The use of artificial roughness on the underside of the absorber plate is an effective and economic way to improve the thermal performance of a solar air heater. Several experimental investigations, ...involving different types of roughness elements, have been carried out to improve the heat transfer from the absorber plate to air flowing in solar air heaters. This paper presents an experimental investigation carried out to study the effect of multiple v-rib roughness on heat transfer coefficient and friction factor in an artificially roughened solar air heater duct. The experiment encompassed Reynolds number (Re) from 2000 to 20000, relative roughness height (
e/
D) values of 0.019–0.043, relative roughness pitch (
P/
e) range of 6–12, angle of attack (
α) range of 30–75° and relative roughness width (
W/
w) range of 1–10. Extensive experimentation has been conducted to collect data on heat transfer and fluid flow characteristics of a rectangular duct roughened with multiple v-ribs. Using these experimental data, correlations for Nusselt number and friction factor in terms of roughness geometry and flow parameters have been developed.
This article presents a novel active-mode indirect solar dryer consisting of highly efficiency through-flow evacuated tube collector for air heating. A DC fan powered with solar photovoltaic (PV) ...module is provided for forced air flow through this dryer. The dehydration chamber is of tray type with loading capacity of 6 kg–45 kg depending on the drying product. The dryer was evaluated to dry fenugreek leaves (Trigonella foenum-graecum) and turmeric (Curcuma longa) in semi-continuous mode; and respective overall thermal efficiency was found to be 34.1% and 23.6%. The respective thermal efficiency in open sun drying (OSD) was 5.7% and 5.4%. The quality of dried fenugreek leaves and turmeric was found better than OSD. Economics of the solar dryer indicate the capital cost is negligible in comparison to cumulative present worth of life cycle savings. The values are 211,262 INR (1 US$ = 74.57 INR) and 229,152 INR respectively for fenugreek leaves and turmeric; and capital cost of the dryer is only 50,000 INR. The low value of payback period also confirms economic viability of this dryer. The generalized economic curves have also been plotted.
•Developed a novel active-mode indirect solar dryer for agricultural products.•Quality of dried product better than open sun drying.•Economically feasible as indicated by life cycle savings and payback period.
•To study the progressive development in solar thermal air heating systems.•To study and review the possible ways to augment the performance of solar air heating systems.•To review the best ...performing solar air heating systems along with their limitations.
The use of solar air heaters (SAH) for the collection and effective utilization of solar radiations for thermal applications is widely reported in the literature. The current article aimed to present a comprehensive literature review on history, fundamentals and the latest advancement reported in the field of solar thermal air heating systems. Various designs of solar collectors viz, evacuated tube, flat plate, multiple passages, a cross-section of the flow passage, etc. are reported and discussed. Techniques which are used for performance enhancement of SAHs such as artificial roughness, fins, baffles, vortex generators, etc. are discussed and a comparative performance assessment has been carried to identify thermohydraulic performance parameter to select the optimum configuration that can be further used for applications. A few key recommendations are also concluded from the literature for the effective design and implementation of the SAHs.
A walk-in type solar greenhouse dryer supplemented with solar air heating system has been developed with an objective of sustainable development. One of its novel features is the use of an evacuated ...tube solar air heating system with the greenhouse dryer to achieve required drying temperature for different products in north India plains. This dryer was tested in laboratory in both batch and semi-continuous mode for turmeric (Curcuma longa). The open sun drying was used as control. The thermal efficiency of the dryer for batch and semi-continuous drying obtained are 18.5% and 22.5% respectively. Drying time in comparison to open sun drying has been found to be 55% approximately. The quality of dried turmeric obtained using this dryer is superior to open sun drying in terms of polishing loss, curcumic content, volatile oil content and colour. Its energy payback period and cost payback period were estimated as 2.95 and 1.10 years, respectively, which is very low as compared to its life of 20 years. In the entire lifetime, the CO2 mitigation was found to be 209.21 tons, which proves its suitability.
•Developed evacuated tube solar collector assisted greenhouse dryer.•Drying time reduced to 55% of the open sun drying.•Different economic indicators proved economic viability of this dryer.•Dryer adopted by large number of users.
A 3-dimensional CFD (computational fluid dynamics) investigation has been carried out to study the heat transfer and friction characteristics of solar air heater duct roughened with periodic ...transverse rib. The selected rib roughness is a new concept; it has non-uniform cross-section in the form of saw-tooth. For comparison, transverse ribs with uniform cross-section of circular, square and trapezoidal have also been investigated. The Nusselt number and friction factor have been determined for Reynolds number range of 3000–15,000. The k-ε turbulence model was selected for analysis. The non-uniform cross-section saw-tooth rib was found to result in higher Nusselt number than uniform cross-section ribs for Reynolds number above 7000 due to reduced low heat transfer area downstream of the rib caused by disruption in re-circulations. The maximum enhancement in Nusselt number for duct roughened with saw-tooth rib and trapezoidal rib was 1.78 and 1.50 respectively. The friction factor was found to be lower for saw-tooth rib as compared to uniform cross-section ribs investigated. The maximum enhancement in friction factor for duct roughened with saw-tooth and trapezoidal rib was 2.49 and 3.58 respectively.
•A transverse periodic rib based on a new concept, non-uniform cross-section rib, investigated using CFD.•Non-uniform cross-section rib results in higher Nusselt number than uniform cross-section rib at higher Reynolds number.•Non-uniform cross-section rib results in lower friction factor than uniform cross-section rib.
The interaction of non-monochromatic radiation with arrays comprising plasmonic and dielectric nanoparticles has been studied using the finite-difference time-domain electrodynamics method. It is ...shown that LiNbO
, TiO
, GaAs, Si, and Ge all-dielectric nanoparticle arrays can provide a complete selective reflection of an incident plane wave within a narrow spectral line of collective lattice resonance with a Q-factor of 10
or larger at various spectral ranges, while plasmonic refractory TiN and chemically stable Au nanoparticle arrays provide high-Q resonances with moderate reflectivity. Arrays with fixed dimensional parameters make it possible to fine-tune the position of a selected resonant spectral line by tilting the array relative to the direction of the incident radiation. These effects provide grounds for engineering novel selective tunable optical high-Q filters in a wide range of wavelengths, from visible to middle-IR.
Immune checkpoint blockade has become standard treatment for many types of cancer. Such therapy is indicated most often in patients with advanced or metastatic disease but has been increasingly used ...as adjuvant therapy in those with early-stage disease. Adverse events include immune-related organ inflammation resembling autoimmune diseases. We describe a case of severe immune-related gastroenterocolitis in a 4-month-old infant who presented with intractable diarrhea and failure to thrive after in utero exposure to pembrolizumab. Known causes of the symptoms were ruled out, and the diagnosis of pembrolizumab-induced immune-related gastroenterocolitis was supported by the results of histopathological assays, immunophenotyping, and analysis of the level of antibodies against programmed cell death protein 1 (PD-1). The infant's condition was successfully treated with prednisolone and infliximab.
Summary
Chilling restrains the distribution of mangroves. We tested whether foliar phosphorus (P) fractions and gene expression are associated with cold tolerance in mangrove species.
We exposed ...seedlings of six mangrove populations from different latitudes to favorable, chilling and recovery treatments, and measured their foliar P concentrations and fractions, photochemistry, nighttime respiration, and gene expression.
A Kandelia obovata (KO; 26.45°N) population completely and a Bruguiera gymnorhiza (Guangxi) (BGG; 21.50°N) population partially (30%) survived chilling. Avicennia marina (24.29°N), and other B. gymnorhiza (26.66°N, 24.40°N, and 19.62°N) populations died after chilling. Photosystems of KO and photosystem I of BGG were least injured. During chilling, leaf P fractions, except nucleic acid P in three populations, declined and photoinhibition and nighttime respiration increased in all populations, with the greatest impact in B. gymnorhiza. Leaf nucleic acid P was positively correlated with photochemical efficiency during recovery and nighttime respiration across populations for each treatment.
Relatively high concentrations of nucleic acid P and metabolite P were associated with stronger chilling tolerance in KO. Bruguiera gymnorhiza exhibited relatively low concentrations of organic P in favorable and chilling conditions, but its partially survived population showed stronger compensation in nucleic acid P and Pi concentrations and gene expression during recovery.
Motivation: Computational approaches to protein function prediction infer protein function by finding proteins with similar sequence, structure, surface clefts, chemical properties, amino acid ...motifs, interaction partners or phylogenetic profiles. We present a new approach that combines sequential, structural and chemical information into one graph model of proteins. We predict functional class membership of enzymes and non-enzymes using graph kernels and support vector machine classification on these protein graphs. Results: Our graph model, derivable from protein sequence and structure only, is competitive with vector models that require additional protein information, such as the size of surface pockets. If we include this extra information into our graph model, our classifier yields significantly higher accuracy levels than the vector models. Hyperkernels allow us to select and to optimally combine the most relevant node attributes in our protein graphs. We have laid the foundation for a protein function prediction system that integrates protein information from various sources efficiently and effectively. Availability: More information available via www.dbs.ifi.lmu.de/Mitarbeiter/borgwardt.html. Contact: borgwardt@dbs.ifi.lmu.de
Total joint replacements are an established treatment for patients suffering from reduced mobility and pain due to severe joint damage. Aseptic loosening due to stress shielding is currently one of ...the main reasons for revision surgery. As this phenomenon is related to a mismatch in mechanical properties between implant and bone, stiffness reduction of implants has been of major interest in new implant designs. Facilitated by modern additive manufacturing technologies, the introduction of porosity into implant materials has been shown to enable significant stiffness reduction; however, whether these devices mitigate stress-shielding associated complications or device failure remains poorly understood.
In this systematic review, a broad literature search was conducted in six databases (Scopus, Web of Science, Medline, Embase, Compendex, and Inspec) aiming to identify current design approaches to target stress shielding through controlled porous structures. The search keywords included 'lattice,' 'implant,' 'additive manufacturing,' and 'stress shielding.'
After the screening of 2530 articles, a total of 46 studies were included in this review. Studies focusing on hip, knee, and shoulder replacements were found. Three porous design strategies were identified, specifically uniform, graded, and optimized designs. The latter included personalized design approaches targeting stress shielding based on patient-specific data. All studies reported a reduction of stress shielding achieved by the presented design.
Not all studies used quantitative measures to describe the improvements, and the main stress shielding measures chosen varied between studies. However, due to the nature of the optimization approaches, optimized designs were found to be the most promising. Besides the stiffness reduction, other factors such as mechanical strength can be considered in the design on a patient-specific level. While it was found that controlled porous designs are overall promising to reduce stress shielding, further research and clinical evidence are needed to determine the most superior design approach for total joint replacement implants.
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