809 research outputs found
A “Jellyfish Engineering Experiment” for purifying water quality in large lakes
Article信州大学理学部附属諏訪臨湖実験所報告 9: 149-153(1995)departmental bulletin pape
A Spatiotemporal-chaos-based Encryption Having Overall Properties Considerably Better Than Advanced Encryption Standard
Spatiotemporal chaos of a two-dimensional one-way coupled map lattice is used
for chaotic cryptography. The chaotic outputs of many space units are used for
encryption simultaneously. This system shows satisfactory cryptographic
properties of high security; fast encryption (decryption) speed; and robustness
against noise disturbances in communication channel. The overall features of
this spatiotemporal-chaos-based cryptosystem are better than chaotic
cryptosystems known so far, and also than currently used conventional
cryptosystems, such as the Advanced Encryption Standard (AES).Comment: 11 pages, 3 figure
Plane strain extrusion forging process
Metal forming is one of the oldest materials processing techniques which are still playing important roles in modem life. In metal forming, as in any other manufacturing processes, the ultimate goal is to produce components of a selected material with a required geometrical shape and a structure optimised for the proposed service environment. Of the above production of the desired shape is a major part of the manufacturing process.
Extrusion forging is a metal forming process in which the billet is partially undergoing extrusion, thus forming a boss, and partially deformed laterally. The understanding of the metal flow and the prediction of forging load in such a process is important both for the die design and the product quality control.
Due to the complexity in deformation pattern and the inherent unsteadiness of the operation, it is at present very difficult to obtain a satisfactory analytical solution. In this work, an approximate analysis has been carried out by assuming that the deformation will go through three distinctive modes, and an over-estimation solution has subsequently been formed.
Numerical analysis has been performed using a commercial finite element analysis package. The plane strain extrusion forging of rectangular billets has been simulated using 8-noded elements. Results of deformation profile and forging load are obtained.
Experimental work has been carried out by deforming rectangular billets between two dies, with at least one of them grooved. The effect of material property, forming speed and the lubricating condition at the die-billet interface has been studied experimentally, by applying different billet materials, different forming speeds and different lubricants at the die/billet interfaces.
The analytical approach is capable of predicting the deformed profiles as well as the forging loads for certain die combinations, while for others the result is only valid within about 50% of axial deformation. The results from the finite element analysis give excellent correlation with the experimental results.
From the analytical, numerical and the experimental studies it has been found that the plane strain extrusion forging of rectangular billets between grooved dies takes place with significant inward barrelling. The deformed profile depends mainly on the relative geometry of the die/billet combination, which is characterized by the ratio of the groove width to billet width, and the cross-section aspect ratio of the billet. The material properties of the billet material have been found having little effect on the deformation patterns, though the forging load varied because of the change in the yield stress. The interfacial friction has been noted affecting the forging load as well as the deformed profiles. The effect of the forming speed is mainly on the forging load rather than the deformation geometry.
The present study provides a better understanding of the plane strain extrusion forging process, which is similar to the initial stages of closed the die forging. The results of the study can be applied to the product quality control and tool design in such metal forming operations
Anti-ulcerogenic efficacy and mechanisms of edible and natural ingredients in NSAID-induced animal models
Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) are a class of the most commonly used medicines and proven to be effective for certain disorders. Some people use NSAIDs on daily basis for preventive purpose. But a variety of severe side effects can be induced by NSAIDs. Studies have shown that edible natural ingredients exhibit preventive benefit of gastric ulcer. This paper reviews the efficacy and safety of edible natural ingredients in preventing the development of gastric ulcer induced by NSAIDs in animal models.Methods: A systematic literature search was conducted on PubMed, using the terms “herbal medicines” and “gastric ulcer”, “herbal medicines” and “peptic ulcer”, “food” and “peptic ulcer”, “food” and “gastric ulcer”, “natural ingredient” and “peptic ulcer”, “natural ingredient” and “gastric ulcer”, “alternative medicine” and “peptic ulcer”, “alternative medicine” and “gastric ulcer”, “complementary medicine” and “peptic ulcer”, “complementary medicine” and “gastric ulcer” in papers published in English between January 1, 1960 and January 31, 2016, resulting in a total of 6146 articles containing these terms. After exclusion of studies not related prevention, not in NSAID model or using non-edible natural ingredients, 54 articles were included in this review.Results: Numerous studies have demonstrated that edible natural ingredients exhibit antiulcerogenic benefit in NSAIDinduced animal models. The mechanisms by which edible, ingredient-induced anti-ulcerogenic effects include stimulation of mucous cell proliferation, antioxidation, inhibition of gastric acid secretion, as well as inhibition of H(+), K(+)- ATPase activities. Utilization of edible, natural ingredients could be a safe, valuable alternative to prevent the development of NSAID-induced gastric ulcer, particularly for the subjects who are long-term users of NSAIDs.Keywords: Food, Gastric ulcer, Prevention, Animal models,Nonsteroidal anti-inflammatory drug
On-chip Spectrometer Formed by a Multi-stage Structure
With apparent size and weight advantages, on-chip spectrometer could be a good choice for the spectrum analysis application which has been widely used in numerous areas such as optical network performance monitoring, materials analysis and medical research. In order to realize the broadband and the high resolution simultaneously, we propose a new on-chip spectrometer structure, which is a two-stage structure. The coarse wavelength division is realized by the cascaded Mach-Zehnder interferometers, which is the first stage of the spectrometer. The output of the Mach-Zehnder interferometers are further dispersed by the second stage structure, which can be realized either by arrayed waveguide gratings or by digital Fourier transform spectrometer structure. We further implemented the thermo-optic modulation for the arrayed waveguide gratings to achieve a higher spectral resolution. The output channel wavelengths of the spectrometer are modulated by the embedded heater to obtain the first order derivative spectra of the input optical signal to obtain a 2nm resolution. With respect to the computer simulation and device characterization results, the 400nm spectral range and the nanoscale resolution have been demonstrated
ELEMENTARY RESEARCH ON THE MOST SUITABLE MODE FOR THE ARCHERS OF THE SHAN DONG TEAM
INTRODUCTION: Archery is an ancient sport. In recent years, the development of archery in China has been quite rapid. The performence of this sport in Shan Dong has also rapidly increased, but it is rare for archers` techniques to be quantitatively analyzed. Therefore the movement strcture, kinematic features and influence on the performence of 6 archers on the Shan Dong team were comprehensively compared and analyzed in order to raise their technical level .The best movement techniques were found and combined in the most suitable mode of these six archers. According to this mode, their techniques were improved individually in training .The more rational movement techniques were performed, followed by an exploration of new ways of scientific training in archery.
METHODS: Thirty-six arrow shots of these six archers of the Shan Dong team were analyzed, and the data were processed by the more advanced video analysis system - Bewegungs Analysis System: Pentium 586 computer; 21inch SAMSUNG advanced color monitor (1024%1024); Panasonic Video Cassette Recorder (AG- 7355); the video tape was recorded with time code; the software program to be provided by Germany. The interval between the frames was 0.02 second. The digital filtering method was used for data smothing and a cutoff frequenty of 3 hz was adopted. In measuring, x axis: the direction perpendicular to the target; y axis: the direction perpendicular to the horizontal plane; z axis: the direction of paralleling the target.
RESULTS: 1. A comparison and analysis of six archers in each phase period
1.1 The average time for an arrow to be shot by each varies greatly (from 4.812s to 10.956s). The average time for an arrow to be shot by the same archer is relatively stable. The movement rhythm of the six archers is not the same.
1.2 The shooting time of arrows hitting the ten-point ring is ordinarily from 4.78s to 7.84s, and the aiming time is from 2.46s to 5.60s.The shooting time of arrows hitting the eight-point ring is under 4.32s, and the aiming time is under 2.24s. 2. A comparison and analysis of the kinematic features of these six archers was made.
CONCLUSION AND SUGGESTION:
1.The movement rhythm of Li Changjun, Tang Huan and Zhu Maodong is relatively fast, The movement rhythm of Xin Lei and Li Ming is relatively slow. The movement techniques of Li Meng and Zhu Maodong in forcing to release period are a bit similar. The movement techniques of Xin Lei and Sun Wei in forcing to release period are a bit similar.
2. The best movement techniques of each can be combined in the most suitable mode to train the archers.
3. In training, the movement technique of some of the archers should be improved with rational technique features.
REFERENCES:
Jiang Qian et al. (1993). A Study of Elite Chinese Archers’ Aiming Skills. Sports
Science of China 1
Compact hollow waveguide mid-infrared gas sensor for simultaneous measurements of ambient CO2 and water vapor
A compact, sensitive and stable hollow waveguide (HWG) mid-infrared gas sensor, based on gas absorption lines using wavelength modulation spectroscopy with a second harmonic (WMS-2f) detection scheme, was developed for simultaneous measurements of ambient CO 2 and water vapor. Optimization of the laser modulation parameters and pressure parameter in the HWG are performed to improve the strength of the WMS-2f signal and hence the detection limit, where 14.5-time for CO 2 and 8.5-time for water vapor improvement in system detection limit is achieved compared to those working at 1 atm. The stability of the sensor has been improved significantly by optimizing environmental disturbances, incoupling alignment of the HWG and laser scanning frequency. An Allan variance analysis shows detection limit of the developed sensor of ~3 ppmv for CO 2 and 0.018% for water vapor, which correspond to an absorbance of 2.4 × 10 -5 and 2.7 × 10 -5 , with a stability time of 160 s, respectively. Ambient CO 2 and water vapor measurement have been performed in two days in winter and spring separately. The measurement precision is further improved by applying a Kalman adaptive filter. The HWG gas sensor demonstrates the ability in environmental monitoring and the potential to be used in other areas, such as industrial production and biomedical diagnosis
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