Numerical investigation of microwave-assisted pyrolysis of lignin

A comprehensive three-dimensional mathematical model is developed for studying the microwave-assisted pyrolysis of biomass. Kraft Lignin is considered as biomass feedstock in the model, and a mixture of lignin and char, is used as the sample for pyrolysis. A lumped kinetic model which considers three lumped pyrolysis products (gas, liquid and remaining solid fractions) is coupled with the governing equations for the microwave field, heat transfer, mass transfer, Darcy fluid flow and a transient numerical analysis is performed. The distribution of electric field in the microwave cavity, and the distribution of electric field, temperature, and pyrolysis products within the lignin sample are presented. The lignin sample is predicted to undergo volumetric heating when subjected to microwave heating. Accordingly the reaction zone extends from the center of the biomass sample bed towards the outer surface. Preliminary evaluation of the applicability of the model for assessing the effect of different parameters on the microwave pyrolysis of lignin is also carried out

Development of a Nanosatellite Software Defined Radio Communications System

Communications systems designed with application-specific integrated circuit (ASIC) technology suffer from one very significant disadvantage - the integrated circuits do not possess the ability of programmability. However, Software Defined Radio’s (SDR’s) integrated with Field Programmable Gate Arrays (FPGA) provide an opportunity to update the communication system on nanosatellites (which are physically difficult to access) due to their capability of performing signal processing in software. SDR signal processing is performed in software on reprogrammable elements such as FPGA’s. Applying this technique to nanosatellite communications systems will optimize the operations of the hardware, and increase the flexibility of the system. In this research a transceiver algorithm for a nanosatellite software defined radio communications is designed. The developed design is capable of modulation of data to transmit information and demodulation of data to receive information. The transceiver algorithm also works at different baud rates. The design implementation was successfully tested with FPGA-based hardware to demonstrate feasibility of the transceiver design with a hardware platform suitable for SDR implementation

Peacebuilding as a New Form of Colonialism: A Case Study of Liberia and Sierra Leone

Around two decades ago, legal anthropologist Merry posed the question, "what can we learn about law and globalization today from revisiting the law and colonization literature?" She emphasized how colonial arrangements transformed and affected the fundamental character of contemporary and international law. While peacebuilders, development experts, and human rights activists embrace law as a tool for social change, others have looked back on the history of legal development in the Global South to warn that the rule of law served as a framework for social control. It preserved authority and punished rebellious acts that threatened order while promoting development and social progress. As a result of this reminder, the critical peacebuilding literature has begun to pay attention to how the rule of law and transitional justice frameworks may serve as conceptual, lexical, and discursive foundations for post/neo-colonial control. This article used a historical, empirical, and comparative study of post-war Sierra Leone and Liberia to argue that the transplantation of legal norms and technologies has become more professionalized. In contrast, international efforts to rebuild the rule of law have reinforced social domination by legitimizing external actors as peacebuilders and reconstituting the relationship between the domestic political class and global capital. Social domination refers to the attempt to build an unequal playing field, wherein the country's political and economic elites can leverage and reproduce earlier forms of power relations and domination to consolidate their security within the state apparatus and benefit disproportionately from the security created by a large external presence

A Hybrid Reconfigurable Solar and Wind Energy System

We study the feasibility of a novel hybrid solar-wind hybrid system that shares most of its infrastructure and components. During periods of clear sunny days the system will generate electricity from the sun using a parabolic concentrator. The concentrator is formed by individual mirror elements and focuses the light onto high intensity vertical multi-junction (VMJ) cells. During periods of high wind speeds and at night, the same concentrator setup will be reconfigured to channel the wind into a wind turbine which will be used to harness wind energy. In this study we report on the feasibility of this type of solar/wind hybrid energy system. The key mechanisms optics, cooling mechanism of VMJ cells and air flow through the system were investigated using simulation tools. The results from these simulations, along with a simple economic analysis giving the levelized cost of energy for such a system are presented. An iterative method of design refinement based on the simulation results was used to work towards a prototype design. T he levelized cost of the system achieved in the economic analysis shows the system to be a good alternative for a grid isolated site and could be used as a standalone system in regions of lower demand. The new approach to solar wind hybrid system reported herein will pave way for newer generation of hybrid systems that share common infrastructure in addition to the storage and distribution of energ

A Hybrid Reconfigurable Solar and Wind Energy System

We study the feasibility of a novel hybrid solar-wind hybrid system that shares most of its infrastructure and components. During periods of clear sunny days the system will generate electricity from the sun using a parabolic concentrator. The concentrator is formed by individual mirror elements and focuses the light onto high intensity vertical multi-junction (VMJ) cells. During periods of high wind speeds and at night, the same concentrator setup will be reconfigured to channel the wind into a wind turbine which will be used to harness wind energy. In this study we report on the feasibility of this type of solar/wind hybrid energy system. The key mechanisms optics, cooling mechanism of VMJ cells and air flow through the system were investigated using simulation tools. The results from these simulations, along with a simple economic analysis giving the levelized cost of energy for such a system are presented. An iterative method of design refinement based on the simulation results was used to work towards a prototype design. T he levelized cost of the system achieved in the economic analysis shows the system to be a good alternative for a grid isolated site and could be used as a standalone system in regions of lower demand. The new approach to solar wind hybrid system reported herein will pave way for newer generation of hybrid systems that share common infrastructure in addition to the storage and distribution of energ

An Exploration of Occupational Therapy Faculty Perceptions of Student Behaviors

Occupational therapy (OT) graduate students may demonstrate behaviors in their learning that faculty perceive as unprofessional or resistant. Faculty often attribute these behaviors to personality traits or other qualities residing within the student rather than seeing them as a result of a confluence of intrinsic and extrinsic factors, as Tolman and Kremling proposed in the Integrated Model of Student Resistance (IMSR). This study examined the perceptions of student resistance to learning by surveying OT faculty teaching in entry-level masters and doctoral programs. Participants completed an anonymous, online survey that used a Likert scale rating to collect data about the frequency of active and passive forms of resistance observed in the classroom. Participants also completed open-ended textual questions about what they believed the cause of these behaviors to be. Fifty-one participants completed the survey. We analyzed the data using descriptive statistics and a qualitative analysis of textual responses was conducted. Results showed that OT faculty did encounter behaviors from students that suggested the presence of resistance to learning as described in Tolman and Kremling’s (2017) model. Active and passive behaviors were reported almost equally by participants. Most participants attributed these behaviors to intrinsic factors among students, with few recognizing the role of extrinsic and systemic level factors in causing students to resist learning. While the results of the study affirmed that resistance to learning is present among OT graduate students, OT faculty showed limited awareness of the varied and transactional causes for resistive behaviors. Based on these results, the authors discuss implications for faculty to recognize, prevent, and remediate factors contributing to resistance at the individual, program, and institutional levels. Doing so could better support students and decrease student resistance to learning