Seismic characterization of recycled aggregate concrete

There are significant environmental benefits of recycling waste concrete and reusing it as aggregate for structural concrete, but the use of Recycled Aggregate Concrete (RAC) is yet limited to non-structural applications such as road sub-base. Widespread application of RAC in areas such as seismic design requires an improved knowledge of RAC behavior under multiaxial state of stresses. The main objective of this research is the characterization of seismic properties of RAC by developing a stress-strain model which can reasonably describe the behavior under both unconfined and confined conditions. An extensive experimental program, including testing of several plain RAC cylinders as well as reinforced RAC columns, was conducted. There are numerous variables influencing the behavior of confined RAC, creating unlimited experimental possibilities, so the tests parameters were chosen to be limited to square columns with normal strength RAC and rectilinear tie configurations. Stress-strain curves were obtained for several 4 inches by 8 inches RAC cylinders with compressive strength from 2.5 ksi to 7.5 ksi. Based on the experimental results, a new model for stress-strain behavior of plain RAC was developed. Up to an axial strain of 0.0025, a nonlinear equation is considered for the ascending branch, which is primarily a function of compressive strength and elastic modulus, while the descending branch is a straight line and is a function of compressive strength. A sustaining branch was proposed where the plain RAC is capable of sustaining 10% of the compressive strength. 44 reinforced RAC columns, 10 inches by 10 inches in section and 32 inches in height with nine different combination of tie patterns and spacings were tested under quasi-static (1.6 10-5 per in.) and dynamic (1.6 10-2 per in.) axial straining rates. The columns with a volumetric ratio of ties of 1.5% more were capable of sustaining the load than the columns with lower volumetric ratios. Under the fast straining rate, the columns showed about 27% increase in strength. The columns with sufficient and well-distributed lateral confinement did not also show any stiffness degradation under cyclic loading. Special attention was paid to recording the axial strains at which vertical cracks were developing, as well as the strains at which the cover was no longer effective. These strains were indicative of the gradual transition of axial stresses from cover to the core. Based on these strains and contributions of concrete and longitudinal steel in for each column, a new one-of-a-kind stress-strain model for confined RAC was proposed. The model is comprised of an ascending-transition-descending structure would be suitable to define the behavior. The ascending branch proposed for plain RAC is applicable for confined RAC as well. The transition zone starts at a strain of 0.0020 and ends at a strain where the cover is completely ineffective. The descending branch is a straight line and primarily a function of the lateral reinforcement. The variables required to define the curve were described in terms of the compressive strength of plain RAC, the yield strength of steel tie and the volumetric ratio of the confinement steel. The proposed models for plain and confined RAC were examined under the flexural loading condition using two identical RAC beams. The nonlinear loaddeformation of the beam predicted using the proposed RAC models agreed with the experimental results to within 10%

Jender dalam perspektif Nasaruddin Umar / H Jamali Sahrodi MA and Amin Maulana

Gerakan Kesetaraan Jender (Gender Equality Movement) merupakan respons kaum feminis terhadap ketimpangan sikap sosial terhadap kaum wanita. Keberadaannya, bukanlah menjadi saingan kaum pria. Namun lebih mengedepankan kesetaraan hubungan antara pria-wanita. Perbedaan bologis antara pria dan wanita merupakan kodrat yang bersifat anugerah (taken for granted). Kesetaraan jender menilik pada relasi yang memberi peluang dan peran yang sama antara pria dan wanita. Kelemahan, keterbelakangan dan kondisi yang kurang menguntungkan bagi wanita—sejatinya—bukanlah kodratnya namun lebih disebabkan oleh kesempatan dan peluang untuk mengembangkan diri yang terbatas. Kenyataan berubah bahwa wanita dapat meraih prestasi sebagaimana yang pernah diraih kaum pria setelah diberikan kesempatan dan peluang berpendidikan dan berkarya. Jadi, label dan penyematan wanita lebih bodoh, lemah dan terbelakang dari kaum pria merupakan mitos hasil konstruk sosial. Konstruks sosial ini dapat berubah setelah kesempatan, peran dan peluang diberikan secara sama kepada kaum wanita dan pria

Mengelola Stress di Sekolah

Stres dikenal suatu prilaku negatif yang dialami oleh seseorang, bisa tenaga pendi-didik, tenaga kependidikan atau oleh pegawai di instansi lainnya. Stres disebabkan oleh suatu tekanan yang menyebabkan seseorang tidak stabil dalam berprilaku dan akan mempengaruhi kestabilan dan kefokusan dalam bekerja. Bagi pendidik dan tenaga kependidikan stres bisa disebabkan oleh tuntutan pekerjaan atau masalah pribadi, yang keduanya akan mempengaruhi tekanan mental. Akibatnya kalau dari tuntutan atau masalah tersebut tidak teratasi dapat mempengaruhi kesehatan atau jatuh sakit. Namun demikian, bagi pendidik dan tenaga kependidikan stres harus dapat dikelola dengan baik dengan menggunakan berbagai pendekatan, seperti olahraga, rekreasi, berteman dengan orang yang ilmu agamanya lebih tinggi, dari pendekatan itu, bisa mengurangi volume dari kesetresan seseorang

Nonlinear System Identification of Laboratory Heat Exchanger Using Artificial Neural Network Model

This paper addresses the nonlinear identification of liquid saturated steam heat exchanger (LSSHE) using artificial neural network model. Heat exchanger is a highly nonlinear and non-minimum phase process and often its working conditions are variable. Experimental data obtained from fluid outlet temperature measurement in laboratory environment is used as the output variable and the rate of change of fluid flow into the system as input too. The results of identification using neural network and conventional nonlinear models are compared together. The simulation results show that neural network model is more accurate and faster in comparison with conventional nonlinear models for a time series data because of the independence of the model assignment.DOI:http://dx.doi.org/10.11591/ijece.v3i1.195

The effect of management decision processes on the management of bridges

It is necessary to execute interventions on bridges to ensure that they continue to provide an adequate level of service. It is necessary to inspect them to ensure that these interventions are timed appropriately. As there are negative impacts associated with both inspections and interventions, e.g. the impact on the owner due to the hours of labor and amounts of materials required to perform an inspection and execute an intervention, it is desirable to determine inspection and intervention strategies that minimize these negative impacts (i.e. the optimal management strategy). An important, however often overlooked, factor in determining optimal management strategies, is how management processes affect the determination of the optimal management strategy. In this article it is shown that it is not always possible to determine an optimal management strategy without explicitly taking into consideration management processes, how variations in management processes can be evaluated and that the significance of these variations is dependent on the values of the incurred impacts. First published online: 21 Oct 201

Insights into The Diversity of Nepenthes L. (Nepenthaceae) Across Peninsular Malaysia, Including The First Sighting of an Undescribed Taxon with Flared Peristomes and Quadruple-Row Ventral Wings

The discoveries of six taxa between 2019 and 2022 have brought the total number of Nepenthes species occurring in Peninsular Malaysia to 18. This article serves as a comprehensive overview, incorporating the latest information and taxonomic insights concerning all species native to the peninsula. The information is derived from published taxonomic records and cumulative field observations conducted since 2013. Notably, it further reports heretofore undocumented discoveries, making it a significant contribution to the current knowledge of tropical pitcher plants. These include a sighting of a population of Nepenthes with unusual traits in the upper montane forest of Banjaran Titiwangsa, which may represent the 19th taxon in Peninsular Malaysia. The plants exhibit conspicuously expanded peristomes and an unusual wing morphology, which altogether provide compelling evidence supporting the recognition of these individuals as a distinct and previously unknown species. Therefore, a provisional taxonomic name—Nepenthes sp. Titiwangsa (pesonawangsa_223) A. Amin—is assigned. The species is inferred to belong to the N. macfarlanei group based on its toothed peristome and the presence of fine hairs below the lid. The partial description, species note, photographs, and a dichotomous key of the proposed new species are provided. In addition, a velvety N. sanguinea population has been observed in northern Banjaran Titiwangsa and treated as a new natural variation (var. velutina) in this articl

Sensitivity Analysis for Optimal Parameters for Marine Radar Data Processing

A bird and bat monitoring system has been developed that uses marine radar, IR camera and acoustic recorders for wind farm applications. IR video recording is used to monitor birds and bats activity which will be useful for wildlife biologists in developing mit igation techniques to minimize impact of wind turbines on birds and bats. The goal is to quantify birds and bats activity near wind turbines. Radar will provide z-coordinate (alt itude) and IR camera will provide (x, y) coordinates of birds/bats. Acous tic monitoring is used to identify birds and bats at their species level. This paper deals with the use of marine radar for determining altitudes, direction and quantity (passage rates) of birds/bats. Data from the marine radar is digitized and processed with open source radR software. Since the data is unknown tracking and quantification can be very challenging. This paper deals with the sensitivity analysis and effects of various parameters used in the tracking algorithm so resulting data can be meaningful

Effect of different types of stenosis on generalized power law model of blood flow in a bifurcated artery

This study is focus on generalized power law model of blood flow in a stenosed bifurcated artery under the effect of different types of stenosis. Stenosis can cause the narrowing of the artery that may reduce the flow of blood supply to the heart, and this may lead to the heart attacks. The geometry of the bifurcated artery with different classification of stenosis locations is considered in order to shows four possible morphologies formation of plaque from healthy artery to disease artery. The bifurcated artery is modelled as a two-dimensional rigid wall since the wall of a disease artery is reported to be less flexibility. Few assumptions are considered such as blood are incompressible, laminar, steady and characterized as the generalized power-law model. Simulation results are obtained using COMSOL Multiphysics 5.2, which is a software that based on the finite element method to solve this problem. Results concerning the effect of different locations of stenosis on generalized power law model of the blood flow characteristic such as streamlines pattern are discussed