A Novel Stochastic Approach for Static Damage Identification of Beam Structures Using Homotopy Analysis Algorithm

This paper proposes a new damage identification approach for beam structures with stochastic parameters based on uncertain static measurement data. This new approach considers not only the static measurement errors, but also the modelling error of the initial beam structures as random quantities, and can also address static damage identification problems with relatively large uncertainties. First, the stochastic damage identification equations with respect to the damage indexes were established. On this basis, a new homotopy analysis algorithm was used to solve the stochastic damage identification equations. During the process of solution, a static condensation technique and a L1 regularization method were employed to address the limited measurement data and ill-posed problems, respectively. Furthermore, the definition of damage probability index is presented to evaluate the possibility of existing damages. The results of two numerical examples show that the accuracy and efficiency of the proposed damage identification approach are good. In comparison to the first-order perturbation method, the proposed method can ensure better accuracy in damage identification with relatively large measurement errors and modelling error. Finally, according to the static tests of a simply supported concrete beam, the proposed method successfully identified the damage of the beam.

Effect of Buffer Layer Capacitance on the Electrical Characteristics of Ferroelectric Polymer Capacitors and Field Effect Transistors

We demonstrated the effect of a buffer layer on the electrical characteristics of ferroelectric polymer capacitors and field-effect transistors. Various polymer materials with a dielectric constant between 2 and 42 were used to form buffer layers with a similar thicknesses, but with different capacitances. In order to evaluate the characteristics of the ferroelectrics with a buffer layer, the polarization–voltage characteristics of the capacitor, the transfer characteristics, and the retention characteristics of the transistors were investigated. As the capacitance of the buffer layer increased, high remnant polarization (Pr), high hysteresis, and long retention times were observed. Exceptionally, when poly(methylmethacrylate) and rigid poly(aryl ether) (poly(9,9-bis(4-hydroxyphenyl)fluorene-co-decafluorobiphenyl)) were used as the buffer layer, Pr had a value close to 0 in the dynamic measurement polarization–voltage (P–V) characteristic, but the quasi-static measurement transfer characteristic and the static measurement retention characteristic showed relatively high hysteresis and long retention times. Our study provides a scientific and technical basis for the design of ferroelectric memory and neuromorphic devices.

From Hardware to Operating System: A Static Measurement Method of Android System Based on TrustZone

Android system has been one of the main targets of hacker attacks for a long time. At present, it is faced with security risks such as privilege escalation attacks, image tampering, and malicious programs. In view of the above risks, the current detection of the application layer can no longer guarantee the security of the Android system. The security of mobile terminals needs to be fully protected from the bottom to the top, and the consistency test of the hardware system is realized from the hardware layer of the terminal. However, there is not a complete set of security measures to ensure the reliability and integrity of the Android system at present. Therefore, from the perspective of trusted computing, this paper proposes and implements a trusted static measurement method of the Android system based on TrustZone to protect the integrity of the system layer and provide a trusted underlying environment for the detection of the Android application layer. This paper analyzes from two aspects of security and efficiency. The experimental results show that this method can detect the Android system layer privilege escalation attack and discover the rootkit that breaks the integrity of the Android kernel in time during the startup process, and the performance loss of this method is within the acceptable range.

Measuring the Boxing Punch: Development and Calibration of a Non-Embedded In-Glove Piezo-Resistive Sensor

Biomechanics measurement in boxing is becoming increasingly important for the analysis of boxing technique in order to promote exciting and safer boxing at both amateur and professional levels. Despite this interest, there have been few experiments within this field of research that have utilised a non-embedded in-glove sensor to measure the resultant power generated by a boxing punch. The aim of this study was to develop a dynamic measurement system, utilising a non-embedded in-glove sensor system. Two sensors were utilised; a tri-axial accelerometer to measure acceleration and a piezo-resistive force sensor hand wrap to measure the impact force of a boxer’s punch. The piezo-resistive system was calibrated using a static measurement system utilising simple load cells for force and laser displacement sensors for glove speed measurements. The system was tested on 31 novice boxing athletes participating in the study. A mean impact force of 2.31 kN ± 3.28 kN, an instantaneous velocity prior to impact of 4.73 m/s ± 0.35 m/s, an impact acceleration of 91 g ± 11 g, deceleration immediately following impact of 223 g ± 21 g and a maximum power dissipation of 11.2 kW ± 2.05 kW were measured. These values correspond well with prior studies using alternate measurement approaches. The calibration of the non-embedded in-glove piezo-resistive force sensor on the static measurement system yielded a correlation coefficient of 0.85.

Simultaneous Constant Velocity Measurement of the Motion Errors of Linear Axes

The current standard for machine tool calibration supports the use of quasi-static measurement techniques. When measuring the six degrees of freedom motion errors, the measurements are typically taken consecutively. This introduces uncertainty when comparing the results due to machine deformation during individual measurements. Furthermore, quasi-static measurement techniques are known to be time consuming, a problem that is exacerbated as each degree of freedom must be measured separately. Additionally, the spatial resolution between the selected target positions can have an impact on calibration quality. In the following paper, the benefits of measuring the six motion errors simultaneously while the axis under test is traversing at a nominally constant velocity are presented. Firstly, the motivation for simultaneous continuous capture is presented. Secondly, continuous motion measurements are compared with quasi-static measurements for the six degrees of freedom motion errors showing sub-micrometer and sub-arcsecond correlation. The full effect of a ball screw pitch error is shown which can be missed using traditional quasi-static measurement techniques. Finally, wavelet analysis is performed for further spatial diagnostics along with correlation coefficients calculated to quantify the linear dependency between the six error motions.

A New Method for Static Measurement of two Axles Vehicle Centroid Height

The traditional static measurement method of two axis vehicle centroid has high working intensity and high risk. A new method of centroid measurement is designed in this paper. According to the vehicle axle load changes, tyre flattening radius and suspension deformation, sprung and unsprung weight centroid height change, their respective variations were calculated by scribing method. Then according to the relationship between the vehicle front axle and rear axle load in different angles, the moment balance principle and the principle of mass balance, the geometric relationship was determined of the change amount. The moment balance equation of the vehicle front wheel and the ground is established. The vehicle centroid height, sprung centroid height and non-spring load centroid height are obtained under vehicle horizontal position. This measurement method is different from the existing static measurement of vehicle centroid height, it does not need the fixed suspension, only need to measure several dimensions, we can avoid heavy labor and safety accidents brought by the fixed suspension, it can also reduce the measurement error caused by fixation, but also can draw the centroid location of the sprung mass and unsprung mass.

Pengaruh Pembayangan terhadap Kenyamanan Termal pada Rumah Tinggal di Perumahan Bukti Baruga Antang Makassar

Abstrak_ Penelitian ini dilakukan dengan mengukur kenyamanan termal alami dan mengetahui seberapa besar pengaruh tanaman peneduh terhadap kenyamanan termal alami didalam rumah tinggal. Rumah tinggal dikelompokkan menjadi dua kelompok yaitu rumah tinggal yang ada tanaman peneduh dan rumah tinggal yang tidak ada tanaman peneduh. Data pengukuran statis dilakukan dengan beberapa variabel kenyamanan berupa suhu, kelembaban, dan kecepatan angin kemudian diukur menggunakan alat HOBO temp/RH logger dengan waktu pengukuran dari pukul 06.00-18.00 WITA. Hasil penelitian menunjukkan bahwa rata-rata temperatur tertinggi untuk rumah tinggal yang ada tanaman peneduh 30,2°C dan rumah tinggal yang tidak ada tanaman peneduh 31,3°C. Kemudian rata-rata kelembaban tertinggi rumah tinggal yang ada tanaman peneduh 73% dan yang tidak ada tanaman peneduh 73%, dengan ini kelembaban berada pada zona yang nyaman. Sedangkan hasil rata-rata 0,19 m/s untuk kecepatan angin tertinggi rumah tinggal yang tidak ada tanaman peneduh dan 0,65 m/s rumah tinggal yang ada tanaman peneduh. Hasil survey kenyamanan penghuni menunjukkan sebagian responden masih merasa nyaman namun tetap mengharapkan kondisi kenyamanan termal yang lebih sejuk lagi. Responden beradaptasi dengan kondisi lingkungannya dengan cara memilih pakaian yang nyaman dan tipis serta mengurangi kegiatan yang menimbulkan banyak keringat. Kata kunci : Kenyamanan Termal, Tanaman Peneduh, Rumah tinggal, Responden penghuni. Abstract_ This research was conducted by measuring natural thermal comfort and knowing how much influence the shade plants have on natural thermal comfort in the house. Dwellings are grouped into two groups namely dwellings with shade plants and dwellings with no shade plants. Static measurement data is carried out with several comfort variables in the form of temperature, humidity, and wind speed and then measured using a HOBO temp / RH logger tool with measurement time from 06.00-18.00 WITA. The results showed that the average highest temperature for houses with shade plants was 30.2 ° C and houses without shade plants were 31.3 ° C. Then the highest average humidity of residential houses with 73% shade plants and 73% without shade plants, with this humidity is in the comfort zone. While the average yield of 0.19 m / s for the highest wind speed of houses without shade plants and 0.65 m / s of shade houses. The results of the occupants comfort survey show that some respondents still feel comfortable but still expect cooler conditions of thermal comfort. Respondents adapt to environmental conditions by choosing comfortable and thin clothing and reducing activities that cause a lot of sweat. Keywords : Thermal Comfort, Shade Plants, Residential Houses, Resident Respondents