scholarly journals Modeling of Light Pipes for the Optimal Disposition in Buildings

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4323 ◽  
Author(s):  
Cristina Baglivo ◽  
Marina Bonomolo ◽  
Paolo Maria Congedo
Keyword(s):  
Aspect Ratio ◽  
Strong Correlation ◽  
Internal Surface ◽  
Variable Number ◽  
Horizontal Position ◽  
Simulated Model ◽  
Light Pipe ◽  
Minimum Value ◽  
Plant Area ◽  
Simple Models

A light pipe is an excellent solution to transport and distribute daylight into environments without or with little lighting, guaranteeing comfort inside the rooms. As stated in the literature, the evaluation of the performances of light pipes presents numerous complexities, making the work very difficult for technicians and designers. This study is aimed to present a methodology that is able to identify the potential of light pipes using indices such as daylight autonomy (DA), continuous daylight autonomy (DAc), and useful daylight illuminance (UDI). This paper presents an analysis of daylight obtained by several configurations of simple models of light pipes installed into a 5 × 5 m plant area room. All simulations are carried out in a DAYSIM environment, which allows calculating the annual availability of daylight based on a RADIANCE raytracer backward. Several daylight conditions were analyzed for different light pipe configurations, considering different pipe lengths and a variable number of light pipes. The light pipes are tested also in the horizontal position, for different orientations. The results of all the combinations were compared with the performances of a window with dimensions equal to 1/8 of the internal surface, which was in accordance with the minimum value to be guaranteed by the Italian Regulation (D.M. 5 July 1975 n. 190) for different orientations. The results indicated a difference in daylight distribution, showing a strong correlation between the percentage levels of DA and DAc with the length and number of pipes, during different periods of the year. The simulated model is strongly influenced by the aspect ratio (R = diameter/length). The results show that the illuminance levels decrease drastically, increasing the length.

Die drool theory

2013 ◽  
Vol 33 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Andrew M. Schmalzer ◽  
A. Jeffrey Giacomin
Keyword(s):  
Pressure Drop ◽  
Aspect Ratio ◽  
Analytical Solution ◽  
Production Rate ◽  
Exact Analytical Solution ◽  
Internal Surface ◽  
Tube Flow ◽  
Cohesive Failure ◽  
Open Face ◽  
Slip Layer

Abstract When molten plastic is extruded from a die, it sometimes collects on the open face of the die. Known as die drool, this phenomenon costs plastics manufacturers by requiring die cleaning. This has been attributed to many causes, but none of these has led to an equation for the drool rate. In this work, we provide an exact analytical solution for the drool rate, and we base this solution on a postulate of a cohesive slip layer near the die walls. We thus attribute die drool to cohesive failure within the fluid at an internal surface where the fluid slips on itself. We adimensionalize the drool rate with the production rate, and call this the buildup ratio, BR. We provide an exact analytical solution for BR when the cohesive slip layer either slips at the die wall, or when it does not. We examine two important extrusion geometries: slit (which we then extend to pipe) and tube flow. We identify two new experiments: one to measure BR as a function of pressure drop, and another as a function of the die aspect ratio, and we then use our new theory to design droolometers.

scholarly journals Decay of supersonic rectangular jet issuing from a nozzle with diagonal expansion ramps

2019 ◽  
Vol 23 (6 Part B) ◽  
pp. 3929-3940 ◽  
Author(s):  
Surendra Bogadi ◽  
B.T.N. Sridhar
Keyword(s):  
Reynolds Number ◽  
Aspect Ratio ◽  
Total Pressure ◽  
Internal Surface ◽  
Mixing Rate ◽  
Numerical Studies ◽  
Rectangular Jet ◽  
Core Length ◽  
Supersonic Core Length ◽  
Length Reduction

This paper addresses the effect of expansion ramps on the decay characteristics of a controlled supersonic rectangular jet. A Mach 1.8 rectangular jet issuing from a converging-diverging nozzle of aspect ratio 2 and Reynolds number 1.861?105 is considered as the base model for the study. Two separate nozzle models with expansion ramps placed at the diagonal ends on major and on the minor internal surface are considered for the present study. The diagonal placements of ramps induce additional vortices near the nozzle exit apart from the corner vortices emanating from the rectangular corners. Experimental and computational investigations at different expansion levels are carried to prove the enhanced mixing rate due to the induced vortex. The ramps on the minor side caused maximum supersonic core length reduction of 44% at an inlet total pressure of 4 bar and a minimum of 27% at an inlet total pressure of 8 bar. The maximum and minimum core length reductions caused by the ramps placed on the major side are 22% and 11% at inlet total pressures 6 and 8 bar respectively. Both experimental and numerical studies show that shock waves are rendered weak by the minor side placement of ramps at all expansion levels.

Interaction Relationship for High Aspect Ratio Semi-Elliptical Internal Surface Cracks in CO2 Pipelines

2013 ◽  
Vol 774-776 ◽  
pp. 581-584
Author(s):  
Qiao Jin
Keyword(s):  
Finite Element Method ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Aspect Ratio ◽  
Intensity Factor ◽  
High Aspect Ratio ◽  
Internal Surface ◽  
Surface Cracks ◽  
Interaction Relationship

Surface cracks with aspect ratio can occur in pipelines subjected to corrosion attacks. There are few studies on interaction relationship for double semi-elliptical surface cracks with such high aspect ratio. This paper attempts to develop a finite element method to determine on interaction of two semi-elliptical internal surface cracks with high aspect ratio by analyzing two key fracture mechanics parameters, i.e., the stress intensity factor and the-stress. The numerical results prove that the existing flaw-interaction criteria are too general to lose the worthy of application especially in pipeline engineering.

scholarly journals Impact of Process Parameters on the Quality of Deep Holes Drilled in Inconel 718 Using EDD

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2298 ◽  
Author(s):  
Magdalena Machno
Keyword(s):  
Aspect Ratio ◽  
Process Parameters ◽  
Inconel 718 ◽  
Gas Turbines ◽  
Internal Surface ◽  
Dimensional Accuracy ◽  
Inconel 718 Alloy ◽  
Taper Angle ◽  
The Impact

Advanced engineering materials (e.g., nickel or titanium alloy) are being increasingly applied to produce parts of gas turbines in the aerospace industry. To improve the durability of these parts, many holes, with a length-to-diameter aspect ratio greater than 20:1, are created in their structure. The quality of the holes significantly affects the cooling process of the elements. However, it is challenging to machine materials by conventional methods. When machining a hole with a high aspect ratio, the major problem is effective flushing of the machining area, which can improve the hole’s surface integrity and dimensional accuracy. Consequently, the electro-discharge drilling (EDD) process is good alternative for this application. This paper presents the results of an analysis of the EDD of Inconel 718 alloy. An experiment was conducted to evaluate the impact of process parameters (pulse time, current amplitude, and discharge voltage) on the process’s performance (linear tool wear, taper angle, drilling speed, the hole’s aspect ratio, and surface roughness (Ra and Rz)). The results show that EDD provides us with the possibility to drill holes with an aspect ratio greater than 10:1. The results also demonstrate that holes with an aspect ratio greater than 10:1 and a small taper angle value have a significantly decreased quality of internal surface, especially at the bottom of the hole. This indicates that an insufficient amount of debris is removed from the bottom of the hole.

What catalysis needs from the electron microscopist

1988 ◽  
Vol 46 ◽  
pp. 694-695
Author(s):  
Alexis T. Bell
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Catalyst Deactivation ◽  
Surface Composition ◽  
Internal Surface ◽  
Active Phase ◽  
Atomic Scale ◽  
Metal Catalyst ◽  
Internal Surface Area ◽  
Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

The distribution and density of ciliary tufts on the siphons of Anodonta cygnea (Mollusca: Bivalvia)

1990 ◽  
Vol 48 (3) ◽  
pp. 518-519
Author(s):  
Wen-lung Wu
Keyword(s):  
Osmium Tetroxide ◽  
Internal Surface ◽  
Mechanical Stimuli ◽  
Type Ii ◽  
Sensory Receptors ◽  
Anodonta Cygnea ◽  
Type Iv ◽  
Sem Study ◽  
Inhalant Siphon ◽  
Type V

The mantle of bivalves has come entirely to enclose the laterally compressed body and the mantle margin has assumed a variety of functions, one of the pricipal ones being sensory. Ciliary tufts, which are probably sensory, have been reported from the mantle and siphons of several bivalves1∽4. Certain regions of the mantle margin are likely to be more or less, sensitive to certain stimuli than others. The inhalant siphon is likely to be particularly sensitive to both chemical and mechanical stimuli, whereas the exhalant siphon will be less sensitive to both. The distribution and density of putative sensory receptors on the in-and ex-halant siphon is compared in this paper.The excised siphons were fixed in glutaraldehyde and osmium tetroxide, the whole procedure of SEM study is recorded in Wu's thesis.Type II cilia cover the tips of tentacles, 6.13um. Type IV and type V cilia are found on the surface of tentacles. Type IV cilia are occasionally present at the tips of tentacles, 8 um long. They are the commonest type on the surface of tentacles. Type VI cilia occor in the internal surface of the inhalant siphon, but are not found on the surface of tentacles, 6.7-10um long.

Cultural and Linguistic Adaptation of the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V) Into Hindi

2020 ◽  
Vol 63 (12) ◽  
pp. 3974-3981
Author(s):  
Ashwini Joshi ◽  
Isha Baheti ◽  
Vrushali Angadi
Keyword(s):  
Strong Correlation ◽  
Concurrent Validity ◽  
Interrater Reliability ◽  
Voice Quality ◽  
Weak Correlation ◽  
Voice Assessment ◽  
Perceptual Evaluation ◽  
Severity Grade ◽  
Normal Voice ◽  
Group A

Aim The purpose of this study was to develop and assess the reliability of a Hindi version of the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V). Reliability was assessed by comparing Hindi CAPE-V ratings with English CAPE-V ratings and by the Grade, Roughness, Breathiness, Asthenia and Strain (GRBAS) scale. Method Hindi sentences were created to match the phonemic load of the corresponding English CAPE-V sentences. The Hindi sentences were adapted for linguistic content. The original English and adapted Hindi CAPE-V and GRBAS were completed for 33 bilingual individuals with normal voice quality. Additionally, the Hindi CAPE-V and GRBAS were completed for 13 Hindi speakers with disordered voice quality. The agreement of CAPE-V ratings was assessed between language versions, GRBAS ratings, and two rater pairs (three raters in total). Pearson product–moment correlation was completed for all comparisons. Results A strong correlation ( r > .8, p < .01) was found between the Hindi CAPE-V scores and the English CAPE-V scores for most variables in normal voice participants. A weak correlation was found for the variable of strain ( r < .2, p = .400) in the normative group. A strong correlation ( r > .6, p < .01) was found between the overall severity/grade, roughness, and breathiness scores in the GRBAS scale and the CAPE-V scale in normal and disordered voice samples. Significant interrater reliability ( r > .75) was present in overall severity and breathiness. Conclusions The Hindi version of the CAPE-V demonstrates good interrater reliability and concurrent validity with the English CAPE-V and the GRBAS. The Hindi CAPE-V can be used for the auditory-perceptual voice assessment of Hindi speakers.

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