Differences In Resistance Values Research Articles

Field-free multistate spin–orbit torque devices for programmable image edge recognition circuit

The application of spin–orbit torque (SOT) devices to neuromorphic computing platforms is focused on the development of hardware circuit architectures. However, the inter-device variability, the integration modes of devices and peripheral circuits, and appropriate application scenarios are still unclear, limiting the development of SOT devices in neuromorphic computing. To solve this problem, this paper first proposes a circuit compensation scheme for the difference in resistance values of SOT devices, which solves this variability problem at the circuit level. Moreover, a synergistic scheme with the circuit is developed based on the correspondence between the multistate resistance characteristics of the SOT devices and a convolutional algorithm. To achieve this, a multichannel SOT convolutional kernel circuit architecture is built, which implements an image edge recognition application. Finally, based on a simulation model, an image edge recognition hardware circuit based on our CoPt-SOT devices is implemented, which is capable of performing image edge recognition with an accuracy of 96.33%. This scheme provides technical support and development prospects for SOT devices in neural network hardware applications.

Laterization Process Recognition along the Northern Border of the Congo Craton by Geoelectrical and Geotechnical Data

With the properties of laterites being related to the nature of the rock from which they are derived, twenty vertical electrical surveys and twenty boreholes for geotechnical tests, distributed in two units (plutonic and green belt zones) of the Ntem complex located at the northern limit of the Congo Craton, were implemented to study the formation process of the laterites of this geological structure. The inversion of the geoelectrical data in the plutonic area resulted in three lateritic layers with resistivities of 1090 Ω·m, 1302 Ω·m, and 1122 Ω·m, with induration and leaching indices of 28.9% and 72.56%. In the green belt zone, three lateritic layers were also identified with resistivities of 1080 Ω·m, 943 Ω·m, and 1158 Ω·m, with induration and leaching indices of 28.8% and 72.55%. The similarities of the geomechanical parameters (induration and lixiviation indices) show that these soils experienced similar weathering patterns during the same geological period, confirmed by CBR values, corresponding to PF3 platforms that can be used in road works. However, the average resistivity values in the different geological units (1171.77 Ω·m and 1061.16 Ω·m in plutonic and green belt areas) reflect the observed differences in resistivity values of the bedrock alterations (3413.51 Ω·m and 1569.32 Ω·m in plutonic and green belt areas), showing that these laterites are derived from different bedrock weathering. In addition, the average permeability values obtained in the plutonic zone (k=6.24E−05 cm/s) and in the green belt zone (k=5.82E−05 cm/s) confirm this difference. The reduction in the difference between the resistivities of the laterites compared to the difference observed in the bedrock of the two units highlights the leaching process over a long geological period.

Emissions from Drying in the Wood Based Board Industry

Abstract: The reason why wood-based boards are preferred in many areas of use, especially in furniture, is that they can be produced in desired properties and are cheap. In addition, wood defects such as different work in three dimensions, differences in resistance values, internal stresses and physical changes seen in solid wood are not encountered in wood-based boards. Volatile organic compound (VOC) emissions from wood-based panels occur from the raw materials of the boards and during production stages such as gluing, storage, pressing and drying. Most of the VOCs from wood raw materials are formed during the drying process. VOCs contribute to the formation of nitrogen oxides and photo-oxidants in the presence of sunlight. Photo-oxidants are harmful to humans as they irritate the respiratory and sensitive parts of the lungs. It also disrupts photosynthesis and damages forests and crops. The aim of this study is to evaluate the factors affecting the emissions that occur during the drying process in wood-based boards and the processes applied to reduce the emission.

Quantitative and qualitative analyses of ceramic chipping

ObjectiveTo evaluate edge chip resistance (ReA) and fractographic features of ceramic systems submitted to edge chipping. MethodsSamples were fabricated using the following materials: YZ-yttria-stabilized tetragonal zirconia ceramic (IPS e.max® Zir-CAD); LG-leucite-reinforced glass-ceramic (IPS Empress® CAD); LD-lithium-disilicate glass-ceramic (IPS e.max® CAD); ZF- YZ veneered by a pressable fluorapatite glass-ceramic (IPS e.max® Zir-CAD + IPS e.max® Zir-Press); ZD- YZ-LD fused together by a glass-ceramic (IPS e.max® Zir-CAD + IPS e.max® crystall./connect + IPS e.max® CAD). Half of the sample size was bonded (B) to a dentine analogue substrate (NEMA G10) and the remaining samples were kept non-bonded (NB). Structures were indented (n = 25) at different edge distances (d = 0.3, 0.4, 0.5, 0.6, 0.7 mm) using a universal testing machine to produce chips. Force (F) and d values were recorded and ReA was calculated. Data were statistically analyzed using ANOVA, Student t and Tukey tests (α = 0.05). Chipping was evaluated visually and under optical and scanning electron microscopy based on fractography principles. ResultsData (F vs d) showed a positive linear trend for all groups. There was no significant difference in ReA values at d = 0.5 mm (SE0.5) between NB and B for same ceramic system. Fracture pattern was similar between NB and B for same ceramic system at d = 0.5 mm. ConclusionsBonding neither influenced ReA values nor the fracture pattern that were similar between NB and B structures from same ceramic system. The greater the distance from structure edge, the lesser the chance of chipping occurred.

Multilevel Resistive Switching in P-N Heterostructure Memory.

High storage density is an important requirement for resistive random access memory (RRAM) devices. Multilevel resistive switching (RS) in RRAMs does not require much change to current technologies compared with device size reduction and 3D integration. Herein, five stable resistance states can be obtained in a Pt/p-NiO/n+-Si memory device by controlling the current compliance (CC). The RS mechanism can be attributed to the formation and rupture of localized conducting filaments (CFs) in an NiO film. The conductivity of the low resistance states (LRS) is determined through the combined action of the P-N junction and localized CFs. The CC can be used to effectively modulate the formation of localized CFs and junction resistance. Importantly, different LRS have large differences in resistance values, resulting in multilevel memory. A model is suggested and discussed to account for the observed multilevel memory operation.

Shear bond strength of brackets bonded with nanofilled flowable resins

Introduction and Objective: To evaluate the shear bond strength of brackets fixed with different materials (two light-cured nanofilled low-viscosity resins –Transbond Supreme LV and Flow Tain LV and two light-cured traditional resins – Transbond XT and Transbond Plus Color Change) after 10 min and 24 h, and to evaluate the type of failure. Material and methods: Eighty bovine incisors were selected and randomly divided into groups (n = 10) according to the material and fixation period. The brackets were bonded following the manufacturer's instructions and stored in deionized water at 37 oC for 10 min or 24 h. After, the specimens were submitted to shear bond strength test at 0.5 mm/min and evaluated for adhesive remnant index (ARI). The data were submitted to Kruskal Wallis and Wilcoxon tests (p < 0.05) and the ARI scores to Chi-Square test. Results: There was a significant difference among the materials (p < 0.05 (after 10 min – Transbond XT > Transbond Plus Color Change > Transbond upreme LV = Flow Tain LV and after 24 h – Transbond XT > Transbond Plus Color Change = Transbond Supreme LV = Flow Tain LV). There was osignificant difference in resistance values between 10 min and 24 h, except for Transbond Plus Color Change. Most groups showed adhesive remaining adhered to the enamel (scores 2 and 3) without statistical significant difference (p > 0.05). Conclusion: The light-cured traditional resins showed higher resistance than the nanofilled materials. The period of fixation had no influence on the resistance for different materials, except for Transbond Plus Color Change.

Shear bond strength of brackets bonded with nanofilled flowable resins

To evaluate the shear bond strength of brackets fixed with different materials (two light-cured nanofilled low-viscosity resins – Transbond Supreme LV and Flow Tain LV and two light-cured traditional resins – Transbond XT and Transbond Plus Color Change) after 10 min and 24 h, and to evaluate the type of failure. Material and methods: Eighty bovine incisors were selected and randomly divided into groups (n = 10) according to the material and fixation period. The brackets were bonded following the manufacturer's instructions and stored in deionized water at 37oC for 10 min or 24 h. After, the specimens were submitted to shear bond strength test at 0.5 mm/min and evaluated for adhesive remnant index (ARI). The data were submitted to Kruskal Wallis and Wilcoxon tests (p < 0.05) and the ARI scores to Chi-Square test. Results: There was a significant difference among the materials (p < 0.05) (after 10 min – Transbond XT > Transbond Plus Color Change > Transbond Supreme LV = Flow Tain LV and after 24 h – Transbond XT > Transbond Plus Color Change = Transbond Supreme LV =Flow Tain LV). There was no significant difference in resistance values between 10 min and 24 h, except for Transbond Plus Color Change. Most groups showed adhesive remaining adhered to the enamel (scores 2 and 3) without statistical significant difference (p > 0.05). Conclusion: The light-cured traditional resins showed higher resistance than the nanofilled materials. The period of fixation had no influence on the resistance for different materials, except for Transbond Plus Color Change.

Degrading permafrost mapped with electrical resistivity tomography, airborne imagery and LiDAR, and seasonal thaw measurements

Accurate identification of the relationships between permafrost extent and landscape patterns can help to develop airborne geophysical or remote sensing tools to map permafrost in remote locations or across large areas. These tools will be particularly applicable in discontinuous permafrost where climate warming or disturbances such as human development or fire can lead to rapid permafrost degradation. We have linked field-based geophysical, point-scale, and imagery surveying measurements to map permafrost at five fire scars (1930, 1975, 1988, 2001, and 2010) on the Tanana Flats in central Alaska. Ground-based elevation surveys, seasonal thaw-depth profiles, and electrical resistivity tomography (ERT) measurements were combined with airborne imagery and light detection and ranging (LiDAR) to identify relationships between permafrost geomorphology and elapsed time since fire disturbance. ERT proved to be a robust technique for mapping the presence or absence of permafrost because of the marked difference in resistivity values for frozen versus unfrozen material. There was no clear relationship between elapsed time since fire and permafrost extent at our sites. However, we have found that the transition zone boundaries between permafrost soils and unfrozen soils in the collapse-scar bogs at our sites had complex and unpredictable morphologies. This result suggested that attempts to quantify the presence or absence of permafrost using aerial measurements alone could lead to incomplete results. Taken in total, the results from our study indicated that although ground-based ERT measurements were the most rapid means of mapping permafrost, we were still limited in being able to apply airborne surveying measurements at the landscape scale toward accurately estimating permafrost extent.

Electrical resistance of human soft tissue sarcomas: an ex vivo study on surgical specimens.

This paper presents a study about electrical resistance, which using fixed electrode geometry could be correlated to the tissue resistivity, of different histological types of human soft tissue sarcomas measured during electroporation. The same voltage pulse sequence was applied to the tumor mass shortly after surgical resection by means of a voltage pulse generator currently used in clinical practice for electrochemotherapy that uses reversible electroporation. The voltage pulses were applied by means of a standard hexagonal electrode composed by seven, 20-mm-long equispaced needles. Irrespective of tumor size, the electrode applies electric pulses to the same volume of tissue. The resistance value was computed from the voltage and current recorded by the pulse generator, and it was correlated with the histological characteristics of the tumor tissue which was assessed by a dedicated pathologist. Some differences in resistance values, which could be correlated to a difference in tissue resistivity, were noticed according to sarcoma histotype. Lipomatous tumors (i.e., those rich in adipose tissue) displayed the highest resistance values (up to 1700 Ω), whereas in the other soft tissue sarcomas, such as those originating from muscle, nerve sheath, or fibrous tissue, the electrical resistance measured was between 40 and 110 Ω. A variability in resistance was found also within the same histotype. Among lipomatous tumors, the presence of myxoid tissue between adipocytes reduced the electrical resistance (e.g., 50-100 Ω). This work represents the first step in order to explore the difference in tissue electrical properties of STS. These results may be used to verify whether tuning electric field intensity according to the specific STS histotype could improve tissue electroporation and ultimately treatment efficacy.

NOTA TÉCNICA: RESISTÊNCIA MECÂNICA DO SOLO À PENETRAÇÃO EM FUNÇÃO DA SUA UMIDADE E DO TIPO DE PENETRÔMETRO - DOI: 10.13083/1414-3984.v22n01a08

Com o advento da mecanização agrícola o solo passou a receber uma maior pressão dos pneus das máquinas, que pode ocasionar zonas de impedimento ao desenvolvimento radicular das plantas. O objetivo do trabalho foi avaliar a resistência mecânica do solo a penetração (RP) com penetrômetro eletrônico e de impacto em condições de umidade em área cultivada anteriormente por sorgo forrageiro. O experimento foi conduzido no Campus das Ciências Agrárias da Universidade Federal do Vale do São Francisco – UNIVASF, Petrolina (PE). A coleta de dados da RP foi realizada com penetrômetro eletrônico e de impacto em condições de umidade (3,5 e 6,7%) nas profundidades de 0,00 a 0,50 m, sendo os penetrômetros posicionados a 0,20 m um do outro para a coleta. Para o penetrômetro de impacto verificaram-se altos valores de RP, e não houve diferença nos valores de RP nas diferentes condições de umidade. Para o penetrômetro eletrônico verificou-se que em baixas condições de umidade não se conseguiu realizar a penetração no solo, e que até a camada de 0,30 m verificou-se diferença nos valores de RP, sendo menor na maior umidade do solo. Ocorreu relação entre a umidade e o valor da RP para o penetrômetro eletrônico.

Shear bond strength of nanofilled flowable resins used for indirect bracket bonding

Aim: To evaluate the bond strength of brackets fixed with different materials (two light-cured nanofilled resins - Transbond Supreme LV and Flow Tain LV, a light-cured resin - Transbond XT (control) and two chemically cured resins for indirect bonding - Sondhi Rapid- Set and Custom I.Q.) using the indirect bonding technique after 10 min and 24 h, and evaluate the type of failure. Methods: One hundred premolars were selected and randomly divided into groups (n=10) according to the material and fixation period. The brackets were bonded through the indirect technique following the manufacturer’s instructions and stored in deionized water at 37 o C for 10 min or 24 h. After, the specimens were submitted to a shear bond strength (SBS) test (Instron) at 0.5 mm/min and evaluated for adhesive remnant index (ARI). The data were submitted to ANOVA and Tukey’s test (p Sondhi Rapid-Set > Custom I.Q.). There was no significant difference in resistance values between 10 min and 24 h, regardless of the materials. Most groups showed adhesive remaining adhered to the enamel (scores 2 and 3) without statistically significant difference (p>0.05). Conclusions: It was concluded that the light-cured nanofilled materials used in indirect bonding showed greater resistance than the chemically cured materials. The period of fixation had no influence on the resistance for different materials.

Suitability of Various Measurement Techniques for Assessing Corrosion in Cracked Concrete

A critical evaluation of results from three corrosion assessment methods used in an experimental study to investigate the influence of cracks on the rate of chloride-induced corrosion is presented in this article. The objective was to determine the suitability and reliability of the corrosion assessment methods for application in cracked concrete. Beam specimens (100 x 100 x 500 mm [3.9 x 3.9 x 19.7 in.]) with crack widths of 0.7 and 0.4 mm (0.028 and 0.016 in.), as well as incipient cracks, were made using two binder types (100% CEM I ordinary portland cement [OPC]) and 50/50 OPC/ slag blend), two water-binder ratios (w/b) (0.40 and 0.55) and a constant cover of 40 mm (1.6 in.) to steel reinforcing. The specimens were subjected to repeated cycles of 3-day wetting with 5% NaCl, and 4-day air drying for 32 weeks. Half-cell potential (HCP), resistivity (Wenner probe), and corrosion rate (coulostatic) measurements were taken at the end of each 3-day wetting period. Chloride conductivity tests were also performed on companion cube specimens at 28 and 90 days. No significant differences in resistivity values were noted between cracked and uncracked specimens, despite the fact that the corrosion rate increased with increasing crack width. The insensitivity of resistivity measurements to the presence of cracks was attributed to the fact that measurements were taken after every 3-day wetting period, when the specimens would have been saturated with salt solution. The chloride conductivity and resistivity measurements gave a similar indication of the corrosion rates. HCP and corrosion rate measurements showed a good correlation, and they gave a clear indication of corrosion in cracked reinforced concrete (RC) specimens, although for practical applications, HCP measurements need to be complemented with other corrosion assessment techniques. For the resistivity assessment technique—in addition to concrete quality and magnitude of resistivity—correction factors are required to relate the resistivity of uncracked concrete to corrosion characteristics of cracked concrete. A methodology for the application of correction factors is proposed.

Estimating pulmonary congestion in elderly patients using bio-impedance technique: Correlation with clinical examination and X-ray results

The bio-impedance technique provides a safe, low-cost and non-invasive alternative for lung fluid level monitoring. Here we have investigated the feasibility of a novel bio-impedance system in measuring pulmonary congestion in elderly patients suffering from congestive heart failure (CHF). The system employed a parametric reconstruction algorithm to assess mean lung resistivity. Fourteen patients were studied before and following treatment to reduce lung congestion. Significant correlation was found between the changes of radiographic scores and resistivity values following treatment ( R = 0.57, p < 0.04). A significant difference in resistivity values between patients having low and high congestion degrees was also demonstrated ( p < 0.01). Moreover, the bio-impedance technique successfully diagnosed an improvement of congestion level in 10 out of 14 patients, while the radiographic score indicated such an improvement in only 5 out of the 14 patients. These results, along with our previous validation studies, suggest that the bio-impedance technique is a feasible bedside system for monitoring of pulmonary congested patients, thus facilitating effective treatment strategies.

Electrical properties of structured HIPS/gamma‐irradiated UHMWPE/carbon black blends

AbstractHIPS/UHMWPE and HIPS/XL‐UHMWPE containing carbon black (CB) are unique systems in which CB is attracted to the PE, and thus structuring takes place affecting the morphology and the resultant electrical properties. UHMWPE, having a very high viscosity, was chosen as the dispersed phase within HIPS in place of a conventional polymer in order to explore possibilities of obtaining unique structures that would induce the CB to segregate and form a conductive network. XL‐UHMWPE particles also constitute an interesting dispersed phase, maintaming their highly porous and intricate structure even subsequent to melt processing. In both cases the CB is located at the interface; however, differences in resistivity values are observed. When low UHMWPE or XL‐UHMWPE contents are incorporated, the HIPS/XL‐UHMWPE/CB compositions have lower resistivities due to the heterogeneity of the interface, even at high shear rates. When high UHMWPE or XL‐UHMWPE contents are utilized, the trends reverse: HIPS/UHMWPE/CB depict enhanced conductivity, due to the dominance of UHMWPE particle coalescence and the resultant decrease in surface area. This is contrary to what happens with the XL‐UHMWPE particles, where the surface area increases with their higher contents, since they do not coalesce.

Electrical Resistivity Investigation for Subsurface Exploration along the Right of Way of the Sewage Flow Conveyance System in Alexandria, Egypt

Abstract By using the electrical resistivity Wenner configuration, 22 sounding points were used to study the shallow subsurface geology along a proposed pass for construction of a flow convergence system in a part of Alexandria, Egypt. The study indicated that no abnormal hidden subsurface objects are present to prevent completion of the project. Lateral inhomogeneities are detected by differences in resistivity values. Some saturated limestone layers also are detected. The associated water may hinder the drilling activities. The geophysical data correlate with the results obtained from nearby boreholes.

Study of the Resistivity of Coal Seams of the Jharia Coalfield, India

Abstract An attempt has been made to study electrical properties of coal seams of the Jharia Coalfield, India. For this purpose, variations of resistivity values with percentage of water saturation have been studied in the laboratory for 63 coal samples belonging to 16 coal seams of this coalfield. Effective porosity values for all these samples lie within 5 percent. It has been observed that the resistivity values for the samples decay exponentially with increase in percentage of water saturation. A large difference in resistivity values is seen among the coal seams, even when they are fully saturated with water. Sometimes, samples of the same coal seam also show a large difference in resistivity value under full saturation condition. On account of their complex behavior, no general and clear relationship between “depth and porosity” and “depth and resistivity at 100 percent saturation” for coal seams have been obtained. Resistivity values of coal seams decrease considerably with higher percentage of water saturation, although no clear dependence on porosity values could be established. Field results of a few Schlumberger soundings over coal seams of this coalfield have been correlated with laboratory measurements.