Stabilization of Compressor Surge Using Gain-Scheduled Controller

Gain scheduling is a control method that is used in nonlinear systems to optimize their controlled performance and robustness over a wide range of operating conditions. It is one of the most commonly used controller design approaches for nonlinear systems. In this control technique, the controller consists of a collection of linear controllers, each of which provides satisfactory closed-loop stability and performance for a small operating region, and combined they guarantee the stability of the system along the entire operating range. The operating region of the system is determined by a scheduling signal, also known as the scheduling variable, which may be either exogenous or endogenous with respect to the plan. A good design of the gain-scheduled controller requires a suitable selection of the scheduling variables to properly reflect the dynamics of the system. In this thesis, we apply the gain scheduling control method to the control of compression systems with active magnetic bearings (AMBs). First, a gain-scheduled controller is designed and tested for the rotor levitation control of the AMB system. The levitation controller is designed to guarantee robust rotor levitation over a wide range of rotating speeds. We show through numerical simulation that the rotor vibration is contained in the presence of uncertainties introduced by speed dependent gyroscopic forces. Next, we implement the gain scheduling control method to the active stabilization of compressor surge in a compression system using the AMBs as actuators. Recently, Yoon et al. [1] showed that AMBs can be used to stabilize the surge instability in a compression system. In this thesis, we demonstrate that gain scheduling control can effectively extend the stable operating region of the compression system beyond the limits presented in [1]. For the stabilization of surge, a gain-scheduled controller was obtained by combining six linear controllers that together they cover the full operating range of the compression system. We were able to demonstrate through numerical simulation that the designed surge controller is effective in suppressing the instability down to a throttle valve opening of 12%, and in the presence of random flow disturbance and actuator saturation. An observer-based technique was implemented to achieve a bumpless and smooth transfer when switching between the linear controllers

Perancangan dan Realisasi Antena Biquad untuk WiMAX pada frekuensi 3.3-3.4 GHz

ABSTRAKSI: Seiring dengan perkembangan jaman, teknologi pun kian berkembang. Banyak teknologi – teknologi baru bermunculan pada masa sekarang ini. Setiap Negara pun seakan berlomba – lomba untuk mengembangkan teknologi baru tersebut. Salah satunya adalah WiMAX. Meski tidak terlalu baru di luar sana, tapi bagi Negara Indonesia teknologi tersebut masih baru. Untuk itu dibutuhkan beberapa perangkat pendukung untuk mendukung berkembangnya WiMAX di Indonesia.Pada masa sekarang ini, masih kurang sekali perangkat – perangkat pendukung berkembangnya WiMAX di Indonesia. Salah satu perangkat itu adalah antena user terminal (CPE). Untuk antena user terminal (CPE), sangat dibutuhkan suatu antena yang memiliki gain tepat, arah pancar yang sesuai, akurat, lebih efisien dan bentuk yang kompak. Antena yang dibuat pada penelitian ini berbentuk persegi belah ketupat yang disusun 2 buah dan disebut antena Biquad. Antena yang dibuat dapat bekerja pada frekuensi 3.3 – 3.4 GHz dengan batasan VSWR ≤ 1.3 untuk mendukung aplikasi WiMAX IEEE 802.16e. Pola radiasi antena tersebut adalah omnidirectional sehingga antena dapat memancarkan gelombang ke segala arah dengan polarisasi linier.Dari hasil pengukuran, didapatkan nilai VSWR sebesar 1.027 pada frekuensi kerjanya, yaitu 3.35 GHz. Sedangkan untuk frekuensi 3.3 GHz dan 3.4 GHz masing-masing memiliki nilai VSWR sebesar 1.253 dan 1.208. Gain yang diperoleh dari pengukuran, yaitu sebesar 7.119 dBi. Antena yang telah direalisasikan memiliki pola pancar bidirectional dan berpolarisasi elips mendekati linear.Kata Kunci : Antena Biquad, WimaxABSTRACT: Through the rolling time, technology is just followed the evolution stage. There are so many new found technologies had been discover lately. Every country is just competed each other to show who is the best one. One of the new found technologies is Worldwide Interoperability for Mobile Access (WiMAX). Even it is not truly new out there, but in Indonesia it is still count as the new one. By that reason, in Indonesia still needs some supported equipment to develop WiMAX in Indonesia itself.In this time, supported equipment to develop WiMAX in Indonesia is still in the minor amount of goods. CPE (Customer Premises Equipment) antenna is one of the supported equipments. This antenna is located in the consumer side. Because it is in the consumer side, we have to consider the size of the antenna. So, we need the antenna that has compact design, exact gain, and has the right polarization. By that specification, I would like to make that kind antenna. The antenna has square form and arrayed by 2 antennas. It is called Biquad Antenna. The Biquad Antenna will work at the range frequencies of 3.3-3.4 GHz and has VSWR ≤ 1.3 to support the WiMAX IEEE 802.16e application. It has bidirectional radiation pattern and linear polarization.From the measurements, the antenna has 1.027 in VSWR at its center frequency, 3.35 GHz, and has 1.253 in VSWR at the frequency of 3.3 GHz and 1.208 in VSWR at the frequency of 3.4 GHz. It gain is 7.119 dBi. It has omnidirectional radiation pattern and elliptic polarization which is closely to linear polarization.Keyword: Biquad Antenna, WiMA

Hybrid Approach to Steganography System Based on Quantum Encryption and Chaos Algorithms

This paper proposes a hybrid system for secretly embedding images into the dithered multilevelimage. Confident hybridizations between steganography and quantum encryptions are either rare inliterature or suffer a poor effectiveness in secure communication. This paper scrambles and divides thesecret image into groups to be embedded in the blocks of the cover image using three chaos algorithms.These are Lorenz map, Henon map, and Logistic map algorithms. The encryption of embedded imagesconducted using the quantum one-time pad. Results showed that the proposed hybrid system succeeded inembedding and combining images with quantum cryptography algorithms

The Dream of Return in Ghassan Kanafani’s Returning to Haifa

Home is the place where we are supposed to feel the most secure, comfortable and safe. However, such are the vagaries of human existence; that it is this sanctuary which comes under threat from various forces. Gassan Kanafani, in his fiction, has repeatedly highlighted this problem as it was (and continues to be) faced by several Palestinians in the face of Israeli extremist atrocities. Even while highlighting the problem, Kanafani staunchly advocates the need to hold on to one’s home, even in the face of extreme adversity. Returning to Haifa, on which this paper specifically focuses, is a powerful case in point. This paper attempts to analyse how through the trials of one displaced family, Kanafani has tried to show the need to fight for one’s homeland; because once it is given up, even if we do return later to try to pick up the threads, the narrative often changes beyond our control by then

Functional studies on factor VIII variants containing different lengths of the B-domain AND The construction of a new helper vector for the production of helper-dependent adenovectors

Functional studies on factor VIII variants containing different lengths of the B-domain To evaluate the role of the factor VIII (FVIII) B-domain on FVIII expression, (activity and activation), we constructed several FVIII expression constructs with various lengths of the B- domain and expressed them transiently as well as stably. Practically, B-domain deleted recombinant FVIII (BDD-rFVIII) was generated from the full- length FVIII-cDNA by ligating (on the protein level) Ser743 to Arg1634; the corresponding FVIII-cDNA was then cloned into the pMT2 expression vector. Then, cDNA-fragments of different length (on the protein level: 101, 202, 292, and 394 amino acid long fragments of the B-domain starting from its amino terminal) were cloned between Ser743 and Arg1634. Constructs were then transiently expressed in COS-7, HEK 293 and CHO cells and stably expressed in CHO-DHFR(-) cells by methotrexate selection and amplification. FVIII proteins were then assessed for activity in culture medium by the clotting assay and the chromogenic assay and for antigen in cellular lysates by ELISA. FVIII proteins were purified from stable cell lines media. Our transient expression studies showed that FVIII expression was the highest in COS-7 cells followed by HEK 293 cells. The CHO cells showed the lowest FVIII expression. Transient expression in COS-7 cells (for forty-eight hours) revealed that the constructs containing added lengths of the B-domain showed a higher FVIII: C (~1.1-2.5 folds) and a higher overall expressed protein (total antigen in medium and cellular lysates; ~1.1-3 folds) compared the BDD-rFVIII. The functionality of the expressed proteins in terms of FVIII specific activity was higher in all constructs in comparison to the BDD construct. Comparing the clotting FVIII activity by that of the chromogenic assay, we found that those constructs showed a slightly higher FVIII value within the clotting assay than within the chromogenic assay. In contrast, the BDD construct showed the opposite effect and also showed a significant discrepancy between both assay methods. Activation of purified FVIII proteins by thrombin revealed that the BDD-rFVIII showed a faster generation of the A2 domain than the constructs containing added lengths of the B-domain. In conclusion, our data showed that the inclusion of a 100 amino acids or more of the B- domain sequence eliminates the assay discrepancy and increases the overall expression and functionality of rFVIII protein.The construction of a new helper vector for the production of helper-dependent adenovectors Fully deleted Helper-Dependent Adenovectors (HD-AdV) are so far the ultimate form of Adenovirus vector modifications which lack all the adenovirus genes except the replication and packaging elements. They can accommodate an insert of up to 36 kb. HD-AdVs are produced in HEK 293 cells in the presence of a helper adenovirus that supplies the viral genes in trans. Using this system very high titers of HD-AdV can be prepared now, with small but still measurable helper adenovirus contamination. Within this study we have tried to design a novel hybrid helper virus that can support the production of a HD-AdV, carrying a B-domain-deleted factor VIII-cDNA, in high efficiency without any contamination. In order to avoid contamination of HD-AdV production, the adenoviral sequences in the novel hybrid helper virus was lacking the adenoviral ITRs and the packaging signal, but was flanked by adeno-associated virus (AAV) ITRs. This adenoviral helper sequences was then cloned into the baculovirus expression system. The lack of the Adenovirus packaging signal renders the hybrid helper virus packaging incompetent and thus eliminates the risk of contaminating the HD-AdV preparations. Since the helper virus also lacks the adenoviral ITRs, it will not compete with the HD-AdV for the Adenovirus 5 replication proteins. The lack of the capsid genes within the AAV-sequences should also prevent the generation of AAV particles. To drive the replication of the Ad5-genome in the hybrid helper virus theAAV2-Rep genes were cloned in a separate baculoviral construct. A GFP baculoviral construct was prepared to be used as positive control for transfecting insect cells and infecting HEK 293 cells. We successfully constructed the hybrid helper vector pBac-AAV2-Ad5 with a deletion in the 3’ITR region. The recombinant baculovirus particles (vBac-AAV2-Ad5, vBac-AAV2-Rep and vBac-EGFP) was then produced in insect cells, plaque purified and amplified to high titers. Since the deletion within the 3’-ITR region should have no effect on helper virus production, the produced baculoviruses were used to infect HEK 293 cells, together with the HD-AdV carrying the B-domain-deleted factor VIII-cDNA. Depending on the presence of AAV-ITRs, we expected that the genome of the helper-virus will be replicated, thus improving its efficiency in providing helper function. To verify our strategy in synthesizing the helper virus, we showed that the baculovirus is able to infect HEK 293 cells by eGFP expression and that the Rep gene was expressed in both SF9 cells and HEK 293 cells. After three rounds of infecting HEK293 cells with the helper hybrid virus, we couldn’t see any signs of HD-AdV production. Unexpectedly, the analysis of extracted extra chromosomal DNA showed that the material was the original transfected material and not synthesized within the HEK 293 cells. In conclusion, as the baculovirus was able to infect HEK 293 cells and the Rep genes were also expressed in those cells, we propose that the HD-AdV was not produced because of inefficient or non occurring replication of the Ad5 genes in the Bac/Ad5 hybrid. The presence of only one ITR may be a possible cause. The reconstruction of an helper hybrid with both ITRs would clarify the function of such an adenoviral helper virus system

Effective Leadership, Self-Efficacy, Emotional Intelligence, Information Acquisition and Utilization of Managers in Packaging Companies in Nigeria

This study investigated self-efficacy, emotional intelligence, information acquisition and utilization of determinants of effective leadership of managers in packaging companies in Nigeria. The survey method was used. Total enumeration technique and questionnaire was used for data gathering from a population size of 450 managers in the surveyed companies out of which 400 responded giving a response rate of 88.8 percent. Simple correlation and hierarchical regression analyses were used for data analysis. The study established that there were significant correlations among self-efficacy, emotional intelligence, information acquisition, information utilization and effective leadership of the respondents. It was further established that self-efficacy, emotional intelligence, information acquisition and utilization were significant determinants of effective leadership of managers in the packaging companies in Nigeria. It was therefore recommended that the board of management in the studied companies should endeavour to encourage their managers to acquire and utilize information to enhance their effective leadership. They should give self-efficacy and emotional intelligence training to their managers in order for them to be effective leaders. KEYWORDS: Self-efficacy, Emotional intelligence, Information acquisition, Information utilization, Managers, Nigeria

Study and evaluation of distributed power electronic converters in photovoltaic generation applications

This research project has proposed a new modulation technique called “Local Carrier Pulse Width Modulation” (LC-PWM) for MMCs with different cell voltages, taking into account the measured cell voltages to generate switching sequences with more accurate timing. It also adapts the modulator sampling period to improve the transitions from level to level, an important issue to reduce noise at the internal circulating currents. As a result, the new modulation LC-PWM technique reduces the output distortion in a wider range of voltage situations. Furthermore, it effectively eliminates unnecessary AC components of circulating currents, resulting in lower power losses and higher MMC efficiency.Departamento de Tecnología ElectrónicaDoctorado en Ingeniería Industria

Étude de la qualité des eaux d’une retenue située sous climat aride : cas du barrage Hassan II (Province de Midelt, Maroc)

Les ressources hydriques dont dispose le Maroc sont limitées. Elles sont, par ailleurs, soumises à des variations cycliques extrêmes traduites par la succession des cycles de sécheresse aigue. Celle-ci est devenue un phénomène très fréquent au Maroc, qui contribue à la dégradation des zones humides nationales. Pour subvenir aux besoins en eau de plus en plus croissants, le Maroc s'est doté d'une importante infrastructure de grands barrages. Toutefois, la faisabilité et la gestion de ces ouvrages aménagés se trouvent confrontées à deux problèmes: l'envasement et l'eutrophisation. Ces deux phénomènes sont principalement favorisés par la nature du climat et les caractéristiques intrinsèques des bassins versants. Le bassin versant de la Moulouya est parmi les bassins  hydrographiques les plus importants au Maroc, il abrite jusqu'à nos jours cinq grands barrages, dont le barrage Hassan II qui fut mise en eau en 2005.Ce barrage constitue l’une des plus grandes retenues marocaines avec une capacité de stockage maximale de 400 millions de mètres cubes. Il contrôle un bassin versant de 3 300 km2. Il a comme vocations principales la production d’eau potable, l’irrigation, et la protection des zones aval contre les inondations. Or la prolifération des activités anthropiques, en amont, associées aux caractéristiques du climat de la région d’implantation du barrage, pourront être à l’origine de la dégradation de la qualité de ce plan d’eau. Notre travail étalé sur la période allant de septembre 2011 à août 2012 avait pour objectifs d'étudier la qualité des eaux du réservoir Hassan II et d’en déterminer l’état trophique. Il en ressort qu’il s’agit d’un lac oligotrophe avec une qualité de l’eau allant du bonne à excellente.Mots-clés : barrage Hassan II, Maroc, climat, eau, qualité, eutrophisation

Enhancement of the feeding value of some agro-industrial by-products for laying hens after their solid state fermentation with Trichoderma viride

This study with some agro-byproducts was carried out to provide information on the use of fermentation by-products; brewer's dried grains (BDG), rice bran (RB), palm kernel meal (PKM) and corn bran (CB). Changes in the nutrient compositions of some selected agro industrial by-products on biodegradation with Trichoderma viride and their feeding value as an energy source for layers were investigated. The protein in BDG, RB, PKM and CB increased by 87, 68, 32 and 61%, respectively, when they were fermented with the fungi for 14 days. At the same time, the fiber in the by-products decreased by 35.00, 40.00, 36.50 and 37.50%, respectively with a corresponding increase of 49.00, 37.00, 9.00 and 5.50% in the level of soluble sugars. The energy in the biodegraded by-products increased by 6.30, 5.00, 9.00 and 18.50%, respectively. In a feeding trial with layers, 50% of the maize in a standard commercial diet was replaced with biodegraded BDG, RB and PKM. Birds on the BDG and RB diets had significantly (

Distortions to Agricultural Incentives in Bangladesh

Distorted incentives, agricultural and trade policy reforms, national agricultural development, Agricultural and Food Policy, International Relations/Trade, F13, F14, Q17, Q18,