Numerical analysis of cooldown and warmup for the Large Hadron Collider

As the basis of studies, the paper presents the inventory of components and materials for LHC magnets, especially for main dipoles and quadrupoles firstly. Then a mathematical model and analytical method for LHC transient modes, such as cooldown and warmup of a magnet, a standard cell and the eight LHC sectors, has been developed on the basis of the up-to-date layout of the LHC machine, and validated by experimental data. The model and method do not only consider the momentum and continuity equations as well as the energy equations for helium and materials, but also take into account the pressure evolution in the different headers of the cryogenic distribution line and the effect of the pressure drop across the cryogenic valves. Based on the simulation results, the heat transfer in the magnets has been studied and the transient modes optimized.     

Industrialisation of the insulation vacuum barrier for the large hadron collider (LHC) magnet cryostats

The insulation vacuum (<10⁻⁴ Pa) of the large hadron collider magnet cryostats, thermally protecting the superconducting magnets which operate at 1.9 K in superfluid helium, is divided in to 214 m long segments separated by means of insulation vacuum barriers.The insulation vacuum barrier is a leak-tight stainless steel welded structure, composed of two concentric corrugated cylinders and one internal bellows linked together by a 6 mm thick central plate. As the vacuum barrier mechanically links the cryostat vacuum vessel operating at ambient temperature and the 1.9 K superconducting magnets, it is designed to have minimum heat conductivity. Conduction heat in-leak is intercepted at 65 K by a high-purity copper ring brazed onto the stainless steel central plate and thermally linked to a cryogenic line by a copper-aluminium soldering. The thermal performance has been experimentally validated by cryogenic testing.This paper presents the results obtained after industrialisation, manufacture and testing of prototypes and series units. Qualification of leak-tight welds in thin-sheet stainless steel (thickness 0.15-1.3 mm) has been carried out. Ultrasonic testing is performed on all brazing and soldering. Helium leak testing is performed, using dedicated tooling, to ensure a leak-tightness to a rate better than 10⁻⁹ Pa m³ s⁻¹.     

Vacuum stability and residual gas density estimation for the vacuum chamber upgrade of the ATLAS interaction region of the Large Hadron Collider

The CERN Large Hadron Collider (LHC) has 54 km of ultra-high vacuum (UHV) beam chambers out of which about 90% are at cryogenic temperature (1.9 K) and the rest at room temperature. During operation, the residual gas density in the beam pipes is dominated by beam induced effect such ion, electron and photon-stimulated gas desorption. Therefore, the computation of gas density profile is of great importance to confirm the vacuum stability, and to estimate the beam lifetime. Moreover, the gas density profiles are essential to determine the machine induced background in the experimental areas, and to define the pressure profile in the cryogenic sectors where there is no vacuum instrumentation available.In this paper, the vacuum stability is studied for a newly proposed upgrade of the vacuum chamber at the ATLAS interaction point, using the vacuum stability code called VASCO. The residual gas density profile along the ATLAS vacuum chambers and the effects of photon and electron flux hitting the vacuum chamber walls are presented and analysed.     

多项目、多层次、多方协同的项目管理系统在大型交通工程建设管理中的应用

以泰州长江公路大桥工程项目管理系统为范例,简要介绍了在大型交通工程建设信息化管理中,多项目、多层次、多方协同的项目管理系统的组成、功能和特点。     

Development of technologies for large scale production of titanium and magnesium metals at the defence metallurgical research laboratory,Hyderabad

Titanium has been finding increasing usage as a structural metal in aerospace and many non-aerospace sectors mainly due to its light weight, high strength and outstanding corrosion resistance properties. India is very fortunate to possess the world’s largest and richest mineral deposit for this metal. Early studies on the metal extraction during mid ’60s at the Bhabha Atomic Research Centre, Bombay and pilot plant studies at the Nuclear Fuel Complex, Hyderabad resulted in the establishment of a ‘Technology Development Centre’ at Defence Metallurgical Research Laboratory (DMRL), Hyderabad. DMRL has already demonstrated titanium sponge production feasibility in 2,000 kg batches by the conventional Krcll process and is presently engaged in the development of the more energy saving ‘combined process technology’ in 4,000 kg batches. Fused salt electrolysis is widely employed to produce magnesium metal in integrated titanium plants so as to regenerate magnesium from the by-product magnesium chloride. DMRL has developed magnesium electrolysis technology in a 30 kA monopolar, modular type cell and is now developing the multipolar cell technology in 7kA, 22·2 V, two-module cell equipped with five bipoles in each module. This paper traces the developmental efforts on titanium metal extraction in India and describes the current efforts underway at DMRL for developing the latest energy efficient and cost effective technologies for the large scale production of both titanium and magnesium metals.     

Effects of industrial scale production on the chemical composition of novel coupling agents and its relationship to the mechanical properties of chopped glass fibre mat reinforced thermoset composites

Previously successfully applied polyalkenyl-poly(maleic-anhydride)-ester/amide type additives synthesized in laboratory scale have gone through selection steps then the selected coupling additives were produced in industrial scale process. Additives have been applied for treating the surfaces of glass fibres with and then mechanical properties of the laminated polyester and vinyl–ester based composites have been determined. Results have been focussed on the effect of the size increasing of additive production on the final properties of the laminates. The structures of the additives have been compared based on their FT-IR spectra. Improvement of mechanical properties of composites treated by coupling additives has been found manufactured in industrial scale either. Tensile properties could be improved by 3.2–51.3% with additives from industrial scale related to the same properties of untreated laminates. The Charpy impact strength of laminates treated with coupling agents from industrial scale was higher than that of from lab scale. Fibre–matrix interaction has been studied on SEM micrographs of the fractured faces of the composites. Similarly, the unfavourable results had been caused by the fibres slipping out of the ester matrix.     

Development a new method for pilot scale production of high grade oil palm plywood: Effect of resin content on the mechanical properties,bonding quality and formaldehyde emission of palm plywood

The main objectives of this research were to investigate the formaldehyde emission, some mechanical properties and bonding quality of oil palm trunk (OPT) plywood treated with low molecular weight phenol–formaldehyde (LmwPF), as affected by resin concentration. The mechanical properties are affected by different of amount resin solid contents used. The OPT veneer were treated at either 40%, 32%, 23% or 15% of resin concentration and 12 mm thickness of 3-ply plywood panel were manufactured for each group. In this study the formaldehyde emission, modulus of rupture (MOR), modulus of elasticity (MOE) and bonding quality (shear strength) of OPT plywood were determined. The results revealed that the resin-treatment method was tend to significantly improved the mechanical properties of the OPT plywood panel in which increased solid absorption gives better mechanical properties. Apparently, high mechanical properties were obtained for panel manufacturer from veneer treated with 32% and 40% resin content. The resin-treated OPT plywood provided superior mechanical strength with improvements at least 202% MOE and 159% MOR compared to commercial OPT plywood. Whereas, mechanical properties of the resin-treated OPT plywood were drastically decrease with increasing the water substitution. Formaldehyde emission content of OPT panels decreased upon reduction of resin content into treatment process and were significant at resin concentration. The resin-treated OPT panels at 32% solid content provided a reasonable amount of free formaldehyde (0.359 mg/L) which attained F⁷⁷ according to Japanese Agriculture Standard (JAS). The shear strength of resin-treated OPT plywood panel with 32% and 40% resin content achieved minimum requirements according to the standard European Norms EN 314-1 and EN 314-2 for the interior and exterior application.     

Progress in developing spray-drying methods for the production of controlled morphology particles: From the nanometer to submicrometer size ranges

Control of particle size and morphology has increasingly captured the attention of researchers for decades. The exploration of unique sizes and shapes as they relate to various properties has become a great quest for large field applications. To meet these demands, this review covers recent developments in particle processing. An aerosol-assisted self-assembly technique, with a spray-drying method as a representative of it, to create particles is thoroughly reviewed. Its popularity and its broad use in industry for producing particles are the main reason of this review; thus, elucidation of this method is important for the improvement of particle technology. A practical spray-drying method is described from the step-by-step process to the selection of apparatus types (merits and demerits). Elaboration of particle processing of several morphologies (sphere, doughnut, encapsulated, porous, hollow, and hairy) is discussed in terms of the selection of material types, the addition of supporting materials, and the change of process conditions. Controllable size is also discussed in terms of the adjustment of the droplet size, initial precursor concentration, and the addition of specific techniques. A comparison between a theoretical mechanism and current experimental results (over a 15-year period) are shown to clarify how particles with various sizes and morphologies are designed. This method must be considered an art rather than a science because of its advantages in creating wonderful and unique particle shapes. The performance of various particle morphologies is also demonstrated, which is essential for an understanding of the importance that shape can exert on practical use. Because the method outlined here can be broadly applied to the production of various types of functional materials, we believe that this report contributes new information to the field of chemical, material, environmental, and medical engineering.     

The periodic system and the idea of a chemical element: From Mendeleev to superheavy elements

Like other scientific concepts, the idea of a chemical element has changed considerably over time, since it was first established in the Enlightenment era. In Dmitri Mendeleev's construction of the periodic system, he distinguished between simple substances and elements as defined by their atomic weights. The foundation of the periodic system on the latter concept led to several challenges. For example, the system seemed unable to accommodate the radioactive substances eventually recognised as isotopes. Around 1920, elements were consequently redefined in terms of their atomic numbers, a nuclear property that could be determined by X‐ray spectroscopy. Although this understanding of an element has stood the test of time, new questions turned up relating to the concept of an element following the syntheses of transuranic elements since the early 1940s. These syntheses of very heavy elements have additionally led chemists and physicists to reconsider the criteria for the discovery of a new element. Recently, elements have been officially recognised on the sole ground that a small number of very heavy atomic nuclei were identified. The paper discusses how the notion of an element was modified during different periods of time, the reasons for the modifications, and the values ascribed to them in the communities of chemists and physicists.     

Finite-element simulation of interfacial crack propagation: Methods and tools for the complete failure process under large scale yielding

Interface crack propagation is described with an advanced finite element model on the basis of a non-linear material law with large plastic deformation and a global energy release rate criterion. The simulation covers the whole failure process in one model, starting from small loads, development of a large plastic zone, onset of cracking and crack propagation until complete rupture.The model implements an elastic-plastic material law including hardening. Numerical stability and reliability strongly depend on the correct implementation of the material law. The central part is the realization of a moving crack. Due to the discrete nature of a finite element model, the crack can only propagate in finite steps resulting in sudden changes of boundary conditions. Smoothing these changes is essential for numerical stability and reasonable computation time.Simulated crack propagation bases on a criterion to decide between further increase of load or further advance of crack. A global energy release criterion is used here and was found to be independent of the specific discretisation.     

From mine to refrigeration: a life cycle inventory analysis of the production of HFC-134a

A life cycle inventory analysis has been conducted for the production of HFC-134a (1,1,1,2-tetrafluoroethane, CH₂FCF₃)¹ through from basic raw materials (crude oil, natural gas, sulphur and fluorspar) to the pure product delivered to industrial customers. The analysis was based on real industrial operations in Japan, USA and UK. It showed that production required limestone, water and transition metal catalysts, in addition to the basic raw materials, and that the energy required to provide these raw materials in a form that can be used at the plants and to process them through intermediates into HFC-134a is the equivalent of 4.52 tonnes of CO₂ per tonne of product. Environmental releases associated with HFC-134a included waste salt brine (to the sea), mine tailings (mainly “country” rock landfilled at the mine) and small quantities of calcium sulphate and spent catalyst (both sent to landfill). In addition, greenhouse gases amounting to the equivalent of 2.1 tonnes of CO₂ per tonne of product were emitted to the atmosphere from the plants studied, an effect very much smaller than that estimated in previous studies mainly because the real release rates from current processes are very much less than those assumed in prior work. The global warming potential^{, 2} of HFC-134a is 1300, meaning that, during the first 100 years following the release of one tonne, the effect on climate change is equivalent to 1300 tonnes of carbon dioxide. Consequently, the 6.6 tonnes of carbon dioxide equivalent, emitted during production in the form of energy required and other greenhouse gases, is of relatively little importance and the key requirement to reduce environmental impact is containment during use.     

A complex approach to the development of the method and equipment for thermal nondestructive testing of CFRP cylindrical parts

Composite materials are being increasingly used in high-tech industries, such as aerospace, automotive manufacture and building inspection. Thermal nondestructive testing (TNDT) has become an accepted method for composite inspection. However, the majority of investigations have dealt with flat or slightly-curved composite components with a thickness of up to 5 mm. Particular studies have been devoted either to NDT modeling with an emphasis on some theoretical issues, or they have been based exclusively on experimental results. There has been some recent interest in the use of composite materials in the nuclear industry. Some critical parts, including centrifuge components, have been made of carbon fiber reinforced polymer (CFRP) composites. The working conditions in a centrifuge include radioactivity and high rotational speed, and the composites used in centrifuges must have very uniform thermal properties and must be free of defects.This paper describes a complex approach to the TNDT of cylindrical parts made of CFRP by starting from thermal properties measurement, theoretical modeling and preliminary experiments, and finishing with the technical requirements for the development of practical equipment capable of operating in both laboratory and industrial conditions.The objects tested were CFRP cylinders with a diameter of 150 mm and a wall thickness of 4–6 mm, and they contained some artificial defects of varying size and depth. Both one- and two-sided test procedures have been analyzed for spot, line and uniform heating. Ultrasonic excitation has also been used as an alternative stimulation technique.In a one-sided test, the depth detection limit has been about 4 mm. Similar results have been observed in the case of ultrasonic stimulation, but the practical implementation of ultrasonic IR thermography to the inspection of cylindrical parts requires further exploration.In a two-sided test, even fairly mild heating resulted in the reliable detection of all defects independent of their size and depth.In all test cases, the highest signal-to-noise ratio occurred after applying the technique of principal component analysis.     

From loop structure to policy-making: a CONWIP design framework for hybrid flow shop control in one-of-a-kind production environment

A feasible constant work in process (CONWIP) policy can guide developer to better implement CONWIP system. The feasible policy should be selected from alternatives by evaluation. Therefore, how to generate more than one CONWIP alternative policy to evaluate is an inevitable problem in CONWIP practice. From the perspective of loop structure, we propose CONWIP design framework (CDF) which is a systematic design approach to obtain CONWIP alternative policies. The basic concepts and components for CDF are discussed in this paper. Based on CDF, we make 10 CONWIP alternative policies for hybrid flow shop in one-of-a-kind production environment, and these alternative policies are evaluated by simulation. The simulation result implies that (i) the CONWIP alternative policy with robustness has the potential to cope with more fluctuations in high-variety production environment; (ii) a better design for CONWIP policy will be able to enhance the system performance in practice; and (iii) the loop structure can serve as a parameter of CONWIP.     

Optical properties of HfO2 thin films deposited by magnetron sputtering: From the visible to the far-infrared

Hafnium oxide (HfO₂ or hafnia) holds promise as a high-index dielectric in optical devices and thermal barrier coatings, because of its transparency over a broad spectrum (from the ultraviolet to the mid-infrared) and chemical and thermal stability at high temperatures. In the present work, thin hafnia films of thicknesses from about 180 to 500 nm are deposited on Si substrates using reactive magnetron sputtering. The crystalline structure and surface topography are characterized by X-ray diffraction and atomic force microscopy, respectively. The optical and radiative properties of the film-substrate composites are measured at room temperature using spectroellipsometry and Fourier-transform infrared spectrometry. The optical constants are obtained from about 0.37 to 500 μm by fitting suitable models to the experimental results. Optical properties and dielectric function modeling are discussed with correlation to both film thickness and surface roughness. It is found that a single-oscillator dielectric-function model can describe radiative properties from about 1 to 20 μm. By combining Cauchy's formula (for the visible and near-infrared regions) with a multiple-oscillator Lorentz model (for the far-infrared region), a dielectric function is obtained for the HfO₂ films that is applicable from the visible to the far-infrared.     

Surface plasmon resonance-based biosensors: From the development of different SPR structures to novel surface functionalization strategies

Surface plasmon resonance (SPR)-based biosensors are very powerful tools for the study of biomolecular interactions, chemical detection and immunoassays. This paper reviews the performance of various SPR structures and detection schemes focusing on propagating surface plasmons generated in planar structures. Some aspects of their surface functionalization, the key element which imparts biofunctionality to these structures and hence transforming them into biosensors, will also be discussed accordingly. The ultimate performance of SPR-based biosensors will thus be determined by both their inherent optical performance and suitable surface functionalization.     

Dependence of the electrical and optical properties on the bias voltage for ZnO:Al films deposited by r.f. magnetron sputtering

Aluminum-doped zinc oxide (ZnO:Al) thin films were deposited on glass, polycarbonate (PC), and polyethylene terephthalate (PET) substrates by r.f. magnetron sputtering. The substrate dc bias voltage varied from 0 V to 50 V. Structural, electrical and optical properties of the films were investigated. The deposition rate of ZnO:Al films on glass substrate initially increased with the bias voltage, and then decreased with further increasing bias voltage. It was found that the best films on glass substrate with a low as 6.2 × 10^− 4 Ω cm and an average transmittance over 80% at the wavelength range of 500-900 nm can be obtained by applying the bias voltage of 30 V. The properties of the films deposited on polymer substrate, such as PC and PET, have a similar tendency, with slightly inferior values to those on glass substrate.     

从先锋到主流——运动图形动画在信息时代广泛应用的原因探究

在信息时代运动图形动画受到普遍关注的语境下,讨论该形式的美学特征及其被广泛应用的原因。从设计语言的演变切入,分别从现代设计的发展过程对运动图形动画的视觉影响,现代数字化工具的诞生对运动图形动画制作效率的影响,信息时代的碎片化特征对运动图形动画的传播影响这三方面进行分析,指出该形式备受关注与美学特征、制作效率和传播途径这三方面因素有关。得出运动图形动画的广泛应用取决于设计语言的轮回、制作工具的便捷和信息时代的快速传播这一结论。     

Cognitive inflexibility and the development and use of strategies for solving complex dynamic problems: effects of different types of training

Performance in dynamic complex problem tasks is affected by cognitive inflexibility, whereby people are sometimes unable to adapt their strategies to unexpected changes in their surroundings. This cognitive inflexibility only affects a person's performance when the environmental changes are relevant to the particular problem-solving strategy that they are using. This paper describes a new methodology to detect cognitive flexibility in the use of strategies and presents an experiment designed to test the hypothesis, proving that the type of training affects cognitive flexibility.     

The Climbing Drum Peel Test: An alternative to the Double Cantilever Beam for the determination of fracture toughness of monolithic laminates

The experimental determination of the fracture toughness of inter-ply interfaces in monolithic composite specimens is far from trivial: even in standard test methods such as the Double Cantilever Beam (DCB), some precautions must be taken in the choice of the test configurations and in the post-treatment of the experimental results. Furthermore, non standard measurements such as the crack tip position during propagation are generally required. In this paper, we investigate an alternative test configuration, the Climbing Drum Peel (CDP) test, classically used in the ‘adhesives’ community. The adaptation of the CDP specimen configurations to the testing of monolithic composites is discussed and a systematic comparison is carried out between the CDP and the DCB tests in terms of global and local indicators of the crack propagation behavior.