Experimental and numerical investigation of hybrid armor against a ballistic impact

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Payman S. Ahmed ◽  
Basim M. Fadhil ◽  
Samir Mshir ◽  
Mohamed Salar
Keyword(s):  
Minimum Cost ◽  
Experimental Tests ◽  
Ballistic Impact ◽  
Body Armor ◽  
Content Type ◽  
Impact Wave ◽  
Intermediate Layers ◽  
Fiber Reinforced Polymer Composites ◽  
Main Challenge ◽  
Time Required

PurposeThe main challenge in preparing body armor is achieving a high protection level by using lightweight materials with minimum cost.Design/methodology/approachIn this study, a three-hybrid multilayered armor system is prepared for protection against a ballistic impact wave. These armor systems consist of glass or ceramic tile as a front layer followed by three intermediate layers made of woven fiber reinforced polymer composites and a back layer made of either aluminum or polypropylene.FindingsAll armor systems were successful in impeding the projectile from perforating, that is materials selection played an important role in stopping the ballistic impact wave. Almost an identical ballistic behavior was recorded between the experimental and numerical simulation by using ANSYS AUTODYN which means that the simulation could be used in advance to reduce the time required for practical experiments and the cost of using materials in experimental tests will be lessened. The effect of projectile geometry also had been studied, and it showed a noticeable role in changing ballistic behavior.Originality/valueThe originality of this research is in using carbon and glass fiber which are woven together in addition to adding polypropylene layers in armor preparation.

Economical Aspects of Cutting Speed Selection When Turning Stepped Parts

1971 ◽  
Vol 93 (4) ◽  
pp. 1113-1119 ◽  
Author(s):  
L. Kops
Keyword(s):  
Cutting Speed ◽  
Minimum Cost ◽  
Turbine Disk ◽  
Constant Speed ◽  
Graphical Form ◽  
Propeller Shaft ◽  
Analytical Comparison ◽  
Speed Selection ◽  
Time Required ◽  
Speed Method

The concept is developed of analytical comparison between two methods of cutting speed selection when cutting stepped parts: the constant rpm method and constant cutting speed method. Formulas for cost and time of machining stepped parts are derived and analyzed for two different examples of stepped parts: short ones with large differences in diameters (turbine disk) and long ones with small differences in diameters (propeller shaft). The results presented in graphical form show the advisable operating regions for the use of one of the two methods considered. The effect of time required to change the rpm on the effectiveness of the constant speed method is examined and the limit of applicability is determined. It is found that a reduction of as much as 1/3 in cost and time may be obtained when the constant speed method is applied in the case of the turbine disk. It is noted also that the minimum-cost speed and minimum-time speed depend on the choice of the method and on the shape of the machined part as well. The conclusions set out the conditions under which the use of the constant cutting speed method is justified.

Ultrasound-guided stereotaxic biopsy using a new apparatus

1986 ◽  
Vol 65 (4) ◽  
pp. 550-554 ◽  
Author(s):  
Mitchel S. Berger
Keyword(s):  
Tissue Sample ◽  
Near Field ◽  
Ct Scanner ◽  
Ultrasound Guided ◽  
Content Type ◽  
Delayed Hemorrhage ◽  
Stereotaxic Biopsy ◽  
Time Required ◽  
Immunodeficiency Syndrome ◽  
Burr Holes

✓ A skull-mounted apparatus is described for use with ultrasound probes 16 mm in diameter (5.0-MHz probes for near-field and 7.5-MHz probes for far-field lesions). The system permits ultrasound-guided stereotaxic biopsy of intracranial lesions through a burr hole in awake or anesthetized patients. This apparatus has been used in 19 patients for biopsy of central nervous system lesions 1.5 to 5 cm in diameter and for drainage of abscess cavities and cysts. The time required to obtain a tissue sample after incision of the skin ranged from 25 to 40 minutes. The only complication was a delayed hemorrhage in a patient with acquired immunodeficiency syndrome. The advantages of this method over those guided by computerized tomography (CT) include less time required for the entire procedure, immediate confirmation of the biopsied target by imaging the echogenic needle track, assessment of cyst or abscess drainage, and detection of hemorrhage within minutes after biopsy. The apparatus may be especially useful in pediatric patients because it obviates the need for general anesthesia during transport to and from the CT scanner. This ultrasound-guided system does not require a craniotomy, craniectomy, or two separate burr holes.

Obstacle detection based on depth fusion of lidar and radar in challenging conditions

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Guotao Xie ◽  
Jing Zhang ◽  
Junfeng Tang ◽  
Hongfei Zhao ◽  
Ning Sun ◽  
...  
Keyword(s):  
False Alarm ◽  
Experimental Tests ◽  
Point Clouds ◽  
Calibration Method ◽  
Obstacle Detection ◽  
Environmental Perception ◽  
Fusion Model ◽  
Content Type ◽  
Self Calibration ◽  
Temporal Relationships

Purpose To the industrial application of intelligent and connected vehicles (ICVs), the robustness and accuracy of environmental perception are critical in challenging conditions. However, the accuracy of perception is closely related to the performance of sensors configured on the vehicle. To enhance sensors’ performance further to improve the accuracy of environmental perception, this paper aims to introduce an obstacle detection method based on the depth fusion of lidar and radar in challenging conditions, which could reduce the false rate resulting from sensors’ misdetection. Design/methodology/approach Firstly, a multi-layer self-calibration method is proposed based on the spatial and temporal relationships. Next, a depth fusion model is proposed to improve the performance of obstacle detection in challenging conditions. Finally, the study tests are carried out in challenging conditions, including straight unstructured road, unstructured road with rough surface and unstructured road with heavy dust or mist. Findings The experimental tests in challenging conditions demonstrate that the depth fusion model, comparing with the use of a single sensor, can filter out the false alarm of radar and point clouds of dust or mist received by lidar. So, the accuracy of objects detection is also improved under challenging conditions. Originality/value A multi-layer self-calibration method is conducive to improve the accuracy of the calibration and reduce the workload of manual calibration. Next, a depth fusion model based on lidar and radar can effectively get high precision by way of filtering out the false alarm of radar and point clouds of dust or mist received by lidar, which could improve ICVs’ performance in challenging conditions.

scholarly journals Time required to move cash through slot machines

2018 ◽  
Vol 21 (3) ◽  
pp. 376-384 ◽  
Author(s):  
Karen Kelly ◽  
Carl James Schwarz ◽  
Ricardo Gomez ◽  
Kim Marsh
Keyword(s):  
British Columbia ◽  
Slot Machines ◽  
Content Type ◽  
The Public ◽  
Average Value ◽  
The Mean ◽  
Time Required ◽  
Rest Breaks ◽  
Mean Time ◽  
Practical Implications

Purpose The purpose of this paper is to present an empirical study on the time needed to load and disburse cash using bill validators on slot machines and stand-alone cash dispensers in casinos in British Columbia under a Ticket In Ticket Out (TITO) system. Design/methodology/approach Testing took place over two days, using 18 machines. The results were extrapolated to estimate the approximate time required to process $1,000,000 with different average bill amounts in the cash mix and three different bill validator machines in common use. The average value per bill using the cash mix used by the public in the casino was $33.11 [standard error (SE) $2.11]. Findings The mean time/accepted note ranged from 4.12 to 9.65 s, depending on bill validator type. This implies that the time needed to load $1,000,000 onto credit slips using bill validators on slot machines ranges from 35 to 81 h, excluding rest breaks and other breaks. The time needed to redeem $1,000,000 is estimated to be 3 h. Practical/implications The implications of these finding for illicit actors to successfully launder large amounts of cash are discussed. Given the time needed to physically handle the cash, and other control systems currently in use in casinos in British Columbia, processing large amounts of cash using bill validators on slot machines would require a highly organized team that would find it difficult to elude detection. Originality/value The trial results provide a baseline estimate to be used going forward when investigating or proposing money laundering methodologies that include slot machines.

Teleradiology uppsala–sydney for nighttime emergencies: preliminary experience

2007 ◽  
Vol 48 (8) ◽  
pp. 851-853 ◽  
Author(s):  
H. Eklöf ◽  
E. Radecka ◽  
P. Liss
Keyword(s):  
Working Hours ◽  
Turnaround Time ◽  
Imaging Systems ◽  
The Internet ◽  
Main Challenge ◽  
Reduced Costs ◽  
Digital Imaging Systems ◽  
Time Required ◽  
Radiological Examinations ◽  
Sydney Australia

Background: The development of digital imaging systems for radiology in combination with the possibility to transfer large quantities of data over the Internet has increased the interest in teleradiology. Transferring nighttime examinations to an evaluation center in a daytime zone may provide improved patient security, better working hours for radiologists, and reduced costs for emergency radiological services. Purpose: To evaluate the time required for transferring radiological information from Uppsala (Sweden) to Sydney (Australia). Material and Methods: A radiologist in Sydney reported on radiological examinations performed in Uppsala. The time required for downloading 75 examinations and returning 24 reports was registered. Results: Downloading was completed in <60 min for all conventional radiological examinations, but only 44% of computed tomography (CT) examinations with >65 images. Reports were completed in <10 min. Turnaround time was directly related to the time required for downloading the images. The Sydney report was available in Uppsala within 30 min of the in-house report in 79% of examinations. Conclusion: The main challenge for emergency teleradiology is the time required for downloading large volumes of data over the Internet.

Simulation of edge quality in fused deposition modeling

2019 ◽  
Vol 25 (3) ◽  
pp. 541-554 ◽  
Author(s):  
Antonio Armillotta
Keyword(s):  
Fused Deposition Modeling ◽  
Experimental Tests ◽  
Geometric Errors ◽  
Content Type ◽  
Fused Deposition ◽  
Graphical Simulation ◽  
Deposition Modeling ◽  
Edge Quality ◽  
Input Variables

Purpose The purpose of this paper is to propose a method for simulating the profile of part edges as a result of the FDM process. Deviations from nominal edge shape are predicted as a function of the layer thickness and three characteristic angles depending on part geometry and build orientation. Design/methodology/approach Typical patterns of edge profiles were observed on sample FDM parts and interpreted as the effects of possible toolpath generation strategies. An algorithm was developed to generate edge profiles consistent with the patterns expected for any combination of input variables. Findings Experimental tests confirmed that the simulation procedure can correctly predict basic geometric properties of edge profiles such as frequency, amplitude and shape of periodic asperities. Research limitations/implications The algorithm takes into account only a subset of the error causes recognized in previous studies. Additional causes could be integrated in the simulation to improve the estimation of geometric errors. Practical implications Edge simulation may help avoid process choices that result in aesthetic and functional defects on FDM parts. Originality/value Compared to the statistical estimation of geometric errors, graphical simulation allows a more detailed characterization of edge quality and a better diagnosis of error causes.

scholarly journals Edge quality in fused deposition modeling: I. Definition and analysis

2017 ◽  
Vol 23 (6) ◽  
pp. 1079-1087 ◽  
Author(s):  
Antonio Armillotta ◽  
Marco Cavallaro
Keyword(s):  
Fused Deposition Modeling ◽  
Experimental Tests ◽  
Geometric Errors ◽  
Geometric Accuracy ◽  
Process Map ◽  
Content Type ◽  
Fused Deposition ◽  
Deposition Modeling ◽  
Geometric Variables ◽  
Physical Phenomena

Purpose The purpose of this paper is to discuss the problem of the geometric accuracy of edges in parts manufactured by the Fused Deposition Modeling process, as a preliminary step for an experimental investigation. Methodology/approach Three geometric variables (inclination, included and incidence angles) were defined for an edge. The influence of each variable on the geometric errors was explained with reference to specific causes related to physical phenomena and process constraints. Findings Occurrence conditions for all causes were determined and visualized in a process map, which was also developed into a software procedure for the diagnosis of quality issues on digital models of the parts. Research limitations/implications The process map was developed by only empirical considerations and does not allow to predict the amount of geometric errors. In the second part of the paper, experimental tests will help to extend and validate the prediction criteria. Practical implications As demonstrated by an example, the results allow to predict the occurrence of visible defects on the edges of a part before manufacturing it with a given build orientation. Originality/value In literature, the geometric accuracy of additively manufactured parts is only related to surface features. The paper shows that the quality of edges depends on additional variables and causes to be carefully controlled by process choices.

scholarly journals Mechanical characterization of concrete block used on infill masonry panels

2018 ◽  
Vol 9 (3) ◽  
pp. 281-295 ◽  
Author(s):  
Patricia Raposo ◽  
André Furtado ◽  
António Arêde ◽  
Humberto Varum ◽  
Hugo Rodrigues
Keyword(s):  
Mechanical Characterization ◽  
Experimental Tests ◽  
Concrete Block ◽  
Masonry Walls ◽  
Compression Tests ◽  
Content Type ◽  
Average Resistance ◽  
Concrete Blocks ◽  
Simple Compression ◽  
Infill Masonry

Purpose The infill masonry walls in recent worldwide earthquakes have shown that it is necessary to conduct further studies to characterize the behavior of existing buildings and, in particular, of infill masonry walls under seismic activity. The lack of characterization studies of infill walls made by concrete blocks justifies the investigation reported herein, which includes experimental tests on sample sets to evaluate the mechanical properties of masonry components (units and mortar) and assemblages (wallets) made with masonry units from Faial. For the later, normal compressive, diagonal tensile/shear and out-of-plane flexural strengths were obtained according to standard procedures, the results of which are presented in the manuscript. The paper aims to discuss these issues. Design/methodology/approach One experimental campaign was conducted with the aim to mechanically characterize concrete blocks masonry samples. Several experimental tests were carried out in full-scale masonry concrete wallets according to the constructive methodology used. Findings Based on the data obtained from the mechanical characterization tests of the concrete masonry blocks, it can be seen that under simple compression, the masonry specimens’ average resistance is about 6 times superior than the average resistance to diagonal shear/tension, while the stiffness is almost doubled. In simple compression tests, it was observed that the masonry specimens cracked in areas of higher drilling of the blocks. In the tensile tests by diagonal compression, it was found that the test specimens were mainly fissured by the block/mortar joint interfaces, following the delineation of settlement and top joints. Originality/value There are no experimental results available in the literature for this type of bricks that can contribute to the development of numerical studies.

The effect of environmental humidity/water absorption on tribo-mechanical performance of polymers and polymer composites – a review

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kawaljit Singh Randhawa ◽  
Ashwin Patel
Keyword(s):  
Mechanical Properties ◽  
Polymer Composites ◽  
Tribological Properties ◽  
Fiber Reinforced Polymer ◽  
Content Type ◽  
Wear Rates ◽  
Mechanical And Tribological Properties ◽  
Reinforced Polymer ◽  
Fiber Reinforced Polymer Composites ◽  
Water Conditions

Purpose The mechanical and tribological properties of polymers and polymer composites vary with different environmental conditions. This paper aims to review the influence of humidity/water conditions on various polymers and polymer composites' mechanical properties and tribological behaviors. Design/methodology/approach The influence of humidity and water absorption on mechanical and tribological properties of various polymers, fillers and composites has been discussed in this paper. Tensile strength, modulus, yield strength, impact strength, COF and wear rates of polymer composites are compared for different environmental conditions. The interaction between the water molecules and hydrophobic polymers is also represented. Findings Pure polymer matrices show somewhat mixed behavior in humid environments. Absorbed moisture generally plasticizes the epoxies and polyamides and lowers the tensile strength, yield strength and modulus. Wear rates of PVC generally decrease in humid environments, while for polyamides, it increases. Fillers like graphite and boron-based compounds exhibit low COF, while MoS2 particulate fillers exhibit higher COF at high humidity and water conditions. The mechanical properties of fiber-reinforced polymer composites tend to decrease as the rate of humidity increases while the wear rates of fiber-reinforced polymer composites show somewhat mixed behavior. Particulate fillers like metals and advanced ceramics reinforced polymer composites exhibit low COF and wear rates as the rate of humidity increases. Originality/value The mechanical and tribological properties of polymers and polymer composites vary with the humidity value present in the environment. In dry conditions, wear loss is determined by the hardness of the contacting surfaces, which may not effectively work for high humid environments. The tribological performance of composite constituents, i.e. matrix and fillers in humid environments, defines the overall performance of polymer composite in said environments.

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