Papers by Keyword: Frequency

Abstract: Empirical acoustic models were developed for dense-graded and open-graded asphalt concrete. Tire/pavement noise data were collected from in-service flexible pavements at different frequency bands for four consecutive years. These data were panel structured, and with a portion of observations missed arbitrarily. A Monte Carlo Markov Chain (MCMC) sampling and a multiple imputation (MI) algorithm were used to capture the unobserved heterogeneity and deal with missing observations by Bayesian simulations that are associated with the data. Models for the two mixes at different frequency bands were constructed. Major findings of the study include: first, tire/pavement noise increases with age at all frequency bands; second, tire/pavement noise level increases with air-void content of the surface mixes at medium and high frequencies but decreases at low frequencies; third, tire/pavement noise level increases with mean profile depth (MPD) at low and medium frequencies but decreases at high frequencies; and fourth, open-graded mix has low noise level compared to its dense-graded counterpart.

Abstract: In order to identify structural damage locations and extent, a method based on ridge estimation and modal strain energy is presented in this paper. First, structural modal strain energy is given and a modal strain energy sensitivity damage equation is obtained. Then, considering the TikhonovTT regularization theoryTT, a ridge estimation method is proposed to solve the damage equation and ridge parameter of the method is optimized. Simulation results demonstrate that the proposed damage detection method based on ridge estimation and modal strain energy can identify structural damage locations and extent with good accuracy.

Abstract: In this paper, based on the programmable frequency dividers HMC394 and AD company's integer PLL chip ADF4107, in the premise of not reducing the phase detector frequency, improved the frequency resolution and effectively inhibits the phase stray. Designed a frequency source with high performance index: high resolution is 10kHz, low phase noise is-91.27dBc/Hz @10kHz, low spurious is less than-60dBc, high harmonic suppression is less than-60dBc,the design method is simple, low cost, flexible control, high performance and widely used.

Abstract: Ground-supported tanks are used to store a variety of liquids. During earthquake activity the liquid exerts impulsive and convective pressures (sloshing) on the walls and bottom of the rectangular tank. This paper provides theoretical background for analytical calculating of circular frequencies and hydrodynamic pressures developed during an earthquake in rectangular container. Analytical results of first natural frequency are compared with experiment.

Abstract: In this paper we introduce the concept of an agile electronic pest control intelligent device for commercial usage and we have evaluated its performance in comparison with other existing similar technologies. The frequency and intensities are changed with respect to the target pest however human behavior has been found to be inert with their exposure. The unit has been tested in lab conditions as well as field testing done have given encouraging results. The device can be a standalone unit and hence work for small scale viz. kitchen garden on the other hand multiple devices acting in coordination with each other give the desired output on a larger scale. Lastly, we chose a tricopter over the wider used quadcopter for greater yaw and agility. The work was funded by IEEE under AiyeHum – 2012 and the prototype was successfully built and tested. The system response effectiveness was found to 86.5% up to a distance of 15 meters.

Abstract: the low pressure oil chamber and the high pressure oil chamber act directly on Both sides of the rotary valve. It will be large axial force to the valve body If the system working pressure is greater. The resulting outcome is low vibration frequency of the rotary valve driven hydraulic exciter. How to improve the hydraulic exciter frequencyWe can improve the speed of the rotary valve or increase the number of rotary valve guide groove. But if we increase the tank guided number ,the diameter of the rotary valve spoo must be increased. Design a rotary valve without axial force can solve the problem of the rotary valve spool shaft size restricted. By calculation and analysis of the rotary valve spool suffered axial force . The work of a single rotary valve chamber pressure problems can be solved spool axial force

Abstract: During bridges and culverts design effort, in order to avoid defects of manual calculating and plotting, people use excel table to build worksheet calculating model and plot Pearson—III theoretic frequency curve, Excel software can do data calculating as well as data processing, it has powerful functions, so can plot more accurate, ocular precise frequency curve, the graphics are easy to adjust, all these make the model practical and highly optimized for general use.

Abstract: The dynamic characteristics of the self-excited oscillation pulsed jet is tested by using pulsed jet impact variable cross-section beam in submerged conditions and make comparison with continuous jet, analyzing the effects of operating parameters and nozzle structure parameters on the dynamic characteristics of the pulsed jet. The result show that the oscillating frequency of jet decreases with the increase of cavity length while increases with the increase of the pump pressure. The energy of pulsed jet has obvious change with different cavity length.

Abstract: Food contamination has become critical issue and is being worse due to the insensitive detection devices. One of the dangerous food contaminations is by Escherichia coli (E.coli) O157:H7, one of the harmful bacterial pathogens which is distributed in soil, marine and estuarine waters, the intestinal tract of animals, or water contaminated with fecal matter. A small amount of E.coli with the dose fewer than 100 organisms in food products or water is enough to cause serious gastrointestinal illness to human. Hence, the ultra-high sensitive, label free biosensors have been designed in this research for the low concentration E.coli detection. Surface acoustic waves (SAW) devices have been initially developed and used for the high-volume low-cost TV component. Due to the ultra-sensitivity to the surface perturbation, SAW based devices have been modified to be sensors. Initially, SAW sensors were developed for gas detections and have been moving towards biological detections recently. Shear horizontal surface acoustic wave (SHSAW), one of the SAW based types is most suitable for the liquid based application as it has the advantage of acoustic energy is not being radiated into liquid. However, the main SHSAW design components are the operating frequency and wave length. These are strictly depended on the inter digital transducers (IDTs) design. Therefore, this paper is presenting the IDTs design concept and pattern development by using computer aid design (CAD) software.

Abstract: In the process of calculating the crankshaft frequency and vibration mode, free mode is always applied for the crankshaft modal analysis. Considering the effect of centrifugal force generated by the rotation to the crankshaft frequency and vibration mode, the frequency and vibration mode of multi-speed cases are calculated, and compared, which fully shows the vibration situation of the crankshaft in the process of actual working situations, the results match actual situation.