scholarly journals Impedance Model of Cylindrical Nanowires for Metamaterial Applications

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1104 ◽  
Author(s):  
Mehboob Alam ◽  
Ali Mahmood ◽  
Shahida Azam ◽  
Madiha Saher Butt ◽  
Anwar Ul Haq ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Wave Impedance ◽  
Complex Problem ◽  
Cylindrical Wave ◽  
Cross Sectional ◽  
Impedance Model ◽  
Full Wave ◽  
Artificial Materials ◽  
Mode Solution ◽  
New Applications

In metamaterials, metallic nanowires are used for creating artificial materials to functionalize them for various nanophotonics applications. Strong polarization-dependent response coupled with complex dielectric function at optical frequencies gives additional degrees of freedom to achieve scattering, absorption, and other benefits that go much beyond what is possible with conventional materials. In this paper, we propose an extended cylindrical wave impedance approach at optical frequencies to model the internal and external impedance of the metallic nanowire. Equivalent analytical expression for the scattering, extinction, and absorption cross-sectional area efficiencies are derived in terms of impedances. The motivation is to develop an all-mode solution ( TM n and TE n modes), by bringing the complex problem of plasmonic nanowire to linear system theory, where established methods can be applied to enable new applications. The equivalence of the impedance solution is compared with electromagnetic field solution and numerical full-wave field simulations. The proposed solution is accurate and may contribute to the rapid and efficient future designs for the metallic nanowire-based nanophotonic metamaterials.

Multi-Channel Metamaterial Sensor Based on Split Ring Resonator

2013 ◽  
Vol 787 ◽  
pp. 24-29
Author(s):  
Jie Zhang ◽  
Wei Shi ◽  
Mo Hai Guo
Keyword(s):  
Degrees Of Freedom ◽  
Microstrip Line ◽  
Ring Resonator ◽  
Single Channel ◽  
Split Ring Resonator ◽  
Split Ring ◽  
Full Wave ◽  
Artificial Materials ◽  
Design Aspect ◽  
Good Agreement

Metamaterials are artificial materials engineered to have exotic properties that may not be found in nature, and it provides a novel tool to significantly enhance the sensitivity of sensors, and open new degrees of freedom in sensing design aspect. In this paper, a metamaterial sensor based on microstrip-line-excited SRR is developed, and its properties are analyzed in theory and simulated by full wave simulations. The results show good agreement with the theory. On this basis, single-channel sensor is extended to two channels and even four channels sensor. By observing and comparing the transmission profile by putting different sample on every channel, we found that the multi-channel sensor can work independently and posses good selectivity. Furthermore, the sensitivity of sensor will be greatly enhanced with the increase of SRR thicknesses. This work would pave a new way to design sensor with higher performance.

scholarly journals In-situ monitoring for liquid metal jetting using a millimeter-wave impedance diagnostic

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Tammy Chang ◽  
Saptarshi Mukherjee ◽  
Nicholas N. Watkins ◽  
David M. Stobbe ◽  
Owen Mays ◽  
...  
Keyword(s):  
Liquid Metal ◽  
Millimeter Wave ◽  
Manufacturing Systems ◽  
Wave Impedance ◽  
In Situ Monitoring ◽  
Full Wave ◽  
Drop On Demand ◽  
The Time Domain ◽  
Metal Droplets

AbstractThis article presents a millimeter-wave diagnostic for the in-situ monitoring of liquid metal jetting additive manufacturing systems. The diagnostic leverages a T-junction waveguide device to monitor impedance changes due to jetted metal droplets in real time. An analytical formulation for the time-domain T-junction operation is presented and supported with a quasi-static full-wave electromagnetic simulation model. The approach is evaluated experimentally with metallic spheres of known diameters ranging from 0.79 to 3.18 mm. It is then demonstrated in a custom drop-on-demand liquid metal jetting system where effective droplet diameters ranging from 0.8 to 1.6 mm are detected. Experimental results demonstrate that this approach can provide information about droplet size, timing, and motion by monitoring a single parameter, the reflection coefficient amplitude at the input port. These results show the promise of the impedance diagnostic as a reliable in-situ characterization method for metal droplets in an advanced manufacturing system.

Three-Dimensional Solutions for Rotor Blades Using High-Order Geometrical Nonlinear Beam Finite Elements

2019 ◽  
Vol 64 (3) ◽  
pp. 1-10
Author(s):  
Matteo Filippi ◽  
Alfonso Pagani ◽  
Erasmo Carrera
Keyword(s):  
Finite Elements ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Shear Deformation Theory ◽  
High Order ◽  
Rotor Blades ◽  
Constitutive Law ◽  
Displacement Fields ◽  
Cross Sectional ◽  
The Cross

This paper proposes a geometrically nonlinear three-dimensional formalism for the static and dynamic study of rotor blades. The structures are modeled using high-order beam finite elements whose kinematics are input parameters of the analysis. The displacement fields are written using two-dimensional Taylor- and Lagrange-like expansions of the cross-sectional coordinates. As far as the Taylor-like polynomials are concerned, the linear case is similar to the first-order shear deformation theory, whereas the higher-order expansions include additional contributions that describe the warping of the cross section. The Lagrange-type kinematics instead utilizes the displacements of certain physical points as degrees of freedom. The inherent three-dimensional nature of the Carrera unified formulation enables one to include all Green–Lagrange strain components as well as all coupling effects due to the geometrical features and the three-dimensional constitutive law. A number of test cases are considered to compare the current solutions with experimental and theoretical results reported in terms of large deflections/rotations and frequencies related to small amplitude vibrations.

scholarly journals Determinants of Infertility Among Couples Seeking Treatment in A Selected Clinic in Dhaka City

2014 ◽  
Vol 13 (3) ◽  
pp. 42-45 ◽  
Author(s):  
Mossamat Afroza Chowdhury ◽  
Md Monoarul Haque ◽  
Shahanaz Chowdhury ◽  
Md Shafiullah Prodhania
Keyword(s):  
Family Income ◽  
Polycystic Ovary ◽  
Complex Problem ◽  
Female Infertility ◽  
Sexual Disorders ◽  
Infertile Couple ◽  
Dhaka City ◽  
Male Factor ◽  
Cross Sectional ◽  
The Government

Background: Infertility is a global health issue affecting approximately 8-10% of couples and has multidimensional problem with social, economic and cultural implications, which can take threatening proportions in countries with strong demographic problems. Objective: To investigate the determinants of infertility among couples seeking treatment. Methodology: A cross sectional study was conducted in selected private clinic of Dhaka city among 196 infertile couple by face to face interview using pretested semi structured questionnaire.Results: The sample studied consisted of 196 infertile couple. One third (38%) aged 26-30 years, majority Muslims (96%), housewives (72%) and one fourth (24%) had education level of secondary to higher secondary. Slightly more than half of their family income was taka 5361-21270. More than three fourth (66%) had primary infertility. Concerning the determinants of infertility polycystic ovary, hormonal imbalance, and fallopian tube blockage was 19%, 16% and 7% respectively but unexplained factors (28%) crossed the other factors. Only male factor was 10% and combined male and female factors were 10% among study subjects. Regarding the daily habits of the male participants, 18% were smokers.Conclusions: The determinants of female infertility are problems in the fallopian tubes and the uterus, disorders of menstruation, sexual disorders, age and ovarian failure. Female infertility is a complex problem that should be considered carefully by the government and stakeholders in each country in order to find effective interventions and solutions.DOI: http://dx.doi.org/10.3329/cmoshmcj.v13i3.21021

scholarly journals Impedance Model-Based Optimal Regulation on Force and Position of Bimanual Robots to Hold an Object

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Darong Huang ◽  
Hong Zhan ◽  
Chenguang Yang
Keyword(s):  
Degrees Of Freedom ◽  
Target Position ◽  
Internal Force ◽  
Robot System ◽  
Joint Torques ◽  
Impedance Model ◽  
Generalized Momentum ◽  
Optimal Target ◽  
End Effectors ◽  
Bimanual Robot

Bimanual robots have been studied for decades and regulation on internal force of the being held object by two manipulators becomes a research interest in recent years. In this paper, based on impedance model, a method to obtain the optimal target position for bimanual robots to hold an object is proposed. We introduce a cost function combining the errors of the force and the position and manage to minimize its value to gain the optimal coordinates for the robot end effectors (EE). To implement this method, two necessary algorithms are presented, which are the closed-loop inverse kinematics (CLIK) method to work out joint positions from desired EE pose and the generalized-momentum-based external force observer to measure the subjected force acting on the EE so as to properly compensate for the joint torques. To verify the effectiveness, practicality, and adaptivity of the proposed scheme, in the simulation, a bimanual robot system with three degrees of freedom (DOF) in every manipulator was constructed and employed to hold an object, where the results are satisfactory.

A Computational Study of Insect Wing Cross-Sectional Geometry on Flight Performance

2015 ◽  
Author(s):  
Jeffrey Feaster ◽  
Francine Battaglia ◽  
Javid Bayandor
Keyword(s):  
Cross Section ◽  
Degrees Of Freedom ◽  
Insect Flight ◽  
Computational Study ◽  
Flight Performance ◽  
Cross Sectional ◽  
Insect Wing ◽  
Agile Flight ◽  
Robotic Applications ◽  
Three Degrees Of Freedom

The influence of cross-sectional geometry on flight performance is investigated for an insect wing using bee-like kinematics. Bee flight is of particular interest due to its mechanical simplicity, utilizing only three degrees of freedom, a high flap frequency, and mechanically linked front and hind wings. These unique flapping flight kinematics result in extremely agile flight characteristics, capable of carrying extraordinary loads relative to the bee’s weight, at a biologically capable efficiency. The performance of a corrugated insect wing and a more intuitively aerodynamic profile are compared computationally. At velocities from 1–3 m/s, the approximated cross-section is foudn to overpredict the lift generated by the corrugated profile by up to 18%. At higher velocities, 4 and 5 m/s, the approximated profile underpredicts the lift generated by the corrugated cross-section by 15%. Based upon this information the cross-sectional geometry of an insect’s wing is significant to the investigation and quantification of insect flight characteristics, for both computational analysis and future robotic applications.

Study on low vibration isolator arrangement of marine gearboxes based on an impedance model

2020 ◽  
Vol 44 (4) ◽  
pp. 580-591
Author(s):  
Yafeng Ren ◽  
Shan Chang ◽  
Geng Liu
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Isolator ◽  
Underwater Noise ◽  
Impedance Model ◽  
Multiple Degrees Of Freedom ◽  
Stiffness Characteristics ◽  
Local Stiffness ◽  
Isolation Performance ◽  
Synthesis Approach ◽  
Flexible Model

To reduce the underwater noise of ships, gearboxes are usually flexibly installed on the ship’s foundation. A reasonable isolator arrangement can effectively reduce the vibration transmitted from the gears to the foundation. In this paper, a dynamic model of a single-stage vibration-isolated gear system is established based on an impedance synthesis approach. This model is a multiple degrees of freedom, multi-mount, and flexible model that can take into account the local stiffness of the housing and foundation. By studying the influence of installation span, installation offset, and number of isolators on the vibrations of the ship’s foundation, it was determined that reducing isolator span is beneficial to isolation, increasing isolator offset can slightly reduce vibration, increasing the number of isolators does not always increase vibration, and the local stiffness characteristics of the housing and foundation have a greater influence than other factors on the isolation performance.

scholarly journals Adherence of Patients with Diabetes to a Lifestyle Advice and Management Plan in Basra, Southern Iraq

2019 ◽  
Vol 25 (3-4) ◽  
pp. 100-105 ◽  
Author(s):  
Rawnaq Adil Aladhab ◽  
Majid Hameed Alabbood
Keyword(s):  
Management Plan ◽  
Cross Sectional Study ◽  
Complex Problem ◽  
Common Reason ◽  
Diabetic Patients ◽  
Lifestyle Advice ◽  
Cross Sectional ◽  
Adherence To Medication ◽  
Patients With Diabetes ◽  
Southern Iraq

<b><i>Background:</i></b> Poor adherence to treatment regimens is a complex problem, especially for those with chronic illnesses. Noncompliance is believed to be the most common reason for treatment failure in diabetic patients, leading to the absence of metabolic control and accelerating disease-related complications. Data on the adherence of people with diabetes in Iraq are lacking. <b><i>Objectives:</i></b> The purpose of this study was to measure the rate of adherence among Iraqi patients with diabetes. <b><i>Methods:</i></b> This was a cross-sectional study conducted in the Specialized Endocrine and Diabetes Center in Basra, southern Iraq, during the period from June to August 2018. Data were collected by completing an interviewing questionnaire consisting of 13 questions. <b><i>Results:</i></b> A total of 231 patients were included in the study (54.5% were female). Mean age was 51.85 ± 13.55 years. 65.4% of the participants were taking their medications at the right times. The most common reason for not taking their medication (48.8%) was difficulty in remembering the dosage times. 40.7% of the participants were sedentary. Only one-third of the patients followed their doctors’ instructions regarding diet. <b><i>Conclusions:</i></b> The rate of adherence to medication regimens and lifestyle advice was unsatisfactory in this study group. The awareness of diabetic patients and their caring physicians about the importance of adherence to therapy, exercise, and diet should be emphasized.

MASS SELECTION IN A PIG POPULATION. 2. THE EFFECTS OF INBREEDING WITHIN THE SELECTED POPULATIONS

1977 ◽  
Vol 57 (4) ◽  
pp. 627-634 ◽  
Author(s):  
HITOSHI MIKAMI ◽  
H. T. FREDEEN ◽  
A. P. SATHER
Keyword(s):  
Litter Size ◽  
Reproductive Performance ◽  
Degrees Of Freedom ◽  
Regression Coefficients ◽  
Longissimus Dorsi ◽  
Mass Selection ◽  
Cross Sectional ◽  
Litter Weight ◽  
Daily Gain ◽  
Size At Birth

The regression of reproductive performance of dams and post-natal performance of progeny on inbreeding was examined for a population of replicated lines subjected to mass selection over a period of nine generations. Inbreeding advanced by 2.0–2.3% per generation. Regression coefficients per 1% increase in inbreeding, based on 817 degrees of freedom for first parity sows, were −.56 ±.23 kg for dam weight at first parturition (12 mo), −.48 ±.19 kg for dam weight change from parturition to weaning, −.013 ±.034 for litter size at birth, −.103 ±.033 for litter size at weaning and −1.36 ±.36 kg for litter weight at weaning. Regressions for post-natal traits, estimated for progeny produced by second parity dams during the final three generations (638 df) were 10.3 ± 4.0 g for birth weight, 16.8 ± 32.7 g for weaned weight, −4.53 ± 1.22 g for post-weaning daily gain, −.34 ±.16 mm for backfat,.10 ±.04 cm2 for cross-sectional area of the longissimus dorsi, and.09 ±.04% for estimated yield of trimmed retail product from the carcass.

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