Fundamental Experimental Investigations Research Articles

Study on fractured rock-like materials for geomechanical model test based on 3D printing technology

The geomechanical model test has been verified to be an important way to solve some puzzling geotechnical issues. So far, there are mainly three methods used to construct geological models: pouring, tamping, and small block masonry. However, several disadvantages arise when using these artificial methods, including consuming too much time and cost, difficulty in guaranteeing uniformity of the density of different layers, most importantly, being unable to simulate detailed tectonic discontinuities, like faults or fissures. In view of the fact that three-dimensional printing (3DP) technology can easily produce complex fractured structures, 3DP technology is introduced to the research of the geomechanical model test. However, what kind of material is suitable to simulate rock mass and how to fabricate fractured rock-like material specimens are still two complicated problems. In this paper, a cement-based material is used to simulate fractured rock-like material specimens. This kind of material is proved to reach low strength and low elastic modulus by adjusting the mix ratio. What’s more, a method to fabricate small block masonry used in geomechanical model test with 3D printing fracture network is proposed. A series of tests are conducted for these 3DP fractured models, and the corresponding results show that their mechanical properties and failure characteristics are consistent with experimental results of other rock specimens with certain similarity, and geomechanical model test. These fundamental experimental investigations demonstrate the potential feasibility and prospects of 3DP technology in geomechanical model test.

Producing High Workable & High Strength Concrete Mix Having 6 Hour Retardation

The goal of this study is to work out different experiments for retarding concrete setting time, which needed to reach slump 15 cm after six hours from mixing of concrete having grade C700. Six hours comprise 1.5 hour for transporting and 4.5 hours needed for constructability method, this long time for casting concrete is owing to a long transporting time of the concrete from the plant to the site and also the time needing for casting the concrete by using the slide form of high ring concrete wall, for these reasons there are needs to retard the concrete setting time with increasing the workability for concrete, using super-plasticizers is one of the best methods to improve the properties of the concrete, from fundamental experimental investigations on retardation, setting time and the concrete mixture with high strength of 626 kg / cm2 after 7days and 755kg / cm2 after 28 days can be achievable by using super-plasticizers

Experimental Study of Gas-Slag-Matte-Tridymite Equilibria in the Cu-Fe-O-S-Si-Al System at 1573 K (1300 °C) and P(SO2) = 0.25 atm

Fundamental experimental investigations have been conducted to study the effect of Al2O3 on the equilibria between the gas phase (CO-CO2-SO2-Ar) and slag-matte-tridymite phases in the Cu-Fe-O-S-Si-Al system at 1573 K (1300 °C) and P(SO2) = 0.25 atm. The experimental technique used is based on equilibration, rapid quenching and electron probe x-ray microanalysis. New experimental data have been obtained for the four-phase gas-slag-matte-tridymite equilibria system for a range of alumina concentrations up to 20.4 mass% in the slag phase as a function of matte grade, including the concentrations of dissolved sulphur and copper in slag, and Fe/SiO2 ratios in slag. The results obtained for 1573 K (1300 °C) are also used to analyse the effect of temperature on phase equilibria in the range of conditions investigated to that of reported for 1473 K (1200 °C) in the literature. The results obtained show that the concentrations of sulphur, copper and “FeO” in slag decrease with increase of Al2O3 concentration in slag while it has no detectable effect on concentration of sulphur in matte for a given matte grade. The new data provided in the present study are of direct relevance to the pyrometallurgical processing of copper and will be used as an input for optimisation of the FactSage thermodynamic database for the copper-containing, multi-component multi-phase system.

Innovative decoupling system for the seismic protection of masonry infill walls in reinforced concrete frames

Reinforced concrete frame structures with masonry infills often exhibit serious damage after earthquake events, as the infills are generally installed without additional constructive measures in contact to the reinforced concrete frame. The masonry infills constructed in this way experience an unplanned interaction with the surrounding RC frame and thus become part of the horizontal load-bearing system with in-plane loading. This interaction combined with seismically induced loads perpendicular to the infill panel often leads to total collapses of the masonry infills and heavy damages to the RC frames. This fact was the motivation to develop an innovative system for decoupling the RC frame and the masonry infill with a special profile made of elastomeric cellular material within the collaborative European research project INSYSME (Innovative Systems for Earthquake Resistant Masonry Enclosures in Reinforced Concrete Buildings). The profile allows relative displacements between the RC frame and the masonry infill and serves at the same time as a support for out-of-plane loads. The article first explains the design and installation of the system and provides an overview of the load bearing capacities determined through small specimen tests on the system components. Subsequently, fundamental experimental investigations on traditional and decoupled RC frames infilled with high thermal insulating clay bricks for separate and combined in-plane ‬and out-of-plane loading are presented. Based on a detailed evaluation and comparison of the test results, the performance and effectiveness of the developed system are illustrated.

Experimental and theoretical investigation of deep vibro compaction

AbstractDeep vibro compaction (vibroflotation) is a soil improvement technique, which was patented by the company Keller in the 1930s and since then it has been continually developed and has been successfully used worldwide for deep compaction of granular soils. The methods for quality control of the compaction works are largely empirical in nature and therefore often unreliable. In a current research project, fundamental experimental investigations on real‐time quality control for the deep vibro compaction were executed. Large‐scale test measurements and numerical simulations were performed to investigate the three‐dimensional vibrator movement during the compaction process. Reliable measurements with measuring instruments on the vibrator tube during the compaction process have been conducted within the current large‐scale field tests. This paper presents the layout of the large‐scale in‐situ tests, moreover, selected test results are shown, and possible indicators of the changing soil conditions are discussed.

BJOG Editor-in-Chief number 8: James Young 1943-1963.

James Young was born in Edinburgh on 24 April 1883 and graduated MB ChB with first class honours from Edinburgh University in 1905. In 1910 he was awarded the gold medal for his MD thesis Reproduction of the Human Female, later published as a book. He self-funded cancer research, suggesting that a form of ‘pleomorphic bacterium’ isolated from 34 human cancers might be carcinogenic; it would be more than 50 years before the herpes virus was suggested as the cause of cervical cancer. However, he found more acceptance of his research into the causes of eclampsia, considered to be ‘a poison or toxin’ released by infarctions in the placenta (hence the term ‘pre-eclamptic toxaemia’). His comprehensive review of the topic was published in the Journal of the Royal Society of Medicine in 1914, following which his studies were interrupted by involvement in military campaigns in Gallipoli, Egypt, Palestine and France, about which he wrote a book, With the 52nd division in three continents. He reached the rank of lieutenant colonel, was twice mentioned in dispatches and in 1919 was awarded the Distinguished Service Order. He developed his clinical practice in the Edinburgh Royal Infirmary and the Simpson Memorial Maternity Hospital. His 1929 paper in the British Medical Journal highlighted the recurrence of pre-eclampsia in successive pregnancies; he concluded that ‘in view of the large risk of recurrence the need for antenatal supervision from an early stage in the event of the subsequent pregnancy should be clearly explained to the patient’. More controversially, he opined that ‘toxaemia in two or more pregnancies is an indication for the prevention of any further pregnancy’. In 1934 he was elected to a professorship in the University of London at the newly created British Postgraduate Medical School at Hammersmith (later to become the Institute of Obstetrics and Gynaecology), subsequently concentrating on training, teaching and writing. In 1937 he was appointed assistant editor of our Journal, becoming joint Editor in 1943 and Editor-in-Chief from 1946 until 1963 – a record for editorial longevity. His Textbook of Gynaecology ran to 11 editions. His administrative responsibilities included being Governor of the Imperial Cancer Research Fund and Chairman of the Scientific Advisory Committee of the National Birthday Trust. He was elected honorary Fellow of the American Association of Obstetricians and Gynecologists and a corresponding Fellow of the German Gynaecological Society. He piloted the Journal through its acquisition by the Royal College of Obstetricians and Gynaecologists in 1950 (following which, for the first time, the editor was paid a salary), was widely read and wrote in a literary style that contrasts with the minimalist orthodoxy of modern scientific writing. He regarded fundamental experimental investigations as ‘gold compared with the trash of case records…while an intensive study of ten cases may be rewarding, the study of 1000 cases of the same condition is in its nature likely to be perfunctory and sterile’. A strict but kindly man, he enjoyed sharing music with his wife, daughter, stepdaughter and two stepsons. He died in the year that he demitted office as Editor. None declared. Completed disclosure of interests form available to view online as supporting information. Image is available online as supporting information to the article.

Model-Based Formulation of Biofuel Blends by Simultaneous Product and Pathway Design

Oxygenated species obtained from the selective chemo-catalytic refunctionalization of lignocellulosic materials and rationally formulated mixtures thereof can be tailored to the needs of advanced internal combustion engine concepts like low temperature compression-ignition or highly boosted spark-ignition combustion. In the present contribution, we present a framework for model-based formulation of biofuel blends with tailored properties by considering the fuel’s molecular composition as the fundamental design degree of freedom. To this end, optimization-based reaction pathway screening is combined with mathematical fuel property prediction by means of structural group contribution and quantitative structure–property relationship modeling in order to formulate and solve an integrated product and pathway design problem. The model-based approach is envisioned (i) to guide fundamental experimental investigations of the combustion behavior of blended biofuels toward the most favorable mixtures and (ii) to ide...

Plastic flow and its control in sheet–bulk metal forming of thin-walled functional components

This paper deals with a manufacturing process for sheet metal components with integrated functional elements by sheet–bulk metal forming. In a single forming stage a cup-shaped base body with thin-walled features is deep drawn and its geometry is calibrated by upsetting. The fundamental numerical and experimental investigations include the analysis of the die filling behaviour, part geometry and mechanical properties due to strain hardening with respect to the variation of the blank layout, forming force and material strength. Finally, the process limits are identified and approaches for their enhancement by the application of tailored surfaces are presented.

Investigations on the thermal workpiece distortion in MQL deep hole drilling of an aluminium cast alloy

Dry machining is frequently applied in cutting operations, in order to reduce the energy consumption and the production costs. In deep hole drilling operations minimum quantity lubrication (MQL) is used to obtain a reliable chip evacuation, since completely dry machining is not feasible. Due to the low cooling effect of MQL, the drilling process generates a high thermal load on the workpiece, which leads to thermally induced workpiece deformations. This paper presents fundamental experimental investigations on the workpiece temperature, the resulting in-process deformations and the achievable straightness accuracy of the borehole. The investigations focus on two different strategies for enhancing the deep hole drilling using MQL. Initially, a high-feed process guiding is introduced, in order to obtain a higher productivity and to reduce the heat input into the workpiece. The second approach is a novel radial spindle compensation, which performs a directional control of the straightness deviation of the deep hole.

In Memoriam: Professor Arthur E. Bergles (1935–2014), the Pioneering Advocate of Enhanced Heat Transfer and Energy Conservation

In Memoriam: Professor Arthur E. Bergles (1935–2014), the Pioneering Advocate of Enhanced Heat Transfer and Energy Conservation

Influence of superplasticizer on the non-Newtonian characteristics of cement paste

The superplasticized cement paste usually exhibits non-Newtonian characteristics, which depend on the type of superplasticizer and its dosage. Current attempts in the cement paste rheology literature have mainly focused on reducing the data from steady shear experiments to simple constitutive models, and exploring the influence of superplasticizer dosage and type based on these model parameters. In this study, the non-Newtonian behavior of the cement paste is characterized based on more fundamental experimental investigations without recourse to any specific model. Steady shear, creep and recovery, and stress relaxation experiments were conducted on a variety of superplasticizer and cement paste combinations, and the transition from non-linear viscoelastic to non-Newtonian and subsequently to linearly viscous fluid, as the dosage is increased were observed. Additionally, Marsh cone experiments were conducted to determine the optimum dosages and it was found that dosages determined based on Marsh cone were close to the dosages at the transition to the linearly viscous behaviour.

High-Performance Air Cooling Condenser With Liquid–Vapor Separation

In this investigation, an innovative idea was introduced to design a new kind of high-performance air cooling condensers. This kind of condenser functions to automatically separate liquid from gas and makes condensation always occur in droplet and unsteady thin film condensation mode everywhere in the whole condenser, which results in very high average heat transfer coefficient. An introduction is presented to describe the basic principle and structure of the novel heat exchanger technology, particularly the understanding from the fundamental experimental investigations. Furthermore, a series of experiments was conducted to validate the high performance of an air-conditioning system with an innovative condenser. Though heat transfer area of the condenser was about 37% less, the performance was as good as or even better than that of the original one.

First-principles study of benzene adsorption on theSiC(001)−(3×2)surface

Adsorption of benzene on the $\text{SiC}(001)\text{\ensuremath{-}}(3\ifmmode\times\else\texttimes\fi{}2)$ surface is investigated employing density-functional theory within the generalized gradient approximation. Due to the relatively large Si dimer distance on the clean surface, benzene appears to adsorb only in a standard-butterfly configuration on single dimers. Such a well-defined structure might turn out to be of particular interest for fundamental experimental investigations as well as for surface functionalization by organic molecules. The reaction pathway of benzene from an initial state in vacuum to the final adsorption state in the standard-butterfly configuration on the surface is explored and the reaction process is analyzed employing maximally localized Wannier functions. The electronic structure of the optimized adsorption configuration is discussed in terms of the surface-band structure, charge and state densities, as well as scanning tunneling microscopy images.

Improvement of Condensation Heat Transfer by Surface Modifications

Condensation processes are of importance for many heat transfer applications where a large amount of energy has to be transferred by a working fluid using the latent heat available during the phase transition. Whether ideal dropwise or filmwise condensation or a mixed condensation form can be realized depends on the properties of the heat transfer surface. The quantities that mainly influence the condensation form are the surface tension of the condensing fluid, the surface roughness or structure, and the surface energy of the condenser surface. During the past two decades at LTT-Erlangen, experimental and theoretical work has been carried out to reduce the surface energy of common heat transfer surfaces in such a way that stable dropwise condensation can be reached and maintained for extended time periods. In this situation, heat transfer is superior to filmwise condensation for at least one order of magnitude. The methods that have been developed and extensively tested for a selective adjustment of dropwise condensation of water at metallic surfaces are surface coating by diamond-like carbon films (DLC) and ion implantation. For both methods, the principles and fundamental experimental investigations are explained, and for ion implantation, a technical utilization is presented in the form of its application to sea water desalination plants based on mechanical vapor compression.