bluuebunny/crossref_metadata_2025 huggingface dataset:
Adhesion characteristics of geopolymer mortar to concrete and rebars
Authors: Pareek Sanjay , Kashima Hiroo , Maruyama Ippei , Araki Yoshikazu
Published: January 2019

In recent years, geopolymers have gained a wide attention as highly ecological-friendly building materials, having a capability to cut down 70% of CO2 emissions in comparison to the ordinary cement concrete. In this study, geopolymer mortars are proposed as repair materials for reinforced concrete structures, due to their superior acid resistance, heat resistance and high strength in comparison to the existing repair materials. The objective of this study is to investigate the adhesion properties of geopolymer mortars to concrete substrates with different surface treatments, steel plates and rebars. As a result, the geopolymer mortars are found to have excellent adhesion properties to dry concrete substrates, steel plates and rebars. Concrete substrates treated with grinder, further enhanced the adhesion properties of geopolymer mortars. On the other hand, poor adhesion of geopolymer mortars to wet concrete substrates was observed due to the presence of water on the interfacial zone, which decreased the alkali concentration of the geopolymer, resulting in lower adhesion strength. In general, geopolymer mortars are found to have suitable adhesion properties to the concrete substrates, steel plates and rebars and can be applied as repair materials for reinforced concrete structures.
Influence of polypropylene fiber on early strength of self-compacting concrete
Authors: Karolina Rahmi , Siregar Abdiansyah Putra
Published: January 2019

One of the development of concrete technology in construction’s world is Self-Compacting Concrete. Self-Compacting Concrete (SCC) is an innovative concrete that able to “flow” and condensed by gravity and its own weight with little vibration or even without a vibration device at all. However, these concrete still have deficiencies like general concrete that is weak to tensile. To increase the tensile strength of the concrete is by adding fiber into the mix. One type of fiber that can be used as an additive to the mix is Polypropylene fibers. This study aims to determine the effect of adding polypropylene fibers to the mechanical properties and characteristics of SCC concrete and to know the optimal polypropylene fiber content in the manufacture of Self Compacting Concrete. Fiber addition variations are 0 kg / m3; 0.25 kg / m3; 0.5 kg / m3 and 0.75 kg / m3. The result of the research showed that the variation of 0.5 kg / m3 and 0.75 kg / m3 addition of fibers didn’t fulfill the requirements to be categorized as a SCC concrete. The results of hard concrete test showed the highest compressive strength that is on the SCC PP concrete of 22.31 MPa at the age of 1 day and 46.24 at the age of 28 days. The highest strength is on the SCC 0.25 PP concrete of 6.52 MPa at the age of 1 day and 10.07 at the age of 28 days. The highest flexural strength is on the SCC 0.25 PP concrete of 6.76 at the age of 1 day and 8.60 at the age of 28 days.
Material quantity estimation modelling of bridge sub- substructure using regression analysis
Authors: Alhusni M Khazin , Triwiyono Andreas , Septhia Irawati Inggar
Published: January 2019

In construction field, a time completion and an adherence to budget are two factors that mainly influence the successful of the projects. The adherence to the budget can be achieved when the estimated budget is closed to the actual cost. For the owners, cost estimation is necessary as a guidance in determining the amount of investment. Therefore, it is very important to know the estimation of the project cost by using the limited data before the detailed plans and specifications of the project are identified. However, in the case of bridge substructure preliminary cost estimation, there is a lack information about material quantity estimation models due to the difficulties of soil characteristic and hydrological conditions. Hence, this research aims to develop the estimation of material quantity models of the abutment and caisson of bridge, with the Presetressed Concrete I-Girder (PCI Girder) superstructure located in Sleman district, Yogyakarta province, Indonesia. The database used for developing model was obtained by conducting sub-structure structural analysis of 15 abutments and 45 caissons. The bridges have a various span length, abutment height, and caisson depth. Material quantity estimation models were analysed by the multiple regression analysis methods. The span length and the abutment height are determined as independent variables to predict the concrete volume, the reinforcing steel weight, the caisson concrete volume, the cyclops concrete volume and the caisson reinforcing steel weight. This research proposed 11 equation models to estimate the concrete volume and reinforcing steel weight of abutment and caisson.
Progressive Collapse Assessment: A review of the current energy-based Alternate Load Path (ALP) method
Authors: Asnawi Subki Nur Ezzaryn , Mansor Hazrina , Sahol Hamid Yazmin , Parke Gerard
Published: January 2019

The Alternate Load Path (ALP) is a useful method that has generated a considerable recent research interest for the assessment of progressive collapse. The outcome of the ALP analysis can be assessed either using the force-based approach or the energy-based approach. The Unified Facilities Criteria (UFC- 4- 023-03) of progressive collapse guideline - have outlined that the force-based approach can either be analysed using static or dynamic analysis. The force-based approach using static analysis is preferable as it does not require a high level of skill and experience to operate the software plus no effort is required in scrutinising the validity of the analysis results output. However, utilising the static approach will eliminate the inertial effect in capturing the actual dynamic response of the collapsed structure. In recent years, the development of the energy-based progressive collapse assessment is attracting widespread interest from researchers in the field; as the approach can produce a similar structural response with the force-based dynamic analysis by only using static analysis. Most of the current energy-based progressive collapse assessments are developed following the requirements which are given in the progressive collapse guidelines provided by the Unified Facilities Criteria. However, little attention is given to the development of the energy-based approach using the Eurocode standards as a base guideline. This article highlights the merits of utilising the energy-based approach against the force-based approach for a collapsed structure and explains the collapse mechanism of a steel frame in the perspective of the energy concept. The state of the art of energy-based progressive collapse assessment for a structural steel frame is reviewed. The comprehensive review will include insights on the development of the energy-based method, assumptions, limitations, acceptance criterion and its applicability with the European standards. Finally, potential research gaps are discussed herein.
Analysis and experiments of the effect of reinforcement of wood beam using carbon fiber reinforced polymer against bending strength
Authors: Sitorus Torang , Desharma Silvy
Published: January 2019

Flexural reinforcement on wood beams is intended to increase the maximum load capacity that can be supported by wood beams until they are collapse. One of the most widely used resilient reinforcements currently used is reinforcement using Carbon Fiber Reinforced Polymer (CFRP) which is a combination of high strength with light weight material. This reinforcement is intended for historical buildings that need more load capacity that can be supported due to changes in building function, or the increase of the load on the building. The purpose of this research is to know the effect of reinforcement of wood beams with CFRP and variation of length of reinforcement to flexible strength of wood beams, and beam behavior reinforced with CFRP due to loading. Structural beam testing using mahogany logs with cross sectional size 75x100mm2 along 2 m consisting of 4 types of samples with each type consists of 2 pieces of sample. The first sample was a wood beams without reinforcement, the second sample was a wood beams with a reinforcing length of ¼ spans in the middle, a third sample was a wood beams with a reinforcing length ¾ spans in the middle, and a fourth sample was a wood beams with retrofitting along the length of the span. From the test it is found that the maximum load increase that can be supported by the sample with the length of reinforcement ¼ span, ¾ span, and along the span has increased the maximum load respectively that is 4.393%, 37.340%, and 48.323% compared to wood beams without reinforcement. The average damage occurring in samples with CFRP is debonding failure.
Assessment system of condition of typical building infrastructure using fuzzy analitical hierarchy procces (FAHP) method
Authors: Javiri Firman , Aminullah Akhmad , Triwiyono Andreas
Published: January 2019

Conditions existing infrastructure needs to be maintained, it can be operated / function, so we need a good maintenance. Operation and maintenance activities carried out in a sustainable manner, to restore, optimize, and service live function according to design life. Assessment of the condition is a link between opration and maintenance functions. If the conditions are bad, then the operation will not be optimal, which could result in malfunction. In this research, case studies assess the conditions of student dormitory buildings with prototype design. Weighting component using Fuzzy Analytical Hierarchy Process as a method of analysis. The results of the analysis show that by using the FAHP method, the weighting of building components from the assessment of the subjectivity of expert respondents can be calculated. The result of this weighting Component can be used as a calculation factor of the value of the condition of the building, and can be applied to student dormitory buildings with typical design.
Delamination mechanism of GFRP sheet bonded on the reinforced concrete beams
Authors: Djamaluddin Rudy , Hijriah  , Irmawati Rita , Faharuddin  , Wahyuningsih Rossy T.
Published: January 2019

Fiber reinforced polymer (FRP) has been developed to be applied for a strengthening of the deteriorated structures. In the form of a sheet, the FRP may be applied for the strengthening of the structures by bonding it to the concrete surface. Glass composed FRP (GFRP) sheet is most commonly used due to its relatively lower cost compared to the other FRP materials. GFRP sheet is applied externally by bonding it on the concrete surface. The strengthened structures should be monitored periodically to ensure the health of the strengthened structures. Regarding the development of monitoring system of the strengthened structure, it is important to study the delamination phenomenon of the bonded GFRP. Therefore the delamination mechanism is important to be clarified. Many studies have been done to investigate the bonding characteristics of GFRP sheet under direct tensile loading. However, the studies on the bonding characteristics of GFRP sheet on the strengthened beams due to flexural loadings are still limited. A series of concrete beams strengthened with GFRP sheet on extreme tension surface were prepared. The beam specimens ware loaded under four-point bending test gradually up to the ultimate capacity. Results indicated that prior to final delamination, a local delamination occurred which was indicated by the suddenly decreasing of an applied load. The delamination of the GFRP sheet may be initiated by the flexural cracks occurred on the beams.
Modelling the performance of a corroded pipe section repaired with three-parts epoxy grout and with three-parts epoxy grout plus nanofiller
Authors: Hj Kariya Siti Norasyikin , Lim Pang Jen
Published: January 2019

Steel pipelines have been used for the transportation of oil and gas for more than a century. With exposure to the harsh condition of the environment, steel pipelines are subjected to corrosion that deteriorates their function through metal loss. To remedy this, several repair techniques have been developed to extend their service life, particularly, techniques that do not interrupt the flow of the oil and gas. There are three main components in a Fibre-reinforced Polymer (FRP) composite repair which are (1) FRP composite wrap, (2) infill material, and (3) interlayer adhesive. Past research had looked at enhancing the infill material, which is usually an epoxy grout, with the aim to reduce or remove the number of FRP composite wrap layers. One of the ways to enhance the infill material is to add Graphene Nanoplatelets (GNPs) to the epoxy grout. This was proven by carrying out different mechanical tests on a neat three-part epoxy (Infill A) and a three-part epoxy with 0.1% GNPs added by weight (Infill B). With the mechanical properties obtained for both infill materials, the pipe sections were then modelled with a finite element software to determine the repair performance without the use of FRP composite wrap. The difference of failure pressures between the pipe repaired using Infill A and Infill B over the unrepaired pipe were 2.7% and 4.2% respectively. The failure of the repair was due to the debonding of the infill materials from the pipe section. However, this research has provided significant information in understanding the properties of the infill materials as well as the numerical modelling on a repaired pipe section.
Damage mechanism of existing RC slabs with reinforcing steel plate
Authors: Namba Kenta , Fujiyama Chikako , Niina Tsutomu
Published: January 2019

The purpose of this study was to clarify the damage mechanisms of existing reinforced concrete (RC) slabs with reinforcing steel plates through the use of a three-dimensional nonlinear finite element analysis. An actual wheel load running test was simulated. Two panels of RC slab were cut from existing bridges and were used as the test specimens. Simulation models were built for each specimen with different modeling concepts for the rebar; RC elements, and solid elements. After the wheel load running simulations, the strains were examined through use of the strain contours at various cross sections. In the model using solid element for the rebars, the mechanisms for the generation and development of the horizontal cracks were analyzed in detail. Furthermore, the strain components of the referential elements were carefully analyzed for different loading cycles and positions. Although the decisive cause of the horizontal crack has not been clarified yet, the crack development processes were mostly demonstrated through this study.
Degradation of submerged/wet concrete under cyclic compression and cyclic shear
Authors: Fujiyama Chikako , Koda Yasuhiro , Sento Noriaki
Published: January 2019

The aim of this study is to identify a specific degradation of concrete that has been observed in bridge decks made of reinforced concrete (RC). To control the phenomenon, fundamental studies were conducted. Compressive loads and external water pressure were cyclically applied to submerged concrete cylinder specimens with different pre-loading and restraint conditions. The turbidity of the water in the tank was generally observed during the loading, and the pH of the turbid water steadily increased as the number of cycles increased. Thereafter, fine aggregates without a cement matrix were found on the inner surfaces of split specimens. These phenomena were quantitatively analyzed, and the analyses suggested that cyclic water pressure acted on the inside of pre-cracked specimens and washed out their cement matrix. The degradation of a rough cracked surface was also examined using the cyclic shear test, with/without a water supply to the crack. The shear slip and the orthogonal displacement were clearly amplified with an increase in the number of cycles when the water supply was present. The mechanical properties of cracked concrete with water in shear was discussed in accordance with that of liquefaction. These fundamental studies could help to determine the acceleration factors of the degradation and provide certain thresholds for practical use.
Displacement analysis of dam based on material parameters using numerical simulation and monitoring instrumentation
Authors: Undayani Cita Sari , Partono Windu , Retno Wardani Sri Prabandiyani
Published: January 2019

On the dams, there are many parameters may change and be different from design. Therefore, it is necessary to analyse the parameters so that it can comply with conditions in the field. By knowing the material parameters can foresee events in the future during operational condition of dam. It is because material parameters can influence behaviour of the structure. Displacement, one aspect in failure of dam, is considered due to its function to accommodate design of camber in dam crest and provide early warning system. Displacement behaviour is related to material parameters in term of Young’s modulus and Poisson ratio. Nevertheless, difficulties for testing material in the dam make approach method to analysis material parameters are required. One of them is done by numerical simulation. In this study, the review of displacement is in the core zone at different elevations and different water level conditions. Value of material parameters which influence displacement were determined using back analysis method. Then, it could be analysed displacement result between modelling and monitoring instrumentation using Settlement Gauge. Results show good agreement trend between those displacement’s results. Moreover, the displacement’s value from simulation model analysis is greater than Settlement Gauge.
Dynamic interaction between elastic plate and transversely isotropic poroelastic medium
Authors: Keawsawasvong Suraparb , Senjuntichai Teerapong
Published: January 2019

In this paper, dynamic response of an elastic circular plate, under axisymmetric time-harmonic vertical loading, resting on a transversely isotropic poroelastic half-space is investigated. The plate-half-space contact surface is assumed to be smooth and fully permeable. The discretization techniques are employed to solve the unknown normal traction at the contact surface based on the solution of flexibility equations. The vertical displacement of the plate is represented by an admissible function containing a set of generalized coordinates. Solutions for generalized coordinates are obtained by establishing the equation of motion of the plate through the application of Lagrange’s equations of motion. Selected numerical results corresponding to the deflections of a circular plate, with different degrees of flexibility, resting on a transversely isotropic poroelastic half-space are presented.
Improving seismic behaviour of irregular building through double column and console beam application
Authors: Sumarsono Ririt Aprilin , Fajari Muhammad Aji
Published: January 2019

Recent years, the shape of building is getting sophisticated; otherwise the environmental load such as earthquake, wind, and wave cannot longer be neglected during analysis. Accommodating U-shaped building for analysis, we noticed the irregularity in both horizontal and vertical direction will create severe damages to the structure under the earthquake. In order to prevent destruction to the structural member, assigning dilatation is one possible way by utilizing double column or console beam system to break the irregularity of the building plan. During analysis, the model of non shear wall system is also built in order to compare the effectiveness between both systems. Strong evidence of double column system performance is less than console beam is answered from behavioural parameters of the both system under earthquake. Higher period, displacement and drift are peril for the double column system compare to console beam system application. Hence, console beam system is beneficially selected to solve irregularities in horizontal direction as the discontinuity of the load transfer is relatively small. Hereinafter, installing earthquake resistant system can be reconsidered after the dilatation was applied to strengthen certain direction which was marked as the weak axis of the building structure.
The attenuation coefficient of barite concrete subjected to gamma-ray radiation
Authors: Budi Gogot Setyo , Koentjoro Hurijanto , Wijaya Joshua , Sikomena Evan Filbert
Published: January 2019

Barite is a non-metallic mineral, which composed of Barium Sulfate (BaSO4), has specific gravity about 4.5. It can be used for high density concrete as a shielding against gamma-ray. This paper presents the use of barite as concrete aggregates to block gamma-ray radiation. Two concrete grades fc’25 and fc’35 were prepared. The effect of barite to the attenuation coefficient of samples was studied by replacing coarse aggregate with barite and replacing both coarse and fine aggregates with barite. The results show that the protection ability of the concrete using barite aggregates subjected to gamma-ray is better than those of concrete using barite as coarse aggregate and the normal one. The attenuation coefficient of concrete fc’25 with barite as aggregates and concrete with barite as coarse aggregate is 0.294 cm-1 and 0.230 cm-1, respectively; The attenuation coefficient of concrete fc’35 with barite as aggregates and concrete with barite as coarse aggregate is 0.304 cm-1 and 0.271 cm-1, respectively; While the attenuation coefficient of normal concrete fc’ 25 and fc’35 is 0.205 cm-1 and 0.225 cm-1, respectively. The average density of normal concrete fc’ 25 and fc’35 was 2252 kg/m3 and 2323 kg/m3, 3004 kg/m3 and 3064 kg/m3 for concrete with barite as coarse aggregate, and 3461 kN/m3 and 3464 kg/m3 for concrete using barite for its aggregates.
Dynamic on-line multimodal route planning with least expected travel time in the stochastic and time-dependent bus network
Authors: Li Jinjian , Doniec Arnaud , Boonaert Jacques , Lozenguez Guillaume
Published: January 2019

Route planning system in bus network is very important on providing passengers a better experience for public transportation services. This work presents a new on-line dynamic path planning algorithm in a stochastic and time-dependent bus network, with the objective of least expected travel time. Firstly, an initial optimal path is found when a passenger leaves from the starting location at time t for the destination location. Secondly, when the passenger reaches a bus stop, the real time traffic condition is checked to decide whether the optimal path should be modified and re-calculated. If so, the shortest path algorithm is re-applied to find the new path. The simulation scenario is executed to show the performance and efficiency of the proposed dynamic path planning system.
Preliminary establishment and analysis of automated driving benchmark in China
Authors: Hui Xiong , Wang Yinghan , Ge Qiang , Gu Ziqing , Cui Mingyang , Wang Jianqiang , Li Keqiang , Xu Qing
Published: January 2019

In order to promote the localization of Automated Driving (AD) in China, it is necessary to collect large-scale traffic scene data with Chinese characteristic for future analysis. In this paper, we propose the methodologies and rules of establishing AD benchmark involving how to configure sensors, how to design the collection schema to show Chinese traffic characteristics and the rules of elaborating distinctive scenes and routes, what to label, and it is also demonstrated that the benchmark can support the future application of extended AD research. Data collection lasted about one month covering diverse scene data such as campus, highway, park, etc. from three representative Chinese cities and driving data from 30 different drivers. Moreover, some statistical results and analyses are produced in accordance with the designed methodologies as instances of potential application. Up to now, the dataset contains about 7,000 labelled image frames and corresponding LiDAR, GPS and Controller Area Network (CAN) data. Labels cover scene type, road user, traffic sign, traffic light, and lane marker. This benchmark can help researchers better understand Chinese traffic situation in aspects of environmental perception, driving behavior analysis, risk assessment, automated vehicle decision and control.
Integration of Genetic Algorithm and Support Vector Machine to Predict Rail Track Degradation
Authors: Falamarzi Amir , Moridpour Sara , Nazem Majidreza , Hesami Reyhaneh
Published: January 2019

Gradual deviation in track gauge of tram systems resulted from tram traffic is unavoidable. Tram gauge deviation is considered as an important parameter in poor ride quality and the risk of train derailment. In order to decrease the potential problems associated with excessive gauge deviation, implementation of preventive maintenance activities is inevitable. Preventive maintenance operation is a key factor in development of sustainable rail transport infrastructure. Track degradation prediction modelling is the basic prerequisite for developing efficient preventive maintenance strategies of a tram system. In this study, the data sets of Melbourne tram network is used and straight rail tracks sections are examined. Two model types including plain Support Vector Machine (SVM) and SVM optimised by Genetic Algorithm (GA- SVM) have been applied to the case study data. Two assessment indexes including Mean Squared Error (MSE) and the coefficient of determination (R2) are employed to evaluate the performance of the proposed models. Based on the results, GA-SVM model produces more accurate outcomes than plain SVM model.
The effect of logistics service on firm financial performance in textile industry: evidence from Da Nang city, Vietnam
Authors: Hoang Van Hai , Nguyen Truong Son
Published: January 2019

The purpose of this study is to understand an effect of the logistics service on firm financial performance in textile industry of Da Nang city, Viet Nam. A questionnaire was developed to survey several critical factors in the logistics services. Factor analysis method was applied to find some major configurations for each influential factor, and multi-regression method was employed to analyze the influence of critical factor on the firm financial performance. The results showed that internal logistics, inbound logistics, outbound logistics, support activities, and cost of logistics have significantly positive relationship with the firm financial performance. Interestingly, the cost of logistics becomes the main factor affecting the firm financial performance in the textile industry.
A Hybrid Meta heuristic Algorithm for the Balanced Line Production under Uncertainty
Authors: Aungkulanon Pasura , Luangpaiboon Pongchanun , Montemanni Roberto
Published: January 2019

This study proposes a hybrid Golden Ball Algorithm for solving a balanced line production for a garment firm in Thailand. At present, production lines are those in which the timing of the job movement between stations is coordinated in such a way that all of the jobs are indexed simultaneously via some heuristic sequencing or dispatching rules. This research studies the balanced line production problem with some stochastic patterns, and develops a Golden Ball Algorithm or GBA and its variants to solve the problem. To assess the effectiveness of the proposed hybrid algorithm, a computational study is conducted for both deterministic and stochastic patterns of the problem. The comparisons are made for two different levels of processing times and due date. It can be concluded that the variant HGBA2 of the algorithm by adjusting answers of the successor function on both custom training and successor phases, is slightly more effective than the other hybrid approaches in terms of quality of solutions under uncertainty.
Modeling of Damped Vibrations of Cantilevered Piezoelectric Actuators
Authors: Liao Dan , Yuan Yanhui , Yang Kunchao , Liang Hao , Gu Xiaoqin
Published: January 2019

Damped vibrations of cantilevered piezoelectric actuators were modeled and analyzed. The differential equations of motion derived by the extended Hamilton’s principle were a boundary-value problem with nonhomogeneous boundary conditions. An equivalent boundary-value problem with homogeneous boundary conditions was established through transformation and solved by modal analysis. Responses in time and frequency domains for unimorph and bimorph were obtained. Frequency response functions under excitations of voltage and tip force were verified by three-dimensional finite element method (FEM). Discrepancies between the analytical and FEM results were within 3%. Effects of distributed viscous damping were investigated using the analytical model. Numerical results showed that the vibration amplitude and resonant frequencies changed in opposite directions with increasing damping. This phenomenon was also reported in literature on generic cantilevers of a single material.
Study on Application of Infrared Spectrum Technology in Power Equipment
Authors: Li Yongxiang , Wang Tianzheng , Yuan Hui , Yang Gang , Zhang Na
Published: January 2019

In this paper, the application of infrared spectrum acquisition technology in power equipment is studied. Infrared spectrum identification and analysis technology and fault diagnosis technology can monitor and analyze the operation parameters of important equipment in real time, so as to improve the work efficiency of substation staff and achieve higher economic benefits. Therefore, infrared spectrum technology has great practical value and application prospect in power equipment.
Design and Implementation of IoT-based HVAC and Lighting System for Energy Saving
Authors: Jang Hyeonwoo , Kang Byeongkwan , Cho Keonhee , Jang Kyu hee , Park Sehyun
Published: January 2019

Building Energy Management System(BEMS) technology is under study as one of the various solutions to environmental problems such as depletion of energy resources, global warming, and climate change. Solving the energy problems of the future BEMS is not the only goal. Occupants must be guaranteed a comfortable environment. HVAC systems and lighting systems are a large part of building energy consumption, which also means that it is an important part of energy conservation. In this paper, we propose IoT-based HVAC and Lighting(I-HVAC&L) system for HVAC system and lighting system management. With I-HVAC&L System, you can save energy efficiency without compromising the convenience of residents’.
La coulée continue des aciers. Un exemple de développement technique où l’étroite coopération entre métallurgistes, constructeurs et exploitants a été d’une grande fécondité
Authors: Saleil Jean , Le Coze Jean
Published: January 2019

Les divers organes de la machine de coulée continue sont passés en revue dans leur fonctionnalité, leurs perfectionnements successifs et leur influence sur la qualité du produit.
La coulée continue des aciers. Un exemple de développement technique où l’étroite coopération entre métallurgistes, constructeurs et exploitants ont été d’une grande fécondité
Authors: Saleil Jean , Le Coze Jean
Published: January 2019

Cet article est composé de quatre parties complémentaires l’une de l’autre mais publiées séparément. Dans la partie I, se trouve une description du fonctionnement des machines de coulée continue et l’historique du remarquable développement de cette technique de coulée appliquée aux aciers. La partie II présente les multiples problèmes qui furent résolus pour arriver à faire correctement fonctionner ces machines et leur permettre de délivrer des produits de qualité. Dans la partie III, sont développées les questions métallurgiques posées par la solidification des produits en continu et la complexité inhérente à chaque famille d’acier (bas carbone, inoxydables, alliés). La partie IV décrit quelques types particuliers de machines et notamment celles destinées à la production de bandes, avec l’ensemble des problèmes spécifiques posés par ces techniques.
„Lithium in der Behandlung der Altersdepression. Was spricht dafür, was dagegen?“
Authors: Stühler Sina , Quante Arnim
Published: January 2019

Anliegen Die Lithiumaugmentation ist eine der Behandlungsoptionen bei therapieresistenter Depression. In diesem Review soll die Studienlage zu der Anwendung von Lithium im höheren Lebensalter bei unipolarer Depression zusammengefasst werden.

Methode Es wurde eine selektive Literaturrecherche in PubMed durchgeführt. Es konnten insgesamt 15 relevante Artikel (Plazebokontrollierte Studien und Übersichtsarbeiten) miteinbezogen werden. Ergebnisse: Sowohl die klinischen Studien als auch die Reviews sprechen sich positiv für die Lithiumaugmentation im Alter aus. Die Remissionsraten und das Ansprechen auf das Lithium allgemein sind sehr hoch. Nierenschäden als gefürchtete Nebenwirkungen treten nur selten auf. Auch über längere Anwendung hinaus zeigt sich das Lithium als wirksam und verträglich, wobei Laborkontrollen engmaschiger durchgeführt werden sollten.

Schlussfolgerung Lithium präsentiert sich als wirksames Medikament bei therapieresistenter unipolaren Altersdepression. Im klinischen Alltag ist der Einsatz bei fehlender Kontraindikation zu empfehlen.
Suizid und Suizidprävention im psychiatrischen Krankenhaus
Authors: Schneider Barbara , Wolfersdorf Manfred , Wurst Friedrich M.
Published: January 2019

Auch unter optimalen Bedingungen gibt es keine absolut sichere Suizidprävention. Dennoch gibt es Standards, die im psychiatrischen Krankenhaus hilfreich sind. Dazu gehören die Herstellung einer hilfreichen und fürsorglichen Beziehung unter der Mitarbeit des Patienten, die Diagnostik und adäquate psychotherapeutische und medikamentöse Therapie der Grunderkrankung sowie die Regelung von engmaschiger Betreuung, Ausgang und Besuch.
Advancements in Visible-Light-Enabled Radical C(sp)2–H Alkylation of (Hetero)arenes
Authors: Sun Alexandra , McAtee Rory , McClain Edward , Stephenson Corey
Published: January 2019

The Minisci reaction, which encompasses the radical C–H alkylation of heteroarenes, has undergone revolutionary development in recent years. The application of photoredox catalysis to alkyl radical generation has given rise to a multitude of methods that feature enhanced functional group tolerance, generality, and operational simplicity. The intent of this short review is to bring readers up to date on this rapidly expanding field. Specifically, we will highlight key examples of visible-light-driven Minisci alkylation strategies that represent key advancements in this area of research. The scope and limitations of these transformations will be discussed, with a focus on examining the underlying pathways for alkyl radical generation. Our goal is to make this short review a stepping stone for further synthetic research development. Sections are organized based on alkyl radical precursor reagents.

1 Introduction

2 Alkyl Carboxylic Acids and Carboxylic Acid Derivatives

3 Alkylboronic Acids

4 Potassium Alkyl- and Alkoxymethyltrifluoroborates

5 Alkyl Halides

6 Alcohols and Ethers

7 Conclusion
Synthesis of 4-(Arylmethyl)proline Derivatives
Authors: Loosli Simon , Foletti Carlotta , Papmeyer Marcus , Wennemers Helma
Published: January 2019

A synthesis of 4-(arylmethyl)proline by using Suzuki cross-couplings was developed. The route permits access to a variety of 4-substituted proline derivatives bearing various aryl moieties that expand the toolbox of proline analogues for studies in chemistry and ­biology.
Origins of Contrasteric π-Facial Selectivity in Epoxidations of Encumbered Tetrahydropyridines by a Bifunctional Peracid
Authors: Chen Shuming , Wang Sining , Houk K.
Published: January 2019

The origins of contrasteric diastereoselectivity in the epoxidation of encumbered tetrahydropyridines have been elucidated via density functional theory (DFT) calculations. A strong energetic preference for OH···N hydrogen bonding was found for epoxidation transition states of the unsubstituted tetrahydropyridine. For hexasubstituted tetrahydropyridines, the diastereofacial selectivity is dictated by both the strong OH···N hydrogen bonding and the conformational preference of the tetrahydropyridine substrate.
Anatomie des oberflächlichen Venensystems des
Beines
Authors: Brenner E.
Published: January 2019

Das oberflächliche Venensystem des Beines beginnt mit den epifaszialen Venen, das sind
die diversen Venennetze der Subkutis, die Vv. saphenae accessoriae, die V. epigastica
superficialis, die V. circumflexa ilium superficialis und die Vv. pudendae externae. Diese
münden in die beiden intrafaszialen Venen, die V. saphena magna und die V. saphena parva
ein. Diese wiederum münden in das tiefe Ve-nensystem ein, die V. saphena magna konstant im
Hiatus saphenus, die V. saphena parva in etwas mehr als zwei Dritteln der Fälle in der
Fossa poplitea. Zudem bestehen zahlreiche Verbindungen zwischen oberflächlichem und tiefem
Venensystem über die Vv. perforantes. Die oberflächlichen Venen stehen untereinander über
Vv. communicantes in Verbindung. In den oberflächlichen Venen finden sich zahlreiche
parietale Klappen, zumeist mit zwei, in kleineren und kleinsten Venen auch mit nur einem
Klappensegel. An der Mündung der V. saphena magna kann sich zudem eine ostiale Klappe,
Astklappe, befinden. Die Wand der oberflächlichen Venen besitzt den typischen
dreischichtigen Aufbau mit einer Tunica intima, einer Tunica media und einer Tunica
externa. Die Tunica intima besitzt, zumindest in der V. saphena magna nachgewiesen, eine
Membrana elastica interna. In der Tunica media finden sich innen longitudinal angeordnete
Bündel glatter Muskulatur, nach außen gefolgt von dichten Bündeln zirkulär angeordneter
glatter Muskulatur. In der Tunica externa können ebenfalls noch längsgerichtete
Muskelfaserbündel zu finden sein. Sowohl die V. saphena magna als auch die V. spahena
parva liegen in einer eigenen Faszienhülle, deren Boden von der Fascia cruris bzw. der
Fascia lata und deren oberflächliches Blatt von der jeweiligen Fascia saphena gebildet
wird. Innerhalb dieser „Saphenous Compartments” werden die jeweiligen Venen durch
Ligamenta saphena seitlich verankert. Etwa 60 großvolumige, klinisch bedeutende Vv.
perforantes verbinden das oberflächliche mit dem tiefen Venensystem. Zumindest eine Klappe
in einer V. perforans verhindert dabei einen Rückstrom aus dem tiefen Venensystem.
Efficacy of an over-the-scope clip for preventing adverse events after duodenal endoscopic submucosal dissection: a prospective interventional study
Authors: Tashima Tomoaki , Ohata Ken , Sakai Eiji , Misumi Yoshitsugu , Takita Maiko , Minato Yohei , Matsuyama Yasushi , Muramoto Takashi , Satodate Hitoshi , Horiuchi Hajime , Matsuhashi Nobuyuki , Nonaka Kouichi , Ryozawa Shomei
Published: January 2019

Background Duodenal endoscopic submucosal dissection (ESD) remains technically challenging, with a high risk of severe adverse events. Because exposure of the duodenal post-ESD mucosal defect to pancreatic juice and bile acid reportedly induces delayed perforation and bleeding, we examined whether defect closure using an over-the-scope clip (OTSC) system was useful for preventing postoperative adverse events.

Methods From April 2016 to February 2017, a total of 50 consecutive patients with superficial non-ampullary duodenal epithelial tumors (SNADETs) larger than 10 mm, with no more than semi-circumferential spread, were prospectively enrolled in this study. All of the lesions were treated by experienced ESD operators and the post-ESD mucosal defect was closed using OTSCs.

Results All of the SNADETs were completely removed by ESD, with an R0 resection rate of 88.0 %. The mean procedure and closure times were 67.3 ± 58.8 minutes and 9.8 ± 7.2 minutes, respectively. Although complete defect closure was achieved in 94.0 % of the patients (47/50), two patients required surgical conversion. Delayed perforation occurred in only one patient (2.1 %), who did not have successful closure of the defect, as misplacement of the OTSC exposed the muscle layer. Meanwhile, delayed bleeding occurred in three patients (6.3 %); however, the bleeding was easily controlled using endoscopic coagulation. The mean duration of postoperative hospitalization was 5.5 ± 7.2 days.

Conclusions Prophylactic defect closure using OTSCs may be effective in reducing severe adverse events after duodenal ESD.
Biconical geometries in rheometers: Exact solution for the flow field and implications for the design of measuring systems
Authors: Bohr Philipp , Stettin Heiko , Läuger Jörg
Published: January 2019

Rheometric investigations using cone-plate geometries are one of the most basic flow situations. This publication presents our findings on the analytic solution for the velocity field in the gap between two conical boundaries for rheometric flows, which has been designed by us and is referred to as “cone-pan.” The formulae are derived from the Navier-Stokes-equation in a suitable coordinate system and found in accordance with previous findings. We experimentally verify the formulae for Newtonian fluids and investigate in brief the limits of stability of this flow experimentally and from a literature discussion. A qualitative discussion of non-Newtonian effects, based on the available literature, is provided for reasons of completeness.
A new optical fiber dew point humidity sensor based on the virtual instrument
Authors: Tan Chunhua , Huang Xuguang , Lei Hongyan , Zhang Linna , Chen Jie , Meng Hongyun
Published: January 2019

In this paper, a new, automatic method of measuring air dew-point (DP) is presented. The system also realizes a relative-humidity sensing function, based on dew point and temperature measuring channels acquired data. The DP is detected on the surface of a lithium chloride-polyvinyl alcohol film fabricated on an optic fiber head using an optical system. The refractive index of the sensing film will be at its maximum value when the dew or frost starts to form at DP. A setup which includes a dew point sensor head and a measurement/control/data collection interface is assembled to enable automated measurements. Several programs are designed using the LabVIEW 8.6 environment to measure the dew point sensing properties of our sensor, such as response-recovery curves, temperature characteristic, and humidity calculation. Anti-interfered and good stability are its main advantages. The sensor can operate in the range of dew point temperature from 0 to 30 °C and relative humidity (RH) from 11% to 83% RH. The repeatability of the sensor was implemented with a standard deviation of 0.09 °C. The results showed that the measured dew point values and RH values were in very good agreement with reference values and with an accuracy of less than ±0.3 °C, 1% RH, respectively, over the whole temperature range.
Image-plate sensitivity to x rays at 2 to 60 keV
Authors: Rosenberg M. J. , Thorn D. B. , Izumi N. , Williams D. , Rowland M. , Torres G. , Haugh M. , Hillyard P. , Adelman N. , Schuler T. , Barrios M. A. , Holder J. P. , Schneider M. B. , Fournier K. B. , Bradley D. K. , Regan S. P.
Published: January 2019

The sensitivity of Fuji SR and MS image plates (IPs) used in x-ray spectrometers on OMEGA and the National Ignition Facility has been measured using two techniques. A set of radioisotopes has been used to constrain image-plate sensitivity between 6 and 60 keV, while a Manson source has been used to expose image plates to x rays at energies between 1.5 and 8 keV. These data have shown variation in sensitivity on the order of 5% for a given IP type and scanner settings. The radioisotope technique has also been used to assess IP fading properties for MS-type plates over long times. IP sensitivity as a function of scanner settings and pixel size has been systematically examined, showing variations of up to a factor of 2 depending on the IP type. Cross-calibration of IP scanners at different facilities is necessary to produce a consistent absolute sensitivity curve spanning the energy range of 2–60 keV.
CVD growth and properties of on-axis vanadium doped semi-insulating 4H-SiC epilayers
Authors: Karhu Robin , Sveinbjörnsson Einar Ö. , Magnusson Björn , Ivanov Ivan G. , Danielsson Örjan , Ul Hassan Jawad
Published: January 2019

Highly resistive homoepitaxial layers of 4H-SiC have been grown on the Si-face of nominally on-axis, n-type substrates using chemical vapor deposition. Vanadium tetrachloride has been used as the V-dopant which is responsible for the high resistivity of the epilayers. 100% 4H-polytype was reproduced in the epilayers using the optimized on-axis growth process. The upper limit of vanadium tetrachloride flow rate was also established to achieve high resistivity epilayers free of 3C polytype inclusion. A resistivity of more than 1 × 105 Ω cm has been achieved in epilayers with a very low concentration of V (1 × 1015 cm−3). Owing to the low concentration of V, superior epilayer structural quality was achieved compared to V-doped and standard high purity semi-insulating bulk grown material of similar resistivity. Epitaxial layers with varying vanadium tetrachloride flow have also been grown to study the influence of V concentration on the polytype stability, structural quality, and optical and electrical properties of epilayers. A clear correspondence has been observed in the flow-rates of vanadium tetrachloride, the atomic concentration of V, and electrical, optical, and structural properties of epilayers.
Atomic layer deposited Al2O3 capping layer effect on environmentally assisted cracking in SiNx barrier films
Authors: Kim Kyungjin , Pierron Olivier N. , Graham Samuel
Published: January 2019

We investigated the effect of an atomic-layer-deposited alumina (Al2O3) capping layer (2 or 10 nm thick) on the environmentally assisted cracking (EAC) properties of 250-nm-thick, plasma-enhanced-chemical-vapor-deposited silicon nitride (SiNx) barrier films on polyethylene terephthalate polymer substrates, using in situ optical microscopy tensile tests and numerical modeling. The 10-nm-thick capping layer resulted in a 5% decrease in crack onset strain, corresponding to the cracking of the Al2O3/SiNx bi-layer. Even though the Al2O3 layer itself is immune to EAC, its use as a capping layer did not significantly improve the mechanical reliability of the Al2O3/SiNx bi-layer under strain in ambient conditions, except for a minor 30%-50% increase in the driving force threshold required to induce crack growth. An effective capping layer should remain un-cracked during the cracking of the underlying SiNx, and a parametric study showed that it was not possible with alumina. A high fracture energy, low elastic modulus (e.g., organic material) layer is required such that cracking only occurs in the SiNx layer, presumably expected to protect SiNx from EAC degradation.
Magneto-open-circuit voltage in organic-inorganic halide perovskite solar cells
Authors: Zhang Xiao , Wei Mengmeng , Qin Wei
Published: January 2019

Organic-inorganic hybrid perovskite solar cells have space charge polarization (SCP) and bulk dipolar polarization (BDP), and it is possible to use external stimuli to tune the photovoltaic response. Here, under the stimulus of an external magnetic field, both SCP and BDP were tuned, to obtain magnetic field dependent open-circuit voltage (VOC). The application of a magnetic field is an effective way to change SCP, indicating that VOC performance is sensitive to SCP. When the SCP in perovskite solar cells was decreased, VOC increased from 1.0 V to 1.1 V, and the power conversion efficiency increased from 17.8% to 19.6%.
Bulk ferromagnetic tips for spin-polarized scanning tunneling microscopy
Authors: Haze Masahiro , Yang Hung-Hsiang , Asakawa Kanta , Watanabe Nobuyuki , Yamamoto Ryosuke , Yoshida Yasuo , Hasegawa Yukio
Published: January 2019

We characterized the performance of electrochemically etched bulk Fe and Ni tips as a probe of spin-polarized scanning tunneling microscopy (SP-STM). Through the observation of the striped contrast on the conical spin-spiral structure formed in Mn double layers on a W(110) substrate, the capability of both the tips to detect the magnetic signal was clarified. We also confirmed that the magnetized direction of the Fe and Ni tips can be flipped between the two out-of-plane directions by external magnetic fields. Our results demonstrate that the ex-situ prepared tips are reliable in SP-STM for the samples that are not susceptible to a stray magnetic field.