Dual Sampling Method Research Articles

A dual-sampling based evolutionary algorithm for large-scale multi-objective optimization

The vast search space in large-scale multi-objective optimization represents a significant challenge for evolutionary algorithms to converge towards the Pareto Front. As an effective search strategy, direction-guided sampling technique could improve the search efficiency by exploring along the approximated directions to approach the Pareto set. However, the approximated directions may fail to interact with the true Pareto set and result in inefficient search. To address this issue, a dual-sampling method is proposed in this paper. In addition to the samples along the directions approximated by direction-guided sampling, fuzzy Gaussian sampling is applied to adjust the search direction and generate more accurate and evenly distributed solutions. Moreover, a convergence-and-diversity-based mating selection is introduced to balance the exploration and exploitation. The experiments on 72 test benchmarks with bi- and tri-objectives and 500–5000 decision variables show the superiority of the proposed algorithm compare with the state-of-the-art algorithms.

Tapped delay line for compact time-to-digital converter on UltraScale FPGA and its coding method

The time-to-digital converter (TDC) is the primary instrument for measuring time intervals. A common solution for FPGA-based TDCs is to construct a tapped delay line (TDL) for time interpolation to produce a sub-clock time resolution. The jitter and quantization, granularity and uniformity of the delay cells, and so on in TDL, determine the achievable TDC time resolution and linearity. To achieve higher linearity, a TDL and its encoding method for compact TDC on the UltraScale FPGA is proposed in this paper. A dual-sampling method with TDL is adopted, which improves precision and efficiency by directly encoding the state of the delay line, allowing further subdivision of the delay unit in combination with wave union. The bin width of the TDL obtained based on our method is measured here using the code density calibration method and draw the integral nonlinearity and differential nonlinearity. Based on the chain structure and encoding method proposed in this article, the TDL and encoding layout have been optimized to achieve a more compatible UltraScale FPGA and can also be further applied to multi-channel TDC.

Assessing Different Types of HIV Communication and Sociocultural Factors on Perceived HIV Stigma and Testing among a National Sample of Youth and Young Adults.

In the United States, racial/ethnic and sexual youth and young adults (YYA) of color are disproportionately affected by HIV. Subsequently, YYA experience HIV stigma and engage in increased risk behaviors and reduced HIV testing. HIV communication has been identified as a potential buffer to HIV stigma, resulting in health-seeking behaviors, such as HIV testing. In this study, we respond to a meaningful gap in the literature by examining different types of HIV communication and their impact on HIV stigma and HIV testing in a diverse sample of YYA. We analyzed secondary data from the Kaiser Family Foundation National Survey of Teens and Young Adults on HIV/AIDS. A 40-question, web-based survey was conducted with 1437 youth (ages 15–24). Recruitment included a dual sampling method from households with: (1) listed phone numbers, (2) unlisted phone numbers, (3) telephones, (4) no telephone, and (5) only cell phone access. The purpose of the survey was to establish participants’ HIV knowledge, communication, experiences, and testing behaviors. Findings suggested an association between intimate-partner HIV communication, increased HIV testing, and reduced HIV stigma. We also identified differentials in HIV testing and stigma based on gender, income, age, and sexual minority status, explained by HIV communication. Further research is needed that examines ways to use intimate-partner HIV communication to reduce stigma and increase HIV testing among YYA of different sociodemographic characteristics and sexual orientations.

High Throughput Data Relay in UAV Wireless Networks

As a result of their high mobility and reduced cost, Unmanned Aerial Vehicles (UAVs) have been found to be a promising tool in wireless networks. A UAV can perform the role of a base station as well as a mobile relay, connecting distant ground terminals. In this paper, we dispatch a UAV to a disaster area to help relay information for victims. We involve a bandwidth efficient technique called the Dual-Sampling (DS) method when planning the UAV flight trajectory, trying to maximize the data transmission throughput. We propose an iterative algorithm for solving this problem. The victim bandwidth scheduling and the UAV trajectory are alternately optimized in each iteration, meanwhile a power balance mechanism is implemented in the algorithm to ensure the proper functioning of the DS method. We compare the results of the DS-enabled scheme with two non-DS schemes, namely a fair bandwidth allocation scheme and a bandwidth contention scheme. The DS scheme outperforms the other two non-DS schemes regarding max-min average data rate among all the ground victims. Furthermore, we derive the theoretical optimal performance of the DS scheme for a given scenario, and find that the proposed approach can be regarded as a general method to solve this optimization problem. We also observe that the optimal UAV trajectory for the DS scheme is quite different from that of the non-DS bandwidth contention scheme.

A 3.9 ps Time-Interval RMS Precision Time-to-Digital Converter Using a Dual-Sampling Method in an UltraScale FPGA

Field programmable gate arrays (FPGAs) manufactured with more advanced processing technology have faster carry chains and smaller delay elements, which are favorable for the design of tapped delay line (TDL)-style time-to-digital converters (TDCs) in FPGA. However, new challenges are posed in using them to implement TDCs with a high time precision. In this paper, we propose a bin realignment method and a dual-sampling method for TDC implementation in a Xilinx UltraScale FPGA. The former realigns the disordered time delay taps so that the TDC precision can approach the limit of its delay granularity, while the latter doubles the number of taps in the delay line so that the TDC precision beyond the cell delay limitation can be expected. Two TDC channels were implemented in a Kintex UltraScale FPGA, and the effectiveness of the new methods was evaluated. For fixed time intervals in the range from 0 to 440 ns, the average RMS precision measured by the two TDC channels reaches 5.8 ps using the bin realignment, and it further improves to 3.9 ps by using the dual-sampling method. The time precision has a 5.6% variation in the measured temperature range. Every part of the TDC, including dual-sampling, encoding, and on-line calibration, could run at a 500 MHz clock frequency. The system measurement dead time is only 4 ns.

Comparison Between In vivo Gate's Method and in Vitro Plasma Sampling Method for GFR Measurement Using 99m-Tc DTPA

Objective: To compare between Gates GFR measurement using 99m Tc DTPA scintigraphy (in vivo method) as compared to in vitro blood sampling method (single and dual blood samples).Patients and methods: this prospective study included 40 normal individuals (group 1) and 40 patients with obstructive uropathy (group2) .The age of the group 1 ranging from: 22 to 65with mean age of 47.1±14.08 and in group 2it ranges between 27 years to 64 years with mean age of 49.12±9.1 .Group 1 included: 22 males, 18females, while group 2 included 24 males and 16 females. Both groups subjected to 99m-Tc DTPA renal scan using 8 mCi followed by blood sampling at 60 mins and 180mins post injection. Serum creatinine level was estimated for both groups and it was within normal level. Results: In group 1, the mean GFR using in vivo method was115.7 ± 29, and using in vitro method with single blood sample it was 100.1 ±16.1, and using dual blood sampling method it was 100.3±20.1.There was no significant difference between in vivo and in vitro methods (single sample and dual samples) for measuring GFR, in group 1 (p>0.05). In group 2, GFR using in vivo method was 74.1 ± 14.5, while using in vitro single sample method it was 77.5 ±24.9, and by using in vitro dual sample it was 76.8 ±24.8 with no significant difference using in vitro single sample and dual sample measurements. There is high significant correlation between in vitro single and dual sample in both groups,(r=0.90) for control group and (r=0.91) for patients group, while moderate significant correlation was found between in vivo and in vitro radionuclide single sample methods in both control and patients groups (r=0.46 and 0.57). Also moderate correlation was evident between in vivo and in vitro radionuclide dual sample methods in both groups (r=0.42 and0.68).Conclusion: No significant difference in measurement of GFR using both in vitro and in vivo methods in control group and in obstructive uropathy group ,however there is moderate correlation between in vivo and in vitro (single and dual sample) method in both groups but there is high correlation between in vitro method using single blood sample and dual blood samples.

Photothermal Spectroscopic Measurements by Dual Sampling Method in Intermittent-Contact-Mode Atomic Force Microscopy

We have proposed a dual sampling method in intermittent-contact-mode atomic force microscopy with a piezoresistive cantilever for photothermal (PT) measurements. This method realizes a sensitive detection of thermal expansion in a sample by excluding crosstalk from photoabsorption signals generated at the piezoresistive sensor on the cantilever. We have confirmed the feasibility of this method through the excitation photon energy dependence of the PT signal measured on Si and GaAs.

Region of interest tomography in industrial applications

Region of interest (ROI) tomography allows the reconstruction of a particular area of interest within a larger structure. However, projections restricted to a ROI may include contributions from objects external to that ROI. These contributions will lead to inconsistencies in the data and give rise to artifacts in the image. In order to reduce these artifacts, we make use of a dual-sampling method. The external region is scanned at a lower resolution than the ROI but the information thus gained can be used to correct for the contribution of external objects to the ROI raysums. Before reconstruction of an image we interpolate between the external raysums to give a data set with equal sampling step size throughout. We have investigated the use of both cubic spline and polynomial fitting routines for this interpolation. This technique is of particular use where an initial low resolution scan is used to locate areas of interest which can then be scanned in greater detail. Thus the information gained in the low resolution scan can be used to correct for artifacts in the later high resolution scan.

A color image sampling method with suppression of moiré fringes

When halftone screened images are sampled by discrete array sensors such as CCD line sensor, moiré fringes sometimes appear because of aliasing errors. We have proposed a “Dual Sampling Method (DSM)”, which can effectively suppress the moiré fringes by carrying out twice sampling procedures with different sampling ratio. In this paper, we discuss the possibility of applying the DSM to color images. Two methods are described: the first one applied DSM to each primary color images, and the second one only to intensity data. A computer simulation shows the effectiveness of both methods.

Suppression of moiré fringes due to sampling of halftone screened images

When a halftone screened image is discretely sampled by, for example, a CCD array, moiré fringes sometimes appear. These moiré fringes are caused by aliasing errors due to the improper sampling rate. To suppress these fringes, a dual sampling method is proposed. In this method, halftone screened images are sampled twice with different sampling rates, and the selection of proper frequency components less suffering from aliasing errors can effectively suppress moiré fringes.