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2021 ◽  
Author(s):  
Chris Gu ◽  
Yike Wang

Modern-day search platforms generally have two layers of information presentation. The outer layer displays the collection of search results with attributes selected by platforms, and consumers click on a product to reveal all its attributes in the inner layer. The information revealed in the outer layer affects the search costs and the probability of finding a match. To address the managerial question of optimal information layout, we create an information complexity measure of the outer layer, namely orderedness entropy, and study the consumer search process for information at the expense of time and cognitive costs. We first conduct online random experiments to show that consumers respond to and actively reduce cognitive cost for which our information complexity measure provides a representation. Then, using a unique and rich panel tracking consumer search behaviors at a large online travel agency (OTA), we specify a novel sequential search model that jointly describes the refinement search and product clicking decisions. We find that cognitive cost is a major component of search cost, while loading time cost has a much smaller share. By varying the information revealed in the outer layer, we propose information layouts that Pareto-improve both revenue and consumer welfare for our OTA. This paper was accepted by Juanjuan Zhang, marketing.


Author(s):  
Hongze An ◽  
Donatien NGENDABANYIKWA ◽  
Guozhe Meng ◽  
Wang Yanqiu ◽  
Wang Junyi ◽  
...  

Abstract A novel conversion film containing cerium and molybdenum was synthesized on the rebar surface, and then the pitting sensitivity of the rebar was improved in a concrete environment containing chloride. This conversion film presented a two-layer structure, which involved CeMoOx as the outer layer and FeOx as the inner layer. The film with two-layer structure exhibited a strong corrosion resistance after being immersed in an alkaline environment (pH=12.5) added with 0.1 M NaCl, and the charge transfer resistance (Rt) could reach 5.88×106 Ω·cm2 after immersion for 1600 h, which was approximately 2.5 times the initial Rt value. Moreover, it was found that the film has a self-heal property when being damaged beyond the pitting potential. The anticorrosion mechanism of the film and its self-healing mechanism were discussed in depth in this study.


2021 ◽  
Vol 5 ◽  
pp. 216-232
Author(s):  
Tao Chen ◽  
Bijie Yang ◽  
Miles Robertson ◽  
Ricardo Martinez-Botas

Real-gas effects have a significant impact on compressible turbulent flows of dense gases, especially when flow properties are in proximity of the saturation line and/or the thermodynamic critical point. Understanding of these effects is key for the analysis and improvement of performance for many industrial components, including expanders and heat exchangers in organic Rankine cycle systems. This work analyzes the real-gas effect on the turbulent boundary layer of fully developed channel flow of two organic gases, R1233zd(E) and MDM - two candidate working fluids for ORC systems. Compressible direct numerical simulations (DNS) with real-gas equations of state are used in this research. Three cases are set up for each organic vapour, representing thermodynamic states far from, close to and inside the supercritical region, and these cases refer to weak, normal and strong real-gas effect in each fluid. The results within this work show that the real-gas effect can significantly influence the profile of averaged thermodynamic properties, relative to an air baseline case. This effect has a reverse impact on the distribution of averaged temperature and density. As the real-gas effect gets stronger, the averaged centre-to-wall temperature ratio decreases but the density drop increases. In a strong real-gas effect case, the dynamic viscosity at the channel center point can be lower than at channel wall. This phenomenon can not be found in a perfect gas flow. The real-gas effect increases the normal Reynolds stress in the wall-normal direction by 7–20% and in the spanwise direction by 10–21%, which is caused by its impact on the viscosity profile. It also increases the Reynolds shear stress by 5–8%. The real-gas effect increases the turbulence kinetic energy dissipation in the viscous sublayer and buffer sublayer <inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mo stretchy="false">(</mml:mo><mml:msup><mml:mi>y</mml:mi><mml:mo>∗</mml:mo></mml:msup><mml:mo><</mml:mo><mml:mn>30</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math></inline-formula> but not in the outer layer. The turbulent viscosity hypthesis is checked in these two fluids, and the result shows that the standard two-function RANS model (<inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>k</mml:mi><mml:mo>−</mml:mo><mml:mi>ϵ</mml:mi></mml:math></inline-formula> and <inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mi>k</mml:mi><mml:mo>−</mml:mo><mml:mi>ω</mml:mi></mml:math></inline-formula>) with a constant <inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:msub><mml:mi>C</mml:mi><mml:mi>μ</mml:mi></mml:msub><mml:mo>=</mml:mo><mml:mn>0.09</mml:mn></mml:math></inline-formula> is still suitable in the outer layer <inline-formula><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"><mml:mo stretchy="false">(</mml:mo><mml:msup><mml:mi>y</mml:mi><mml:mo>∗</mml:mo></mml:msup><mml:mo>></mml:mo><mml:mn>70</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math></inline-formula>, with an error in ±10%.


2021 ◽  
Author(s):  
Jingyuan Zhang ◽  
Wouter van der Valk ◽  
Matthew Steinhart ◽  
Karl Koehler

Abstract The inner ear detects sound, head movements, and gravity using specialized epithelial cells and neurons. Decreased function in these cells can lead to hearing loss and dizziness. Inner ear disorders impact millions worldwide; however, current therapeutic options are limited. While animal models are a powerful system to assess auditory and vestibular dysfunction, in vitro inner ear models are gaining importance in translational research. Here, we provide a stepwise approach for generating inner ear organoids (IEOs), which contain supporting cells, hair cells, and neurons. Our differentiation regimen, using defined medium components and diluted extracellular matrix proteins, guides a 3D spheroid of pluripotent stem cells into otic progenitor cells by mimicking the environmental cues that occur during fetal development. Control of the TGF and BMP pathways early in the culture, promotes patterning of the spheroid, with an outer layer of surface ectoderm and an inner core of neuroectoderm. Later, FGF activation and BMP inhibition induce placode formation in the outer layer and neural crest cell migration from the core. These two cell lineages co-develop into otic vesicle-like structures surrounded by a layer of mesenchymal, neuronal, and glial cells that can be maintained in culture for over 100 days. The IEOs described in this protocol are a promising tool for otology research.


2021 ◽  
pp. 152808372110545
Author(s):  
Rochak Rathour ◽  
Apurba Das ◽  
Ramasamy Alagirusamy

During an operation, the turnout gear for firefighters must meet two important requirements: thermal protection and comfort. As comfort and protection are inherently incompatible, it is impossible to satisfy both. As part of this study, the outer layer of multilayered turnout suits was analyzed under the influence of various factors such as intensity of heat flux, pick density, and air space between the fabric and the sensor. Choosing Nomex IIIA was based on its inherent properties that are conductive to thermal protection. To simulate the environment encountered during firefighting, benchtop experiments were designed. A system equation for the prediction of the protection time (t-protection) was developed based on a three-factor and three-level Box–Behnken model. The predicted values of t-protection obtained for all the experimental blocks in the design space were subjected to ANOVA analysis which showed that the system equation, as well as the coefficients of linear interactive and square terms, is significant, so the system equation can be efficiently used for predicting t-protection. The validity of the system equation was verified by using the same experimental blocks and estimating t-protection using the Stoll criteria. The accuracy of the system equation was checked by comparing t-protection and t*-protection which revealed a linear relationship with a high correlation coefficient (R2 = 0.975). To analyze the effects of the independent variables on protection time, 3D surface response curves were created. The nature of the surfaces was critically analyzed by developing regression equations for the contours and the diagonals.


2021 ◽  
pp. 1-10
Author(s):  
Zhili Chen ◽  
Hamed Rahimi ◽  
Chee Meng Chew

Abstract This paper proposed a systematic framework to automatically design and fabricate optimized soft robotic fingers. The soft finger is composed of a soft silicone structure with inner air chambers and a harder outer layer, which are fabricated by molding process and 3D printing, respectively. The softer layer is utilized for actuation while the supportive hard structure is used to impose constraints. The framework applies a topology optimization approach based on RAMP method to obtain an optimal design of the outer layer of the soft fingers. Two basic motion primitives (bending and twisting) of the soft finger were explored. A multi-segmented soft bending finger and a soft twisting finger were designed and fabricated through the proposed framework. This work also explored the combination of bending and twisting primitives by developing a combined bending-twisting soft finger. The soft fingers were characterized by free and blocked movement tests. The experiments showed that the triple-segmented soft finger can achieve a maximum of 50.5 no-load bending under the actuation pressure of 53 kPa. The blocked movement test on the multi-segmented soft actuating finger showed that this finger could generate up to a maximum of 0.63 N force under 57 kPa actuation pressure in 7 seconds of inflating time. The developed twisting soft finger was shown to achieve tip rotation of up to 219 degrees under 29 kPa actuation pressure. Finally, the potential capability of the bending-twisting soft fingers was verified through applications like screwing and object grasping.


Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 4042
Author(s):  
Thi My Do ◽  
Yang Yang ◽  
Aipeng Deng

Cardiovascular diseases, including coronary artery and peripheral vascular pathologies, are leading causes of mortality. As an alternative to autografts, prosthetic grafts have been developed to reduce the death rate. This study presents the development and characterization of bilayer vascular grafts with appropriate structural and biocompatibility properties. A polymer blend of recombinant human collagen (RHC) peptides and polycaprolactone (PCL) was used to build the inner layer of the graft by electrospinning and co-electrospinning the water-soluble polyethylene oxide (PEO) as sacrificial material together with PCL to generate the porous outer layer. The mechanical test demonstrated the bilayer scaffold’s appropriate mechanical properties as compared with the native vascular structure. Human umbilical vein endothelial cells (HUVEC) showed enhanced adhesion to the lumen after seeding on nanoscale fibers. Meanwhile, by enhancing the porosity of the microfibrous outer layer through the removal of PEO fibers, rat smooth muscle cells (A7r5) could proliferate and infiltrate the porous layer easily.


2021 ◽  
Vol 8 ◽  
Author(s):  
Quantong Jiang ◽  
Dongzhu Lu ◽  
Chang Liu ◽  
Nazhen Liu ◽  
Baorong Hou

The Pilling-Bedworth ratio of oxides preferentially formed from the precipitated phases in magnesium alloys were calculated. The results showed that the PBR value of Nd2O3 preferentially formed from Mg12Nd was 1.0584, and the PBR value of Y2O3 preferentially formed from Mg24Y5 was 1.1923. Both the Nd2O3 and Y2O3 would provide a good protection to the Mg matrix. The Gd2O3 preferentially formed from Mg3Gd, whereas the MgO preferentially formed from MgNi2. The PBR value of these two oxides were both larger than 2. The corresponding oxides formed from the common precipitated phases Mg17Al12, MgZn2, MgCu2, Mg2Ca, Mg12Ce, and MgAg were all less than 1. The oxide films formed on surfaces of pure Mg and Mg-xY (x = 3, 5, 7 wt.%) alloys at high temperatures were analyzed. The results showed that the oxide films were composed of a Y2O3/MgO outer layer and an inner layer rich with Y2O3. The formation of Y2O3 was mainly caused by the oxidation of Mg24Y5. The more Y2O3 existed in the composite oxidation film, the better corrosion resistance of the Mg-Y samples.


Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3933
Author(s):  
Sung Wook Moon ◽  
Jiae Seo ◽  
Ji-Hun Seo ◽  
Byoung-Ho Choi

Automotive coatings, which comprise multiple layers, i.e., primer, base coating, and clear coat layers, are exposed to various environmental conditions that pose various types of damages to them. In particular, the outer layer of the automotive coating, i.e., the clear coat, is affected significantly by such damages. Therefore, a reliable and durable clear coat must be developed to improve the appearance of automobiles. In this study, a new clear coat based on an acrylic-based clear coat modified using polyrotaxane crosslinkers, which are necklace-shaped supramolecules composed of ring-shaped host molecules, is developed and characterized. The effects of polyrotaxane and silane on the scratch properties and mechanisms of the clear coating are analyzed. It is observed that the critical loads of the clear coat from scratch tests can be improved by adding optimal molecular necklace crosslinkers comprising silane functional groups. The improvement in the scratch properties of the modified acrylic-based clear coat may be attributed to the crosslinking characteristics and dynamic molecular movements of the polyrotaxane. In addition, the effects of environmental factors on the scratch characteristics of the modified acrylic-based clear coat are investigated by addressing the scratch durability of the clear coat.


Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6863
Author(s):  
Desalegn Atalie ◽  
Pavla Tesinova ◽  
Melkie Getnet Tadesse ◽  
Eyasu Ferede ◽  
Ionuț Dulgheriu ◽  
...  

Consumers expect high-performance functionality from sportswear. To meet athletic and leisure-time activity requirements, further research needs to be carried out. Sportswear layers and their specific thermal qualities, as well as the set and air layer between materials, are all important factors in sports clothing. This research aims to examine the thermal properties of sports fabrics, and how they are affected by structure parameters and maintained with different layers. Three inner and four outer layers of fabric were used to make 12 sets of sportswear in this study. Before the combination of outer and inner layers, thermal properties were measured for each individual layer. Finally, the thermal resistance, thermal conductivity, thermal absorptivity, peak heat flow density ratio, stationary heat flow density, and water vapor permeability of bi-layered sportswear were evaluated and analyzed. The findings show that sportswear made from a 60% cotton/30% polyester/10% elastane inner layer and a 100% polyester outer layer had the maximum thermal resistance of 61.16 (×103 K·m2 W−1). This performance was followed by the sample made from a 90% polyester/10% elastane inner layer and a 100% polyester outer layer, and the sample composed of a 100% elastane inner layer and a 100% polyester outer layer, which achieved a thermal resistance value of 60.41 and 59.41 (×103 K·m2 W−1), respectively. These results can be explained by the fact that thicker textiles have a higher thermal resistance. This high-thermal-resistance sportswear fabric is appropriate for the winter season. Sportswear with a 90% polyester/10% elastane inner layer had worse water vapor resistance than sportswear with a 60% cotton/30% polyester/10% elastane and a 100% elastane layer. Therefore, these sports clothes have a higher breathability and can provide the wearers with very good comfort. According to the findings, water vapor permeability of bi-layered sportswear is influenced by geometric characteristics and material properties.


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