuzzy logic.