65 research outputs found
Bebouwingsdichtheid en grondverbruik voor de woningbouw in stadsuitbreidingen
No full textCivil Engineering and Geoscience
Electrochemical Reduction of Carbon Dioxide: Modeling the electrochemical conversion of CO<sub>2</sub> to Formic Acid under high pressure
No full textDue to rising concerns about climate change, a lot of research is currently underway with respect to the development of new technologies which can contribute to the decline of atmospheric CO2, and will allow further penetration of renewables into the energy mix. A promising technology which is currently actively researched is the electrochemical reduction of CO2 (ERC). This technology utilizes otherwise polluting and unwanted CO2 and convertsit into value-added products under the influence of an electrical current. The process can therefore be designed as an energy storage mechanism since electrical energy is stored as chemical bonds. In this research, ERC towards formic acid has been investigated from two perspectives.First, the feasibility of the commercial production of formic acid compared to other products of ERC was investigated. The electrochemical production of the most common reduction products have been compared based on production costs, energy storage capabilities, toxicity and manageability. Due to the relatively low energy consumption for 2-electron products, namely formic acid, carbon monoxide and oxalic acid, it is found that these products have the most promising business case. Additionally, ERC to formic acid is best studied compared to other products, and high selectivities are commonly reported. Formic acid and methanol are liquid at atmospheric conditions, which is beneficial as relatively large amounts of energy per unit volume can be stored without the need of additional compression or cooling. This will also allow for easy transportation. As hydrogen carrier, formic acid has the advantage that it can be decomposed in H2 and CO2 near room temperature. In the second part of this research, the use of numerical modeling to study the reduction of CO2 in an electrochemical cell towards formic acid/formate at elevated CO2 pressures is presented. The model investigates to impact on the cathodic half-cell of a cell designed for the reduction of CO2 in aqueous electrolyte solutions at a constant temperature of 25℃, simultaneously assuming non-limiting conditions with respect to the anodic half-cell. The modeled part of the cell has been divided in three main regions, namely the bulk, cathode surface region and the electrode surface, which are discussed separately. The bulk is assumed to be the region of equilibrated concentrations which are constant in time, as they are not dynamically influenced by any mass transport phenomena. Reactants are supplied from the bulk to the electrode surface and products are removed vice versa via the cathode surface region, which is a thin region in the vicinity of the electrode. The transfer of species within this region and the chemical reactions between the species, form a system of diffusion-reaction equations. This system is solved numerically using appropriate boundary conditions. The actual reduction of CO2 occurs on the electrode surface, and the kinetics of the electrochemical reactions towards HCOO-, CO and H2 are described using Tafel-type kinetics. The electrochemical model has been verified and compared with experimental data, and despite various simplifications has proven to be predictive of the electrochemical reduction of CO2. It is found that the potentially beneficial effects of an elevated CO2 pressure on both the production rate and selectivity, as experimentally observed, can be reproduced with reasonable accuracy. The CO2 concentration at the electrode surface is identified as the main limiting factor for achieving both a high selectivity towards formate and a higher production rate on formate producing metals. The model shows that with an increased CO2 pressure the amount of CO2 dissolved into the solution is increased significantly, resulting in a higher concentration of CO2 at the electrode and less mass transfer limitations
Unraveling decision-making in irrigated farming in Malawi: Using Q methodology to develop typologies on water transport technology adoption
No full textDespite the strong emphasis on irrigation development in Southern Africa, different initiatives from technology developers, policy developers and development organizations to encourage water transport technology adoption have often been disappointing. The lack of long-term success can partly be contributed to a mismatch between farmer realities and technology packages, national irrigation management and development aid policies. In order to better design and promote adoption of water transport technology alternatives, it is important to create a clearer understanding of the full spectrum in which farmers operate and make farming and investment decisions. This study therefore analyses the diversity in decision-making variables influencing the adoption of water transport technologies, and considers the implications for policy & technology developers, researchers and development facilitators. Following the Q-methodology, four different factors of participants with respective sorting characteristics were identified. Thereafter the study reviews how conventional ways of grouping farmers in policy and development programs hold up against the statistically formed factors. The results show that the definitions used in the conventional way of grouping are inadequate in dealing with the subjectivity surrounding adoption of water transport technologies in Malawi. With this new appreciation for the heterogeneity of farmers comes an understanding that technologies, policies and programmes must move away from the traditional one-size-fits-all approaches to more targeted, tailor-made approaches that are more likely to facilitate efficient, sustainable and long-term uptake of water transport technologies. Policies and technology packages do not have to be tailor-made on individual scale, but should recognize the idea that there are many different kinds of farmers that base their decision-making on different variables. Recognizing this and translating it into contextualized support and technology packages can more effectively encourage uptake of water transport technology by farmers. Also, the study shows that Q-methodology can act as an useful tool to better understand farmer decision-making, feeding policy and technology discussions and development. The research seeks to contribute towards the understanding of farmer decision-making and improved action around implementation of water transport systems.Water Managemen
Hardware-Based Methods for Memory Acquisition: Analysis and Improvements
No full textSome server hosters facilitate cyber crime either intentionally (so called “bulletproof hosters”) or unintentionally (“bad hosters”). When dealing with uncooperative hosters during forensic investigations, it may sometimes be necessary to collect data or information on the servers without help from the owner of the server. Data within the RAM might prove insightful in, for example, determining active processes or reveal crypto graphically interesting information like encryption keys. The thesis explains key concepts within memory organization and the PCIe standard.Afterwards, it discusses several techniques for RAM acquisition and categorizes and evaluates them using a model-based approach. The thesis then dives deeper into DMA-based memory acquisition using PCIe and proposes several improvements to current DMA attacks in order to create a better memory acquisition technique. A novel memory acquisition technique is created by hot-plugging aPCIe device and skipping over the regular enumeration procedure. This techniqueal lows the memory acquisition to be executed without a reboot and provides a stealth approach to accessing the memory. Computer Engineerin
Testing Business Model Innovation Tooling for Small and Medium Sized Enterprises: A Multiple Case Study on the Business Model Stress Test
No full textPurposeTechnology on itself does not have a standalone value. Value is allocated by the business model that is used to bring it to the market. A business model describes the value creation and capture mechanisms of the firm. In a dynamic world, businesses face potential disruption when confronted with trends like servitization, digitation, Internet-of-Things, or changing consumer behaviour and competitive pressure. This makes that managers and business owners in all kinds of industries are increasingly forced to innovate their business models. To support managers and business owners in understanding business models and the innovation thereof, tooling has been developed, for instance to assist in mapping a business model, or helping in the transition from an old existing one, to a new business model. However, most of the tooling has been developed based on what large corporations to; it has not been developed in the context of small and medium sized enterprises (SMEs). Considering the fact that 99,8 % of the enterprises in the European Union are SMEs, and that they combined employ almost two third of the working force, business model innovation tooling is just as relevant in its link with SMEs as in its link with large corporations. Secondly, tooling has rarely been tested by independent researchers. As a consequence, it is unknown how business model innovation tooling, designed for SMEs, is used in a natural setting without direct involvement of the developer. Moreover, it is known that the BMI literature stream emerged from e-businesses. Therefore, it is argued that BMI literature, and consequently BMI tooling, is better applicable to companies from that sector. The purpose of this study is to test business model innovation tooling with SMEs, without direct involvement of the original developers. In addition, cases are selected from two dissimilar sectors: e-business and non e-business. To materialize this research, the business model stress test tool is chosen. This tool allows businesses to assess the robustness of their business model, under influence of certain future trends. Results from using the tool are insights in vulnerable business model components, and actions aimed at increasing the robustness. In this context, robustness is defined as the long-term feasibility and viability of the business model.Based on the literature, it is expected that tooling in general leads to business model experiments. These experiments in turn allow for new insights in the robustness of a business model to be generated. Eventually, those insights are turned into actions, that are aimed at improving the business model robustness. On the long term, actions should be successful in the realization of this goal. Also, barriers are identified in the literature, which could hamper the juncture of the identified steps. Barriers lie outside of the influence of the researcher and include market uncertainty, entrenching, reluctance to change, dominant logic, cognitive capability, bounded rationality, company leadership, etc.Research design The stress test tooling has been developed, and is later tested under guidance of one of the developers. Now, this tool is ready for testing by an individual researcher. The research questions questioned in this study is How does the business model stress test contribute to improving the robustness of a business model? This question refers to both if and how the tooling results in an improved robustness. To answer this research question, a qualitative multiple case design is chosen, which follows a combination of actions design research principles, and a traditional case study approach. The stress test is used in a workshop setting with four different case companies from both the marine (as a representation of non e-businesses) and ICT industry (as a representation of e-businesses). Workshops are facilitated by experienced creative facilitators, and took place at an external location. Participants included a group of 3 – 6 employees of the case company, with varying backgrounds. During the workshop, instructions of the stress test itself as designed by the developers are followed. However, for the purpose of this research some intermediate steps were added. During the workshops, the research observed the group and took notes. Apart from the observations, data was also obtained from the results of the workshop, sound recordings of the evaluation afterwards, and two questionnaires that were held with the participants both before and after the workshop. Findings Major findings of this study include that business model innovation tooling indeed leads to thought experiments, which in turn results in insights, which results in actions to improve robustness. If eventually the robustness of the company increases cannot be concluded based on this research. A longitudinal study should be held to further investigate the long-term results of this tooling.During the workshops, the following barriers were found to be present: bounded rationality, cognitive capability, company leadership, dominant logic, organizational culture, and entrenchment. Also, disturbing factors were identified, which include: the role of the researcher and the creative facilitator, focus and involvement of the participants, group composition, incorrect use of the tooling, and the inability of participants to express their opinion. Within the results of the tested hypothesis, and the identified barriers and disturbing factors, no differences were found between e-businesses and non e-businesses. Based on this research, many recommendations are given on how to improve the business model stress test. Apart from that, also general recommendations are given for designers of tooling. It was concluded that guidance is an important driver of results when using tooling. Guiding of both an experience facilitator and guiding questions are very important to establish the goal of the tooling. Practical Implications In this instance, it was observed that the stress test allows manager of technology to be aware of technological trends, before it’s too late. This tool, but also tooling in general allows for a structured process through which insights at various levels of the company can be gained. In that sense, it can be put to work to increase internal support for changing and adapting business model in a dynamic and competitive environment. Originality and Value The novelty of the study lies in the testing of BM tooling in a real-life setting without the involvement of the developer of the tooling. Based on the literature it was found that this is hardly done to date. Management of Technology (MoT
Circumventing Secure JTAG: A detailed plan of attack
No full textForensic science is the cornerstone of the modern justice system, as it allows us to analyze evidence in order to discover the truth behind a crime scene. As mobile phones became more important to our daily lives they've taken up a bigger part in forensic research as well. These devices contain digital traces telling us the story of our lives. Digital forensic research traditionally focused on recovering data, in particular data from broken or undocumented systems. While security was not the primary concern of most manufacturers, this has changed in recent times. Cryptography has become a major roadblock in forensic science, which has shifted the focus from recovery towards exploitation. Traditionally Digital forensic research focused on physical acquisition. While often tools supported logical extraction, this would leave many deleted traces inside of the memory chip intact. Instead methods such as Flasher tools, JTAG-based acquisition, In-System Programming and Chip-off were often used to make images of the physical contents of the memory chip. This would then be analyzed by data-analysts in order to extract evidence from the images. On many modern devices cryptography has ensured that these methods are no longer effective. Software exploitation techniques such as DirtyCow have proven to become much more important in digital forensic science, but more methods should be developed. JTAG is of particular interest in this regard. It is a testing system that was previously left unsecured and providing attackers with an easy way in. More recently manufacturers have started using novel ways of protecting JTAG from malicious use, but very little research exists testing these new security measures. This is a recipe for vulnerabilities. This thesis focuses on attacking Secure JTAG; Samsung's authentication module for ARM CoreSight. Several potential attacks have been highlighted that are potentially applicable to Secure JTAG. A novel model has been developed that allows an attacker to evaluate the complexity of their attacks. While models such as CVSS and DREAD exist, these focus on threat analysis rather than offensive research. Using this model two attacks were chosen: One focusing on reversing the internal JTAG boundary scan chains and the other attempting to force authentication through fault injection. In order to reverse the JTAG boundary scan chains a new set of tools had to be developed. Existing tools were often incapable of communicating with the internal scan chains or did not provide enough freedom to enable research. After their development these new tools were able to confirm that the internal scan chains were secured. The internal boundary scan chains will not be a viable attack vector until the authentication mechanism is circumvented. The second attack focused on a potential fault injection vulnerability in the Secure JTAG authentication scheme. Because Secure JTAG is a purely hardware component it provided a unique challenge. Where normally firmware is analyzed to prove the existence of a vulnerability, Secure JTAG has no such firmware available. This makes discerning between failure because the device is not vulnerable and failure because of chance nearly impossible. To increase confidence in the attack and decrease attack space this project focused on Electromagnetic Side-channel Analysis. By locating the signals produced by Secure JTAG authentication it is possible to greatly reduce the attack space, thereby increasing confidence in the attack. In the end correlating signals were located near the high-power processor of the chip, albeit not the hashing engine itself. This lowered the attack space enough for an eventual fault injection attack.Computer Science | Cyber SecurityComputer Science | Data Science and Technolog
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