scholarly journals Length Effect on the Stress Detection of Prestressed Steel Strands Based on Electromagnetic Oscillation Method

Sensors ◽  
2019 ◽  
Vol 19 (12) ◽  
pp. 2782 ◽  
Author(s):  
Zhang ◽  
Tu ◽  
Li ◽  
Cui ◽  
Zheng
Keyword(s):  
Electromagnetic Oscillation ◽  
Oscillation Circuit ◽  
Steel Strand ◽  
Long Time ◽  
Set Up ◽  
Frequency Relationship ◽  
Oscillation Frequencies ◽  
Structural Engineers ◽  
In Transit ◽  
Oscillation Method

Prestress detection of structures has been puzzling structural engineers for a long time. The inductance–capacitance (LC) electromagnetic oscillation method has shown a potential solution to this problem. It connects the two ends of a steel strand, which is simulated as an inductor, to the oscillation circuit, and the stress of the steel strand can be calculated by measuring the oscillation frequency of the circuit through a frequency meter. In the previous studies, the authors found that stress-frequency relation of 1.2 m steel strand was negatively correlated, while the stress-frequency of 10 m steel strand was positively correlated. To verify this conflict, two kinds of electrical inductance models of steel strands were established to fit the lengths. With the models, the stress-frequency relations of steel strands with different lengths were analyzed. After that, two kinds of experimental platforms were set up, and a series of stress-frequency relationship tests were carried out with 1.2 m, 5 m, 10 m and 15 m steel strands. Theoretical analysis and experimental results show that when the length is less than 2.013 m, the stress and oscillation frequencies are negatively correlated; when length is more than 2.199 m, the stress and oscillation frequencies are positively correlated; while when length is between 2.013 m and 2.199 m, the stress-frequency relationship is in transit from negative correlation to positive correlation.

scholarly journals Acceptance of a Symptom-Based Approach for COVID-19 rtRT-PCR Testing to Conserve Resources in a Lower Middle-Income Setting

2021 ◽  
Vol 12 ◽  
pp. 215013272098771
Author(s):  
S. M. Rashed Ul Islam ◽  
Tahmina Akther ◽  
Md. Abdullah Omar Nasif ◽  
Sharmin Sultana ◽  
Saif Ullah Munshi
Keyword(s):  
Primary Method ◽  
Chain Reaction ◽  
Middle Income ◽  
Clinical Recovery ◽  
Clinical Presentations ◽  
Long Time ◽  
Nasopharyngeal Secretion ◽  
Polymerase Chain ◽  
Set Up

SARS-CoV-2 initially emerged in Wuhan, China in late 2019. It has since been recognized as a pandemic and has led to great social and economic disruption globally. The Reverse Transcriptase Real-Time Polymerase Chain Reaction (rtRT-PCR) has become the primary method for COVID-19 testing worldwide. The method requires a specialized laboratory set up. Long-term persistence of SARS-CoV-2 RNA in nasopharyngeal secretion after full clinical recovery of the patient is regularly observed nowadays. This forces the patients to spend a longer period in isolation and test repeatedly to obtain evidence of viral clearance. Repeated COVID-19 testing in asymptomatic or mildly symptomatic cases often leads to extra workload for laboratories that are already struggling with a high specimen turnover. Here, we present 5 purposively selected cases with different patterns of clinical presentations in which nasopharyngeal shedding of SARS-CoV-2 RNA was observed in patients for a long time. From these case studies, we emphasized the adoption of a symptom-based approach for discontinuing transmission-based precautions over a test-based strategy to reduce the time spent by asymptomatic and mildly symptomatic COVID-19 patients in isolation. A symptom-based approach will also help reduce laboratory burden for COVID-19 testing as well as conserve valuable resources and supplies utilized for rtRT-PCR testing in an emerging lower-middle-income setting. Most importantly, it will also make room for critically ill COVID-19 patients to visit or avail COVID-19 testing at their convenience.

Risk Factors for Typhoid Fever Occurrence and Recurrence in Gombe Metropolis, Gombe State, Nigeria

2021 ◽  
Vol 23 (11) ◽  
pp. 381-401
Author(s):  
Umar Abdullahi Tawfiq ◽  
◽  
Shohaimi Shamarina ◽  
Syafinaz Amin Nordin ◽  
Mohd Noor Hisham Mohd Nadzir ◽  
...  
Keyword(s):  
Risk Factors ◽  
Epidemiological Data ◽  
Simple Random Sampling ◽  
Chi Square ◽  
Long Time ◽  
Chi Square Test ◽  
The Government ◽  
Set Up ◽  
Associated Risk Factors ◽  
At Home

Typhoid is a life-threatening disease that has remained endemic in parts of Africa and Asia where its burden is elevated by the inefficiency of control efforts which have been hampered by lack of epidemiological data, among others. In Nigeria, such data is absent in most of the States like Gombe where the disease has been rife for a long time, hence, to bridge that knowledge gap, this study was set up to determine the host-associated risk factors for typhoid occurrence and recurrence in Gombe. A questionnaire that was designed and validated for this location was used to obtain data from 663 respondents using simple random sampling and analyzed using the Chi-square test for association and binomial logistic regression to obtain risk factors for typhoid occurrence and recurrence, respectively. The study revealed that occurrences were statistically significantly associated with the variables for vaccination (χ2 = 39.729, p < 0.01), having houseboy/girl (χ2 = 16.909, p < 0.01), typhoid patient at home (χ2 = 13.393, p < 0.01), hand washing before handling food (χ2 = 22.856, p < 0.01), consuming iced/frozen items (χ2 = 16.805, p < 0.01), boiling drinking water (χ2 = 49.633, p < 0.01), and eating commercially available foods/drinks (χ2 = 27.864, p < 0.01), while recurrences were statistically significantly predicted by „not sure of been vaccinated‟ (OR = 2.962, CI = 1.290 to 6.802, p < 0.01), „not having another typhoid patient at home‟ (OR = 1.799, CI = 0.998 to 3.244, p < 0.01), and „drinking unboiled water sometimes‟ (OR = 2.130, CI = 1.023 to 4.434, p < 0.01). It is believed that these findings will guide efforts by the Government for health interventions against typhoid in the study area, thus improving the quality of life for the population.

scholarly journals Highland Hill tribe language - an extinct language system needed to be saved

2020 ◽  
Vol 9 (2) ◽  
pp. 3-7
Author(s):  
Tang Minh Chau
Keyword(s):  
Root Culture ◽  
Language System ◽  
Hill Tribe ◽  
Long Time ◽  
Hill Tribes ◽  
Set Up ◽  
Culture And Language

Highland is a typical area in Vietnam with a great deal of unique things for people to study and discover. Among them are culture and language, the two reciprocal elements to create communities called Hill tribes. Original Hill tribes came to the Highland long time ago and set up their life based on their root culture until now. When studying about Hill tribes, we realize that their culture is very interesting and worth tracing. Therefore, how to conserve Hill tribes’ culture is what we need to take into consideration as soon as possible.

Application and Impact of Social Network in Modern Society

2019 ◽  
pp. 30-49 ◽  
Author(s):  
Mamata Rath
Keyword(s):  
Social Network ◽  
Social Systems ◽  
Personal Data ◽  
Modern Society ◽  
Work Culture ◽  
Security Measures ◽  
Home Office ◽  
Emerging Trends ◽  
Long Time ◽  
Set Up

Social network and its corresponding website permits a client to make a profile, set up an authorized account to create a digital representation of themselves, to select other members of the site as contacts, make connections with them, communicate and engage with these users in different social activities, etc. So, social network includes details of persons, group details, their friends list, contact list, business, affiliations, personal data, personal preferences, and historical information. In this age of smart communication and technology, most of the time people are connected with mobile smart telephones in their work culture, home, office, or any other related places. As they are constantly associated with social systems for long time, they get new posts, messages, and current refreshed news readily available in a flash. This is the constructive part of social networking that individuals consistently remain refreshed with most recent news and innovation. This chapter presents an overview of social network design, various issues, and emerging trends that are evolved simultaneously with modern age. It also presents a detail study on application and impact of social network in modern society as well as exhibits an exhaustive review of security measures in social sites.

Statistical-Mathematical Methods Used in Analysis of Trade in Industrial Products

2019 ◽  
Vol 34 ◽  
pp. 315-325
Author(s):  
Tomiță Constantin Vasile ◽  
Luminița Popescu ◽  
Cora Ionela Dăniasă ◽  
Anica Iancu ◽  
Virgil Popescu
Keyword(s):  
Dairy Products ◽  
Economic Importance ◽  
Mathematical Methods ◽  
Close Link ◽  
Human Needs ◽  
Commodity Production ◽  
The People ◽  
Long Time ◽  
Set Up ◽  
The Moment

Dairy products are of great socio-economic importance in Romania today. These products have both nutritional and economic importance. The market is the economic category of commodity production in which it expresses the totality of the sale-purchase acts viewed in an organic unit with the relations it generates and in connection with the space in which it takes place. The market originated a long time ago, being related to the moment when, in order to satisfy their existential needs, "discovered" and increasingly "conscious", the people exchanged between them, respectively collectivities, the surpluses held by each individual - individually or collectively. The exchange, set up as a means of realizing its own interests, has seen various forms and has evolved continuously, being still the foundation of all the economies of the world. The market has grown based on the amplification and diversification of human needs. The satisfaction of these needs is given by the close link between producers and consumers.

scholarly journals A study of two-dimensional flow past an oscillating cylinder

1999 ◽  
Vol 385 ◽  
pp. 255-286 ◽  
Author(s):  
H. M. BLACKBURN ◽  
R. D. HENDERSON
Keyword(s):  
Experimental Studies ◽  
Cross Flow ◽  
Relaxation Oscillator ◽  
Two Dimensional ◽  
Flow State ◽  
Long Time ◽  
Two Dimensional Flow ◽  
Vorticity Production ◽  
Oscillation Frequencies ◽  
Motion Amplitude

In this paper we describe a detailed study of the wake structures and flow dynamics associated with simulated two-dimensional flows past a circular cylinder that is either stationary or in simple harmonic cross-flow oscillation. Results are examined for Re=500 and a fixed motion amplitude of ymax/D=0.25. The study concentrates on a domain of oscillation frequencies near the natural shedding frequency of the fixed cylinder. In addition to the change in phase of vortex shedding with respect to cylinder motion observed in previous experimental studies, we note a central band of frequencies for which the wake exhibits long-time-scale relaxation oscillator behaviour. Time-periodic states with asymmetric wake structures and non-zero mean lift were also observed for oscillation frequencies near the lower edge of the relaxation oscillator band. In this regime we compute a number of bifurcations between different wake configurations and show that the flow state is not a unique function of the oscillation frequency. Results are interpreted using an analysis of vorticity generation and transport in the base region of the cylinder. We suggest that the dynamics of the change in phase of shedding arise from a competition between two different mechanisms of vorticity production.

The Forced Creep Analysis of Nonmetallic Material

2012 ◽  
Vol 184-185 ◽  
pp. 692-695 ◽  
Author(s):  
Shan Qi Zeng ◽  
Zhi Jie Zhang
Keyword(s):  
Nonmetallic Material ◽  
Creep Model ◽  
Operating Life ◽  
Time Curve ◽  
Creep Properties ◽  
Creep Analysis ◽  
Material Creep ◽  
Long Time ◽  
Set Up ◽  
Force Creep

Nonmetallic material by stress which less the yield stresses long time, it would force creep. Nonmetallic materials’ operating life depended on the creep degree. The paper set up creep model using ANSYS, create the nonmetallic material creep strain-time curve, got the creep properties of nonmetallic material. To provide effective basis of calculate the nonmetal materials’ operating life.

scholarly journals Note on the spreading of solids on water surfaces

1926 ◽  
Vol 110 (754) ◽  
pp. 441-443 ◽  
Keyword(s):  
Vapour Pressure ◽  
Myristic Acid ◽  
Two Dimensional ◽  
Water Surfaces ◽  
Long Time ◽  
Set Up

Cary and Rideal (1), in their recent excellent studies of spreading of solid and liquid substances on water, show that the rate of passage of molecules from a crystal of myristic acid, into a film on the surface, is proportional at any moment to F e —F, where F is the compression in the film and F e the compression at which the film is in equilibrium with the crystal and no more spreading occurs. Experimentally they could detect no compression until enough had spread to cover the whole available surface with a film packed to the density of an expanded film at no compression—about 46 Å. U. Probably their measurements were not sufficiently accurate to detect a compression much less than 0∙5 dynes per cm., if this persisted for a long time. But if their theory, which agrees well with the views on spreading of one of us (2), is correct, a small compression should be set up very soon after the crystal is placed in the surface, and this should rise to, and remain constant at, the "two-dimensional vapour pressure” of myristic acid, for some time, before the spread film has reached the density of the expanded film. In this region F is negligible compared with F e , hence the rate of spreading from the crystal is constant.

Microwave Assisted Synthesis of Ru3Pd6Pt Cathode Catalyst in a PEM Fuel Cell

2013 ◽  
Vol 16 (3) ◽  
pp. 147-150 ◽  
Author(s):  
F. Leyva-Noyola ◽  
O. Solorza-Feria
Keyword(s):  
Fuel Cell ◽  
Large Scale ◽  
High Pressures ◽  
Cost Effective ◽  
Pem Fuel Cell ◽  
Reduction Reaction ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Long Time ◽  
Set Up

Nanoparticles of Ru3Pd6Pt have been previously produced by different synthesis routes that involve high temperatures and relative high pressures and long time. The usage of a conventional microwave assisted synthesis reduces environmental risk impact as well as the cost effective production in large scale with minimum set up modifications. These features are the motivations for the use of microwaves in the synthesis of the Ru3Pd6Pt catalyst for PEM fuel cell applications to reduce the Pt loading. In this communication a tri-metallic electrocatalyst was produced by the reduction of the corresponding metallic salts, RuCl3, PdCl2, and H2PtCl6 in ethylene glycol using a modified conventional microwave device. Oxygen reduction reaction kinetic analysis results conducted to a Tafel slope, (-b = 41.2 ± 1.7 mV dec-1) at low overpotential, and exchange current density (i0 = 3.01 ± 0.39 × 10-5 mA cm-2) in 0.5M H2SO4. This electrocatalyst exhibited good performance and stability in a single H2/O2PEM fuel cell.

Time-Domain Analysis and Experimental Verification of Portable Grounding System’s TGR

2014 ◽  
Vol 705 ◽  
pp. 259-262
Author(s):  
Xin Bo Qu ◽  
Bi Hua Zhou ◽  
Ya Peng Fu ◽  
Li Juan Yang ◽  
Nan Zhang
Keyword(s):  
Time Domain ◽  
Time Domain Analysis ◽  
Frozen Soil ◽  
Lightning Protection ◽  
Grounding System ◽  
Grounding Resistance ◽  
Long Time ◽  
New Type ◽  
Set Up ◽  
Difference Time

The portable grounding system plays an important role in the lightning protection system of mobile equipments. But the traditional earth electrodes composed of vertical rods wouldn’t work well or would take a long time to set up in some conditions such as frozen soil, hard clay and so on. In this paper, a new type of portable grounding system which can be quickly spread and folded has been designed. To analyze the TGR’s (Transient Grounding Resistance) time-domain characteristics, the grounding systems have been modeled and simulated with FDTD (Finite Difference Time Domain). The influence rule of electrodes’ number and down-lead’s position to TGR has been studied with numerical analysis and validated with experiments. The results show that the new grounding system works well even on cement floor.

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