An Upper Bound Solution for the Compression of an Orthotropic Cylinder

The upper bound theorem is used in conjunction with Hill’s quadratic yield criterion for determining the force required to upset a solid cylinder. The kinematically admissible velocity field accounts for the singular behavior of the real velocity field in the vicinity of the friction surface if the maximum friction law is adopted. The regime of sticking is also taken into consideration. The effect of this regime on the upper bound limit load is revealed. In particular, the kinematically admissible velocity field that includes the regime of sticking may result in a lower upper bound than that with no sticking. The boundary value problem is classified by a great number of geometric and material parameters. Therefore, a systematic parametric analysis of the effect of these parameters on the compression force is practically impossible. An advantage of the solution found is that it provides a quick estimate of this force for any given set of parameters.

Measuring Reading Anxiety in College Students

Extensive research has been conducted on math anxiety, yet research on reading anxiety is extremely limited, despite similar affective experiences being reported by readers. The goal of the present study was to create a brief reliable scale for measuring reading anxiety in college students, a time when reading demands are particularly high. Results revealed individual differences in reading anxiety levels in a sample of 402 university students, showing reliable measurements from a 10 item scale. These individual differences were also shown to relate to reading fluency, reading self-concept, self-perception of reading ability compared to others, reading enjoyment, and reading for pleasure frequency. Furthermore, group differences in reading anxiety were observed between students with and without a known learning disability. How well each of the 10 items differentiated levels of reading anxiety were explored using a graded response model. The last item, which simply asked participants whether they had reading anxiety provided the most information to differentiate between those with medium and high amounts of reading anxiety. This item also correlated well with the total score suggesting this item may be a useful quick estimate of reading anxiety in college students.

Ship-Wave Impact Generated Sea Spray: Part 2 — Formulating Spray Frequency

In certain, but not all, circumstances a cloud of spray forms after a wave impacts a ship. The frequency of spray events affects the icing process. Previous spray frequency formulas are derived empirically from field observations considering only the ship’s forward speed and oceanographic conditions. The significance of various degrees of ship motions on the spray frequency is ignored. However in reality, the interrelationships of heave and pitch motions under wave actions together with surge motion determine the number of spray events that a ship may experience in a given period of time. This paper introduces a theoretical model for estimating the frequency of sea spray considering ship motions. Ship motions can be easily estimated by strip/panel methods. However, in this work, the aim was to develop a simple framework for a quick estimate of spray frequency. The model inputs are, therefore, restricted to ship’s principal particulars, its operating conditions, and the environmental conditions. The wave-induced motions are estimated by semi empirical analytical expressions. A novel spray threshold is developed to keep the deck wetness frequency separated from the spray frequency. The proposed spray frequency formula is validated against available full-scale field measurements from a Russian fishing vessel, MFV Narva, and reasonable agreement is found. Limitations of previous empirical formulas are also discussed.

A quick laboratory method for assessment of blood penetration and splash resistance of PPE fabrics during the COVID-19 pandemic situation

In the current outbreak of COVID-19, healthcare facilities are hit by a shortage of supply of Personal Protective Equipments (PPE) owing to extensive local and global demands and restrictions on their import or export. To circumvent this, trials with several indigenous materials suitable to qualify for PPEs and sterilisation techniques for their reuse are being carried out. Prior to their commercialisation or reuse, it is imperative to evaluate the resistance of the PPE-fabrics against penetration of synthetic blood under applied pressure in the range of 40 - 300 mmHg as per test standards. Generally, two types of tests are recommended, namely, the Penetration Test and Splash Resistance Test, the former being more stringent. While the final certification of PPEs is carried out by authorised agencies, a first impression quick estimate of the choice of fabric can be made by using a simple laboratory set up. This study describes set ups developed in the laboratory to carry out these tests. Evaluation of the fabrics, post-gamma irradiation, was also carried out. Microscopic examinations were performed to investigate radiation induced structural changes in fabrics showing degraded performance. The developed set ups are useful for selection of fabrics and to assess the feasibility of reuse of PPEs, which is the need of the hour in this pandemic situation.

Long-term trends and variations in haze-related stagnation intensity in North China during 1980-2018

<p>Recently, the climatological and environmental communities have paid significant attention to the long-term trends and variations in haze-related weather conditions in North China (NC). This study investigates the issue based on a quantified air stagnation index (ASI<sub>E</sub>) that combines the stagnation intensity with the background emissions, considering that haze occurrence strongly depends on the rate of emission. ASI<sub>E</sub> shows a close spatial and temporal relationship with the observed PM<sub>2.5</sub> concentrations, and a strong sensitivity to haze occurrence in NC. The change in ASI<sub>E</sub> revealed an approximate 19% increase in the annual stagnation intensity over the period of 1980-2018, due to significant decreases in PBLH and ventilation potency. The interannual variations in stagnation intensity were very significant. The percentage change of ASI<sub>E </sub>was as high as 50-70% in some years. However, there was an apparent drop in stagnation intensity during 2013-2018, which possibly contributed to the recently reported improvement in aerosol concentration in NC. It also shows that such low-frequency oscillation occurred twice during 1980-2018. Hence, once the current trend of decreasing stagnation intensity changes, haze events may become more common in the future. Finally, we present a quick estimate for the emission reduction ratio that can balance the variations and trend of stagnation intensity using a simple linear model, which can be used to evaluate the difficulty of the “clean air challenge” in NC. The results suggest that the enforcement of the emission reduction plan should be tailored according to the stagnation conditions in the case study year and region.</p>

INTEGRATED ASSESSMENT OF THE CREDIT POLICY EFFICIENCY

The credit policy is a basis of receivables management. The competent combination of its parameters allows to increase a greater effect of commercial crediting applying by the company. The purpose of this study is to develop a methodology for assessing the effectiveness of various credit policy types: conservative, moderate and aggressive. The comparative analysis of three methods of assessment of the credit policy efficiency is carried out in the article: The NPV analysis, the valuation model based on the average daily margin and the model for assessing the impact of changes in the company’s credit policy. As a result, the technique of the full and quick estimate methods of the credit policy ef-ficiency, including calculation of individual, intermediate and integrated indicators are offered. The method is based on three groups of the indicators, reflecting the company credit policy efficiency in the following directions: quality receivables management, receivables costs maintenance and influ-ence on a company financial condition. The influence of each of the indicator and indicators groups when using different credit policy’s types were proved in the article and that allowed to transform them to a general integrated indicator. This technique allows to estimate in a complex and objectively efficiency of the credit policy operating in the company.

Implementing an Energy Calculator in a Mobile Based Application for Solar Potential Measurement

Solar photovoltaic (PV) technology has matured to become a technically viable large scale source of sustainable energy. Understanding the rooftop PV potential is critical for utility planning, accommodating grid capacity, deploying financing schemes and formulating future adaptive energy policies. The NIWE (National Institute of Wind Energy) under MNRE (Ministry of New and Renewable Energy) is an esteemed institute dedicated to Indian wind and solar renewable energy generation and monitoring. The SRRA (Solar Radiation and Resource Assessment) is a division under NIWE that is responsible for solar energy monitoring throughout India. They have created the Solar Radiation Map of India using high quality, ground measured solar data. This asks the question, whether it is possible to get a quick estimate of a solar installation. Thus, the paper explains the problems in the field of solar potential measurement and the deployment of a calculator in a mobile front platform. The mobile app would quickly and effortlessly give a rough estimate on what a solar installation could save in power consumption costs.

Development of a Screening Frequency Scanning Test Method

Fatigue crack growth rates (FCGR) in corrosive environment depends on loading frequency. Frequency scanning testing is often used to determine this effect. However, it is well known that the effect of loading frequency also depends on the magnitude of stress intensity factor range, ΔK. It is generally found that, with decreasing loading frequency, FCGR decreases in the low ΔK regime, increases and then decreases after reaching the saturating loading frequency in the intermediate ΔK regime, and keeps increasing in the high ΔK regime. To accurately characterise the effect of loading frequency on FCGR, several frequency scanning tests are required for a particular application (corrosive environment, material, welding procedure etc), each at a different ΔK level. These are time consuming and expensive tests. A novel screening frequency scanning test method has thus been developed. The method is similar to the step load fracture toughness test method often used to make a quicker estimate of fracture toughness of material in corrosive environment. In the screening frequency scanning test, both loading frequency and ΔK are changed in steps. At a relatively low and constant ΔK level, loading frequency is reduced in steps, after a certain amount of crack growth. Once the FCGR exhibits decreasing or has achieved a saturating loading frequency with decreasing loading frequency, ΔK is then increased to another higher level and the above process is repeated; the above procedures are repeated until the target maximum ΔK and the lowest loading frequency have been achieved. This method allows an estimate of the effect of loading frequency on FCGR in a large ΔK range using a single specimen. The results of the screening frequency scanning tests demonstrated that this method was feasible and provided a good and quick estimate of the effect of loading frequency on FCGR.