Wave attenuation and focusing by a parabolic arc pontoon breakwater

In the multifunctional system consisting of point absorber wave energy converters and a pontoon breakwater, the breakwater plays an essential role in attenuating waves on the lee side and amplifying waves for a better energy harvesting on the stoss side. The structure of breakwater is expectedly improved to enhance its wave attenuation and amplification at the same time. Here we present a novel parabolic arc breakwater and show that for a range of typical regular incident waves, it can attenuate more wave elevation and focus high waves in several regions in comparison to a straight breakwater. In further frequency-domain investigations, a special relatively-low frequency associated with the parabolic arc breakwater configuration is found and named as the critical frequency, closed to which splendid attenuation and focusing performance can be achieved. A systematic parametric study on the geometric factors (draft, width, and chord length) of the parabolic arc breakwater is thereafter carried out to examine their influence on the attenuation and focusing performance at the critical frequency. We find that an increase of the draft can reduce the critical frequency greatly so as to let it be within the real sea states, meanwhile slightly affecting the attenuation performance. An increase of the chord length has an uncertain but not large influence on the attenuation performance, whereas it enhances substantially the focusing performance. Simultaneously, an amplification rate up to 3.06 in two relatively-large focal areas in a prescribed deployment zone and an average attenuation rate of approximately 68% in a prescribed protection zone could be obtained in a commonly observed coastal wave.</p

Wave attenuation and focusing by a parabolic arc pontoon breakwater

In the multifunctional system consisting of point absorber wave energy converters and a pontoon breakwater, the breakwater plays an essential role in attenuating waves on the lee side and amplifying waves for a better energy harvesting on the stoss side. The structure of breakwater is expectedly improved to enhance its wave attenuation and amplification at the same time. Here we present a novel parabolic arc breakwater and show that for a range of typical regular incident waves, it can attenuate more wave elevation and focus high waves in several regions in comparison to a straight breakwater. In further frequency-domain investigations, a special relatively-low frequency associated with the parabolic arc breakwater configuration is found and named as the critical frequency, closed to which splendid attenuation and focusing performance can be achieved. A systematic parametric study on the geometric factors (draft, width, and chord length) of the parabolic arc breakwater is thereafter carried out to examine their influence on the attenuation and focusing performance at the critical frequency. We find that an increase of the draft can reduce the critical frequency greatly so as to let it be within the real sea states, meanwhile slightly affecting the attenuation performance. An increase of the chord length has an uncertain but not large influence on the attenuation performance, whereas it enhances substantially the focusing performance. Simultaneously, an amplification rate up to 3.06 in two relatively-large focal areas in a prescribed deployment zone and an average attenuation rate of approximately 68% in a prescribed protection zone could be obtained in a commonly observed coastal wave.</p

Addition of T2-Guided Optical Tomography Improves Noncontrast Breast Magnetic Resonance Imaging Diagnosis.

BACKGROUND: While dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) is recognized as the most sensitive examination for breast cancer detection, it has a substantial false positive rate and gadolinium (Gd) contrast agents are not universally well tolerated. As a result, alternatives to diagnosing breast cancer based on endogenous contrast are of growing interest. In this study, endogenous near-infrared spectral tomography (NIRST) guided by T2 MRI was evaluated to explore whether the combined imaging modality, which does not require contrast injection or involve ionizing radiation, can achieve acceptable diagnostic performance. METHODS: Twenty-four subjects-16 with pathologically confirmed malignancy and 8 with benign abnormalities-were simultaneously imaged with MRI and NIRST prior to definitive pathological diagnosis. MRIs were evaluated independently by three breast radiologists blinded to the pathological results. Optical image reconstructions were constrained by grayscale values in the T2 MRI. MRI and NIRST images were used, alone and in combination, to estimate the diagnostic performance of the data. Outcomes were compared to DCE results. RESULTS: Sensitivity, specificity, accuracy, and area under the curve (AUC) of noncontrast MRI when combined with T2-guided NIRST were 94%, 100%, 96%, and 0.95, respectively, whereas these values were 94%, 63%, 88%, and 0.81 for DCE MRI alone, and 88%, 88%, 88%, and 0.94 when DCE-guided NIRST was added. CONCLUSION: In this study, the overall accuracy of imaging diagnosis improved to 96% when T2-guided NIRST was added to noncontrast MRI alone, relative to 88% for DCE MRI, suggesting that similar or better diagnostic accuracy can be achieved without requiring a contrast agent

Sensitivity of MRI-Guided Near-Infrared Spectroscopy Clinical Breast Exam Data and Its Impact on Diagnostic Performance

In this study, data from breast MRI-guided near infrared spectroscopy (NIRS) exams delivered to 44 patients scheduled for surgical resection (ending in 16 benign and 28 malignant diagnoses) were analyzed using a spatial sensitivity metric to quantify the adequacy of the optical measurements for interrogating the tumor region of interest, as derived from the concurrent MRI scan. Along with positional sensitivity, the incorporation of spectral priors and the selection of an appropriate regularization parameter in the image reconstruction were considered, and found to influence the diagnostic accuracy of the recovered images. Once optimized, the MRI/NIRS data was able to differentiate the malignant from benign lesions through both total hemoglobin (p = 0.0037) and tissue optical index (p = 0.00019), but required the relative spatial sensitivity of the optical measurement data to each lesion to be above 1%. Spectral constraints implemented during the reconstruction were required to obtain statistically significant diagnostic information from images of H2O, lipids, and Tissue Optical Index (TOI). These results confirm the need for optical systems that have homogenous spatial coverage of the breast while still being able to accommodate the normal range of breast sizes

The diploid genome sequence of an Asian individual

Here we present the first diploid genome sequence of an Asian individual. The genome was sequenced to 36-fold average coverage using massively parallel sequencing technology. We aligned the short reads onto the NCBI human reference genome to 99.97% coverage, and guided by the reference genome, we used uniquely mapped reads to assemble a high-quality consensus sequence for 92% of the Asian individual's genome. We identified approximately 3 million single-nucleotide polymorphisms (SNPs) inside this region, of which 13.6% were not in the dbSNP database. Genotyping analysis showed that SNP identification had high accuracy and consistency, indicating the high sequence quality of this assembly. We also carried out heterozygote phasing and haplotype prediction against HapMap CHB and JPT haplotypes (Chinese and Japanese, respectively), sequence comparison with the two available individual genomes (J. D. Watson and J. C. Venter), and structural variation identification. These variations were considered for their potential biological impact. Our sequence data and analyses demonstrate the potential usefulness of next-generation sequencing technologies for personal genomics

Rock Macro&ndash;Meso Parameter Calibration and Optimization Based on Improved BP Algorithm and Response Surface Method in PFC 3D

In order to obtain the calibration law of rock macro and meso parameters under three-dimensional conditions, based on the parallel bond model, starting with the basic theory of PFC and the qualitative relationship between macro and meso parameters, an orthogonal experimental scheme is designed. An improved BP algorithm is proposed, which has a function with gradient factor, adaptive Nesterov momentum method, and adaptive learning rate for the lightweight analysis of meso parameters. The sensitivity between macro and meso parameters is quantified, and the key meso parameters are screened out. Based on the lightweight model, the correlation and influence mechanisms between macro and meso parameters are analyzed. It was found that the elastic modulus increases linearly with the increase in equivalent modulus. The parallel bond stiffness ratio can inhibit the growth of the elastic modulus, and the elastic modulus decreases greatly when the stiffness is relatively high. There is a linear relationship between Poisson&rsquo;s ratio and stiffness ratio, and the increase in the friction coefficient will cause the nonlinear decrease in it. The strength parameters have an incentive effect on the peak strength. When the tensile and shear strengths of the parallel bond are at a high level, the combination has the most significant effect on the increase in the peak strength. The internal friction angle mainly has a certain influence on the postpeak strength of the rock, because it has a control effect on the particle sliding on both sides of the shear zone when the sample is loaded after the peak. Based on the central composite experimental design and response surface method, a nonlinear model of macro&ndash;meso parameters described by multiple subresponse surfaces is obtained. Finally, the mathematical model of parameter calibration is established, and the optimal solution of rock meso parameters is obtained by using optimization techniques. Through the example verification, it was found that the numerical experiment and laboratory test results are close in the stress characteristics, stress evolution, and failure mode of the sample, which proves the effectiveness and reliability of the calibration method. The research results have a certain reference value for PFC parameter calibration

Rock Macro–Meso Parameter Calibration and Optimization Based on Improved BP Algorithm and Response Surface Method in PFC 3D

In order to obtain the calibration law of rock macro and meso parameters under three-dimensional conditions, based on the parallel bond model, starting with the basic theory of PFC and the qualitative relationship between macro and meso parameters, an orthogonal experimental scheme is designed. An improved BP algorithm is proposed, which has a function with gradient factor, adaptive Nesterov momentum method, and adaptive learning rate for the lightweight analysis of meso parameters. The sensitivity between macro and meso parameters is quantified, and the key meso parameters are screened out. Based on the lightweight model, the correlation and influence mechanisms between macro and meso parameters are analyzed. It was found that the elastic modulus increases linearly with the increase in equivalent modulus. The parallel bond stiffness ratio can inhibit the growth of the elastic modulus, and the elastic modulus decreases greatly when the stiffness is relatively high. There is a linear relationship between Poisson’s ratio and stiffness ratio, and the increase in the friction coefficient will cause the nonlinear decrease in it. The strength parameters have an incentive effect on the peak strength. When the tensile and shear strengths of the parallel bond are at a high level, the combination has the most significant effect on the increase in the peak strength. The internal friction angle mainly has a certain influence on the postpeak strength of the rock, because it has a control effect on the particle sliding on both sides of the shear zone when the sample is loaded after the peak. Based on the central composite experimental design and response surface method, a nonlinear model of macro–meso parameters described by multiple subresponse surfaces is obtained. Finally, the mathematical model of parameter calibration is established, and the optimal solution of rock meso parameters is obtained by using optimization techniques. Through the example verification, it was found that the numerical experiment and laboratory test results are close in the stress characteristics, stress evolution, and failure mode of the sample, which proves the effectiveness and reliability of the calibration method. The research results have a certain reference value for PFC parameter calibration

Numerical Simulation Analysis Method of the Surrounding Rock and Support Bearing Capacity in Underground Cavern

After the excavation of an underground cavern, how the surrounding rock and the support work together to bear the excavation load is an important prerequisite to correctly analyze the joint force characteristics; effectively play the role of support; and ensure the safety, efficiency, and economy of underground cavern construction. Starting from the elastic-plastic load release characteristics of surrounding rock, this paper proposes a calculation method of the elastic load coefficient of surrounding rock and a graded release method of plastic load, which ensures the actual effect of the synergistic action of the first support and surrounding rock. Based on the elastic-plastic damage evolution characteristics of surrounding rock, a weighted iterative calculation method of elastic-plastic damage is proposed, and an evaluation method of load release ultimate bearing capacity of surrounding rock is determined. By monitoring the change law of rock acoustic wave velocity with surrounding rock damage, the relationship between the wave velocity and the damage coefficient of the surrounding rock in the excavation process is deduced, and it is proposed to determine the latest support time for first support by using the measured rock damage wave velocity. Through the numerical simulation analysis of a diversion tunnel excavation and support, the damage evolution law of the surrounding rock with the release of the excavation load is studied. The ultimate bearing capacity of various surrounding rocks and supporting opportunity is determined. The results demonstrate the validity and practicality of the analysis and calculation methods in this paper, which provide a new idea and analysis method for quantifying the bearing capacity of surrounding rock and determining the support timing in the excavation and support design of underground caverns

Identification of SSR markers closely linked to the yellow seed coat color gene in heading Chinese cabbage (Brassica rapa L. ssp. pekinensis)

Research on the yellow-seeded variety of heading Chinese cabbage will aid in broadening its germplasm resources and lay a foundation for AA genome research in Brassica crops. Here, an F2 segregating population of 1575 individuals was constructed from two inbred lines (brown-seeded ‘92S105’ and yellow-seeded ‘91-125’). This population was used to identify the linkage molecular markers of the yellow seed coat trait using simple sequence repeat (SSR) techniques combined with a bulk segregant analysis (BSA). Of the 144 SSR primer pairs on the A01-A10 chromosomes from the Brassica database (http://brassicadb.org/brad/), two pairs located on the A06 chromosome showed polymorphic bands between the bulk DNA pools of eight brown-seeded and eight yellow-seeded F2 progeny. Based on the genome sequence, 454 SSR markers were designed to A06 to detect these polymorphic bands and were synthesized. Six SSR markers linked to the seed coat color gene were successfully selected for fine linkage genetic map construction, in which the two closest flanking markers, SSR449a and SSR317, mapped the Brsc-ye gene to a 40.2 kb region with distances of 0.07 and 0.06 cM, respectively. The molecular markers obtained in this report will assist in the marker-assisted selection and breeding of yellow-seeded lines in Brassica rapa L. and other close species