Taper Line Research Articles

Cumulative effect of digital manufacturing techniques, preparation taper and finish line designs on the retention of aged temporary molar crowns − An in vitro study

ObjectiveThis study evaluated the effects of finish-line design, tooth preparation taper or total occlusal convergence (TOC), and digital production technology on the retention of provisional crowns for molars. Material and MethodsDifferent taper angles (10° TOC and 20° TOC) and finish line designs (chamfer and shoulder) were used to prepare four mandibular first molar teeth. Two subgroups of the prepared teeth received temporary crowns that were either “Computer-Aided Design” and “Computer-Aided Manufacturing (CAD/CAM) milled or 3D printed. Hence, eight test groups of temporary crowns containing 10 samples each were created. Groups 1–4 were milled, and Groups 5–8 were 3D printed specimens. A consistent procedure was used to cement 80 temporary crowns. The specimens were thermocycled for a total of 5000 heat cycles, initially at 5 °C for 30 s (dwell time) and then at 55 °C for 30 s. The pull-off force necessary to remove the temporary crowns was recorded, and the tensile strength, which served as the dependent variable, was calculated. Analysis of variance (ANOVA) was used to assess the variations in retention forces among the test groups. ResultsThe mean tensile strengths at maximum load [MPa] were higher in Groups 5, 6, 7, 8 (6.6 MPa, 6.91 MPa, 7.65 MPa, and 7.45 MPa respectively) as compared to the mean tensile strengths at maximum load [MPa] in Groups 1, 2, 3, 4 (2.35 MPa, 3.52 MPa, 3.21 MPa, and 2.45 MPa respectively). ConclusionFor extended periods, 3D-printed crowns with steeper preparation tapers (20° TOC) and shoulder finish lines exhibited enhanced retention.

Design of a Simulated Tri-Bandwidth circular patch with slot for X and C bands applications

Scientists continue to improve the performance and efficiency of microstrip antenna designs as technology evolves, aiming to improve their adaptability to different environments and constraints. These antennas play an important role in modern communication technologies and in signal path systems demonstrate development, computer modeling and testing of microstrip line and coaxial cable with G-shaped slots in the strip. The antenna was designed and simulated using CST simulation software. Antenna performance was analyzed, considering several factors such as return loss, gain, directness, bandwidth, 3D radiation patterns and more. Simulated results showed that the proposed antennas exhibit a wide frequency range, with the microstrip line feed antenna and coaxial cable obtaining a value of 61% and 65%, respectively. These two antennas exhibited remarkable gain which are 7.784 dBm and 7.787 dBm, respectively. The microstrip line achieved a maximum feed efficiency of 93.12%, while the coaxial cable achieved a maximum feed efficiency of 97.65%. The findings suggest that providing the antenna with coaxial cable as opposed to fine tape line improves its performance. Antennas with coaxial cable have wider bandwidth, higher gain, and better efficiency compared to microstrip line antennas.

Low Speed Impact of an Elastic Ball with Tapes and Clay Court

The study aims to investigate the normal and oblique impact of an elastic sphere (tennis ball) on a granular surface (clay) and two different plastic tape lines. In this research, we model the impact force with a mathematical elastoplastic force model, and a differential approach is used. The model is applied for an impact with granular material (green clay) and plastic surfaces (line tapes). We investigated the normal and oblique impact dynamics of a sphere (tennis ball). The impact duration is divided into two phases: compression with an elastoplastic force and restitution with an elastic force. The laboratory experiments in various configurations are recorded with a high frame-per-second camera and analyzed using image processing methods. The mathematical model for the impact with rebounds is verified with the experimental set-up for the considered surfaces. The viscoelastic and elastic forces agree well with the experimental data. The impact parameters of the granular surface and plastic tapes are compared. The ANOVA test suggests robust statistical significance in the coefficient of restitution between granular surfaces and plastic tapes. Our force model for impact performs well, and the impact responses of the sphere on the granular surface and the plastic line tapes are significantly different.

Optimization of fiber orientation and layer thickness in thin carbon fiber-reinforced plastic curved structures

In automated carbon fiber-reinforced plastic (CFRP) lamination technologies, such as AFP, the design of the path for accurate tape application is challenging. Therefore, a molding technology that allows the use of variable tape widths and thicknesses, which are fixed in previous methods, is currently being developed. Fiber orientation and layer thickness should be optimized in a 2D plane. However, for structures with free-form surfaces, such as propellers, three-dimensional (3D) manufacturing design becomes necessary. A method is proposed here for optimizing the fiber orientation and layer thickness of a prepreg tape for a 3D propeller model with a curved surface structure. This method enables curve boundary-agnostic tape lines, by projecting curves created on a two-dimensional plane onto a curved surface. Multi-objective optimization with displacement and weight as objective functions reduced the displacement by 20.0% while maintaining strength. These results are likely to be informative for weight reduction and manufacturing design of CFRP structural components.

The Effect of a Digital Manufacturing Technique, Preparation Taper, and Finish Line Design on the Marginal Fit of Temporary Molar Crowns: An In-Vitro Study.

The aim of this study is to investigate the combined effect of a digital manufacturing technique (subtractive vs. additive), preparation taper (10° vs. 20° TOC), and finish line (chamfer vs. shoulder) on the marginal adaptation of temporary crowns following cementation with a compatible temporary cement. Four mandibular first molar typodont teeth were prepared for full coverage crowns with standard 4 mm preparation height as follows: 10° TOC with the chamfer finish line, 10° TOC with the shoulder finish line, 20° TOC with the chamfer finish line and 20° TOC with the shoulder finish line. Each of the four preparation designs were subdivided into two subgroups to receive CAD/CAM milled and 3D-printed crowns (n = 10). A total of 80 temporary crowns (40 CAD/CAM milled and 40 3D-printed) were cemented to their respective die using clear temporary recement in the standard cementation technique. The samples were examined under a stereomicroscope at ×100 magnification following calibration. Linear measurements were performed at seven equidistant points on each axial surface and five equidistant points on each proximal surface. One-way ANOVA analysis and Tukey HSD (Honestly Significance Difference) were performed. The best marginal fit was seen in group 8, while the poorest fit was noted in group 2. Shoulder finish lines and 10° TOC resulted in higher marginal gaps, especially in CAD/CAM milled group. The selection of 3D-printed crowns may provide a better marginal fit within the range of clinical acceptability. Marginal gaps were within clinical acceptability (50 and 120 µm) in all groups except group 2.

Assessment of students’ cognitive abilities by intelligent systems when applying for a job

The modern information and digital society is radically changing the conditions of life and the ways of social interaction. Intelligent systems are replacing human potential. The replacement of human resources with intelligent systems is happening rapidly and at the same time imperceptibly. Cognitive abilities of students are natural evolutionary-embedded data. The scientific problem of the research consists in the complexity of the phenomenology of the study of unconscious cognitive processes. The purpose of this study is to analyze cognitive abilities and develop a barcode card as a method of a unified measurement system. The Tape line converter was used in the study, which converts qualitative immeasurable indicators into quantitative ones. The results of the study clearly demonstrate the quantitative characteristics of the range of cognitive abilities available to students. The research contribution consists in several directions: an individual characteristic of each function of cognitive abilities has been developed; in the near digital future, intelligent systems that are able to calculate the amount of functionality of cognitive abilities with the help of a CbS barcode card will hire specialists for work. The value of research work consists in a new way of revealing the inner evolutionary inherent in nature and improved by experience and skills of the range of qualities of cognitive abilities. The practical significance of the results of the work can be implemented as a pilot project in the search system for employees for a certain position.

An easily-prepared impedance matched Josephson parametric amplifier* *Project partially supported by the National Key R&D Program of of China (Grant No. 2016YFA0301801), the National Natural Science Foundation of China (Grant Nos. 61521001 and 61571219), and PAPD, Dengfeng Project B of Nanjing University.

An impedance matched parametric amplifier (IMPA) with Josephson junctions is fabricated and characterized. A hybrid structure containing coplanar and strip structures is implemented to realize an impedance taper line and a plate capacitor in an LC nonlinear resonator based on Josephson junctions. The upper plate of the capacitor is isolated with SiN x without grounding as well as the strips. Such easily-prepared designs greatly reduce the requirements for lithography alignment and precision, which makes the fabrication process more reliable. The experimental results show that in such IMPA a gain higher than 25 dB with a bandwidth of about 100 MHz can be obtained. This broadband amplifier operates close to the quantum limit. By adjusting the working point, a higher bandwidth of about 400 MHz can be obtained with a gain of about 17 dB.

SIZE REDUCTION OF KLOPFENSTEIN-BALUN TRANSFORMER FOR BALANCED ANTENNAS

A BALUN transformer converts impedance into another one and also converts an unbalanced line into a balanced line. A compact size broadband BALUN transformer is designed using Klopfenstein taper line transformer approach to transform 50Ω impedance into 100 Ω. The results of the conventional BALUN are compared with the proposed compact size BALUN. In order to reduce the length of the BALUN, a curved microstrip line is used. The proposed compact size BALUN is 56 %- 70 % smaller in size w.r.t the conventional BALUN but at the cost of 6% - 11% reduction in the overall band. The conventional BALUN has measured % bandwidth of 165 while the reduced size BALUN has 159. The measured results are in agreement with the simulated results.

A single‐layer high‐gain dipole antenna array with a bidirectional radiation pattern based on parallel‐strip line

A single-layer dipole antenna array with quasi-Yagi configuration has been proposed and demonstrated, which provides a dual radiation pattern with the same sense. This antenna is mainly composed of a substrate-supported parallel strip line (PSL) and several periodic dipole elements. Fed by PSL, dipole elements can be stimulated with a uniform power, forming a linear dipole antenna array. By adjusting the elements separation appropriately, the step phase of array factor can be tuned to achieve the same directivity as the element dipole. When an SubMiniature version A (SMA) coaxial connector is connected at the beginning of PSL, the fundamental mode TEM in the PSL is excited and the radiation electromagnetic wave from the dipole elements is achieved. A taper line between the SMA and PSL can be used to reduce the discontinuity, minimizing the reflection coefficient of the port. According to the theory of classical Yagi antenna, the gain can be further improved by introducing multiple directors, achieving the gain increment of about 3 dBi in the proposed design. Considering 5 GHz frequency band applications (4.85–5.2 GHz), the experimental and simulated results show the proposed antenna array has a working bandwidth ( | S 11 | ≤ − 10 d B ) from 4.85 to 12 GHz.

Older adults reduce the complexity and efficiency of neuromuscular control to preserve walking balance.

Healthy aging modifies neuromuscular control of dynamic balance. Challenging tasks could amplify such modifications, providing clinical insights. We examined the effects of age and walking condition difficulty on neuromuscular control of walking balance. We analyzed whole-body kinematics and activity of 13 right leg and trunk muscles in 17 young (11 males and 6 females; age 24±3years) and 14 older adults (3 males and 11 females; age 69±4years) while walking on a taped line on the floor and a 6-cm wide beam. Spatiotemporal parameters of gait, margin of stability, motor performance, and muscle synergies were estimated. Regardless of age, maintaining walking balance was more difficult on the beam compared to the taped line as evidenced by a shorter distance walked (17.3%), a reduction in step length (5.8%) and speed (10.3%), as well as a 40.0% smaller margin of stability during beam vs. tape walking. The number of muscle synergies was also higher during beam vs. tape walking. Compared to younger adults, older adults had larger margin of stability during beam walking. Older adults also had higher muscle co-activity within each muscle synergy and greater variance accounted for by the first muscle synergy regardless of condition. Such age-effects may be interpreted as a safer, less efficient, and less complex neuromuscular modular control strategy. In conclusion, beam walking increased the difficulty of maintaining walking balance and induced adaptations in modular control. It seems that healthy older adults reduce the complexity and efficiency of neuromuscular control of walking to preserve walking balance.

A new impedance matching approach for microstrip Rotman lens based on analyzing the standing wave pattern of an electric field

AbstractThis article proposes a new impedance matching method to provide an energy transformer between 50 Ω beam ports and the cavity of a Rotman lens. The model is derived from a quarter length transition line impedance transformer. The suggested matching technique is based on determining and analyzing standing wave patterns of electric field signals underneath feeding lines of the beam ports when they are excited with a designed frequency of 2.45 GHz. The proposed approach demonstrates the ability of the model to achieve an acceptable return loss compared to traditional taper line model matching methods, even though it increases the operating bandwidth frequency based on the measured results. Moreover, it solves the optimization iteration time consuming that is required to determine the tapering line length used in the conventional impedance matching techniques. The predicted results of the return loss are validated by measurements of the fabricated prototype microstrip lens printed on an FR‐4 substrate that is designed to work in the industrial, scientific, and medical (ISM) band in order to form five beams in the directions −26°, −13°, 0°, 13°, and 26°.

A Comparative Analysis of Slope Height Using Simple Methods

Analysis of slope stability is crucial for the design of many engineering processes such as open pit mine and highway. Slope stability is generally evaluated by limit equilibrium and numerical analyses, and rock mass classification systems. The slope height is used as the input parameter in many of these methods. Advanced methods such as LiDAR and TLS are expensive and time consuming and they require professional use. Therefore, researchers generally need to use simple methods for the measurement of slope height because of their cheapness, rapidity and portability. In this study, height of the rock slopes was determined with tape line, laser meter, altimeter, clinometer and geological compass. Measurements were taken from steep (90) and inclined slopes (75). Further, various models were developed in the laboratory for understanding the mechanism of methods in inclined slopes (45–90). The findings of methods used compared with each other and the reliability of the methods was discussed. Strengths and weakness of the methods were highlighted. This study indicated that some factors (measurement distance, slope width, the inclination of the ground, rugged surface in toe of the slope, etc.) can negatively affect the estimations of slope height.

Design and implementation of microstrip rotman lens for ISM band applications

This work presents the design and implementation of Rotman lens as a beam steering device for Industrial, Scientific, and Medical (ISM) applications. 2.45 GHz is considered as a center frequency design with (2-6) GHz frequency bandwidth. The beam steering is examined to cover ±21o scan angle with maximum main lobe magnitude 10.1 dBi, rectangular patch antennas are used as radiation elements to beam the output far field. The work is extended to compare between the tapered line which is used for matching between 50-Ω ports and lens cavity. CST microwave simulation studio results show that the rectangular taper line can yield 2 dB return loss less than linear taper line with a little bit shifting in responses for same input and load impedance.

Drip Line Flushing with Chlorine May Not Be Effective in Reducing Bacterial Loads in Irrigation Water Distribution Systems

Irrigation water distribution systems are used to supply water to produce crops, but the system may also provide a protected environment for the growth of human pathogens present in irrigation water. In this study, the effects of drip tape installation depth and sanitization on the microbial quality of irrigation groundwater were evaluated. Drip tape lines were installed on the soil surface or 5 or 10 cm below the soil surface. Water samples were collected from the irrigation source and the end of each drip line every 2 weeks over an 11-week period, and the levels of Escherichia coli, total coliforms, aerobic mesophilic bacteria, and enterococci were quantified. Half of the lines installed at each depth were flushed with sodium hypochlorite for 1 h during week 6 to achieve a residual of 10 ppm at the end of the line. There was a statistically significant (P = 0.01) effect of drip tape installation depth and sanitizer application on the recovery of E. coli, with increased levels measured at the 5-cm depth and in nonsanitized lines, although the levels were at the limit of detection, potentially confounding the results. There was no significant effect of drip tape depth on total coliforms, aerobic mesophiles, or enterococci. In contrast, a statistically significant increase (P < 0.01) in the recovery of total coliforms was recorded from the ends of lines that received chlorine. This may be indicative of shedding of cells owing to degradation of biofilms that formed on the inner walls of the lines. These findings emphasize the need to better understand conditions that may lead to corrosion and increases in bacterial loads inside drip lines during flushing. Recommendations to growers should suggest collecting groundwater samples for testing at the end of drip lines rather than at the source. Guidelines on flushing drip lines with chlorine may need to include water pH monitoring, a parameter that influences the corrosive properties of chlorine.

Novel tunable branch‐line coupler for WLAN applications

ABSTRACTIn this article, a tunable branch‐line coupler with a novel structure is designed to operate at 5.7GHz. A design method is based on miniaturization method with adjusting the resonance frequency. The proposed coupler without taped line feed structures operated at 5.62 GHz, and it has a size of 55.8 mm2 while its performance is reasonable. To improve the performance, the taped line feed structures are added. The wideband response exhibits that the proposed coupler acts properly with the spurious harmonics up to 11.4 GHz. In addition, at 5.7 GHz, the good insertion loss (2.3 dB) and coupling factor (2.6 dB) are obtained. The proposed coupler is simulated, fabricated, and measured. The results show that there is a good agreement between the simulation and measurement results. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1081–1084, 2015

MANEJO DA REGA NA CULTURA DO CRISÂNTEMO DE CORTE CULTIVADO EM AMBIENTE PROTEGIDO

The aim of this research was to identify the soil water tension that results in the best quality of the cut chrysanthemum. The experimental design was totally randomized with 3 repetitions, subdivided in 30 parcels, each one controlled by a register, with drip tape lines. Treatments were defined for 10 soil water tension levels: 5, 10, 15, 20, 25, 30, 35, 40, 45 e 50 kPa. Evaluations of leaf area, driy weight, diameter and plant hight were done each 14 days period, using 3 plants per parcel. Results showed that there was no difference between treatments for most of the evaluated variables. 50 kPa resulted in taller stems and larger number of packets A1. but induced high water loss by percolation. We suggest growers to use tension between 10 at 20 kPa for a good balance between irrigation cost and flower quality.

Breaking News: Verbotonal rehabilitation: Are we doing enough?

Breaking News: Verbotonal rehabilitation: Are we doing enough?

The all‐ceramic, inlay supported fixed partial denture. Part 1. Ceramic inlay preparation design: a literature review

The effect of cavity design is a controversial and underrated factor in the clinical success of ceramic inlays and inlay supported prosthesis. Many articles and studies have been conducted into the advantages and disadvantages of isolated aspects of preparation design, but lacking is a review of the most relevant papers which bring together a consensus on all the critical features. Hence, a review and analysis of cavity depth, width, preparation taper and internal line angles is warranted in our attempts to formulate preparation guidelines that will lead to clinically successful, all-ceramic inlay restorations and ceramic inlay supported prosthesis.

A 50 m laser interferometer for automatic calibration of surveying tapes using wireless communication

A 50 m linear measuring interferometer, consisting of a precision laser interferometer, a 51 m long guide rail, a moving carriage, an optical microscope with a CCD camera and an image processor, is described here. The system is designed for the automatic calibration of surveying tapes. The carriage can move up to 50 m along the guide rail. The dc servo motor, which is fixed on the carriage, drives the carriage and its speed is controlled by a computer through wireless communication. The CCD camera captures the image of tape lines through the microscope fixed on the stage, and the image is wireless transferred to the image processor installed in the computer. The image processor calculates the deviation between the center of the line and the field-of-view of the CCD camera, and the laser interferometer measures the displacement of the carriage simultaneously. Finally, the intervals between lines are determined using the deviation and the reading of the laser interferometer. The calibration process is performed automatically after the installation of the tape. The estimated expanded uncertainty of the steel tape measurement is at the confidence level of approximately 95%.

Drying of Thin Films of Polymer Solutions Coated over Impermeable Substrates

The manufacturing of adhesive tapes, photographic films, magnetic media, and many other products involves the coating and drying of thin films of polymeric solutions or emulsions over an impermeable substrate. Wet thickness may vary from 1 micron to 500 microns and solid content from 3% to 50% or more. The drying process generally occurs in convective ovens, where air temperature, air flow rate, and solvent partial pressure may be adjusted. In many cases, it is the manufacturing step that controls the productivity; therefore, it is very important to optimize the oven conditions to minimize the oven residence time without causing defects on the coated film and keeping the residual solvent inside the final product within specification limits. A drying model and a simulation software based on it were developed in order to solve the transient mass and heat transfer equations that describe the drying of a polymer solution containing two different solvents. The resulting system of equations shows strong non-linearity due to the free surface and the dependence of diffusion coefficients on solvent concentration and film temperature. The integration in time was performed with a fully implicit method, and at each time step, Newton's method was used to solve the resulting non-linear system of algebraic equations. An example of using the drying simulator to optimize an industrial adhesive tape line is discussed. The gain in productivity achieved by the analysis was greater than 40%.