Filling with separating curves

A pair $(\alpha, \beta)$ of simple closed curves on a closed and orientable surface $S_g$ of genus $g$ is called a filling pair if the complement is a disjoint union of topological disks. If $\alpha$ is separating, then we call it as separating filling pair. In this article, we find a necessary and sufficient condition for the existence of a separating filling pair on $S_g$ with exactly two complementary disks. We study the combinatorics of the action of the mapping class group \M on the set of such filling pairs. Furthermore, we construct a Morse function $\mathcal{F}_g$ on the moduli space $\mathcal{M}_g$ which, for a given hyperbolic surface $X$, outputs the length of shortest such filling pair with respect to the metric in $X$. We show that the cardinality of the set of global minima of the function $\mathcal{F}_g$ is the same as the number of \M-orbits of such filling pairs.Comment: 30 Pages, 16 Figures, Theorem 1.3, Subsection 4.1, Lemma 7.8 are added to the previous versio

Complexity in Bolza surface

A surface in the Teichm\"uller space, where the systole function attains its maximum, is called a maximal surface. For genus two there exists a unique maximal surface which is called the Bolza surface. In this article, we study the complexity of the set of systolic geodesics on the Bolza surface. We show that any non-systolic geodesic intersects the systolic geodesics in $2n$ points, where $n\geq 5$. Furthermore, we show that there are $12$ second systolic geodesics on the Bolza surface and they form a triangulation of the surface.Comment: 11 pages, 11 figure

Optimized Performance of One-Bed Adsorption Cooling System

Adsorption cooling system can be driven by solar energy or waste heat, so it will effectively reduce fossil fuel consumptions when total system is well-designed. On the other hand, the system tends to have a large size, which will be an obstacle to install adsorption cooling systems to small to medium scale cooling demands, such as automobiles, houses, or shops. The study was aiming at the reduction of system size of adsorption cooling systems for refrigeration and air-conditioning applications. To simplify the system, we investigated one-bed configuration of adsorption cooling system. In general, one-bed adsorption cooling system would result in a large temperature fluctuation at chilled water outlet. To overcome that drawback and to maximize the cooling capacity, the cycle time, namely, pre-heating, desorption, pre-cooling, and adsorption times, of one-bed adsorption cooling system was optimized. In case of two-bed adsorption cooling system, two adsorbers operates in reverse phase each other, which means that the degree of freedom for cycle time optimization is two. In case of one-bed adsorption cooling sytem, four processes can be independently optimized. In our study, activated carbon-ethanol pair was chosen as the adsorbent-refrigerant pair because of a high adsorption capacity of activated carbons against ethanol. Using adsorption isotherms and kinetic data of activated carbon-ethanol pair measured by our research group, a lumped parameter model of one-bed adsorption cooling system was developed. The four parameters of cycle time were optimized using global optimization method, and the optimal time settings were effectively found. The results showed the effect of cycle time optimization on the cooling performance of one-bed adsorption cooling system

Vaccination, Compliance with Preventive Measures and Mental Health during COVID-19 among Adults in Bangladesh: Do Vaccination and Compliance with Preventive Measures Improve Mental Health?

Background and Objective: In addition to the reduction of risk of COVID-19 transmission and mortality, vaccination and compliance with the preventive measures of COVID-19 may have important additional benefits for the improvement of mental health. This study examined the levels and determinants of vaccination, compliance with preventive measures, and anxiety, depression and stress among Bangladeshi adults. It also examined the effects of vaccination and compliance with preventive measures on mental health status among Bangladeshi adults. Methods: Data for the study come from an online survey conducted during November and December 2021 among Bangladeshi adults. A total of 615 adults participated in the survey. A 21-item Depression, Anxiety, and Stress scale (DASS 21) were used for collecting data on mental health. Both descriptive and inferential statistical methods including multiple logistic regression were used for data analysis. Results: About 69% of Bangladeshi adults were vaccinated with at least one dose; 87% of adults believed that vaccines are moderate to highly effective in reducing COVID-19 infection. Among the preventive measures during a pandemic, the level of complete compliance with wearing masks and hand washing was almost universal, while the compliance level with other preventive measures was moderate. Vaccinated people had a 55% (OR=0.45; 95%CI:0.26-0.82), 67% (OR=0.33; 95%CI:0.12-0.91), and 44% (OR=0.56; 95%CI:0.27-0.97) lower chance of suffering from depression, anxiety, and stress, respectively than non-vaccinated people. People with complete compliance had 64% (OR= 0.36; 95%CI:0.18-0.72), 71% (OR=0.29; 95%CI:0.15-0.58), and 74% (OR=0.26; 95%CI:0.13-0.50) lower risk of suffering from depression, anxiety, and stress, respectively, than respondents with irregular preventive behaviors. Conclusion: This study documents the important psychological benefits of vaccination and compliance with preventive measures of COVID-19

Experimental study of multi-pass solar air thermal collector system assisted with sensible energy-storing matrix

Analysis of heat transfer around the components of multi-pass solar air heating collector and its per�formance enhancement has been presented using experimental approach. Radiation and convection heat transfer from the system covers and collector plate to the flowing airstreams in the collector system have been investigated. Geological porous matrix has been used as thermal energy reservoir. Test rig was set up under daily average solar insolation, ambient temperature, wind speed, and relative humidity of 302.40 Wm-2, 29.30 �C, 0.58 ms�1 , and 48.53%, respectively. Thermal performance evaluation of the multi-pass solar air collector has been conducted in accordance with the ASHRAE standard specified for the solar air heating systems. Thermal collector efficiency range of 51.91e72.55% has been achieved with an optimum air mass flow rate of 0.013 kgs�1 . System evaporative capacity range of 1:158 � 10�3 - 1:205 � 10�3 kgs�1 was computed. The matrix has extended the span of system operation for more than 3 h after sunset. Comparison of the outcome of multi-pass solar collector performance with the reported study has been done with good agreement. However, an improvement in performance through heat transfer from collector to the flowing air could be achieved

Performance Analysis of Solar Adsorption Cooling System - Effect of Position of Heat Storage Tank

An insulated storage tank has been added with adsorption cooling system run by solar heat collected by CPC panel. It has been expected and seen that the storage tank has a vital contribution in the performance of the chiller. The storage tank is connected with a solar heat driven single stage two bed basic adsorption chillers activated with silica gel-water pair in two ways. The tank is connected in such a way that (i) the solar collectors supply hot water to the desorption bed, the outflow of the desorber is collected in the reserve tank. The reserve tank supplies water to the collector and complete the heat transfer cycle. (ii) The solar collector supply hot water which is collected in the storage tank first and then supplied to the desorber. The outflow of the desorber is carried to the collector again. Comparative studies have been conducted at the steady state for both of the systems with heat storage. It has been observed that the system is robust with design (i) while with design (ii) performance enhances beyond the sunset time with heat storage

Synthesis, Characterization and CO2 Sorption Capacity Measurements of Selected Ionic Liquid Polymers

Ionic liquids (ILs) technology has been emerged as most prominent approach for the CO2 capture, which is an important phenomena in oil & natural gas industry during the gas sweetening process. The remarkable performance of IL polymers for the CO2 capture provided new opportunities to upgrade this technology in recent years. Therefore, in the present study, we have prepared different IL polymers namely poly(1-vinylimidazole), poly(1-vinyl-3-ethylimidazolium bromide), poly(1-vinyl-3-ethylimidazolium bis(trifluoro methylsulfonyl))imide and zeolite incorporated poly(1-vinyl-3-ethylimidazolium bis(trifluoro methylsulfonyl)imide materials and evaluated their CO2 capture efficiency. The synthesized IL polymers were characterized by FT-IR, FE-SEM and EDX. The CO2 sorption experiments were conducted using gas sorption cell, and the results revealed that zeolite incorporated IL polymer has adsorbed highest amount of CO2 (1.58mol) and recorded the highest pressure drop over other IL polymers. © 2020 Author(s).One of the authors A. Vijaya Bhasker Reddy thankful to Centre of Research in Ionic Liquids (CORIL), Universiti Teknologi PETRONAS, 32610 Seri Iskandar, Perak, Malaysia for providing post-doctoral fellowship

Preparation and assessment of ionic liquid and few-layered graphene composites to enhance heat and mass transfer in adsorption cooling and desalination systems

Adsorption systems can utilise low-temperature renewable and waste heat sources, which have emerged as a feasible alternative to conventional water desalination and cooling systems. However, the material of poor heat and mass transfer performance stall their widespread utilisation. This article presents the development and investigation of new composites employing few-layered graphene platelets and ionic liquids, namely ethyl-methylimidazolium methane sulfonate ([EMIM][CH3SO3]) and Ethyl-methylimidazolium-chloride ([EMIM][Cl]) to address such challenges. The impact of the few-layered graphene platelets, thermal properties, water adsorption properties of the developed composites and their thermal diffusivity were experimentally investigated. Besides, the overall cyclic performance was studied experimentally at the material level and computationally at the component level by employing a previously validated 2D dynamic heat and mass transfer model. The experimental investigation indicated that pristine few-layered graphene has a surface area of 56.8978 m2/g and a relatively high thermal diffusivity of 22.23 mm2/s. The developed composites showed higher thermal diffusivity than the baseline adsorbent silica gel. The highest thermal diffusivity was 11.84 mm2/s for GP-CH3SO3-10, 394 times higher than silica gel. Water adsorption characteristics of the composites were carried out, and the Dubinin–Astakhov (D-A) model was employed to model the experimental isotherms with good accuracy. The cumulative advanced adsorption and thermal characteristics of the developed composites resulted in higher cyclic performance by up to 82 % and 85 % than that of the baseline silica gel