Эффект насыщающегося поглотителя в длинноволновых вертикально-излучающих лазерах, реализованных по технологии спекания

Vertical-cavity surface-emitting lasers emitting at the spectral range of 1.55 µm based on heterostructures with a buried tunnel junction (BTJ) with a height step of 15 nm are studied. The devices are realized using wafer fusion technique of heterostructures grown by molecular beam epitaxy and demonstrate a single-mode lasing regime at the 8 μm BTJ-diameter. With a decrease in the BTJ-diameter, a sharp increase in the threshold current, accompanied by an abrupt increase in the output optical power and resonance frequency at the lasing threshold are observed. Stable single-mode lasing is due to the smoothing of the boundary of the overgrown surface relief, which leads to a smooth change in the profile of the effective refractive index in the lateral direction, while maintaining effective current confinement, which makes it possible to significantly reduce the transverse optical confinement factor for high-order modes even at large BTJ-diameter. However, at small BTJ-diameter, it also leads to the formation of a saturable absorber in the non-pumped parts of the active region.

A Practical Positioning Method in End-Plate Surface Distance Measurement with Nano-Meter Precision

End-plate surface distance is important for length value dissemination in the field of metrology. For the measurement of distance of two surfaces, the positioning method is the key for realizing high precision. A practical method with nanometer positioning precision is introduced in consideration of the complexity of positioning laser sources of the traditional methods and new methods. The surface positioning is realized by the combination of laser interference and white light interference. In order to verify the method, a 0.1 mm height step is made, and an experiment system based on the method is established. The principle and the basic theory of the method are analyzed, and the measures to enhance the repeatability from optical and mechanical factors and signal processing methods are presented. The experimental result shows that the surface positioning repeatability is in the order of 10 nm. The measurement uncertainty evaluation shows that the standard uncertainty is 21 nm for a 0.1 mm step. It is concluded that the method is suitable to be applied to the length measurement standard of the lab.

Modeling and Analysis on Energy Consumption of Hydraulic Quadruped Robot for Optimal Trot Motion Control

Energy consumption is an important performance index of quadruped robots. In this paper, the energy consumptions of the quadruped robot SCalf with a trot gait under different gait parameters are analyzed. Firstly, the kinematics and dynamics models of the robot are established. Then, an energy model including the mechanical power and heat rate is proposed. To obtain the energy consumption, a cubic spline interpolation foot trajectory is used, and the feet forces are calculated by using the minimization of norm of the foot force method. Moreover, an energetic criterion measuring the energy cost is defined to evaluate the motion. Finally, the gait parameters such as step height, step length, standing height, gait cycle, and duty cycle that influence the energy consumption are studied, which could provide a theoretical basis for parameter optimization and motion control of quadruped robots.

Dynamic bipedal locomotion over stochastic discrete terrain

Owing to their morphology and mechanical design, bipedal robots have the ability to traverse over a wide range of terrain including those with discrete footholds such as stepping stones. This paper addresses the challenge of planar dynamic robotic walking over stochastically generated stepping stones with significant variations in step length and step height, and where the robot has knowledge about the location of the next discrete foothold only one step ahead. Specifically, our approach utilizes a two-step periodic gait optimization technique to build a library of gaits parametrized by their resulting step lengths and step heights, as well as the initial configuration of the robot. By doing so, we address the problems involved during step transition when switching between the different walking gaits. We then use gait interpolation in real-time to obtain the desired gait. The proposed method is successfully validated on ATRIAS, an underactuated, human-scale bipedal robot, to achieve precise footstep placement. With no change in step height, step lengths are varied in the range of [23:78] cm. When both step length and step height are changed, their variation are within [30:65] cm and [−22:22] cm, respectively. The average walking speed of both these experiments is 0.6 m/s.

Die Forming Simulation of PM Parts Based on AMESim

The mathematical model of cylindrical compact simulation is established by using the mathematical model of the net pressure P1 and the loss pressure P2 in AMESim environment, basing on the physical model of the powder metallurgical cylindrical blank. The simulation model of multi-step P/M parts is established by disassembling and transformation of parts, which is successfully introduced to the hydraulic system simulation. The corresponding velocity and displacement curves are obtained by running batch the three parts of B, C, A, following the principle that the speed of different height step mode is equal to the pressing rate. When the piston reaches a certain equilibrium displacement, , , and respectively range from 20 to 100, from 20 to 50, and from 50 to 2000. According to the corresponding suppression curve obtained, corresponding optimized parameters could be got to meet the requirements of the pressing speed with the AMESim optimization function.

GAMBARAN TINGGI BADAN SEBELUM TIDUR DAN SETELAH BANGUN PAGI PADA MAHASISWA FAKULTAS KEDOKTERAN UNSRAT MANADO

Anthropometry is a measurement of the parts of human body. Nowadays there are so many studies and theories about anthropometry. One of them is difference between measurement of morning body height and evening body height. People should be taller in the morning than in the evening. This study’s goal is to obtain the description of human body height at different measurement time, by the time after morning wake-up and before sleep in the night from the students at Medical Faculty of Sam Ratulangi University in Manado. This study is a descriptive study with the cross-sectional approach. Samples were taken by purposive sampling. The amount of sample was calculated based on Slovin formula, with the total amount of sample is 75 people. The result showed that there is a body height step-up when the body height is measured after morning wake-up than before night sleep. The average of man’s body height step-up is 1.5 cm height and woman’s body height step-up is 1,6 cm height. T-test showed that there is a significant difference of body height between before sleep and after morning wake up with the value of p<0.01. Conclusion: The research can be concluded that there is a significant difference between before night sleep and after morning wake-up body height, in which the height step-up happens in the morning than in the evening.Keywords: body height, before sleeping, after waking upAbstrak: Antropometri merupakan pengukuran terhadap bagian-bagian tubuh manusia. Saat ini sudah banyak penelitian dan teori tentang antropometri. Salah satunya adalah terdapat perbedaan hasil pengukuran tinggi badan pada pagi dan malam hari. Seseorang dapat menjadi lebih tinggi pada pagi hari dibandingkan pada malam hari. Penelitian ini bertujuan untuk melihat gambaran tinggi badan yang diukur pada 2 waktu yang berbeda, yaitu setelah bangun pagi dan sebelum tidur pada mahasiswa Fakultas Kedokteran UNSRAT Manado. Penelitian ini merupakan penelitian deskriptif dengan pendekatan potong silang. Sampel diambil secara purposive sampling. Besar sampel dihitung dengan rumus Slovin dengan jumlah sampel penelitian 75 orang. Hasil penelitian menunjukkan bahwa terdapat peningkatan tinggi badan pada pengukuran setelah bangun pagi dibandingkan sebelum tidur. Rata-rata peningkatan pada laki-laki sebesar 1,5 cm dan perempuan 1,6 cm. Melalui uji t didapatkan bahwa terdapat perbedaan signifikan antara tinggi badan sebelum tidur dan setelah bangun pagi dengan nilai p<0,01. Simpulan: Dapat disimpulkan bahwa terdapat perbedaan signifikan antara tinggi badan sebelum tidur dan setelah bangun pagi, dimana terjadi peningkatan tinggi badan pada pagi hari dibandingkan malam hari.Kata kunci: tinggi badan, sebelum tidur, setelah bangun pagi

AFM and Ellipsometry Studies of Ultra Thin Ti Film Deposited on a Silicon Wafer

An ultra- thin Ti film with a thickness of less than 30 nm was deposited on the surface of a silicon wafer by the filtered arc deposition system. A novel technique was adopted to create a height step between the coated area and non-coated area (silicon wafer) during deposition. The surface morphology and thickness of the film was detected by atomic force microscopy (AFM). The AFM results showed that the deposited film formed a smooth structure on the silicon wafer and the height step between the coating and silicon wafer was clear enough to give the thickness of the deposited film. The composition of the deposited film was detected by a combined use of Ellipsometry and AFM. Natural oxidisation of Ti (TiO2) was found on the top of the Ti film after deposition, and the thickness of TiO2 was determined by ellipsometry to be about 0.6 nm.