234 research outputs found
UTP CarPool System
Transportation has been one of the main problems with students in university, especially
for university in the remote area. Only a minor portion of students has their own
transport, more over, the University Tecknologi Petronas is located far away from the
city, students there have faced a lot of difficulties when they want to go out of the
campus. UTP car pooling system has been developed with the purpose to overcome that
problem. The system will let a student share his private vehicle with one or more people
that have common or aligned destination. This concept has been familiar in the United
State and many countries in Europe but not in Malaysia. UTP Car Pooling System is a
web based system will be implemented by open source software, which will bring the
flexibility and reusability to the system. Apache will be used as Web Server while MySql
will be the backend Database. PHP will act as a middleware, to generate the dynamic
content to display at the client side. Because of mobile blooming and characteristic of
car pooling system, the system will take the advantage of wireless technology to provide
service to mobile users via their hand phones. The system development will consist of
three phases with three particular versions. During the first phase, the system will be set
up on PC platform, so that user can access the service via their computers. After the
second phase, a lot of enhancement will be made such as ability to notify users via email
and SMS. The last phase will produce another version for micro browser, which is
totally supported by every hand phone. At that time, UTP Car Pooling System will have
ability to bring an alternative method of transportation to UTP student, which can help
them to overcome one of their main problems. Mobility is the main characteristic that
makes UTP car pool system different from others one. Most of the systems now, based
on author's research does not support handphone as well as SMS notification, which
are the most used in communication. Therefore, UTP CarPool System does not only
promote this concept system in UTP as well as Malaysia, but also a deep enhancement
of car pool system fields
Optimal Control for Torpedo Motion based on Fuzzy-PSO Advantage Technical
The torpedo is a nonlinear object which is very difficult to control. Via to manage the rudder angle yaw, the diving plane angle, and the fin shake reduction, the torpedo yaw horizontal, the depth vertical and roll damping of the system are controlled accurately and steadily. In this paper, the particle swarm optimization is used to correct the imprecision of architecture fuzzy parameters. The coverage width of membership function and the overlap degree influence of neighboring membership functions are considered in the method to adjust dynamically from the system errors. Thereby optimizing the control signal and enhancing the torpedo motion quality. The proposed method results in a better performance compared to the other control method such as adaptive fuzzy-neural that proved effective of the proposed controller
Numerical Simulation of the Stability of Rock Mass around Large Underground Cavern
Geotechnical problems are complicated to the extent and cannot be expected in other areas since non-uniformities of existing discontinuous, pores in materials and various properties of the components. At present, it is extremely difficult to develop a program for tunnel analysis that considers all complicated factors. However, tunnel analysis has made remarkable growth for the past several years due to the development of numerical analysis method and computer development, given the situation that it was difficult to solve formula of elasticity, viscoelasticity, and plasticity for the dynamic feature of the ground when the constituent laws, yielding conditions of ground materials, geometrical shape and boundary conditions of the structure were simulated in the past. The stability of rock mass around an underground large cavern is the key to the construction of large-scale underground projects. In this paper, the stability analysis was carried out based on those parameters by using 2D FEM RS2 program. The calculated stress and displacements of surrounding rock and rock support by FEM analysis were compared with those allowable values. The pattern of deformation, stress state, and the distribution of plastic areas are analyzed. Finally, the whole stability of surrounding rock mass of underground caverns was evaluated by Rocscience - RS2 software. The calculated axial forces were far below design capacity of rock bolts. The strong rock mass strength and high horizontal to vertical stress ratio enhanced safe working conditions throughout the excavation period. Thus wide span caverns and the system of caverns could be stability excavated sedimentary rock during the underground cavern and the system of caverns excavation by blasting method. The new method provides a reliable way to analyze the stability of the caverns and the system of caverns and also will help to design or optimize the subsequent support. Doi: 10.28991/CEJ-2022-08-01-06 Full Text: PD
Influence of temperature on mechanical characteristics of 1018 low carbon steel estimated by ultrasonic non-destructive testing method
The temperature dependence of ultrasonic velocities propagated in low carbon steel 1018 has been investigated by the A-scan mode of the ultrasonic non-destructive testing method. Experimental results show that these velocities are linearly dependent on temperature of the carbon steel sample in the range of 0 to 50 °C. Based on the experimental velocities of the longitudinal wave and the shear one, mechanical characteristics of this carbon steel including Poisson's ratio (υ), Young’s modulus (E), shear modulus (G), and bulk modulus (K) have been calculated. These mechanical characteristics have also been linear response with respect to the increase of sample’s temperature. By using linear fitting approach, the temperature dependence coefficients of these mechanical characteristics have been analyzed and estimated to be 9.76×10-6/°C, −0.057 GPa/°C, −0.023 GPa/°C, and −0.038 GPa/°C for v, E, G, and K, respectively. It is concluded that the influence of the temperature on the mechanical properties of the carbon steels is necessary determined due to the improved accuracy of the ultrasonic testing method
Carbon assessment for Robusta coffee production systems in Vietnam: a case study in Dak Lak
Carbon assessments have proliferated to identify climate friendly practices in Arabica producing systems, though little attention is given to Robusta. In this study, we evaluated the climate impact of Robusta production via quantification of carbon stock and greenhouse gas (GHG) emissions in the intensive shaded and unshaded coffee farms of the world’s largest Robusta producing region, Vietnam’s Central Highlands. We find due to the linear relationship between fertilizer use and yields, emissions from input use on a per unit product basis are not significantly different between the intensive and less intensive systems. However, when accounting for carbon sequestered in shade and coffee trees, the less intensive systems are carbon positive (sequestering more than they emit) per unit of green coffee bean produced
Domain/Multi-Domain Protection and Provisioning in Optical Networks
L’évolution récente des commutateurs de sélection de longueurs d’onde (WSS -Wavelength Selective Switch) favorise le développement du multiplexeur optique d’insertionextraction reconfigurable (ROADM - Reconfigurable Optical Add/Drop Multiplexers) à plusieurs degrés sans orientation ni coloration, considéré comme un équipement fort prometteur pour les réseaux maillés du futur relativement au multiplexage en longueur d’onde (WDM -Wavelength Division Multiplexing ). Cependant, leur propriété de commutation asymétrique complique la question de l’acheminement et de l’attribution des longueur d’ondes (RWA - Routing andWavelength Assignment). Or la plupart des algorithmes de RWA existants ne tiennent pas compte de cette propriété d’asymétrie.
L’interruption des services causée par des défauts d’équipements sur les chemins
optiques (résultat provenant de la résolution du problème RWA) a pour conséquence la
perte d’une grande quantité de données. Les recherches deviennent ainsi incontournables afin d’assurer la survie fonctionnelle des réseaux optiques, à savoir, le maintien des services, en particulier en cas de pannes d’équipement. La plupart des publications antérieures portaient particulièrement sur l’utilisation d’un système de protection permettant de garantir le reroutage du trafic en cas d’un défaut d’un lien. Cependant, la conception de la protection contre le défaut d’un lien ne s’avère pas toujours suffisante en termes de survie des réseaux WDM à partir de nombreux cas des autres types de pannes devenant courant de nos jours, tels que les bris d’équipements, les pannes de deux ou trois liens, etc. En outre, il y a des défis considérables pour protéger les grands réseaux optiques multidomaines composés de réseaux associés à un domaine simple, interconnectés par des liens interdomaines, où les détails topologiques internes d’un domaine ne sont généralement pas partagés à l’extérieur.
La présente thèse a pour objectif de proposer des modèles d’optimisation de grande
taille et des solutions aux problèmes mentionnés ci-dessus. Ces modèles-ci permettent de générer des solutions optimales ou quasi-optimales avec des écarts d’optimalité mathématiquement prouvée. Pour ce faire, nous avons recours à la technique de génération de colonnes afin de résoudre les problèmes inhérents à la programmation linéaire de
grande envergure.
Concernant la question de l’approvisionnement dans les réseaux optiques, nous proposons
un nouveau modèle de programmation linéaire en nombres entiers (ILP - Integer
Linear Programming) au problème RWA afin de maximiser le nombre de requêtes acceptées
(GoS - Grade of Service). Le modèle résultant constitue celui de l’optimisation
d’un ILP de grande taille, ce qui permet d’obtenir la solution exacte des instances RWA
assez grandes, en supposant que tous les noeuds soient asymétriques et accompagnés
d’une matrice de connectivité de commutation donnée. Ensuite, nous modifions le modèle
et proposons une solution au problème RWA afin de trouver la meilleure matrice de
commutation pour un nombre donné de ports et de connexions de commutation, tout en
satisfaisant/maximisant la qualité d’écoulement du trafic GoS.
Relativement à la protection des réseaux d’un domaine simple, nous proposons des
solutions favorisant la protection contre les pannes multiples. En effet, nous développons
la protection d’un réseau d’un domaine simple contre des pannes multiples, en utilisant
les p-cycles de protection avec un chemin indépendant des pannes (FIPP - Failure Independent
Path Protecting) et de la protection avec un chemin dépendant des pannes
(FDPP - Failure Dependent Path-Protecting). Nous proposons ensuite une nouvelle formulation
en termes de modèles de flots pour les p-cycles FDPP soumis à des pannes
multiples. Le nouveau modèle soulève un problème de taille, qui a un nombre exponentiel
de contraintes en raison de certaines contraintes d’élimination de sous-tour. Par
conséquent, afin de résoudre efficacement ce problème, on examine : (i) une décomposition
hiérarchique du problème auxiliaire dans le modèle de décomposition, (ii) des
heuristiques pour gérer efficacement le grand nombre de contraintes.
À propos de la protection dans les réseaux multidomaines, nous proposons des systèmes
de protection contre les pannes d’un lien. Tout d’abord, un modèle d’optimisation
est proposé pour un système de protection centralisée, en supposant que la gestion du
réseau soit au courant de tous les détails des topologies physiques des domaines. Nous
proposons ensuite un modèle distribué de l’optimisation de la protection dans les réseaux
optiques multidomaines, une formulation beaucoup plus réaliste car elle est basée
sur l’hypothèse d’une gestion de réseau distribué. Ensuite, nous ajoutons une bande pasiv
sante partagée afin de réduire le coût de la protection. Plus précisément, la bande passante
de chaque lien intra-domaine est partagée entre les p-cycles FIPP et les p-cycles
dans une première étude, puis entre les chemins pour lien/chemin de protection dans une
deuxième étude. Enfin, nous recommandons des stratégies parallèles aux solutions de
grands réseaux optiques multidomaines.
Les résultats de l’étude permettent d’élaborer une conception efficace d’un système
de protection pour un très large réseau multidomaine (45 domaines), le plus large examiné
dans la littérature, avec un système à la fois centralisé et distribué.Recent developments in the wavelength selective switch (WSS) technology enable
multi-degree reconfigurable optical add/drop multiplexers (ROADM) architectures with
colorless and directionless switching, which is regarded as a very promising enabler for
future reconfigurable wavelength division multiplexing (WDM) mesh networks. However,
its asymmetric switching property complicates the optimal routing and wavelength
assignment (RWA) problem, which is NP-hard. Most of the existing RWA algorithms
do not consider such property.
Disruption of services through equipment failures on the lightpaths (output of RWA
problem) is consequential as it involves the lost of large amounts of data. Therefore,
substantial research efforts are needed to ensure the functional survivability of optical
networks, i.e., the continuation of services even when equipment failures occur. Most
previous publications have focused on using a protection scheme to guarantee the traffic
connections in the event of single link failures. However, protection design against single
link failures turns out not to be always sufficient to keep the WDM networks away from
many downtime cases as other kinds of failures, such as node failures, dual link failures,
triple link failures, etc., become common nowadays. Furthermore, there are challenges
to protect large multi-domain optical networks which are composed of several singledomain
networks, interconnected by inter-domain links, where the internal topological
details of a domain are usually not shared externally.
The objective of this thesis is to propose scalable models and solution methods for
the above problems. The models enable to approach large problem instances while producing
optimal or near optimal solutions with mathematically proven optimality gaps.
For this, we rely on the column generation technique which is suitable to solve large
scale linear programming problems.
For the provisioning problem in optical networks, we propose a new ILP (Integer
Linear Programming) model for RWA problem with the objective of maximizing the
Grade of Service (GoS). The resulting model is a large scale optimization ILP model,
which allows the exact solution of quite large RWA instances, assuming all nodes are
asymmetric and with a given switching connectivity matrix. Next, we modify the model
and propose a solution for the RWA problem with the objective of finding the best switching
connectivity matrix for a given number of ports and a given number of switching
connections, while satisfying/maximizing the GoS.
For protection in single domain networks, we propose solutions for the protection
against multiple failures. Indeed, we extent the protection of a single domain network
against multiple failures, using FIPP and FDPP p-cycles. We propose a new generic
flow formulation for FDPP p-cycles subject to multiple failures. Our new model ends
up with a complex pricing problem, which has an exponential number of constraints due
to some subtour elimination constraints. Consequently, in order to efficiently solve the
pricing problem, we consider: (i) a hierarchical decomposition of the original pricing
problem; (ii) heuristics in order to go around the large number of constraints in the
pricing problem.
For protection in multi-domain networks, we propose protection schemes against
single link failures. Firstly, we propose an optimization model for a centralized protection
scheme, assuming that the network management is aware of all the details of the
physical topologies of the domains. We then propose a distributed optimization model
for protection in multi-domain optical networks, a much more realistic formulation as it
is based on the assumption of a distributed network management. Then, we add bandwidth
sharing in order to reduce the cost of protection. Bandwidth of each intra-domain
link is shared among FIPP p-cycles and p-cycles in a first study, and then among paths
for link/path protection in a second study. Finally, we propose parallel strategies in order
to obtain solutions for very large multi-domain optical networks.
The result of this last study allows the efficent design of a protection scheme for a
very large multi-domain network (45 domains), the largest one by far considered in the
literature, both with a centralized and distributed scheme
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