scholarly journals A Comprehensive Review on Multiband Reconfigurable Antenna

2021 ◽  
pp. 377-388
Author(s):  
Preeti Rani ◽  
◽  
Tejbir Singh ◽  
Meenu Kaushik ◽  
Vishant Gahlaut
Keyword(s):  
Wireless Communication ◽  
High Performance ◽  
Wireless System ◽  
The Past ◽  
Multiband Antennas ◽  
Single Antenna ◽  
Interference Level ◽  
System A ◽  
New Generation

The advancement of wireless communication is markedly accountable from the past two decades. A variety of designs and techniques have been established in the domain of reconfigurable multiband antennas for different wireless services. Now a days, a high quality of communication with reduced size is required for new generation wireless system. A multiband reconfigurable functionality offers a flexible and high-performance design by single antenna only. A brief review on multiband antenna with different reconfigurable techniques is presented in this paper. Moreover, the new possibilities for future wireless communication system have been demonstrated. A reconfigurable system along with minimal interference level over the fixed or non-reconfigurable transceivers has been discussed in detail.

scholarly journals An Overview of the Reliability Analysis Methods of Tunneling Equipment

2020 ◽  
Vol 14 (1) ◽  
pp. 218-229
Author(s):  
Sina Ahmadi ◽  
Mohsen Hajihassani ◽  
S. Moosazadeh ◽  
H. Moomivand
Keyword(s):  
Reliability Analysis ◽  
Labor Costs ◽  
Goods And Services ◽  
The Past ◽  
Negative Results ◽  
System A ◽  
Equipment Reliability ◽  
Tree Methods ◽  
The Cost

The absolute prevention of damage occurrence is not possible, thus reducing the probability of failure in a system and its impact is very important regarding the operation of a whole system. A failure in a system or in its subsystems makes negative results such as the stop in the production process, rising labor costs, and increasing the cost of maintenance. Reliability, in recent years, is mentioned as one of the most significant aspects of the quality of goods and services. In the past, reliability concerned sensitive and complex industries such as military, nuclear, and aerospace where the lack of their reliability could cause irreparable damage to the entire system. However, today it has become a universal concern. Tunneling equipment has grown in size and complexity and therefore, lack of reliability may cause massive costs to this equipment. Therefore, reliability determination in order to identify the components and subsystems with low reliability is essential. The aim of this study is to review the methods of tunneling equipment reliability analysis including statistical analysis, failure mode and effects analysis, Markov and fault tree methods. In addition, previous available research on the reliability analysis of tunneling equipment is presented.

scholarly journals Concepts of Hyperloop Wireless Communication at 1200 km/h: 5G, Wi-Fi, Propagation, Doppler and Handover

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 983
Author(s):  
Ali Tavsanoglu ◽  
César Briso ◽  
Diego Carmena-Cabanillas ◽  
Rafael B. Arancibia
Keyword(s):  
Wireless Communication ◽  
Communication Systems ◽  
High Capacity ◽  
Careful Study ◽  
System A ◽  
5G Network ◽  
Vacuum Tubes ◽  
Guided Propagation ◽  
Confined Environment ◽  
New Generation

The new generation of capsules that circulate through vacuum tubes at speeds up to 1200 km/h, which is being developed, demands communication systems that can operate at these speeds with high capacity and quality of service. Currently, the two technologies available are the new generation of 802.11ax networks and 5G NR. Using these technologies at such high speeds in a confined environment requires a careful study and design of the configuration of the network and optimization of the physical interface. This paper describes the requirements for critical and business communications, proposing a WLAN and 5G network design based on the analysis of the propagation characteristics and constraints of vacuum tubes and using propagation measurements and simulations made in similar environments at frequencies of 2.5/5.7/24 GHz. These measurements and simulations show that propagation losses in this environment are low (4–5 dB/100 m), as a consequence of the guided propagation, so that the use of bands is preferred. Finally, considering the propagation constraints and requirements of a Hyperloop system, a complete wireless communication system is proposed using two networks with 802.11 and 5G technology.

scholarly journals Virtual reassembly and completion of a fragmentary drinking vessel

2016 ◽  
Vol 7 (15) ◽  
pp. 67 ◽  
Author(s):  
Despoina Tsiafaki ◽  
Anestis Koutsoudis ◽  
Fotis Arnaoutoglou ◽  
Natasa Michailidou
Keyword(s):  
Essential Role ◽  
Collection System ◽  
Ancient Greek ◽  
Automated Data Collection ◽  
The Past ◽  
System A ◽  
Geometrical Features ◽  
And Function ◽  
3D Digitisation

<p class="VARAbstract">A  key  issue  in  the  study  of  cultural  assets  is theiroften  fragmentary  condition.  This  causes  serious  problems  and questions regarding theirstudy and presentation. Pottery fragments are the most numerous findings in every excavation. Furthermore, pottery plays an essential role for the reconstruction of the past, since it providesinformation for all aspects of  life  (private,  public,  religion,  death,  economy,  society,  trade,etc.). Therefore,a  thorough  study  and  presentation  of pottery fragments contribute to a better knowledge of the past.The focus of this work is the visualisation of an ancient Greek  drinking  vase,  a kantharos,  which  was  unearthed  during  the  excavations  at  the  settlement  of  Karabournaki (ancient Therme) in the area of Thessaloniki (Greece). It dates to the Archaic period (7th-6thc. B.C.) and it was found in fragments  among  the  settlement's  architectural  remains.  The  vase  is  of  great  archaeological  significance  due  to  its peculiarities  in  terms  of  shape,  decoration  and  function. Therefore,its  digital  completion  and  3D  reconstruction  willcontribute to its betterstudy and scholarly publication along with a general contribution to the field of pottery studies.We discuss  on  the  3D  digitisation  of  the kantharosfragments  that  werebased  onStructure from Motion/Multiple  View Stereovision  (SfM/MVS)  and  a  custom  automated  data  collection  system.  A  detailed  description  of  the  digitisation pipeline is given along with details related to the quality of the 3D digital replicas of the sherds. Furthermore, we presentour  manual  virtual  reassembly  and  reconstruction  pipelineof  the kantharosby  describing  the  challenges,  issues  and ambiguities discovered while analysing the geometrical features of each sherd. A number of photorealistic reconstruction visualisations  of  the  artefact  are  presented  in  order  to  question  the  applicability  of  the  solution  for  the  actual reconstruction</p>

scholarly journals A Competitive Analysis of East African Cement Companies using the High Performance Organisation Framework

2020 ◽  
Vol 7 (4) ◽  
pp. 454-470
Author(s):  
Evans Makini Osano ◽  
André de Waal
Keyword(s):  
Economic Development ◽  
Financial Performance ◽  
East Africa ◽  
Competitive Analysis ◽  
High Performance ◽  
Job Creation ◽  
Environmental Issues ◽  
East African ◽  
The Past

Sub-standard infrastructure is one of the most significant challenges for economic development in East Africa. Specifically, the availability of affordable, locally produced cement is critical to infrastructural and economic development and job creation in the region. Thus, it is critical for cement companies to achieve better operational and financial results so they can satisfy the need for higher-quality cement for infrastructure projects and to deal with increasing environmental issues. In this article we evaluate, using de Waal’s high performance organisations (HPO) framework, the quality of three cement companies in Kenya and Tanzania to identify improvements these companies can make to their internal organisation and operations so they can achieve better financial and operational results. The research results indicate that whilst all three companies were yet to achieve HPO status, the best performing company with the highest HPO score also had the best financial performance over the past 10 years. The research also resulted in a series of recommendations on the basis of the weaknesses identified in the cement companies.

scholarly journals Organization Development for Improving Public Enterprises

1976 ◽  
Vol 1 (2) ◽  
pp. 27-40
Author(s):  
Nitish R. De
Keyword(s):  
Organization Development ◽  
Public Enterprises ◽  
The West ◽  
The Past ◽  
System A ◽  
The Future ◽  
Effective System ◽  
Appreciative System ◽  
Work And Life

Organization Development with its process focus, as developed in the West, may not be able to deal with several problems of social reality like alienation from work and life, tension ridden culture of consumerism, effects of future shocks, etc. The picture is complicated in developing countries where bureaucratic‐work orientation with concomitant values and attitudes dominate public enterprises. The need for the establishment of an effective system for the continuous rise in the quality of life is quite important in public enterprises. A new culture has to be developed. There is a need to internalize a larger “appreciative system” with OD strategies in terms of the process and design. This may lead to “eco-system,” a meaningful linkage of the past and the future through the present, an ideal-seeking approach to the future. Such an approach may free 00 from its narrow confines.

Designing a Polymer Gear for Use in the Environment of an Internal Combustion Engine

2011 ◽  
Author(s):  
Rod Kleiss ◽  
Frank J. Ferfecki
Keyword(s):  
Combustion Engine ◽  
Material Selection ◽  
Consumer Products ◽  
Balance System ◽  
Gear Design ◽  
The Past ◽  
System A ◽  
Injection Molded

Much has been written about the advances in polymer gearing over the past few years. After fitful starts in toys and consumer products, the design and quality of these gears have improved dramatically. Materials advances over the past 20 years have been significant as well. This paper describes the methodology of designing a net shape PolyEtherEtherKetone (PEEK) injection molded gear for an automotive mass balance system. The case study referenced (ref 1) shows that, when compared to the high quality ground iron gears in the same system, a net shape injection molded PEEK polymer gear provides a 3db noise reduction, as much as 9% reduction in power consumption, a 69% mass reduction and meets the application durability requirements. The paper describes the design of the injection molded gear’s unique tooth profile, material selection, part design, mold design, and inspection methods. The paper focuses on the differences in gear design and inspection methods between injection molded gears and their metal counterparts.

scholarly journals Effect of Sputtering Oxygen Partial Pressure on the Praseodymium-Doped InZnO Thin Film Transistor Using Microwave Photoconductivity Decay Method

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1044
Author(s):  
Huansong Tang ◽  
Kuankuan Lu ◽  
Zhuohui Xu ◽  
Honglong Ning ◽  
Dengming Yao ◽  
...  
Keyword(s):  
Thin Film ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
High Performance ◽  
Thin Film Transistor ◽  
Preparation Process ◽  
Defect States ◽  
Photoconductivity Decay ◽  
New Generation

The praseodymium-doped indium-zinc-oxide (PrIZO) thin film transistor (TFT) shows broad application prospects in the new generation of display technologies due to its high performance and high stability. However, traditional device performance evaluation methods need to be carried out after the end of the entire preparation process, which leads to the high-performance device preparation process that takes a lot of time and costs. Therefore, there is a lack of effective methods to optimize the device preparation process. In this paper, the effect of sputtering oxygen partial pressure on the properties of PrIZO thin film was studied, and the quality of PrIZO thin film was quickly evaluated by the microwave photoconductivity decay (µ-PCD) method. The μ-PCD results show that as the oxygen partial pressure increases, the peak first increases and then decreases, while the D value shows the opposite trend. The quality of PrIZO thin film prepared under 10% oxygen partial pressure is optimal due to its low localized defect states. The electric performance of PrIZO TFTs prepared under different oxygen partial pressures is consistent with the μ-PCD results. The optimal PrIZO TFT prepared under 10% oxygen partial pressure exhibits good electric performance with a threshold voltage (Vth) of 1.9 V, a mobility (µsat) of 24.4 cm2·V−1·s−1, an Ion/Ioff ratio of 2.03 × 107, and a subthreshold swing (SS) of 0.14 V·dec−1.

Immunoferritin localization of intracellular antigens in positively stained frozen sections

1978 ◽  
Vol 36 (2) ◽  
pp. 168-169
Author(s):  
K. T. Tokuyasu
Keyword(s):  
Surface Tension ◽  
Water Surface ◽  
Thin Layers ◽  
The Other ◽  
Positive Staining ◽  
Frozen Sections ◽  
The Past ◽  
Ultrathin Frozen Sections ◽  
Definition Of

During the past investigations of immunoferritin localization of intracellular antigens in ultrathin frozen sections, we found that the degree of negative staining required to delineate u1trastructural details was often too dense for the recognition of ferritin particles. The quality of positive staining of ultrathin frozen sections, on the other hand, has generally been far inferior to that attainable in conventional plastic embedded sections, particularly in the definition of membranes. As we discussed before, a main cause of this difficulty seemed to be the vulnerability of frozen sections to the damaging effects of air-water surface tension at the time of drying of the sections.Indeed, we found that the quality of positive staining is greatly improved when positively stained frozen sections are protected against the effects of surface tension by embedding them in thin layers of mechanically stable materials at the time of drying (unpublished).

The Contribution of Intermediate-Voltage, High-Resolution Electron Microscopy In Materials Science: An Appraisal

1990 ◽  
Vol 48 (1) ◽  
pp. 478-479
Author(s):  
John L. Hutchison
Keyword(s):  
High Resolution ◽  
Materials Science ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
The Past ◽  
Resolution Electron ◽  
Extreme Sensitivity ◽  
Electron Microscopes ◽  
New Generation ◽  
Small Metal Particles

Over the past five years or so the development of a new generation of high resolution electron microscopes operating routinely in the 300-400 kilovolt range has produced a dramatic increase in resolution, to around 1.6 Å for “structure resolution” and approaching 1.2 Å for information limits. With a large number of such instruments now in operation it is timely to assess their impact in the various areas of materials science where they are now being used. Are they falling short of the early expectations? Generally, the manufacturers’ claims regarding resolution are being met, but one unexpected factor which has emerged is the extreme sensitivity of these instruments to both floor-borne and acoustic vibrations. Successful measures to counteract these disturbances may require the use of special anti-vibration blocks, or even simple oil-filled dampers together with springs, with heavy curtaining around the microscope room to reduce noise levels. In assessing performance levels, optical diffraction analysis is becoming the accepted method, with rotational averaging useful for obtaining a good measure of information limits. It is worth noting here that microscope alignment becomes very critical for the highest resolution.In attempting an appraisal of the contributions of intermediate voltage HREMs to materials science we will outline a few of the areas where they are most widely used. These include semiconductors, oxides, and small metal particles, in addition to metals and minerals.

Technology and Hospital Information System: A Case of Implementation of Electronic Clinical Records in Hospital Maternity Irene Neto in Lubango, Angola

2019 ◽  
Vol 10 (11) ◽  
pp. 1131-1135
Author(s):  
Tomas Hambili Paulo Sanjuluca ◽  
◽  
Ricardo Correia ◽  
Anabela Antunes de Almeida ◽  
Ana Gloria Diaz Martinez ◽  
...  
Keyword(s):  
Maternity Hospital ◽  
Management Support ◽  
Retrospective Case ◽  
System A ◽  
Clinical Records ◽  
Retrospective Case Study ◽  
The Impact ◽  
And Child Health

Introduction: In order to have a good assessment of the quality of maternal and child health care, it is essential that there is up-to-date and reliable information. Objective: To evaluate the impact of the implementation of a computerized database of clinical processes in the admission, archive and medical statistics section, of Maternity hospital Irene Neto/Lubango-Angola. Methodology: A descriptive study with a quantitative and qualitative approach to carry out a retrospective case study deliveries and newborns, records from 2014 to 2017. Final considerations: The implementation of this project may contribute to the improvement of clinical management support management of the hospital as well as facilitating access to information for research and scientific production.

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