Tubular guidance systems for daylight: Achieved and predicted installation performances

Tubular daylight-guidance systems are linear devices that channel daylight into the core of a building. The development, over the last decade, of materials with high specular reflectance has led to a large number of passive zenithal systems; the most commercially successful type of daylight guidance being installed in many parts of the world. The rapid change in technology has not been matched by the development of either reliable and standardised design methods or design criteria against which the systems may be evaluated. This paper presents the results of several surveys of daylight guidance systems in 13 working buildings. These give an indication of the conditions created, which are used as the bases of suggested design criteria. A critical review of existing performance prediction methods notes that these lag far behind comparable methods for electric lighting and conventional glazing. A number of improved methods of prediction, currently under consideration by the CIE Technical Committee TC3-38, are presented and each is tested against measured data from the installation surveys.     

Impact of interconnection photovoltaic/wind system with utility on their reliability using a fuzzy scheme

Reliability analysis has been considered as an important step in any system design process. A reliable electrical power system means a system which has sufficient power to feed the load demand during a certain period or, in other words, has small Loss of Load Probability (LOLP). LOLP is defined as an expected fraction of load not met by its power needs from electrical power system during its lifetime. Photovoltaic (PV)/Wind Energy System (WES) Hybrid Electric Power System (PV/WES HEPS) differs considerably from the Utility Grid (UG) in its performance and operating characteristics. With the interconnection of PV/WES as a HEPS into the UG, the fluctuating nature of the energy produced by these systems has a different effect on the overall system reliability than that of the fluctuating nature of energy produced by UG. Therefore, this paper presents a complete study, from reliability point of view, to determine the impact of interconnecting PV/WES HEPS into UG. Four different configurations of PV/WES/UG have been investigated and a comparative study between these four different configurations has been carried out. The overall system is divided into three subsystems, containing the UG, PV and WES. The generation capacity outage table has been built for each configuration of these subsystems. These capacity outage tables of UG, PV/UG, WES/UG and PV/WES/UG are calculated and updated to incorporate their fluctuating energy production. This paper also presents a fuzzy logic technique to calculate and assess the reliability index for each HEPS configuration under study.     

Resonant tunneling through double barriers, perpendicular quantum transport phenomena in superlattices, and their device applications

New results on the physics of tunneling in quantum well heterostructures and its device applications are discussed. Following a general review of the field in the Introduction, in the second section resonant tunneling through double barriers is investigated. Recent conflicting interpretations of this effect in terms of a Fabry-Perot mechanism or sequential tunneling are reconciled via an analysis of scattering. It is shown that the ratio of the intrinsic resonance width to the total scattering width (collision broadening) determines which of the two mechanisms controls resonant tunneling. The role of symmetry is quantitatively analyzed and two recently proposed resonant tunneling transistor structures are discussed. The third section deals with perpendicular transport in superlattices. A simple expression for the low field mobility in the miniband conduction regime is derived; localization effects, hopping conduction, and effective mass filtering are discussed. In the following section, experimental results on tunneling superlattice photoconductors based on effective mass filtering are presented. In the fifth section, negative differential resistance resulting from localization in a high electric field is discussed. In the last section, the observation of sequential resonant tunneling in superlattices is reported. We point out a remarkable analogy between this phenomenon and paramagnetic spin resonance. New tunable infrared semiconductor lasers and wavelength selective detectors based on this effect are discussed.     

Developing a procurement path determination chart SEM-based approach

The choice of an appropriate procurement system is crucial to construction project success. Procurement selection is largely based on path determination charts, with at least eight key criteria needing to be weighted by decision-makers. Including certain criteria whilst ignoring client-borne transaction costs (TCs) resulting from environmental uncertainties simplifies this process. TCs are ‘unseen’ costs associated with pre- and post-contract work. The effects of uncertainties in the transaction environment and procurement systems on TCs are investigated, comparing the traditional and design-build procurement systems. A cross-sectional sample approach was deployed, involving survey questionnaire and results verification through ‘real-world’ cases. Data was sought from construction professionals in management, design and operation of construction projects. The research participants evaluate their time spent on procurement activities using a five-point Likert scale. Hypotheses of the relations between environmental uncertainties, procurement systems, and pre- and post-contract TCs are tested using a structural equation modelling (SEM) approach. The study found that TCs account for about 46.75% and 42.88% of the daily time spent by project managers in traditional and design-build procurement systems in New Zealand respectively. The study concludes that the TC concept is a useful framework for determining objective instead of subjective opinions for procurement decisions.     

Rheology of natural fibers thermoplastic compounds: Flow length and fiber distribution

The presented study investigates the flow length and the corresponding fiber content distribution in the injection‐moulded natural fiber reinforced thermoplastics and its relation to fiber type and processing parameters such as injection pressure, temperature, injection rate and mould tempering by increasing die temperature. In this research, polypropylene compounds with nominally 30 wt % hemp and sisal fibers are investigated. The influence of the injection pressure (500 and 1000 bar), melt temperature (180°C, 200°C, and 220°C), and die temperature (23°C and 80°C) on the fiber content distribution all over the sample is investigated. An increasing linear trend of fiber content along the spiral length is observed as an evidence of a fiber/polymer multiflow system. A pattern for fiber content distribution with respect to the fiber length along the injected spiral can be distinguished, where the longer fibers are usually found at the end of the injected part and the shorter fibers remain near mould entrance point. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39861.     

On optimal filters with maximum number of constraints on amplitude and phase characteristics

For optimal filters specified amplitude and phase (or group delay) characteristics, it is required that all the free parameters of the transfer function be used for the approximation. To achieve this requirement, the number of constraints on the amlitude and phase characteristics is defined first on general interpolation bases. Constant or arbitrarily prescribed lowpass or bandpass group delay and amplitude characteristics are approximated in the maximally flat, ripple or mixed sense for lumped filters, whereas highpass and band rejection characteristics are also considered for distributed or sampled data filters. The relationship between the number of free parameters and the number of amplitude and phase constraints for a given degree is derived for non-reciprocal as well as for reciprocal lossy and reciprocal reactant cases. Conditions are derived for the distribution of free parameters between the passband and stopband amplitude and phase characteristics for transfer functions with Hurwitzian denominator and also for monotonic amplitude characteristics in the transition band. Some published separate and simultaneous approximation methods are evaluated and compared on the above bases. It is pointed out that some of these methods do not satisfy the above requirements, although the optimal solution would exhibit higher performances.     

The glass transition temperature of nitrated polystyrene/poly(acrylic acid) blends

Low-molecular-weight polystyrene was nitrated to different levels. The nitrated polystyrene was blended with different molecular weights of poly(acrylic acid), PAA. The glass transition temperatures (T_g) for the mixtures were investigated by differential scanning calorimetry. A single T_g was observed for all blends, indicating single-phase blends. In general, it was found that the T_g increases with molecular weight of PAA. The T_g values of the blends showed a positive deviation from the linear average T_g as a result of strong hydrogen bonding between the segments of the component polymers. The observed T_g values were not adequately represented by simple predictive equations or by single-parameter fitting equations. However, two-parameter fitting equations gave a reasonable representation of the data.     

Theranostic Interpolation of Genomic Instability in Breast Cancer

Breast cancer is a diverse disease caused by mutations in multiple genes accompanying epigenetic aberrations of hazardous genes and protein pathways, which distress tumor-suppressor genes and the expression of oncogenes. Alteration in any of the several physiological mechanisms such as cell cycle checkpoints, DNA repair machinery, mitotic checkpoints, and telomere maintenance results in genomic instability. Theranostic has the potential to foretell and estimate therapy response, contributing a valuable opportunity to modify the ongoing treatments and has developed new treatment strategies in a personalized manner. “Omics” technologies play a key role while studying genomic instability in breast cancer, and broadly include various aspects of proteomics, genomics, metabolomics, and tumor grading. Certain computational techniques have been designed to facilitate the early diagnosis of cancer and predict disease-specific therapies, which can produce many effective results. Several diverse tools are used to investigate genomic instability and underlying mechanisms. The current review aimed to explore the genomic landscape, tumor heterogeneity, and possible mechanisms of genomic instability involved in initiating breast cancer. We also discuss the implications of computational biology regarding mutational and pathway analyses, identification of prognostic markers, and the development of strategies for precision medicine. We also review different technologies required for the investigation of genomic instability in breast cancer cells, including recent therapeutic and preventive advances in breast cancer.     

Physiologic Insulin Resensitization as a Treatment Modality for Insulin Resistance Pathophysiology

Prevalence of type 2 diabetes increased from 2.5% of the US population in 1990 to 10.5% in 2018. This creates a major public health problem, due to increases in long-term complications of diabetes, including neuropathy, retinopathy, nephropathy, skin ulcers, amputations, and atherosclerotic cardiovascular disease. In this review, we evaluated the scientific basis that supports the use of physiologic insulin resensitization. Insulin resistance is the primary cause of type 2 diabetes. Insulin resistance leads to increasing insulin secretion, leading to beta-cell exhaustion or burnout. This triggers a cascade leading to islet cell destruction and the long-term complications of type 2 diabetes. Concurrent with insulin resistance, the regular bursts of insulin from the pancreas become irregular. This has been treated by the precise administration of insulin more physiologically. There is consistent evidence that this treatment modality can reverse the diabetes-associated complications of neuropathy, diabetic ulcers, nephropathy, and retinopathy, and that it lowers HbA1c. In conclusion, physiologic insulin resensitization has a persuasive scientific basis, significant treatment potential, and likely cost benefits.