Circular Trough Research Articles

Nonimaging Behavior of Circular Trough Concentrators With Tubular Receivers

Abstract This paper presents a detailed analysis of the optical performance of circular trough concentrators with tubular receivers. First, a simple analytical formula for the achievable geometric concentration ratio as a function of the rim angle and acceptance angle is developed. Notably, the development reveals the existence of three distinct concentration ratio regimes: a first regime where the receiver is sized based on the reflection of the edge rays from the rim alone, a second regime where the receiver is sized based on the rim and the edge ray caustics, and a third regime where two reflections from the mirror are permitted. Several exemplary designs are proposed and further analyzed using Monte Carlo ray tracing to obtain transmission angle curves and receiver flux distributions. For an acceptance angle of 1 deg, the circular trough concentrator with circular receiver is found to achieve a maximum geometric concentration ratio of 7.695× with a peak flux of 30 suns. For large acceptance angles (10 deg), the circular trough achieves a geometric concentration ratio as high as 82% of that of a parabolic trough. This noteworthy performance, along with the fact that a circular mirror is amenable to an inflated polymer construction, makes this configuration promising for low-cost, low-concentration solar thermal applications.

Stable quantum droplets with higher-order vortex in radial lattices

The existence and stability of quantum droplets are studied in ultracold atoms in Bose–Einstein condensates with a radial period lattice under the Lee–Huang–Yang correction. Both stable bell-shaped and ring-shaped zero-vorticity quantum droplets are found in this radial lattice. It is found that the existence curves of the zero-vorticity quantum droplets could violate the V–K criterion, which is a necessary condition to form stable solitons. Under the effect of the radial lattice potential, vortex quantum droplets can be still stable when embedded vorticity S is up to S=10. The vortex quantum droplets can be trapped at the first as well as at the second circular trough of the radial lattice. The stability areas of the vortex quantum droplets with different embedded vorticity S are identified by the long time evolution. The chemical potential of the vortex quantum droplets also violates the V–K criterion. The peak value and effective area of the vortex quantum droplets are independent of the vorticity S, while it only depends on the total norm and the potential of the radial lattice. The double ring quantum droplets, with different embedded vorticity in their inner and outer ring, are also discussed.

Concentration ratio for a solar trough concentrator with circular mirror and flat receiver

We present a simple analytical formula for the geometric concentration ratio of a circular trough optical concentrator coupled to a flat (planar) receiver. The receiver is sized to achieve full collection (no spillage) for any combination of acceptance and rim angle. The development reveals the existence of two concentration ratio regimes, one controlled by the edge ray caustics, and the other controlled by the intersection of the edge rays from the rim alone. Notably, we show that in the latter rim ray regime, the circular trough achieves the exact same geometric concentration ratio as a parabolic trough. The provided formula fills a gap towards the development of a complete catalogue of concentration ratio formulas for different concentrator/receiver geometries.

An open-aperture partially-evacuated receiver for more uniform reflected solar flux in circular-trough reflectors: Comparative performance in air heating applications

Trough reflectors can produce a reflected solar flux density that is highly concentrated in specific regions of the receiver surface causing higher thermal losses as well as increasing the likelihood of mechanical damage to the receiver. Time-dependent three-dimensional computational fluid dynamics models were developed and used to compare optical and thermal performances of unglazed tubular, evacuated tubular, and open-aperture evacuated receivers for air heating applications. An evacuated partial-annulus receiver with a non-evacuated open-aperture in the high-density solar flux area produced a more uniform concentrated solar flux distribution. With an open aperture to high-density solar flux, an open-aperture evacuated receiver (i) avoids a dense distribution of reflected solar flux in a specific area of an absorber surface thereby contributing to realizing long-term mechanical integrity, (ii) gives a greater optical performance in all types of trough reflector than an evacuated tubular receiver, (iii) tolerates optical mispositioning and (iv) is particularly suited for use with circular trough reflectors.

Modular Line-Focused Space Solar Power Satellite

The Space Solar Power Satellite is an ultra-large space structure, which collects sunlight directly in space and then transmits it into the ground. Since the idea was invented in 1968, scientists around the world have proposed several typical conceptual design models. Nevertheless, the conceptual models have not been implemented for technological, manufacturing, and cost reasons. This paper presents a novel Space Solar Power Satellite scheme with modular line-focused concentrators and low concentration photovoltaic modules. First, the line-focused mode is analyzed and the optical performance of the circular trough concentrator is evaluated via ray-trace technique. Then, shape optimization for the cell array based on the Bézier curve is carried out to improve the optical property. Numerical examples indicate that the optimized cell array could obtain high power collection efficiency and suitable energy distribution. Moreover, the area of the photovoltaic cell array is reduced, which is conducive to cost reduction. Furthermore, modular design is conducted on the circular trough concentrator. Finally, the primary scheme of the novel Space Solar Power Satellite is designed with the previous modular concentrator and optimized cell array.

Effect of dietary protein levels on growth performance, hematological profile and biochemical composition of fingerlings rainbow trout, Oncorhynchus mykiss reared in Indian himalayan region

A 10-week feeding trial was undertaken to determine the optimum dietary protein requirement of fingerling rainbow trout, Oncorhynchus mykiss. Six casein-gelatin based isocaloric (20.90 kJ 100 g−1, gross energy) diets containing graded levels of dietary protein (300–550 g kg−1 crude protein) were formulated. Twenty fingerlings (1.56 ± 0.22 g; 5.80 ± 0.50 cm) were randomly stocked in triplicate groups in 75 L circular trough fitted with continuous flow-through system (water volume 2–2.5 L−1) and fed experimental diets at 5% BWday−1 at 0800, 1200 and 1700 h. Significant (P < 0.05) differences in live weight gain, specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER) and body protein deposition (BPD) were noted. Quadratic regression analysis of SGR, FCR, PER and BPD data indicated requirements for dietary protein at 464.5, 471.0, 444.0 and 449.6 g kg−1 of dry diet, respectively. Maximum protein, low moisture and intermediate body fat contents were recorded with fish fed at 450 kg−1 protein diet, while highest HSI value was observed at lowest protein level. Significant differences (P < 0.05) were also observed in Hb, Hct and RBC values of fish fed varying protein diets. Based on the above results, it is recommended that rainbow trout fingerlings require protein in the range of 450–471 g kg−1 for its optimum growth and efficient feed utilization.

Circular troughs in tessera terrain on Venus: Morphometry, structural analysis and possible formation model

Detailed observations on Venus tessera terrain reveal the presence of tectonic structures, characterized by a subcircular trough, limiting an internal area with the average elevation of the surrounding terrain. We named this new type of tectonic structures Circular Troughs. Here we show the results of a morphometric study and a structural analysis based on data from 609 structures obtained through a global survey on Venus. Circular Troughs have an average outer radius of 12 ± 4.4 km, an average inner radius of 9 ± 3.9 km and an average trough width of 3 ± 1.2 km. A comparison with other tectonovolcanic structures on Venus shows that they are smaller and their size-distribution is more bounded. Although Circular Troughs show morphological similarities with some corona types, their size distribution is significantly smaller than coronae indicating a shallower geodynamic formation process. A shape preferred orientation analysis shows that Circular Troughs in Western Ovda are elongated parallel to long-wavelength tessera folds indicating that they are at least partially deformed by them, thus Circular Trough formation predates or it is contemporary with folding. A detailed structural analysis suggests that they were generated by small scale diapirism exclusively developed in tessera terrain. Several hypotheses could explain this small scale diapirism inside tessera terrain including volcanically driven compositional diapirism, small scale thermal diapirism or compositional cold diapirism, considering that the probable dessication of an ancient ocean would have generated evaporitic deposits in the past later buried by younger geological units.

Manufacturing technology for the high-precision right-angle square body

This study proposed and evaluated a highly precise method employing various diameters and shapes of punch to manufacture right-angled square-bodied products. In this method, a trough is not only engraved on the die but also designed into the punch. Five diameters and shapes of the punch were collocated with a circular trough around the square shape of a die cavity. In the tests, a ram descended to a fixed level, and part of the billet was forced into the trough without touching its bottom. This causes high hydrostatic stress on the cutting edge of the die. The pressure substantially reduces the occurrence of fractures in test products. The punch with a square trough engraved on its face produced a product with favorable shape and precision compared with other punch shapes. The results revealed that the proposed method can produce a product with a long and burnished surface with a roughness of 0.02–0.12 μm. The tolerance band for the width and thickness ranges from IT1 to IT3, and that for the right angle is 0.02–0.06°. The proposed method is a new rapid prototyping technology and has greater levels of precision than conventional manufacturing methods.

Crossing Axes of Workpiece and Tool at Grinding of the Circular Trough with Variable Profile

Abstract In the article the method of grinding with crossed axes of the tool and the workpiece got further developed. The work discloses a method of processing details having an external surface with a profile in the form of an arc of a circle of variable radius (for example, rolls of pipe rolling mills). The particular three-dimensional geometric models of the processing, shaping and profiling of abrasive wheels have been developed. A method for controlling the grinding process, which ensures the removal of allowances along equidistant curves has been offered. The developed method of grinding provides a constant depth of cutting according to the coordinate of profile processing. This is achieved at the expense of the synchronous inclination of the wheel and its insertion by the size of the allowance. The diameter of grinding wheel affects on the maximum angle of orientation of the wheel has been proven. It has been shown that increasing the diameter of the abrasive wheel has led to a slight decrease in value orientation angle.

Effect of phase change material on concentric circular tubular solar still-Integration meets enhancement

In this work, a compound parabolic concentrator (CPC)-concentric circular tubular solar still (CCTSS) with phase change material (PCM) is presented. The experiment is conducted with and without PCM in the CCTSS. The PCM is loaded (450g of paraffin wax/tube) in the specially designed circular trough of the tubular solar still. The water temperature (Tw), air temperature (Tair), outer cover temperature (Toc) and fresh water production are measured in frequent intervals of time. The results showed that the fresh water production of CPC-CCTSS with and without PCM integration were 5779ml/m2/day and 5330ml/m2/day. Therefore, the PCM enhanced the fresh water productivity by 8%.

Effects of Dietary Protein Levels on the Growth, Feed Utilization and Haemato-Biochemical Parameters of Freshwater Fish, Cyprinus Carpio Var. Specularis

An 8-week feeding trial was conducted to study the effects of dietary protein levels on the growth, feed utilization and haemato-biochemical parameters of mirror carp, Cyprinus carpio specularis (1.50 ± 0.02 g; 4.5 ± 0.05 cm). Six casein-gelatin based isocaloric (367 kcal 100 g-1, gross energy) diets containing graded levels of dietary protein (25%-50% CP) were formulated. 20 fish were randomly stocked in triplicate groups in 75L circular trough fitted with continuous flow-through system and fed experimental diets at 4% BW/day at 0800 and 1700h. Maximum live weight gain (258%), best feed conversion ratio (FCR) (1.63) and protein efficiency ratio (PER) (1.53) were obtained in fish fed diet containing 40% dietary protein. However, quadratic regression analysis live weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary protein at 43.5%, 41.6%, 34.7% and 37.3% of dry diet, respectively. Significantly higher whole body protein, low moisture and intermediate body fat contents were recorded at 40% protein containing diet (P 0.05). Based on the above results, it is recommended that 41.5% protein level would be useful for optimum growth and efficient feed utilization of this fish species.

Eponym of Naso-Jugal Fold and Tear Trough.

The aim of this study is to find out the eponym of the naso-jugal fold and tear trough and to make a suggestion to standardize the terminology.In a PubMed search, the search terms (naso-jugal) and (fold OR groove); (tear trough) and (anatomy) were used, which resulted in 48 and 37 titles, respectively. Eliminating duplicated titles, 80 abstracts were reviewed. Among them, 18 full papers were reviewed. Two papers were excluded and 3 mined papers were added. Finally, 19 papers were reviewed.In a paper published by an ophthalmologist Dr David Miller, "tear trough" was first used for designating the circular trough carved into a scleral contact in 1969. In the remaining 18 papers including 1 conference presentation, 6 terms were used for the same structure; naso-jugal fold (4), naso-jugal groove (4), naso-jugal ditch (1), tear trough (5), tear trough deformity (6), and tear trough depression (1). Whitnall first used "naso-jugal" and 10 other papers stated "naso-jugal." Eight papers cited Whitnall (2), Duke-Elder (2), and Loeb (4) in the origin of the term "naso-jugal." Flowers adapted "tear trough" for the cheek groove and 12 other papers wrote "tear trough." Eleven papers cited Flowers (9), Le Louarn (1), Mendelson (1) when referring to the origin of the term "tear trough."The name of the structure should contain "naso-jugal" rather than "tear trough" because "naso-jugal" was coined earlier and expresses the location of the structure. The recommended term should be "the deepened naso-jugal groove" since it deepens with age.

Experimental investigation of a semi circular trough solar water heater

This paper studies the experimental analysis of a semi circular trough absorber solar water heater with baffles for improving the outlet water temperature. To increase the contact time of water with solar radiation and decreasing the flow rate of water baffles are kept in the absorber at a distance of 0.1 m. Studies are conducted for different flow rates of water in the absorber and flow rates increased by 2, 4, 8 and 16 times the base value of 0.133 kg/min. Results show that there is an increase in the outlet water temperature by 66.5 and 50°C with respect to inlet temperature during summer and winter, respectively, with an average inlet temperature of 34°C at minimum mass flow. The maximum water temperature during summer and winter conditions are found as 65 and 60°C respectively. Also, results show that the percentage increase in temperature of outlet water and average water temperature depends on solar intensity.

Leidenfrost levitated liquid tori

Levitating a liquid over a vapor film was limited to droplets. Here we show that on curved substrates a larger quantity of fluid can be suspended. This opens a new possibility for exploring free-liquid-surface phenomena without any contact with a solid. In one of the simplest possible situations, a large fluid torus is levitated over a circular trough. A poloidal flow inside the ring generates a wave on its inner side, making it polygonal. This wave is described by a solitonic model which balances surface tension and the pressure depletion due to the distortion of the poloidal flow.

Dietary amino acidl-methionine requirement of fingerling Indian catfish,Heteropneustes fossilis(Bloch-1974) estimated by growth and haemato-biochemical parameters

An 8-week feeding trial was conducted to determine the dietary tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (6.10 ± 1.15 cm, 4.44 ± 0.50 g). Six isonitrogenous (40 g 100 g−1) and isoenergetic (17.90 kJ g−1) amino acid test diets were formulated with gradation of 0.1 g 100 g−1 containing graded levels of l-tryptophan (0.04–0.54 g 100 g−1, dry diet). Fish were stocked in triplicate groups, in 75-L circular trough with flow-through system and fed experimental diets at 4% BW/day twice daily. Maximum live weight gain (258%), best feed conversion ratio (FCR) (1.54) and protein efficiency ratio (PER) (1.62) were obtained in fish fed diet containing 0.34 g 100 g−1 tryptophan. However, quadratic regression analysis of weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary tryptophan at 0.37, 0.33, 0.32 and 0.33 g 100 g−1 of dry diet, respectively. Significantly (P 0.05) among treatments except for diets 0.04 and 0.14 g 100 g−1. Excellent somatic and haematological indices values were obtained at the requirement level. Based on above results, it is recommended that the diet for H. fossilis should contain tryptophan at 0.32 g 100 g−1, dry diet, corresponding to 0.80 g 100 g−1 dietary protein for optimum growth and efficient feed utilization.

Dietary arginine requirement of fingerling Indian catfish (Heteropneustes fossilis, Bloch)

An 8-week feeding trial was conducted to determine the dietary arginine requirement of fingerling Indian catfish, Heteropneustes fossilis (6.25 ± 1.30 cm, 4.8 ± 0.65 g). Six isonitrogenous (400 g Kg−1) and isoenergetic (17.90 kJ g−1) amino acid test diets were formulated with gradation of 2.5 g Kg−1 containing graded levels of l-arginine (8.5–21.0 g Kg−1, dry diet). Fish were randomly stocked in triplicate groups, in 75-l circular trough with flow-through system and fed experimental diets at 4 % BW/day at 0800 and 1800 h. Maximum live weight gain (277 %), best feed conversion ratio (FCR) (1.52) and protein efficiency ratio (PER) (1.64) were obtained in fish fed diet containing 16.0 g Kg−1 arginine. However, quadratic regression analysis of live weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary arginine at 16.80, 16.30, 16.11 and 16.10 g Kg−1 of dry diet, respectively. Significantly (p 0.05) low among all the treatments except at diet I and diet II. Based on the above results, it is recommended that the diet for young H. fossilis should contain arginine at 16.32 g Kg−1, dry diet, corresponding to 40.80 g Kg−1 dietary protein for optimum growth and efficient feed utilization.

Dietary amino acid l-tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (Bloch), estimated by growth and haemato-biochemical parameters

An 8-week feeding trial was conducted to determine the dietary tryptophan requirement of fingerling Indian catfish, Heteropneustes fossilis (6.10 ± 1.15 cm, 4.44 ± 0.50 g). Six isonitrogenous (40 g 100 g⁻¹) and isoenergetic (17.90 kJ g⁻¹) amino acid test diets were formulated with gradation of 0.1 g 100 g⁻¹ containing graded levels of L-tryptophan (0.04-0.54 g 100 g⁻¹, dry diet). Fish were stocked in triplicate groups, in 75-L circular trough with flow-through system and fed experimental diets at 4% BW/day twice daily. Maximum live weight gain (258%), best feed conversion ratio (FCR) (1.54) and protein efficiency ratio (PER) (1.62) were obtained in fish fed diet containing 0.34 g 100 g⁻¹ tryptophan. However, quadratic regression analysis of weight gain, FCR, PER and body protein deposition (BPD) data indicated requirements for dietary tryptophan at 0.37, 0.33, 0.32 and 0.33 g 100 g⁻¹ of dry diet, respectively. Significantly (P < 0.05) higher body protein, minimum moisture and intermediate fat contents were recorded at 0.34 g 100 g⁻¹ dietary tryptophan diet. Ash content was not significantly different (P > 0.05) among treatments except for diets 0.04 and 0.14 g 100 g⁻¹. Excellent somatic and haematological indices values were obtained at the requirement level. Based on above results, it is recommended that the diet for H. fossilis should contain tryptophan at 0.32 g 100 g⁻¹, dry diet, corresponding to 0.80 g 100 g⁻¹ dietary protein for optimum growth and efficient feed utilization.

Quantification of the forces driving self-assembly of three-dimensional microtissues

In a nonadhesive environment, cells will self-assemble into microtissues, a process relevant to tissue engineering. Although this has been recognized for some time, there is no basis for quantitative characterization of this complex process. Here we describe a recently developed assay designed to quantify aspects of the process and discuss its application in comparing behaviors between cell types. Cells were seeded in nonadhesive micromolded wells, each well with a circular trough at its base formed by the cylindrical sidewalls and by a central peg in the form of a right circular cone. Cells settled into the trough and coalesced into a toroid, which was then driven up the conical peg by the forces of self-assembly. The mass of the toroid and its rate of upward movement were used to calculate the cell power expended in the process against gravity. The power of the toroid was found to be 0.31 ± 0.01 pJ/h and 4.3 ± 1.7 pJ/h for hepatocyte cells and fibroblasts, respectively. Blocking Rho kinase by means of Y-27632 resulted in a 50% and greater reduction in power expended by each type of toroid, indicating that cytoskeletal-mediated contraction plays a significant role in the self-assembly of both cell types. Whereas the driving force for self-assembly has often been viewed as the binding of surface proteins, these data show that cellular contraction is important for cell-cell adhesion. The power measurement quantifies the contribution of cell contraction, and will be useful for understanding the concerted action of the mechanisms that drive self-assembly.

Voltage-assisted asperity formation in styrene butadiene at room temperature: Cross-linking at the nanoscale

Nanoscale surface modification is reported for styrene butadiene rubber using an electrically biased conducting atomic force microscope tip. Under appropriate bias conditions, the local electric field magnitude is of the order of 10 8 ‐10 9 Vm 1 , which is sufficiently large to initiate cross-linking in the rubber. Peaklike surface features, surrounded by a circular trough and a raised ring, are created by careful and controlled retraction of the biased tip. The features’ aspect ratios can be controlled by modifying the tip retraction protocol, tip geometry, and bias voltage. Typical feature dimensions reported here vary from approximately 0.5‐10-nm high and up to several hundreds of nanometer in diameter. Although the temperature of the rubber is above the glass transition and the rubber is in a viscous state, the features are stable over a period of several days once created—which is believed to be due to cross-linking of the rubber during feature formation. Modeling of the electric field distribution in the vicinity of the tip is presented, which strongly supports the assertion that the resulting nonuniform electric field induces nanostructure formation and initiates cross-linking. A mechanism is proposed whereby source material is redistributed in the proximity of the tip/surface region to form the observed features.

Transverse electric scattering by a dielectric biconvex cylinder loaded with a shallow circular trough in a ground plane

The scattering problem of transverse electric wave from a dielectric biconvex cylinder buried in a shallow circular trough of a ground plane is investigated and a rigorous series solution is also derived. Based on the region-matching method, the analysed region is decomposed into two subregions by introducing a semi-circular auxiliary boundary. The magnetic field of each subregion is expressed in terms of cylindrical wave functions with unknown expansion coefficients. After imposing the matching conditions and the boundary condition on the trough surface with the aid of Graf&apos;s addition theorem, the unknown coefficients are determined. Comparisons with published data for a dielectric circular cylinder case show very good agreement. Visible effects of depth-to-half-width ratios of a dielectric biconvex cylinder on echo width, far-field pattern and near-field distribution are illustrated in graphical form.