Influence of the plate thickness and material properties on the violin top plate modes

2021 ◽  
Vol 263 (3) ◽  
pp. 3369-3377
Author(s):  
Evaggelos Kaselouris ◽  
Yannis Orphanos ◽  
Makis Bakarezos ◽  
Michael Tatarakis ◽  
Nektarios A. Papadogiannis ◽  
...  
Keyword(s):  
Material Properties ◽  
Plate Thickness ◽  
Fem Analysis ◽  
Wood Formation ◽  
String Instruments ◽  
Vibrational Behavior ◽  
Vibrational Response ◽  
Optimization And Control ◽  
And Control ◽  
The Impact

In this paper we analyze the vibrational behavior of the violin top plate, for varying plate thickness and material properties via finite element method (FEM) numerical simulations. It is well known that the vibrational properties of the top plates of string instruments influence their sound emission characteristics. Due to the impact of global warming on wood formation and due to their configurability, many manufacturers investigate the use of composite materials to produce musical instruments. Therefore, composite, carbon fiber reinforced epoxy (CFRE) prepreg along with traditional wooden material, such as spruce, are adopted in this study. FEM modal analysis along with a frequency response function (FRF) FEM analysis are performed. The vibrational variations of the plate's response are computed under free conditions. The main vibrational modes and the natural frequencies obtained by the simulations show the influence of the different mechanical and geometric properties on the top plate's vibrational response. The resulting eigenmode frequencies and shapes of the plate in relation to the varying thickness and the material properties used, are discussed. The results of this study offer valuable information on the evaluation of the acoustical characteristics of violins and may be further used on their vibrational behavior optimization and control.

Inventory optimization model considering consumer shift and inventory transshipment in dual-channel supply chains

2019 ◽  
Vol 53 (1) ◽  
pp. 59-79
Author(s):  
Dandan Fan ◽  
Qi Xu ◽  
Tijun Fan ◽  
Fangzheng Cheng
Keyword(s):  
Performance Measure ◽  
Inventory Level ◽  
Dual Channel ◽  
Inventory Optimization ◽  
Markov Chain Theory ◽  
Optimization And Control ◽  
Dual Channel Supply Chain ◽  
And Control ◽  
The Impact ◽  
Inventory Competition

In this paper we consider a dual-channel supply chain which consists of an online store and multiple independent retail stores. In this system, customer shift induces inventory competition while transshipment brings inventory cooperation, both of which inuences inventory optimization and control. Therefore we respectively construct inventory optimization models under the two situations: customer shift and inventory transshipment. Specifically, unilateral customer shift and inventory transshipment are considered, and a one-for-one replenishment strategy is applied. We first solve the equilibrium state probability of on-hand inventory through Markov chain theory, then optimize performance measure (i.e., the total costs) to obtain the optimal basic inventory level. Finally, we analyze the impact of customer shift rate and inventory transshipment rate on the inventory strategies through numerical simulation, and further compare the differences in inventory decisions between the above two situations, which prove that inventory cooperation brought by inventory transshipment is not necessarily better than inventory competition brought by customer shift. In addition, we discuss several insights that are evident from the parametric analysis of the model.

Critical Plate Thickness for Energy Dissipation During Sphere–Plate Elastoplastic Impact Involving Flexural Vibrations

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Deepak Patil ◽  
C. Fred Higgs
Keyword(s):  
Energy Dissipation ◽  
Thin Plate ◽  
Material Properties ◽  
Input Parameter ◽  
Plate Thickness ◽  
Practical Importance ◽  
Sphere Diameter ◽  
Impact Parameters ◽  
Flexural Vibrations ◽  
The Impact

Solid processing storage and conveying units (e.g., hoppers, silos, tumblers, etc.) often involve the collision of granular media with relatively thin walls. Therefore, the impact of a sphere with a thin plate is a problem with both fundamental and practical importance. In the present work, the normal elastoplastic impact between a sphere and a thin plate is analyzed using an explicit finite element method (FEM). The impact involves plastic deformation and flexural vibrations, which when combined results in significant energy dissipation. One way to quantify the energy dissipation is to employ the coefficient of restitution (COR), which is also a key input parameter needed in various granular flow models. The results were validated against the available experimental data. It is observed that, in addition to material properties and impact parameters, the energy dissipation is strongly dependent on the ratio of plate thickness to sphere diameter. A comprehensive parametric study is conducted to evaluate the effect of material properties, geometry, and impact parameters on the energy dissipation. For the impact velocities commonly observed in granular systems (V = 5 m/s or less), it was determined that the energy lost to flexural vibrations can be neglected if the plate thickness is more than twice the sphere diameter, i.e., tcr > 2d. In this scenario, the mode of energy dissipated is primarily due to the plasticity effects.

Thermal simulation of the cooling down of selective laser sintered parts in PA12

2018 ◽  
Vol 24 (7) ◽  
pp. 1117-1123 ◽  
Author(s):  
Xiaopeng Li ◽  
Brecht Van Hooreweder ◽  
Wout Lauwers ◽  
Bavo Follon ◽  
Ann Witvrouw ◽  
...  
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Cooling Time ◽  
Maximum Temperature ◽  
Fe Model ◽  
Cooling Process ◽  
Content Type ◽  
Temperature Homogeneity ◽  
Optimization And Control ◽  
And Control

Purpose The cooling process of polymer components fabricated by selective laser sintering (SLS) plays a vital role in determining the crystallinity, density and the resultant properties of the produced parts. However, the control and optimization of the cooling process remains challenging. The purpose of this paper is to therefore investigate the cooling process of the SLS fabricated polyamide 12 (PA12) components through simulations. This work provides necessary fundamental insights into the possibilities for optimization and control of this cooling process for achieving desired properties. Design/methodology/approach The thermal properties of the PA12 powder and SLS fabricated PA12 components including density, specific heat and thermal conductivity were first determined experimentally. Then, the finite element method was used to optimize a container (a cuboid aluminum box where PA12 parts are built by the SLS) geometry in which the SLS parts can cool down in a controlled manner. Also, the cooling parameters required for maximum temperature homogeneity and minimum cooling time were determined. Findings Two different approximations in the finite element (FE) model were used and compared. It was found that the approximation which considers powder as a solid medium with porous material properties gives better results as compared to the approximation which treats powder as a collection of air and particles with solid material properties. The results also showed that the geometry of the containers has an important influence on the cooling process of the SLS fabricated PA12 components regarding temperature homogeneity and cooling time required. A container with a small width, long length and high height tends to result in a more homogenous temperature distribution during the cooling process. Originality/value Thermal constants of PA12 powder and parts were accurately determined as a starting point for numerical simulations. The FE model developed in this work provides useful and necessary information for the optimization and control of the cooling process of the SLS fabricated PA12 components and can thus be used for ensuring high-quality products with desired component properties.

Suppressed, but Not Forgotten

2011 ◽  
Vol 70 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Beat Meier ◽  
Anja König ◽  
Samuel Parak ◽  
Katharina Henke
Keyword(s):  
Memory Trace ◽  
Thought Suppression ◽  
Test Phase ◽  
Indirect Test ◽  
Final Test ◽  
Test Experiment ◽  
And Control ◽  
Cue Words ◽  
The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

Research Participation Experiences of Informants of Suicide and Control Cases

Crisis ◽  
2010 ◽  
Vol 31 (5) ◽  
pp. 238-246 ◽  
Author(s):  
Paul W. C. Wong ◽  
Wincy S. C. Chan ◽  
Philip S. L. Beh ◽  
Fiona W. S. Yau ◽  
Paul S. F. Yip ◽  
...  
Keyword(s):  
Ethical Issues ◽  
Research Participation ◽  
Self Report ◽  
Initial Contact ◽  
Psychological Autopsy ◽  
Autopsy Study ◽  
The People ◽  
And Control ◽  
The Impact

Background: Ethical issues have been raised about using the psychological autopsy approach in the study of suicide. The impact on informants of control cases who participated in case-control psychological autopsy studies has not been investigated. Aims: (1) To investigate whether informants of suicide cases recruited by two approaches (coroners’ court and public mortuaries) respond differently to the initial contact by the research team. (2) To explore the reactions, reasons for participation, and comments of both the informants of suicide and control cases to psychological autopsy interviews. (3) To investigate the impact of the interviews on informants of suicide cases about a month after the interviews. Methods: A self-report questionnaire was used for the informants of both suicide and control cases. Telephone follow-up interviews were conducted with the informants of suicide cases. Results: The majority of the informants of suicide cases, regardless of the initial route of contact, as well as the control cases were positive about being approached to take part in the study. A minority of informants of suicide and control cases found the experience of talking about their family member to be more upsetting than expected. The telephone follow-up interviews showed that none of the informants of suicide cases reported being distressed by the psychological autopsy interviews. Limitations: The acceptance rate for our original psychological autopsy study was modest. Conclusions: The findings of this study are useful for future participants and researchers in measuring the potential benefits and risks of participating in similar sensitive research. Psychological autopsy interviews may be utilized as an active engagement approach to reach out to the people bereaved by suicide, especially in places where the postvention work is underdeveloped.

Using Work Domain Analysis to Evaluate the Impact of Digitization on Command and Control

2008 ◽  
Author(s):  
Daniel P. Jenkins ◽  
Neville A. Stanton ◽  
Paul M. Salmon ◽  
Guy H. Walker
Keyword(s):  
Command And Control ◽  
Domain Analysis ◽  
Work Domain Analysis ◽  
And Control ◽  
The Impact ◽  
Work Domain

Experimental Study of the Impact of Alisma plantago-aquatica Secretions on Pathogenic Bacteria

2014 ◽  
Vol 1 (3) ◽  
pp. 3-7
Author(s):  
O. Zhukorskyy ◽  
O. Hulay
Keyword(s):  
Pathogenic Bacteria ◽  
Initial Density ◽  
Biologically Active ◽  
Erysipelothrix Rhusiopathiae ◽  
Natural Focus ◽  
Test Species ◽  
Popula Tions ◽  
And Control ◽  
The Impact

Aim. To estimate the impact of in vivo secretions of water plantain (Alisma plantago-aquatica) on the popula- tions of pathogenic bacteria Erysipelothrix rhusiopathiae. Methods. The plants were isolated from their natural conditions, the roots were washed from the substrate residues and cultivated in laboratory conditions for 10 days to heal the damage. Then the water was changed; seven days later the selected samples were sterilized using fi lters with 0.2 μm pore diameter. The dilution of water plantain root diffusates in the experimental samples was 1:10–1:10,000. The initial density of E. rhusiopathiae bacteria populations was the same for both experimental and control samples. The estimation of the results was conducted 48 hours later. Results. When the dilution of root diffusates was 1:10, the density of erysipelothrixes in the experimental samples was 11.26 times higher than that of the control, on average, the dilution of 1:100 − 6.16 times higher, 1:1000 – 3.22 times higher, 1:10,000 – 1.81 times higher, respectively. Conclusions. The plants of A. plantago-aquatica species are capable of affecting the populations of E. rhusiopathiae pathogenic bacteria via the secretion of biologically active substances into the environment. The consequences of this interaction are positive for the abovementioned bacteria, which is demon- strated by the increase in the density of their populations in the experiment compared to the control. The intensity of the stimulating effect on the populations of E. rhusiopathiae in the root diffusates of A. plantago-aquatica is re- ciprocally dependent on the degree of their dilution. The investigated impact of water plantain on erysipelothrixes should be related to the topical type of biocenotic connections, the formation of which between the test species in the ecosystems might promote maintaining the potential of natural focus of rabies. Keywords: Alisma plantago-aquatica, in vivo secretions, Erysipelothrix rhusiopathiae, population density, topical type of connections.

Changes in the Population Density of Pathogenic Microorganisms in Response to the Allelopathic Effect of Thypha Latifolia

2014 ◽  
Vol 1 (1) ◽  
pp. 31-36 ◽  
Author(s):  
O. Zhukorskiy ◽  
O. Gulay ◽  
V. Gulay ◽  
N. Tkachuk
Keyword(s):  
Cell Density ◽  
Allelopathic Effect ◽  
Pathogenic Microorganisms ◽  
Sterile Water ◽  
Erysipelothrix Rhusiopathiae ◽  
Pathogenic Leptospira ◽  
Favorable Conditions ◽  
And Control ◽  
The Impact ◽  
Control Samples

Aim. To determine the response of the populations of Erysipelothrix rhusiopathiae and Leptospira interrogans pathogenic microorganisms to the impact of broadleaf cattail (Thypha latifolia) root diffusates. Methods. Aqueous solutions of T. latifolia root diffusates were sterilized by vacuum fi ltration through the fi lters with 0.2-micron pore diameter. The experimental samples contained cattail secretions, sterile water, and cultures of E. rhusiopathiae or L. interrogans. The same amount of sterile water, as in the experimental samples, was used for the purpose of control, and the same quantity of microbial cultures was added in it. After exposure, the density of cells in the experimental and control samples was determined. Results. Root diffusates of T. latifolia caused an increase in cell density in the populations of E. rhusiopathiae throughout the whole range of the studied dilutions (1:10–1:10000). In the populations of the 6 studied serological variants of L. interrogans spirochetes (pomona, grippotyphosa, copenhageni, kabura, tarassovi, canicola), the action of broadleaf cattail root diffusates caused the decrease in cell density. A stimulatory effect was marked in the experimental samples of the pollonica serological variant of leptospira. Conclusions. The populations of E. rhusiopathiae and L. interrogans pathogenic microorganisms respond to the allelopathic effect of Thypha latifolia by changing the cell density. The obtained results provide the background to assume that broadleaf cattail thickets create favorable conditions for the existence of E. rhusiopathiae pathogen bacteria. The reduced cell density of L. interrogans in the experimental samples compared to the control samples observed under the infl uence of T. latifolia root diffusates suggests that reservoirs with broadleaf cattail thickets are marked by the unfavorable conditions for the existence of pathogenic leptospira (except L. pollonica).

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