Increasing solar panel efficiency in a sustainable manner

Solar panel output is determined by a number of factors: obviously there is the type of panel that determines the conversion efficiency, but also the amount of light falling into the panel is of importance, among other conditions of operation. The output of a panel would e.g. drop when the amount of light falling onto it is reduced, or even when only a part of the panel is covered. Another reason for reduced output lies in the fact that the conversion efficiency drops by about 0.38 % per °C increase in panel temperature. Considering that a panel would be able to produce most of its output on a sunny day, the reduction in efficiency due to heating up is of significant importance. To achieve an optimised output, it is therefore important for the panel to remain clean, but also keep it as cool as possible. Therefore, this paper looks at a method of running water on top of a solar panel in order to clean it and cool it down. To reduce the energy consumption of moving the water from the bottom of the panel back to the top, it exploits the kinetic energy of the water that runs down the panel to pump the water back to the top. Measurements indicate that this approach leads to an average increase in output of about 12 %

Dynamic Capability Building through partnering: An Australian Mobile handset case Study

Dynamic capabilities are increasingly seen as an organisational characteristic for innovation and are regarded as a source of competitive advantage. In a quest for sustainability, service organisations are partnering with their stakeholders, and subsequently are aptly bringing innovation in services to market. Most of existing empirical research regarding dynamic capabilities seeks to define and identify specific dynamic capabilities, as well as their organizational antecedents or effects. Yet, the extent to which the antecedents of success in particular dynamic capabilities, contribute to innovation in service organisations remains less researched. This study advances the understanding of such dynamic capability building process through effective collaboration, and highlights the detailed mechanisms and processes of capability building within a service value network framework to deliver innovation in services. Deploying a case study methodology, transcribing interviews with managers and staff from an Australian telco and its partnering organisations, results show that collaboration, collaborative organisational learning, collaborative innovative capacity, entrepreneurial alertness and collaborative agility are all core to fostering innovation in services. Practical implications of this research are significant, and that the impacts of collaboration and the dynamic capabilities mentioned above are discussed in the context of a mobile handset case study

Estimating Recreational Value of the Foy's Lake: An Application of Travel Cost Count Data Model for Truncated Zeros

Abstract. To estimate the annual recreational value provided by the Foy’s Lake, using the most applicable model for on-site data, is the main objective of this study. To adhere to the objective of this study, individual travel cost method (ITCM) has been applied and zero truncated poisson regression model has been found plausible among other models to estimate the consumer surplus. Based on the estimate, the consumer surplus or recreational benefits per trip per visitor can be recommended as BDT 5,875 or US $73.44 and counting the consumer surplus per trip per visitor, the annual recreational value (total consumer surplus) provided by the lake is found to be BDT 321 million or US$ 40.2 million.Keywords: Individual Travel Cost Method, Zero Truncated Poisson Regression Model, Endogenous Stratification, Consumer Surplus.JEL. C24, Q26, Q51

MECHANISTIC CHARACTERIZATION OF RUBBERIZED ASPHALT MIXTURE AND DESIGN USING FULL SCALE TIRE-PAVEMENT FINITE ELEMENT MODELING

Rubberized half-warm mix asphalt (HWMA) is being considered as one of the promising and sustainable solutions to the current environmental and economic crisis of asphalt industry. A fully mechanistic characterization and performance analysis of this mixture subjected to realistic loading and temperature conditions is necessary before its application in a practical pavement structure. The objective of this research is to characterize the viscoelastic properties of rubberized HWMA at different temperatures and to develop and validate a finite element model of a tire-pavement structure. In this research, a generalized Maxwell model is chosen to represent the time dependent stress-strain behavior of rubberized HWMA. The dynamic modulus test results are used to calculate the viscoelastic model parameters and the resilient modulus test results are used to calculate the elastic modulus of the mixture. A finite element model is developed to conduct numerical experiment of dynamic modulus test. The model parameters are fine-tuned by comparing the finite element simulation results and the laboratory dynamic modulus experimental results. Results show that the viscoelstic model represents the actual rubberized HWMA behavior well in the high loading frequency range and shows deviation in low frequency range indicating that another model or a modification to the existing model is required to represent the behavior of rubberized HWMA for a wide range of loading frequency. The same procedure is followed to calibrate model parameters for neat hot mix asphalt (HMA), warm mix asphalt (WMA) and HWMA mixtures to compare the differences in model predictions and to use in full scale modeling. In addition to the material model, the mechanistic behavior of flexible pavement under realistic loading and boundary condition requires accurate representation of the vehicular load on the pavement. The load from the tire in this study is modeled using both a moving distributed load and rolling tire in contact with pavement in 2- and 3-dimensional simulation domains to understand the relative accuracy of various combinations of simplified and complex modeling techniques and their central processing unit (CPU) cost. The contact pressure and length, which are critical for accurately predicting the pavement performance, are calibrated by matching the pressure distribution exerted at the top of the pavement, especially for 2D simulations. Temperature dependency of pavement materials is considered by incorporating model parameters from low to high range temperatures. The computed longitudinal strain and vertical stress are compared with the measured field data found in the literature. The results show that the values computed with the viscoelastic material model in 3D simulation domain agree well with the measured data. Fatigue and rutting performance of rubberized and neat HWMA pavements is evaluated using the 3D rolling tire-pavement model. Results of neat binder mix have better fatigue resistance compared to the rubberized mixture. Similarly, the effect of layer thickness, pavement temperature and traffic speed are also computed to gain further insights into the applicability of various asphalt mixtures. Finally, the 3D pavement-rolling tire model seems to be a promising tool for obtaining valuable information about mechanistic behavior of various geometric and material combinations for economical design

Design and Assembly of High-Temperature Signal Conditioning System on LTCC with Silicon Carbide CMOS Circuits

The objective of the work described in this dissertation paper is to develop a prototype electronic module on a low-temperature co-fired ceramic (LTCC) material. The electronic module would perform signal conditioning of sensor signals (thermocouples) operating under extreme conditions for applications like gas turbines to collect data on the health of the turbine blades during operation so that the turbines do not require shutdown for inspection to determine if maintenance is required. The collected data can indicate when such shutdowns, which cost $1M per day, should be scheduled and maintenance actually performed. The circuits for the signal conditioning system within the prototype module must survive the extreme temperature, pressure, and centrifugal force, or G-force, present in these settings. Multiple fabrication runs on different integrated silicon carbide (SiC) process technologies have been carried out to meet the system requirements. The key circuits described in this dissertation are - two-stage op amp topologies and voltage reference, which are designed and fabricated in a new SiC CMOS process. The SiC two-stage op amp with PFET differential input pair showed 48.9 dB of DC gain at 500oC. The voltage reference is the first in SiC CMOS technology to employ an op amp-based topology. The op amp circuit in the voltage reference is a two-stage with NFET differential input pair that uses the indirect compensation technique for the first time in the SiC CMOS process to provide 42.5 dB gain at 350oC. The designed prototype module implemented with these circuits was verified to provide signal conditioning and signal transmission at 300oC. The signal transmission circuit on the module was also verified to operate with a resonant inductive wireless power transfer method at a frequency of 11.8 MHz for the first time. A second prototype module was also developed with the previously fabricated 1.2 µm SiC CMOS process. The second module was successfully tested (with wired power supply) to operate at 440oC inside a probe-station and also verified for the first time to sustain signal transmission (34.65 MHz) capability inside a spin-rig at a rotational speed of 10,920 rpm. All designed modules have dimensions of (length) 68.5 mm by (width) 34.3 mm to conform to the physical size requirements of the gas turbine blade

Preparation and Characterization of Activated Biochar for Lithium-Sulfur Battery Application

Utilization of low-value, abundant and sustainable biomass materials for high-value energy storage application was the main goal of this thesis. Energy storage for vehicle electrification and intermittent renewable energy sources such as solar and wind energy made it an urgent necessity to look for next generation energy storage beyond lithium-ion batteries. Lithium-sulfur (Li-S) battery is one of the most promising candidates for the next generation energy storage solutions due to its high theoretical specific capacity (1675 mAh/g), high energy density (2567Wh/kg) and low-cost. However, the commercialization of this battery has been hindered due to several reasons such as the insulating nature of sulfur, intermediate polysulfide dissolution, low Coulombic efficiency and short cycle life. Confining sulfur and polysulfides using porous and conductive carbon materials have gained wide attention to improve Li-S battery performance. Porous carbon structures can physically adsorb sulfur molecule and prevent polysulfide dissolution, whereas nitrogen doping can adsorb polysulfides chemically to improve the Li-S battery performance. Biochar is a carbon-rich, inexpensive and porous material produced as a by-product during biomass pyrolysis for bio-oil production. Being highly porous, carbon-rich and conductive make activated biochar an excellent candidate to be used for sulfur-carbon (S/C) cathode composite. This thesis work was performed focusing on two objectives. The first objective was to investigate the influence of biomass pyrolysis method on physical and chemical properties of chemically activated biochar/carbon. The second goal was to utilize fast pyrolysis biochar derived from inexpensive and abundant canola meal and Douglas-fir wood for the preparation of high-valued lithium-sulfur battery cathode composite. Fast pyrolysis biochar is obtained as a low-value byproduct of high valued liquid fuel through fast pyrolysis of biomass. Some studies with biomass biochar have been performed for lithium sulfur battery. However, fast pyrolysis derived biochar has rarely investigated for any battery application. Additionally, the protein content of canola meal biomass acts as a source of natural nitrogen-doping of activated biochar. Thus, our focus was on investigating the applicability of fast pyrolysis biochar for Li-S battery and to compare the performance with slow pyrolysis biochar and commercial conductive carbon black. For achieving the goals, biochars were prepared using fast pyrolysis and slow pyrolysis method with canola meal and Douglas-fir wood at 500°C temperature. The biochars were further activated using potassium hydroxide (KOH) at 800°C temperature as KOH activation enhanced the carbon content, surface area and pore volume of the activated biochars. Total four types of activated biochars were prepared from two biomass such as CF-AB, CS-AB, DF-AB, and DS-AB. CF-AB and DF-AB were the activated biochars derived from fast pyrolysis biochar of canola meal and Douglas-fir wood, respectively. CS-AB and DS-AB were the activated biochars derived from slow pyrolysis of canola meal and Douglas-fir wood, respectively. Physical and chemical characterizations were performed to evaluate physical and chemical characteristics of the samples (moisture content measurement, elemental analysis, thermogravimetric analysis for ash content and sulfur loading measurement, Raman and FTIR spectroscopy, scanning electron microscopy, and surface area and porosity analysis). CF-AB, CS-AB, and DF-AB activated biochars were selected based on the surface area and pore volume to synthesize S/C composite following melt-diffusion strategy at 155°C. For comparison, S/C composite was synthesized by following the same method using commercial conductive carbon black (CB). Samples were denoted as CF-AB-S, CS-AB-S, DF-AB-S, and CB-S. Additionally, CF-AB-S was washed with toluene to remove the sulfur that existed on the surface of CF-AB-S composite and developed another composite named as CF-AB-S-T. For electrochemical characterizations, such as galvanostatic charge-discharge measurement and cyclic voltammetry, lithium-sulfur cells were assembled in 2032 coin cells. Lithium chips and S/C composites were used as anode and cathode materials, respectively. Activated biochars derived from fast pyrolysis biochars exhibited significantly higher surface area (3355-3277 m2/g) and pore volume (1.58-1.49 cm3/g) in comparison to activated biochars derived from slow pyrolysis biochars. CF-AB-S-T cathode composite exhibited superior initial discharge capacity of 1507 mAh/g at the 0.05 C rate (83.75 mA/g). All the prepared five cells had exhibited initial discharge capacity higher than 1000 mAh g-1 at the 0.05 C rate. Activated biochar derived S/C composite cathodes exhibited stable performance at 40th cycle, and even at the very high 2 C rate. These results indicated the applicability of canola meal and Douglas-fir derived activated biochar as cathode material for Li-S battery and excellent potential of fast pyrolysis derived biochars

UV Dynamics of Different Ring Molecules Studied by Ultrafast Electron Diffraction

Understanding natural light-induced phenomena requires a direct viewing of atomic motion during structural evolution, which, in turn, facilitates controlling and manipulating these light-induced processes. Ultrafast Electron Diffraction (UED) is a structure-sensitive technique that can probe electronic and nuclear dynamics at sub-angstrom spatial and femtosecond time scales. UED has become a vital tool for studying photo-induced molecular dynamics and underlying science. Organic ring systems are prevalent in biology, materials, and pharmaceuticals. Their synthesis and transformation are fundamental in synthetic chemistry, influencing various fields. We used UV photons to photo-excite different cyclic molecules and investigated their photo-dynamics using gas phase UED. The photochemical transformation of quadricyclane involves an ultrafast process in which a highly strained three-membered ring is converted into less strained five and six-membered rings. The isomerization of quadricyclane into norbornadiene has recently garnered considerable attention, particularly within its application as a Molecular Solar Energy Storage (MOST) system. The UV-induced reaction probed by MeV-UED displays simultaneous electronic and nuclear dynamics. Comparison of experimental data with simulations reveals a substantial structural change as the molecule crosses the conical intersection. The analysis also suggests the involvement of a dissociation channel in addition to QD to NB isomerization in photodynamics. Cis stilbene has been serving as a model system for exploring photoisomerization and photocyclization. While the dynamics of the first excited state have been extensively investigated, higher excited states remain less explored. We employed MeV-UED to examine the dynamics following ionization due to the absorption of two UV photons. The experimental data precisely captures the oscillations of the cis-stilbene cation and agrees well with theoretical predictions. Pentamethyl-cyclopentadiene (PMCP) is a small polyene molecule, and investigating its photoreaction can provide valuable insights into reaction mechanisms, which can be applied to studying other complex polyenes. Using our KeV-UED setup, we initiated the photoreaction by pumping with 266nm photon and probed by 90KeV electron beam. The preliminary analysis of this data shows a good pump-probe signal and structural change in the molecule

Unbiased Metagenomic Sequencing for Pediatric Meningitis in Bangladesh Reveals Neuroinvasive Chikungunya Virus Outbreak and Other Unrealized Pathogens.

The burden of meningitis in low-and-middle-income countries remains significant, but the infectious causes remain largely unknown, impeding institution of evidence-based treatment and prevention decisions. We conducted a validation and application study of unbiased metagenomic next-generation sequencing (mNGS) to elucidate etiologies of meningitis in Bangladesh. This RNA mNGS study was performed on cerebrospinal fluid (CSF) specimens from patients admitted in the largest pediatric hospital, a World Health Organization sentinel site, with known neurologic infections (n = 36), with idiopathic meningitis (n = 25), and with no infection (n = 30), and six environmental samples, collected between 2012 and 2018. We used the IDseq bioinformatics pipeline and machine learning to identify potentially pathogenic microbes, which we then confirmed orthogonally and followed up through phone/home visits. In samples with known etiology and without infections, there was 83% concordance between mNGS and conventional testing. In idiopathic cases, mNGS identified a potential bacterial or viral etiology in 40%. There were three instances of neuroinvasive Chikungunya virus (CHIKV), whose genomes were >99% identical to each other and to a Bangladeshi strain only previously recognized to cause febrile illness in 2017. CHIKV-specific qPCR of all remaining stored CSF samples from children who presented with idiopathic meningitis in 2017 (n = 472) revealed 17 additional CHIKV meningitis cases, exposing an unrecognized meningitis outbreak. Orthogonal molecular confirmation, case-based clinical data, and patient follow-up substantiated the findings. Case-control CSF mNGS surveys can complement conventional diagnostic methods to identify etiologies of meningitis, conduct surveillance, and predict outbreaks. The improved patient- and population-level data can inform evidence-based policy decisions.IMPORTANCE Globally, there are an estimated 10.6 million cases of meningitis and 288,000 deaths every year, with the vast majority occurring in low- and middle-income countries. In addition, many survivors suffer from long-term neurological sequelae. Most laboratories assay only for common bacterial etiologies using culture and directed PCR, and the majority of meningitis cases lack microbiological diagnoses, impeding institution of evidence-based treatment and prevention strategies. We report here the results of a validation and application study of using unbiased metagenomic sequencing to determine etiologies of idiopathic (of unknown cause) cases. This included CSF from patients with known neurologic infections, with idiopathic meningitis, and without infection admitted in the largest children's hospital of Bangladesh and environmental samples. Using mNGS and machine learning, we identified and confirmed an etiology (viral or bacterial) in 40% of idiopathic cases. We detected three instances of Chikungunya virus (CHIKV) that were >99% identical to each other and to a strain previously recognized to cause systemic illness only in 2017. CHIKV qPCR of all remaining stored 472 CSF samples from children who presented with idiopathic meningitis in 2017 at the same hospital uncovered an unrecognized CHIKV meningitis outbreak. CSF mNGS can complement conventional diagnostic methods to identify etiologies of meningitis, and the improved patient- and population-level data can inform better policy decisions