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Enhancing the Performance of Piezoelectric Energy Harvesters Using Permanent Magnets

A cantilevered piezoelectric beam with a tip mass at its free end is a common energy harvester configuration. This paper introduces a new principle of designing such a harvester which increases the generated voltage without changing the natural frequency of the harvester: The attraction force between two permanent magnets is used to add stiffness to the system. This magnetic stiffening counters the effect of the tip mass on the natural frequency. Three setups incorporating piezoelectric bimorph cantilevers of the same type in different mechanical configurations are compared theoretically and experimentally to investigate the feasibility of this principle. Theoretical and experimental results show that magnetically stiffened harvesters have important advantages over conventional setups. They generate more voltage and they can be tuned across a wide range of excitation frequencies.

 

 

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Publication Date
Wed Nov 20 2024
Journal Name
Journal Of Baghdad College Of Dentistry
The value of ultrasound and color Doppler ultrasonography in the evaluation of periapical lesions in comparison to histopathological and/or surgical findings

Background: Imaging techniques play a very important role in the specialty of endodontic. The ultrasonographic technique is non-expensive procedure, safe, and reproducible. The aim of the study was to determine the sensitivity, specificity, and accuracy of ultrasound and color Doppler ultrasonography in evaluation of periapical lesions (cyst, granuloma, mixed lesion “cyst within graulomas mass”, and abscess. Subject, Material and method: The sample consists of prospective study for 64 Iraqi participants who attended Karbalaa Specialized Center for Dentistry (males & females). Those patients were diagnosed clinically and radiographically as having periapical lesions of dental origin. They were examined by real time ultrasound and color

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Publication Date
Thu Aug 30 2018
Journal Name
Iraqi Journal Of Science
Investigation the Relationship between Spermatogenesis and the Levels of Some Hormones in a Sample of Infertile Iraqi Males with Azoospermia and Oligospermia

The objective of this study was to assess the levels of antiMullerian hormone (AMH), Follicle stimulating hormone (FSH), testosteron,  luteinizing hormone (LH),  and estradiol (E2) as markers of spermatogenesis between fertile and infertile males. This study was conducted at (AlRamadi Teaching Hospital for maternity and children) and included 136 males partners of infertile couples. Samples were classified according to the WHO criteria of semen analysis into three groups; Azoospermia, Oligospermia, and normal(control). Assay  levels of these hormones were made in the serum and the semen of each sample. The results showed that the level of AMH in serum samples was non-significantly decreased (P>0.05) in both Azo

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Publication Date
Wed Feb 10 2021
Journal Name
Journal Of Legal Sciences
The failure of international law to protect Iraqi cultural property from the intentional destruction by ISIS: A priority worthy of international protection

The destruction and protection of cultural property has been a feature of armed conflicts for thousands of years and it has received increasing international focus over the past two decades. This feature was clearly appeared during the recent armed conflict in Iraq. During the conflict, cultural property was subjected to intentional and organised destruction by members of ISIS. Although there are international legal norms to protect cultural property during armed conflict, however, this destruction has proven the failure of those rules to effectively deter these criminal acts. This Article analyses the framework of international law relevant to the protection of cultural property during of armed conflict in the light of that destruction,

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Publication Date
Thu Feb 28 2019
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
The Impact of Adequacy and Authoritative Evidences in the Audit Risks: An Exploratory Research for A Sample Views of Auditors in Iraq

The Audit evedances represent the reconciliation tools between the Financial data shown on financial statements, and the level of satisfaction level of the Auditor about these statements. According that, the Auditor try to achieve the highest quantity of These evidances, and the most satisfactive of it…, but that will be so hard sometimes, when the internal controlling system is not good, and when the Auditor had some satisfied evidences, but not sharp… So, this research comes to inspect the relation between the quantity, and the level of satisfaction, and argument to prove that evidences gives. This research assumes that getting enough evidences leads to reduce faults, improves the auditing operation, and avoids risks. The research

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Publication Date
Sun Jun 01 2014
Journal Name
Baghdad Science Journal
Study the Inhibitory effect of Rose and blossom bitter orange flowers extracts against different types of bacteria isolated from the oral cavity

The study in duded isolation and identification of microbial isolates from oral cavity to 10 volunteers, diagnosed within the three groups: Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus spp. and Candida albicans . The sensitivity test of all isolates bacteria Streptococcus spp. , S. aureus and S. epidermidis showed high resistance to Ampicillin(100)%,followed Methicillin (88.88)% and Amoxicillin / clavulanic acid(77.77)%, while the resistance for each of Vancomycin and Amoxicillin were (66.66)%, and the resistance to Erythromycin and Pencillin (55.55)% to each of them. The results showed less resistance to Trimethoprim (22.22)% and Cefalotine (11.11)% of all bacteria isolate. Investigation of the pre

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Publication Date
Fri Mar 01 2019
Journal Name
Journal Of Accounting And Financial Studies ( Jafs )
Accounting achievement and its impact on the measurement of operational efficiency: Applied research in the company of refineries Center / Al-Doura refinery

The issue of measurement of operational efficiency and productivity plays a major role in determining the weakness of the company, especially in relation to the productive processes, and thus starting to address these points and improve their performance. Hence the problem of research on how to determine the constraints in the production process, to identify weaknesses in the company. The research aims to clarify the role of throughput accounting in measuring the operational efficiency of the company in addition to clarify some of the constraints and causes behind them. The study concluded a set of conclusions, the most important of which is the availability of throughput accounting indicators that help in measuring operational efficienc

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Publication Date
Sat Feb 02 2019
Journal Name
Journal Of The College Of Education For Women
The principals and techniques of geography text book for fourth secondary: The principals and techniques of geography text book for fourth secondary

Abstract
The curriculum is the major effective tool in achieving the goals of
education and society.

Many countries that want to reach the forefront of developed countries
through their curriculum have realized this fact. School text book, the
application assessment for knowing the rang of success or fail of this text
book in achieving the general aims. therefore this study aims at assessing the
principals and techniques of geography text book for fourth secondary class of
literary studying from the teachers point of view according to the fields of the
book, style of material, technical arrangement of the material, ethnical
arrangement the language of the book, style of the material, technical
arrang

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Publication Date
Wed Nov 20 2024
Journal Name
Journal Of Baghdad College Of Dentistry
The effect of glass flakes reinforcement on the surface hardness and surface roughness of heat-cured poly (methyl methacrylate) denture base material

Background: Heat-cured poly (methyl methacrylate) the principal material for the fabrication of denture base have a relatively poor mechanical properties. The aim of this study was to investigate the effect of glass flakes used as reinforcement on the surface hardness and surface roughness of the heat-processed acrylic resin material. Material and method: Glass flakes (product code: GF002) pretreated with silane coupling agent were added to Triplex® denture base powder using different concentrations. A total of 100 specimens of similar dimensions (65 x 10 x 2.5) mm were prepared, subdivided into 2 main groups of 50 specimens for each of the study tests. Ten specimens for the control group and 40 specimens for each of the experimental gro

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Publication Date
Sun Oct 02 2016
Journal Name
Journal Of The Faculty Of Medicine Baghdad
The effectiveness of irrigation method by normal saline compared to povidone iodine soaking in decreasing the rate of contamination in appendectomy wound

Background: The number of bacteria is important as much as the type of it in developing wound infection. Pressurized irrigation of the surgical wound leads to decrease bacterial number which led to decrease incidence of wound infection.
Objective: to evaluate effectiveness of normal saline irrigation and povidone iodine soaking in decreasing the number of bacteria.
Patient and method: This was a prospective study of 100 patients who were admitted to Al Kadhimyia Teaching Hospital during the period from May 2012 and April 2013 with diagnosis of acute appendicitis. After appendicectomy was done, patients were randomized into two groups, fifty patients (group one) the subcutaneous tissue was irrigated by

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Publication Date
Thu Dec 01 2016
Journal Name
Journal Of Economics And Administrative Sciences
Assessment of Human Investment Efficiency in the Private University Teaching according to the strategy of Higher Education in Iraq and chosen Colleges))

Abstract:

the current research aims at analyzing the efficiency of the private university teaching  that recently expanded after 2003 ,;besides , the commitment of the private colleges ,definitely Al-Maamun and Al-Mansour colleges with strategy  of the ministry of higher  education and scientific  research.  This could be done through many indications that measure the efficiency of the  private university teaching , including ( the indication of  the efficiency of   using human resources and efficiency  in using  the materialistic indications.  But the human efficiency in these colleges , including the sample  of the research ( Maamun 

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