Refine
Document Type
- Doctoral thesis (21)
- Conference proceeding (1)
- Master thesis (1)
- Report (1)
Has Fulltext
- yes (24)
Is part of the Bibliography
- no (24)
Year of publication
- 2016 (24) (remove)
Language
- English (24) (remove)
Keywords
- Deutschland (2)
- Dünnschichtsolarzelle (2)
- Kupferkies (2)
- Model Checking (2)
- Renewable energy (2)
- Abstammungsformel (1)
- Abwasserreinigung (1)
- Amplifier (1)
- Anfrageauswertung (1)
- Anfrageoptimierung (1)
- Atmospheric boundary layer (1)
- Atmosphärische Grenzschicht (1)
- Back Corona (1)
- Bewässerung (1)
- Biogasgewinnung (1)
- Biomass (1)
- Biomasse (1)
- Boden (1)
- Bodengefüge (1)
- Boundary layer theory (1)
- Brandenburg (1)
- Cameroon renewable energy potential (1)
- Chalcopyrit (1)
- Chalcopyrite absorbers (1)
- Chalkopyrit-Absorbermaterialien (1)
- Chalkopyrite (1)
- Coloured extended Stochastic Petri Nets (1)
- Combustion modeling (1)
- Composting (1)
- Computed tomography (1)
- Computertomografie (1)
- Constructed wetland (1)
- Contaminated biowaste (1)
- Counterflow (1)
- Cycling (1)
- Cylindrical structures (1)
- DNS <Internet> (1)
- DNS-SD (1)
- Delta-leaping (1)
- Denitrification (1)
- Denitrifikation (1)
- Direct Numerical Simulations (1)
- Direkte Numerische Simulationen (1)
- Direkte numerische Simulation (1)
- Drahtlose Sensornetze (1)
- Drahtloses Sensorsystem (1)
- Dust Resistivity (1)
- Dust Resistivity Measurement (1)
- ECC (1)
- ESP (1)
- Eingebettete Systeme (1)
- Eingebettetes System (1)
- Elektrifizierung (1)
- Elektrizitätsversorgungsnetz (1)
- Elektroentstaubung (1)
- Elliptische Kurven (1)
- Embedded systems (1)
- Energiemanagement (1)
- Energiemarkt (1)
- Enteropathogens (1)
- Enterophatogene Mikroorganismen (1)
- Entrainment (1)
- Erneuerbare Energie (1)
- Erneuerbare Energie-Gesetz (1)
- Erneuerbare Energien (1)
- Erneuerbare-Energien-Gesetz (1)
- Festkörperphysik (1)
- Finanzliquidität (1)
- Finanzwirtschaft (1)
- Flexible Kraftwerke (1)
- Flexible generation (1)
- Fließverhalten (1)
- Fotovoltaik (1)
- Fotovoltaikanlage (1)
- Gefärbte erweiterte stochastische Petri Netze (1)
- Gefärbtes Petri-Netz (1)
- Geführte Wellen (1)
- Gegenstrom (1)
- Gegenströmung (1)
- Geomorphologie (1)
- Geomorphology (1)
- Grenzschichttheorie (1)
- Guided waves (1)
- Hardware software co-design (1)
- Hardware-Software Co-Design (1)
- High temperature corrosion (1)
- Hochfrequenzverstärker (1)
- Hochtemperaturkorrosion (1)
- Hygenisierung (1)
- Hygienisierung (1)
- Illiquididty (1)
- Industrie 4.0 (1)
- Inertial waves (1)
- Intelligentes Objekt (1)
- Internet der Dinge (1)
- IoT (1)
- Jordanien (1)
- Kamerun (1)
- Kleinräumige Tagebaue (1)
- Kommunikationsprotokoll (1)
- Kompostierung (1)
- Kontamination (1)
- Kontaminierter organischer Abfall (1)
- Kraftwerk (1)
- Kumulus (1)
- LES <Strömung> (1)
- Landformen (1)
- Landforms (1)
- Landschaftsentwicklung (1)
- Large Eddy Simulation (1)
- Large-eddy simulation (1)
- Lastaufnahmekapazität (1)
- Lastwechsel (1)
- Lastwechselverhalten (1)
- Legal (1)
- Legislation (1)
- Leistungsverstärker (1)
- Level Set Methode (1)
- Level set method (1)
- Lie symmetries (1)
- Lightweight cryptography (1)
- Lineage formula (1)
- Liquidität (1)
- Load hosting capacity (1)
- Low-Noise (1)
- Ländlicher Raum (1)
- MATLAB Simulink (1)
- Memory protection (1)
- Microgrid (1)
- Mitigation strategies (1)
- Model checking (1)
- Modellierung (1)
- Nano (1)
- Nanotechnologie (1)
- Nanotechnology (1)
- Neutron radiography (1)
- Neutronenradiografie (1)
- Nitrification (1)
- Nitrifikation (1)
- Nitrogen (1)
- Nondestructive testing (1)
- Numerical simulations (1)
- Numerische Simulationen (1)
- Numerische Strömungssimulation (1)
- One dimensional turbulence (ODT) (1)
- Optimierung (1)
- Organischer Abfall (1)
- Oxidation (1)
- PA (1)
- PRNG (1)
- Particle swam optimization (1)
- Partikel-Schwarm-Optimierung (1)
- Partikelschwarmoptimierung (1)
- Pathogener Mikroorganismus (1)
- Perovskite (1)
- Perowskit (1)
- Perowskite (1)
- Petri nets (1)
- Petri-Netz (1)
- Pflanzenkläranlage (1)
- Photoelectron spectroscopy (1)
- Photoelektronenspektroskopie (1)
- Photovoltaics (1)
- Photovoltaik (1)
- Plattenwelle (1)
- Portfolio optimization (1)
- Potato peels waste (1)
- Preferential flow (1)
- Probabilistic database (1)
- Probabilistische Datenbank (1)
- Probabilistisches Datenbanksystem (1)
- Processes (1)
- Prozesse (1)
- Präferentielle Fließwege (1)
- Query evaluation (1)
- Query optimization (1)
- Rauscharm (1)
- Recht (1)
- Rechtsordnung (1)
- Rechtssystem (1)
- Renewable energy source act (1)
- Resonance (1)
- Resonanz (1)
- Risiko (1)
- Risk (1)
- Role-based access control (1)
- Rollen-basierte Zugriffskontrolle (1)
- Rotating flows (1)
- Rotationsströmung (1)
- Rotierende Strömungen (1)
- Ruanda (1)
- Rural electrification (1)
- Röntgenspektroskopie (1)
- SIMULINK (1)
- Schadensmindernde Maßnahme (1)
- Schadensminderungsmaßnahmen (1)
- Security (1)
- Sensor Networks (1)
- Shock tube (1)
- SiGe (1)
- Sicherheit (1)
- Simulation (1)
- Simulative model checking (1)
- Simulatives Modelchecking (1)
- Small-scale opencast mining (1)
- Smart Object (1)
- Soil (1)
- Solar home system (1)
- Solid-state Physics (1)
- Speicherschutz (1)
- Speicherzugriff (1)
- Stickstoff (1)
- Stochastic simulation (1)
- Stochastische Simulation (1)
- Stochastisches Modell (1)
- Storage sizing (1)
- Stoßrohr (1)
- Stoßwellenrohr (1)
- Stratocumulus (1)
- Tagebau (1)
- Tantal (1)
- Taylor-Couette-Strömung (1)
- Thermo-chemical modeling (1)
- Thermochemische Modellierung (1)
- Thermodynamik (1)
- Thin Film Solar Cells (1)
- Thin film solar cell (1)
- Trägheitswelle (1)
- Trägheitswellen (1)
- Turbulence (1)
- Turbulente Strömung (1)
- Turbulenz (1)
- Two-phase biogasification (1)
- Ultraschall (1)
- Ultraschallprüfung (1)
- Ultrasound (1)
- Uncertainty (1)
- Unsicherheit (1)
- Verbrennungsmodellierung (1)
- Verstärker (1)
- Wasser (1)
- Water (1)
- Wellenausbreitung (1)
- Wiederverwendung (1)
- Wind energy (1)
- Wind energy acceptance (1)
- Windenergie (1)
- Windenergieakzeptanz in Brandenburg (1)
- Windenergieausbau (1)
- Windenergieertrag (1)
- Windkraftanlage (1)
- Windkraftwerk (1)
- X-Band (1)
- X-band (1)
- X-ray spectroscopy (1)
- XMPP (1)
- Zerstörungsfreie Prüfung (1)
- Zinn (1)
- Zufallsgenerator (1)
- Zufallszahl Generator (1)
- Zufällige Liquidationszeit (1)
- Zuverlässigkeit (1)
- Zwei-Phasen-Biogasproduktion (1)
- Zylinder (1)
- Zylinderstrukturen (1)
- mDNS (1)
Institute
- FG Biotechnologie der Wasseraufbereitung (2)
- FG Energieverteilung und Hochspannungstechnik (2)
- FG Numerische Strömungs- und Gasdynamik (2)
- FG Sicherheit in pervasiven Systemen (2)
- FG Öffentliches Recht, insbesondere Umwelt- und Planungsrecht (mit FG Zivilrecht) (2)
- FG Angewandte Physik und Halbleiterspektroskopie (1)
- FG Atmosphärische Prozesse (ehem. Umweltmeteorologie) (1)
- FG Bodenschutz und Rekultivierung (1)
- FG Datenbanken und Informationssysteme (1)
- FG Datenstrukturen und Softwarezuverlässigkeit (1)
This work is devoted to the problem of liquidity that draws a lot of attention after the global financial crisis. We consider an optimization problem for a portfolio with an illiquid, a risky and a riskless liquid asset. We work in Merton’s optimal consumption framework with continuous time. The liquid part of the investment is described by a standard Black-Scholes market. The illiquid asset is sold at an exogenous random moment with prescribed distribution and generates additional liquid wealth dependent on its paper value. We show that one can consider a problem with infinite time horizon and special weight function that is characterized by the probability distribution of the liquidation time instead of a problem with an exogenous random liquidation time. Using the viscosity solution techniques, developed for the problem of optimization in presence of a random income, we prove the existence and uniqueness of the solution for the considered problem with logarithmic utility and modest restrictions on the liquidation time distribution. We find asymptotic bounds for the value function when liquidation time has exponential or Weibull distribution. We find optimal policies in a feedback form and illustrate how they differ from classical Merton’s policies. Through a Lie group analysis we find the admitted Lie algebra for a problem with general liquidation time distribution in cases of HARA and log utility functions and formulate corresponding theorems for all these cases. Using these Lie algebras we obtain reduced equations of the lower dimension for the studied three dimensional partial differential equations. Several of similar substitutions were used in other works before, whereas others are new to our knowledge. The applied method of Lie group analysis gives us the possibility to provide a complete set of non-equivalent substitutions and reduced equations that was not provided for the problem of such type so far. Further research of these equations with numerical and quantitative methods is expected to benefit from such analysis.
The German government has set ambitious targets for wind energy expansion and has implemented policy schemes aimed at facilitating market deployment of wind-generated electricity. Data on German wind energy market has shown that, wind energy generating capacity is increasing correspondingly towards the targeted values. Germany is the largest wind energy market in the EU (wind energy accounting for about 10% of the total electricity consumption in Germany) with an installed capacity of about 38.2 GW onshore by the close of 2014. The success of these policies has prompted other countries globally to adopt similar support schemes for renewable energies. However, the rapid growth of wind energy generation in Germany equally faces numerous challenges. Some of these problems are inherent to the wind energy technology while others are caused by the very policies instruments used to support wind energy expansion, such as limited availability of designated areas for wind energy development, non-uniform regulations, and rising prices. The objective of this research, therefore, is to assess the impact of the German energy and environmental policies on onshore wind energy development and to explore implementation options of the German model in Cameroon.
This research has examined the German onshore wind energy sector from a policy perspective based on existing literature, semi-structured interviews with major stakeholders, a case study of Brandenburg and a survey, with the aim of investigating the acceptance of wind energy and challenges the developers are facing.
Based on the study results, it can be affirmed that the future growth of the German onshore market will come from flexible government policies, which may offer fewer incentives to investors. Indeed, the cost of electricity from renewable energy technologies in Germany is in some cases already below retail rates. There is the need, therefore, to pursue strategic programmes that enhances market integration of wind energy. Furthermore, the study results equally shows that the German feed-in tariff based support scheme in its current form, cannot be implemented in Cameroon. This is because, the purchasing power of the Cameroonian population and the economic constraints of the government, makes it difficult or even impossible to adopt the current EEG model in Cameroon where often, basic needs are subsidized.
The Electric power crisis is one of the major problems in Bangladesh, the gap between demand and generation is increasing day by day. Moreover, most of the power plants are gas based which will be phased out in future. An alternate electric supply is an essential part for electrifying the developing countries, in this context an innovative approach of rural electrification including DC microgrid, mini-grid and nanogrid would be technically and economically feasible. The thesis draws also attention on the development of technology which enables community owned power system to emerge in the rural areas based on distributed SHS and demand of that community.
Firstly, the electric status and renewable potential in Bangladesh are studied and considered those data into the software based simulation to analysis the technical feasibility to implement DC microgrid by Homer pro tools. The distributed RES (Renewable Energy sources) considered solar PV and biomass. The booming of a large number of individual SHS (Solar Home System) in Bangladesh, bottom-up energy sharing concept would have studied to configure the optimal design of microgrid system and different configuration including grid connected and DC and AC system studied.
Secondly, The PV module is highly dependent on cell temperature and solar irradiance, the ambient temperature, and solar irradiance mathematical equation have been considered to model and simulate in MATLAB/SIMULINK based environment. Similarly charge controller, battery operation, and performance analysis with respect to the PV model. In the distributed energy sources are mainly SHS including large size and regular also model and simulate in MATLAB/SIMULINK software. For instance, the thesis mainly focuses on an optimal design, planning, sizing of DC hybrid microgrid, the SHS, and biomass-based power system with the goal of maximizing the efficiency and reliability. Homer Pro tool used in the work for design an optimal configuration and sizing for technical feasibility.
Finally, a model of DC microgrid compresses with micro sources like SHS systems, µ-CHP, the household loads model in MATLAB/SIMULINK. Decentralized SHS control strategies (droop control) and operation also design and model in MATLAB/SIMULINK environment, where DC – DC converter needs to couple SHS and DC microgrid.
With the introduction of the Internet at the end of the last century the modern society was fundamentally changed. Computer systems became an element of nearly all parts of our daily live. Due to the interconnection of these systems local borders are mostly vanished, so that information is accessible and exchangeable anywhere and at anytime. But this increased connectivity causes that physical fences are no longer an adequate protection for computer systems. Whereas the security of commodity computer systems was improved continuously and similarly with their increased connectivity, deeply embedded systems were then and now mostly protected by physical fences. But the ubiquitous availability of embedded systems in personal and commercial environments makes these systems likewise accessible and moves them strongly into the focus of security investigations.
Deeply embedded systems are usually equipped with tiny scale micro controllers, which are limited in their available resources and do not feature secure mechanisms to isolate system resources. Hence, a single error in a local software component is not limited to the component itself, instead the complete system may be influenced. The lack of resource isolation makes tiny scale systems prone for accidental errors but in particular vulnerable for a broad variety of malicious software. For a safe and secure operation of computer systems it is strongly recommended that software components are isolated in such a manner that they have access only to those resources, which are assigned to them. Even though a substantial number of approaches in the context of embedded system’s safety were investigated during the last fifteen years, security was mostly neglected.
This thesis is focused on security aspects where malicious software wittingly tries to bypass available protection mechanisms. The thesis introduces a security platform for tiny scale systems that enforces an isolation of software components considering security aspects. Due to the limited resources of tiny scale systems the proposed solution is based on a co-design process that takes the static and predefined nature of deeply embedded systems into account and includes hardware, compile-time, and run-time partitions to reduce the number of additional run-time components, to avoid performance drawbacks, and to minimize the memory as well as the components footprint overhead. To prove the applicability of the presented platform it was applied and evaluated with two real applications. In addition, an investigation of technologies of commodity computer systems that are suitable to build secure systems is presented. The thesis analyzes their enforcement based on the features provided by the introduced security platform. The contributions of this thesis include an enforcement of a security isolation of system resources on tiny scale systems and enable the development of a broad variety of secure tiny scale system applications.
On the applicability of short key asymmetric cryptography in low power wireless sensor networks
(2016)
The growing popularity of Wireless Sensor Networks (WSN) makes the spectrum of their applications very wide. A great number of the application areas like health monitoring or military applications require a high level of security and dependability from the wireless sensor network. Solving these issues can be supported by providing cryptographic solutions into WSN applications. Since the WSNs mainly consist of low power devices, cryptographic solutions ideal for WSNs should provide computationally lightweight security mechanisms producing small data packets and ensuring confidentiality. Cryptographic mechanisms that have both these features are considered in this thesis, which main objective is the analysis of the applicability of the short key elliptic curve cryptography in WSN environments. Reduced key lengths require modification of the standard ECC security algorithms to provide authentication and also a novel solution for a cryptographic secure pseudo-random number generator. The proposed solution is based on the standard ECC, but it differs in several aspects. The main difference is that the parameters of the used elliptic curve have to be kept secret. This is due to the fact that solving the Discreet Logarithm Problem (DLP) for such short parameters can be done in short time. Additionally, using shorter parameters for the underlying elliptic curves excludes also the use of standard hash functions, what mainly influences the mechanisms for generating the digital signature. Hash functions require large input values and produce relatively large output data that is inapplicable in the shortECC environment. Thus, within this thesis a modified version of standard Elliptic Curves Digital Signature Algorithm is proposed, which does not require any hash function. The shortECC needs pseudo-random numbers in the encryption and the digital signature protocols, but since it operates on numbers that are significantly shorter than the ones used by other cryptographic approaches, pseudo-random number generators for standard approaches are not suitable for shortECC. Thus, the new pseudo-random number generator not involving any additional hardware besides the modules available on the used test platform and operating on 32-bit long integers, is proposed. The randomness of the numbers generated by the proposed algorithm and their applicability for cryptographic purposes was evaluated using the NIST test suites. The shortECC approach was also subjected to cryptanalysis in order to proof its security and determine the circumstances and constraints for its application.
MARCIE manual
(2016)
This manual gives an overview on MARCIE – Model Checking And Reachability analysis done effiCIEntly. MARCIE was originally developed as a symbolic model checker for stochastic Petri nets, building on its predecessor – IDDMC – Interval Decision Diagram based Model Checking – which has been previously developed for the qualitative analysis of bounded Place/Transition nets extended by special arcs. Over the last years the tool has been enriched to allow also quantitative analysis of extended stochastic Petri nets. We concentrate here on the user viewpoint. For a detailed introduction to the relevant formalisms, formal definitions and algorithms we refer to related literature.
Stochastic modelling of biochemical reaction networks is getting more and more popular. Throughout the past decades typical biological models increased in their size and complexity, because of advances in systems and molecular biology, in particular through the high-throughput omic technologies. Here biochemical networks of different levels of detail are modelled, starting with simple chemical reactions and signal transduction networks, up to individual cells and entire organisms. This increases the demand for efficient analysis methods.
A Petri net is a mathematical modelling language for the description of concurrent behaviour of distributed systems. Its advantage is the ease of scalability of the models, which relates to the network’s state space, as well as the structure of the network itself.
In this work, we recall several stochastic simulation algorithms, e.g., exact as well as approximate methods. Furthermore, we introduce an approach to improve the efficiency of stochastic simulation for large and dense networks by a new approximate stochastic simulation algorithm called discrete-time leap method. We depict the wide range of simulative analyses of complex stochastic systems ranging from trace generation to the computation of transient solutions and steady state distributions. We set forth advanced analysis of stochastic models by means of simulative model checking. For the use of simulative model checking, we integrate the continuous stochastic (reward) logic (CS(R)L) and the probabilistic linear-time temporal logic with constraints (PLTLc). Simulative model checking has some limitations compared to the numerical methods, e.g., in principle it is possible to consider nested probabilistic formulas in CS(R)L, but not practical, since the calculation is not feasible in a reasonable period of time. In addition to the transient analysis, the steady state analysis is often of interest; therefore we have implemented two on-the-fly steady state detection methods. The first one is based on a “sample batch means” algorithm and is used in the linear-time temporal logic. The second approximates the steady state distribution and checks for convergence. We apply the aforementioned techniques to several case studies from systems biology and technical systems.
The main contributions of this thesis to scientific knowledge are the development of the discrete-time leap method for the simulation of stochastic models, the approximations of transient solutions and steady state distributions by use of stochastic simulation for stochastic models and Markov reward models, the development of an infinite time horizon model checking algorithm exploiting the steady state property for PLTLc and CSL, and the first simulative model checking algorithm for CSRL incorporating state and impulse rewards. All presented algorithms and methods are implemented in the advanced analysis tool MARCIE.
Vortrag “ICESP XIV. International Conference on Electrostatic Precipitation 2016”, Wroclaw, Polen, 19.-23.09.2016
Back corona and dust resistivity are well known topics in electrostatic precipitation. Back corona results from high dust resistivity and occurs when the field strength in the dust layer surpasses a critical value E crit, which is typically found to be in the order of 15 to 30 kV/cm. Besides the resistivity ρ, the current density is the main parameter: E = i ρ < E crit. Hence, possible actions against back corona include a reduction of ρ by dust conditioning, or a reduction of i, for example by pulsed corona operation.
Much work has been devoted to study the dependence of ρ on dust composition, temperature, humidity, adsorption layers and dust layer porosity, and a variety of different set-ups for dust resistivity measurements has been proposed. Even though some authors report a dependence of ρ on current density or field strength resp., dust resistivity is mostly seen as a material property.
However, in measurements on product dusts in the upper resistivity range, we found that dusts show extremely non-ohmic properties:
Most strikingly, resistivity may vary by several orders of magnitude with time.
Also, the experimental arrangement can change the resistivity results by orders of magnitude: When resistivity is measured with the dust layer exposed to a corona discharge (imitating the situation in a real ESP), ρ depends strongly on the layer thickness. Meanwhile the same dust does not show the strong layer thickness dependence when electrodes are placed on both sides of the dust layer, and also time effects are much less prominent.
Additional findings include that dusts that have been exposed to resistivity measurements show a high level of electrostatic charging afterwards.
An interpretation of these results may be found from the theory of semiconductors and electret materials. Accordingly, highly resistive dust layers do not contain mobile electrons. Current transport occurs only after charge carriers (free electrons or holes) have been injected from the electrodes or from a gas discharge adjacent to the surface.
When the injection process is non-symmetric (e.g. with corona discharge), the current transport through the dust layer can be dominated by charge carriers of one polarity, depending on the polarity of the corona. Some of the effects observed in experiment, namely the layer thickness effect and the current density influence, can indeed be ascribed to unipolar injection and space charge limited conduction.
The time effects can mainly be ascribed to the “deep trapping” of the charge carriers, leading to a high level of immobile space charge. As overall space charge is limited, this reduces the level of mobile space charge available for current transport. The space charge also leads to a deformation of the electric field inside the dust layer, and hence influences injection via the Schottky (thermionic field emission) mechanism.
By integrating the mechanisms of charge transport in dielectrics (injection, drift, immobilization, recombination) into the OpenFOAM® simulation package, rather realistic simulations of time-dependent resistivity are possible. The simulations also are helpful to identify the mechanisms responsible for certain types of resistivity behavior.
Energy demand of continents, countries, communities and individuals will continue to increase in the phase of increasing population and improvement in the living standards of people. The attempt to meet this ever increasing demand and at the same time protect the environment has resulted in the fast growth of power generation from renewable sources of energy especially from wind through wind power plants and solar through photovoltaic power plants. This growth has been facilitated by various support schemes such as feed-in-tariff scheme, feed-in-premium and quota scheme. Further growth is expected in the future. This is because of the existing support schemes and the expectation of the emergence of improved technologies for harvesting renewable energy.
This development of power generation from renewable sources of energy although positive lead to some distinctive negative effects on the existing electrical network to which they are connected. These negative effects are known and well documented. The fluctuating nature of wind and solar radiation at any given location over a given period of observation is seen to translate into the power they feed into the power network. This fluctuating infeed requires more active management of the network by system operators so as to ensure continuous reliable power generation and delivery. Sometimes the management process lead to non-utilization of power produced by the renewables sources. Secondly, expansion and reinforcement of some existing networks are needed in other to accommodate renewable power generators. These come at a cost. Many studies and researches have been dedicated to finding solutions to these issues.
This work agrees with the use of storage systems as means of solving these issues but the question that remains unanswered is what the optimal way is. There is also a further push given to the view of installing renewable energy plants together with storage systems as a unit in this work. The main task presented in this work, however, is a concept of sizing renewable energy plant and storage systems as a unit. The resulting renewable energy plant-storage unit has the objective of supporting the electrical network to which it will be connected. Firstly the support should be by reducing the fluctuating effect from renewable production. Secondly by helping improve the load hosting capacity of the electrical network. This will be by supplying the part of the load demand leading to the reduction of the overall power drawn by connected loads from the electrical power network.
Historic data of renewable resource and also the load demand at the point or bus of connection are the drivers of this concept. With the earlier mentioned objectives and random or stochastic nature of data involved, particle swarm optimization method is employed in implementing the concept of sizing to arrive at an optimal solution of required sizes of the renewable energy plant-storage system.
The concept of sizing is based on proposing an ideal load demand that can be supplied by a utility under normal operating condition at all time. It follows that any extra demand should be supplied by the optimally sized renewable energy plant-storage unit. In this work sizing results of three scenarios presented. A single node network with three different types of the load was used in testing the effect of optimally sized renewable energy plant-storage system on an electrical network. The outcome of this test showed that the optimally sized renewable energy storage-system improved the ability of the test electrical network to support additional load hence load hosting capacity of test network was improved. The process required modelling and simulation all of which were carried out using MATLAB Simulink software.
In this study, the aims were to investigate the die-off levels of pathogens attainable under conventional biotreatments, introduce alternative hygienization options and study their performance at eliminating pathogens from biowaste. In addition, the study investigated feasibility of biotreatment of potato peels waste (PPW) as management option for the peels waste generated in Dar es Salaam city. Pathogens inactivation studies using simulated biowaste (moisture ˃77%w/w) composed of PPW spiked with Escherichia coli and Salmonella senftenbergensis at laboratory-scale resulted into low temperature-time patterns of the aerobic In-vessel composting system and turned the process anaerobic thus demonstrated inefficiency at eliminating the spiked bacteria. Likewise, two-phase anaerobic digestion at continuous stirred tank reactor confirmed incapable at effecting complete inactivation of the bacteria unless substrate residence is prolonged above 72hrs. These distasteful confirmations inevitably advocate the importance of applying either pre- and/or post-biotreatment hygienization processes on biowaste for safer biotreatments. Existing hygienization options including acid/lime conditioning and batch pasteurization were applied, their hygienization efficacy investigated and the latter validated. Acetic acid treatment of biowaste at pH value 4 for 5days or lime treatment at pH value 11-12 for 1day brought complete die-off in E. coli and S. senftenbergensis. Temperature-time combination at 65°C for 30min was sufficient at effecting ˃1log cycle die-off of the spiked enteropathogens with z-Value of 11˚C for S. senftenbergensis hence validates the temperature-time regime of 70˚C for 30min and 70˚C for 60min set by U.S-EPA/625/R-92/013 and Regulations (EC) No. 208/2006 respectively. In addition, alternative hygienization options namely UV radiation and passive solar heating (PSH) were proposed, applied and evaluated. Modes of application and achievable bacteria die-off for all hygienization options are given in Chapter 2 to 6 of this document. Owing to its small investment capital (mostly do yourself construction), independence from fuel supplies and low running costs, the study highly recommend PSH as environmental friendly and economic viable pre- and post- biotreatment hygienization option especially for tropical climates and developing countries with adequate sunshine. In vessel co-composting of PPW with yard-waste at 6:1 ratio gave microbiologically safe and good quality compost. Endowed with higher CO2 removal, mesophilic/thermophilic two-phase anaerobic processing of PPW showed comparable results to biogasification from other biowaste. Biogas productivity from PPW was 2.3lNbiogas/l.day with an average CH4 yield of 0.13-0.35m3/kgoTS input having 58% CH4. The digestion resulted into H2S removal from above LoQ to less than 230ppm with 81% VS removal at substrate OLR of 2.4kgoTS/m3.day input without sign of inhibition. It is estimated that 1.0m3biogas with 5hrs burning potential and equivalent to 3.5kg firewood can be produced from 10.2kg of PPW anaerobic digested. The resulting biogas production would complement household energy need thus conserve forest resources which are subjected to high deforestation rate estimated at 4.1kilotons of wood per day as fuelwood. Digestate resulting from the anaerobic reactors would make valuable fertilizer to urban agriculture thus enhance soil fertility and productivity.