Underwater acoustic signal processing is one of the research hotspots in underwater acoustics.Noise reduction of underwater acoustic signals is the key to underwater acoustic signal processing.Owing to the complexity ...Underwater acoustic signal processing is one of the research hotspots in underwater acoustics.Noise reduction of underwater acoustic signals is the key to underwater acoustic signal processing.Owing to the complexity of marine environment and the particularity of underwater acoustic channel,noise reduction of underwater acoustic signals has always been a difficult challenge in the field of underwater acoustic signal processing.In order to solve the dilemma,we proposed a novel noise reduction technique for underwater acoustic signals based on complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN),minimum mean square variance criterion(MMSVC) and least mean square adaptive filter(LMSAF).This noise reduction technique,named CEEMDAN-MMSVC-LMSAF,has three main advantages:(i) as an improved algorithm of empirical mode decomposition(EMD) and ensemble EMD(EEMD),CEEMDAN can better suppress mode mixing,and can avoid selecting the number of decomposition in variational mode decomposition(VMD);(ii) MMSVC can identify noisy intrinsic mode function(IMF),and can avoid selecting thresholds of different permutation entropies;(iii) for noise reduction of noisy IMFs,LMSAF overcomes the selection of deco mposition number and basis function for wavelet noise reduction.Firstly,CEEMDAN decomposes the original signal into IMFs,which can be divided into noisy IMFs and real IMFs.Then,MMSVC and LMSAF are used to detect identify noisy IMFs and remove noise components from noisy IMFs.Finally,both denoised noisy IMFs and real IMFs are reconstructed and the final denoised signal is obtained.Compared with other noise reduction techniques,the validity of CEEMDAN-MMSVC-LMSAF can be proved by the analysis of simulation signals and real underwater acoustic signals,which has the better noise reduction effect and has practical application value.CEEMDAN-MMSVC-LMSAF also provides a reliable basis for the detection,feature extraction,classification and recognition of underwater acoustic signals.展开更多
The problem of two-dimensional(2 D)direction of arrival(DOA)estimation for double parallel uniform linear arrays is investigated in this paper.A real-valued DOA estimation algorithm of noncircular(NC)signal is propose...The problem of two-dimensional(2 D)direction of arrival(DOA)estimation for double parallel uniform linear arrays is investigated in this paper.A real-valued DOA estimation algorithm of noncircular(NC)signal is proposed,which combines the Euler transformation and rotational invariance(RI)property between subarrays.In this work,the effective array aperture is doubled by exploiting the noncircularity of signals.The complex arithmetic is converted to real arithmetic via Euler transformation.The main contribution of this work is not only extending the NC-Euler-ESPRIT algorithm from uniform linear array to double parallel uniform linear arrays,but also constructing a new 2 Drotational invariance property between subarrays,which is more complex than that in NCEuler-ESPRIT algorithm.The proposed 2 DNC-Euler-RI algorithm has much lower computational complexity than2 DNC-ESPRIT algorithm.The proposed algorithm has better angle estimation performance than 2 DESPRIT algorithm and 2 D NC-PM algorithm for double parallel uniform linear arrays,and is very close to that of 2 D NC-ESPRIT algorithm.The elevation angles and azimuth angles can be obtained with automatically pairing.The proposed algorithm can estimate up to 2(M-1)sources,which is two times that of 2 D ESPRIT algorithm.Cramer-Rao bound(CRB)of noncircular signal is derived for the proposed algorithm.Computational complexity comparison is also analyzed.Finally,simulation results are presented to illustrate the effectiveness and usefulness of the proposed algorithm.展开更多
A new direction finding method is presented to deal with coexisted noncoherent and co- herent signals without smoothing operation. First the direction-of-arrival （DOA） estimation task is herein reformulated as a spa...A new direction finding method is presented to deal with coexisted noncoherent and co- herent signals without smoothing operation. First the direction-of-arrival （DOA） estimation task is herein reformulated as a sparse reconstruction problem of the cleaned array covariance matrix, which is processed to eliminate the affection of the noise. Then by using the block of matrices, the information of DOAs which we pursuit are implied in the sparse coefficient matrix. Finally, the sparse reconstruction problem is solved by the improved M-FOCUSS method, which is applied to the situation of block of matrices. This method outperforms its data domain counterpart in terms of noise suppression, and has a better performance in DOA estimation than the customary spatial smoothing technique. Simulation results verify the efficacy of the proposed method.展开更多
The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained expe...The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained experimentally through tests on specimens under multiaxial loading with that calculated by the variance method. In the statistical approach criteria, several methods have been developed but we have presented only one method, namely the variance method using the equivalent stress. She assumes that the fracture plane orientation is the one on which the variance of the equivalent stress is maximum. Three types of equivalent stress are defined for this method [1]: normal stress, shear stress and combined normal and shear stress. The results obtained were compared with experimental results for multiaxial cyclic stress states, and it emerges that the variance method for the case of combined loading is conservative as it gives a better prediction of the fracture plane.展开更多
Working toward an efficient duration and timeline for the preconstruction phase should be one of the main objectives for project owners.Failing to plan for and coordinate preconstruction decisions in order to control ...Working toward an efficient duration and timeline for the preconstruction phase should be one of the main objectives for project owners.Failing to plan for and coordinate preconstruction decisions in order to control preconstruction duration and manage time variances can lead to financial insecurities,incomplete contract documents,permitting issues,and unrealistic schedules and resource allocation during this phase.To minimize time variances and ensure a productive decision-making process,project owners should be familiar with critical elements in a project that cause variances in the preconstruction phase timeline.In this study,the impacts of eleven critical preconstruction elements on time variances were analyzed.These eleven preconstruction elements are considered critical in how they impact time variances during the preconstruction phase.They were determined to be critical based either on significantly impacting time variance during the preconstruction phase or believed to be critical from findings from previous studies,however,the findings from this study showed no significant impact on the time variances.In most previous studies focusing on the elements impacting project schedules,data were collected by surveying construction professionals.In this study,objective and quantitative data related to project preconstruction elements were used as opposed to self-reported data.Using the results of this study,project owners and stakeholders will be able to evaluate the critical preconstruction elements impacting the timing of their projects and prioritize decisions related to the critical elements early on during the preconstruction phase.展开更多
The valuation of financial derivatives often assumes risk neutrality with respect to the risk-neutral martingale measure,which prevents arbitrage opportunities.However,casual traders may still incur substantial losses...The valuation of financial derivatives often assumes risk neutrality with respect to the risk-neutral martingale measure,which prevents arbitrage opportunities.However,casual traders may still incur substantial losses when trading at this risk-neutral price,especially when the price has to be paid now and the payoff is only realized in the future.This study proposes a new valuation framework that provides risksensitive investors with an additional safeguard.The proposed framework embraces a worst-case perspective while exploiting the underlier’s stochastic process,representing a combination of robust optimization and stochastic programming.Notably,it aims to mitigate losses in the likelier scenarios of the underlying asset’s prices.When the underlier’s returns are independent and lognormally but not necessarily identically distributed,our approach for pricing variance and volatility swaps could be greatly simplified,benefit from parallel computing,and be solved by a two-dimensional grid search.We further derive a closed-form solution in some special stationary cases and provide experimental results to highlight the effect of risk aversion on fending off sizable trading losses.展开更多
In the variance component estimation(VCE)of geodetic data,the problem of negative VCE is likely to occur.In the ordinary additive error model,there have been related studies to solve the problem of negative variance c...In the variance component estimation(VCE)of geodetic data,the problem of negative VCE is likely to occur.In the ordinary additive error model,there have been related studies to solve the problem of negative variance components.However,there is still no related research in the mixed additive and multiplicative random error model(MAMREM).Based on the MAMREM,this paper applies the nonnegative least squares variance component estimation(NNLS-VCE)algorithm to this model.The correlation formula and iterative algorithm of NNLS-VCE for MAMREM are derived.The problem of negative variance in VCE for MAMREM is solved.This paper uses the digital simulation example and the Digital Terrain Mode(DTM)to prove the proposed algorithm's validity.The experimental results demonstrated that the proposed algorithm can effectively correct the VCE in MAMREM when there is a negative VCE.展开更多
In traditional sensing,each parameter is treated as a real number in the signal demodulation,whereas the electric field of light is a complex number.The real and imaginary parts obey the Kramers-Kronig relationship,wh...In traditional sensing,each parameter is treated as a real number in the signal demodulation,whereas the electric field of light is a complex number.The real and imaginary parts obey the Kramers-Kronig relationship,which is expected to help further enhance sensing precision.We propose a self-Bayesian estimate of the method,aiming at reducing measurement variance.This method utilizes the intensity and phase of the parameter to be measured,achieving statistical optimization of the estimated value through Bayesian inference,effectively reducing the measurement variance.To demonstrate the effectiveness of this method,we adopted an optical fiber heterodyne interference sensing vibration measurement system.The experimental results show that the signal-to-noise ratio is effectively improved within the frequency range of 200 to 500 kHz.Moreover,it is believed that the self-Bayesian estimation method holds broad application prospects in various types of optical sensing.展开更多
The Global Position System(GPS)is a reliable method for positioning in most scenarios,but it falls short in harsh environments like urban vehicular scenarios,where numerous trees or flyovers obstruct the signals.This ...The Global Position System(GPS)is a reliable method for positioning in most scenarios,but it falls short in harsh environments like urban vehicular scenarios,where numerous trees or flyovers obstruct the signals.This presents an unprecedented challenge for autonomous vehicles or applications requiring high accuracy.Fortunately,vehicular ad-hoc networks(VANET)offer an effective solution,where vehicle-to-vehicle(V2V)and vehicle-to-infrastructure(V2I)communications are used to enhance location awareness.In V2I communications,the roadside units(RSU)transmit beacon packets,and the vehicle receives numerous packets from different RSUs to establish communication.To further improve localization accuracy,a cross-covariance matrices-alternating least square(CCM-ALS)algorithm is proposed.The algorithm relies on ALS of the CCM for obtaining the position of vehicles in V2I communications.The algorithm is highly precise compared to traditional angle of arrival(AOA)positioning and not inferior to direct position determination(DPD)approaches while being low in complexity,which is crucial for moving vehicles.The numerical results verify the superiority of the proposed method.展开更多
Increases in climate variability, including extremes, may be expected with anthropogenic climate change, but some evidence is contrary. The issue is important because the consequences of variability can be critical fo...Increases in climate variability, including extremes, may be expected with anthropogenic climate change, but some evidence is contrary. The issue is important because the consequences of variability can be critical for ecosystems. It has long been known and often rehearsed that ecological consequences of increased variability may be greater than those that result from expected changes in mean temperature and precipitation. Tree rings have been useful indicators of ecological response to climate change and used as proxies for climate variability;work in the Rocky Mountains, USA, has been particularly informative. Chronologies from two high elevation species ranging over 2500 km were analyzed for changes in variance through time. These spatially extensive and disaggregated tree ring records do not show a consistent pattern of change in variance over the past 500 or 100 years; heteroscedasticity has recently been greater. A lack of consistent response in growth over a period encompassing changes in mean climate indicates that mountain environments, with inconsistent trends in temperature and precipitation,may be too complex to act as sentinels.展开更多
V-raf-leukemia viral oncogene 1(RAF1),a serine/threonine protein kinase,is well established to play a crucial role in tumorigenesis and cell development.However,the specific role of hypothalamic RAF1 in regulating ene...V-raf-leukemia viral oncogene 1(RAF1),a serine/threonine protein kinase,is well established to play a crucial role in tumorigenesis and cell development.However,the specific role of hypothalamic RAF1 in regulating energy metabolism remains unknown.In this study,we found that the expression of RAF1 was significantly increased in hypothalamic AgRP neurons of diet-induced obesity(DIO)mice.Under normal chow diet feeding,overexpression of Raf1 in AgRP neurons led to obesity in mice characterized by increased body weight,fat mass,and impaired glucose tolerance.Conversely,Raf1 knockout in AgRP neurons protected against diet-induced obesity,reducing fat mass and improving glucose tolerance.Mechanistically,Raf1 activated the MAPK signaling pathway,culminating in the phosphorylation of cAMP response element-binding protein(CREB),which enhanced transcription of Agrp and Npy.Insulin stimulation further potentiated the RAF1-MEK1/2-ERK1/2-CREB axis,highlighting RAF1's role in integrating hormonal and nutritional signals to regulate energy balance.Collectively,these findings underscore the important role of RAF1 in AgRP neurons in maintaining energy homeostasis and obesity pathogenesis,positioning it and its downstream pathways as potential therapeutic targets for innovative strategies to combat obesity and related metabolic diseases.展开更多
In this paper, a new feature space for PD （partial discharge） signal separation is presented. Three typical PD defects were experimentally reproduced in a laboratory for obtaining independent PD sources. Signals wer...In this paper, a new feature space for PD （partial discharge） signal separation is presented. Three typical PD defects were experimentally reproduced in a laboratory for obtaining independent PD sources. Signals were acquired with a digital storage oscilloscope and then post-processed with DWT （discrete Wavelet transform） for de-noising. The new feature space for PD source separation was constructed with the variance of each Wavelet coefficient vector and was compared with an established feature space for PD source separation; based on the energy of DWT coefficient vectors. After a space reduction by mean of PCA （principal components analysis）, the separation capability among them was measured by comparing the final classification error after training a neural network Results showed that with this new feature space it is possible to separate different sources of PD signals. Later, the feature space proposed was used to separate two PD sources from a real equipment tested. Further analysis on the reduced feature space has shown the band location of PD signals information for separating purpose.展开更多
The nervous system function requires a precise but plastic neural architecture.The neuronal shape dictates how neurons interact with each other and with other cells,being the morphology of dendrites and axons the cent...The nervous system function requires a precise but plastic neural architecture.The neuronal shape dictates how neurons interact with each other and with other cells,being the morphology of dendrites and axons the central determinant of the functional properties of neurons and neural circuits.The topological and structural morphology of axons and dendrites defines and determines how synapses are conformed.The morphological diversity of axon and dendrite arborization governs the neuron’s inputs,synaptic integration,neuronal computation,signal transmission,and network circuitry,hence defining the particular connectivity and function of the different brain areas.展开更多
This narrative review examines recent advances in salivary biomarkers for oral squamous cell carcinoma(OSCC),a major subtype of oral cancer with persistently low five-year survival rates due to delayed diagnosis.Saliv...This narrative review examines recent advances in salivary biomarkers for oral squamous cell carcinoma(OSCC),a major subtype of oral cancer with persistently low five-year survival rates due to delayed diagnosis.Saliva has emerged as a noninvasive diagnostic medium capable of reflecting both local tumor activity and systemic physiological changes.Various salivary biomarkers,including microRNAs,cytokines,proteins,metabolites,and exosomes,have been linked to oncogenic signaling pathways involved in tumor progression,immune modulation,and therapeutic resistance.Advances in quantitative polymerase chain reaction,mass spectrometry,and next-generation sequencing have enabled comprehensive biomarker profiling,while point-of-care detection systems and saliva-based omics platforms are accelerating clinical translation.Remaining challenges include variability in salivary composition,lack of standardized collection protocols,and insufficient validation across large patient cohorts.This review highlights the mechanistic relevance,diagnostic potential,and translational challenges of salivary biomarkers in OSCC.展开更多
Objective:To investigate the anti-atherosclerosis effect of chikusetsusaponinⅣ(CSⅣ)against high-fat diet-induced atherosclerosis in rats.Methods:A high-fat diet was used for the induction of atherosclerosis in rats,...Objective:To investigate the anti-atherosclerosis effect of chikusetsusaponinⅣ(CSⅣ)against high-fat diet-induced atherosclerosis in rats.Methods:A high-fat diet was used for the induction of atherosclerosis in rats,and the rats received oral CSⅣor atorvastatin.The body weight,organ weights,food intake,calorie intake,lipid parameters,3-hydroxy-3-methylglutaryl coenzyme A(HMG-CoA)/mevalonate ratio,collagen,free fatty acid,cardiac parameters,apolipoprotein(A and B),antioxidant parameters,inflammatory cytokines,and inflammatory parameters were assessed.The mRNA expressions of interleukin-1β(IL-1β),tumor necrosis factor-α(TNF-α),IL-6,IL-17,PI3K,AKT,and mTOR were estimated.Results:CSⅣsignificantly modulated food intake,body weight,organ weight(liver,kidney,and heart),and calories(P<0.05).Total cholesterol,triglycerides,very low-density lipoprotein cholesterol,low-density lipoprotein cholesterol,cardiovascular risk index-1,and cardiovascular risk index-2 were decreased,while high-density lipoprotein cholesterol and anti-atherogenic index were increased significantly in the CSⅣgroup(P<0.05).Besides,CSⅣsignificantly restored the level of HMG-CoA/mevalonate ratio,collagen,free fatty acid,cardiac parameters(creatinine kinase-MB,lactate dehydrogenase,cTnT,cTnI),apolipoprotein(apolipoprotein A and apolipoprotein B),antioxidant parameters(MDA,CAT,GPx,GSH,SOD),inflammatory cytokines(TNF-α,IL-1β,IL-6,IL-10),inflammatory parameters(COX-2,TGF-β,NF-κB),intercellular adhesion molecule-1,vascular cell adhesion molecule-1,and monocyte chemoattractant protein-1.CSⅣalso decreased the mRNA expression of IL-1β,TNF-α,IL-6,IL-17,PI3K,AKT,and mTOR.Conclusions:This study showed the anti-atherosclerosis effect of CSⅣagainst high-fat diet-induced atherosclerosis in rats via alteration of NF-κB/COX-2 and PI3K/AKT/mTOR signaling pathway.展开更多
Accurate time delay estimation of target echo signals is a critical component of underwater target localization.In active sonar systems,echo signal processing is vulnerable to the effects of reverberation and noise in...Accurate time delay estimation of target echo signals is a critical component of underwater target localization.In active sonar systems,echo signal processing is vulnerable to the effects of reverberation and noise in the maritime environment.This paper proposes a novel method for estimating target time delay using multi-bright spot echoes,assuming the target’s size and depth are known.Aiming to effectively enhance the extraction of geometric features from the target echoes and mitigate the impact of reverberation and noise,the proposed approach employs the fractional order Fourier transform-frequency sliced wavelet transform to extract multi-bright spot echoes.Using the highlighting model theory and the target size information,an observation matrix is constructed to represent multi-angle incident signals and obtain the theoretical scattered echo signals from different angles.Aiming to accurately estimate the target’s time delay,waveform similarity coefficients and mean square error values between the theoretical return signals and received signals are computed across various incident angles and time delays.Simulation results show that,compared to the conventional matched filter,the proposed algorithm reduces the relative error by 65.9%-91.5%at a signal-to noise ratio of-25 dB,and by 66.7%-88.9%at a signal-to-reverberation ratio of−10 dB.This algorithm provides a new approach for the precise localization of submerged targets in shallow water environments.展开更多
Type 2 diabetes mellitus has central complications:Diabetes,a metabolic disorder primarily characterized by hyperglycemia due to insufficient insulin secretion,or impaired insulin signaling,has significant central com...Type 2 diabetes mellitus has central complications:Diabetes,a metabolic disorder primarily characterized by hyperglycemia due to insufficient insulin secretion,or impaired insulin signaling,has significant central complications.Type 2 diabetes mellitus(T2DM),the most prevalent type of diabetes,affects more than 38 million individuals in the United States(approximately 1 in 10)and is defined by chronic hyperglycemia and insulin resistance,which refers to a reduced cellular response to insulin.展开更多
Protein aggregates,mitochondrial import stress and neurodegenerative disorders:A salient hallmark of several neurodegenerative diseases,including Parkinson’s disease,is the abundance of protein aggregates(Goiran et a...Protein aggregates,mitochondrial import stress and neurodegenerative disorders:A salient hallmark of several neurodegenerative diseases,including Parkinson’s disease,is the abundance of protein aggregates(Goiran et al.,2022).This molecular event is believed to lead to activation of stress pathways ultimately resulting in cellular dysfunction(Eldeeb et al.,2022).Accordingly,many lines of research investigations focused on dampening the formation of protein aggregates or augmenting the clearance of protein aggregates as a potential therapeutic strategy to counteract the progression of neurodegenerative diseases,albeit with little success(Costa-Mattioli and Walter,2020).Cell stress cues such as the accumulation of protein aggregates lead to the activation of stress response pathways that aid cells in responding to the damage.Despite the notion that the transient activation of these pathways helps cells cope with stressors,persistent activation can induce unwanted apoptosis of cells and reduce overall tissue strength as well as lead to an accumulation of aggregation-prone proteins(Hetz and Papa,2018).Mutations in proteins involved in stress signaling termination can cause conditions like ataxia and early-onset dementia(Conroy et al.,2014).Therefore,it is crucial for stress response signaling to be turned off once conditions have improved.Nevertheless,the mechanisms by which cells silence these signals are still elusive.展开更多
An identification method using Allan variance and equivalent theorem is proposed to identify non-stationary sensor errors mixed out of different simple noises. This method firstly derives the discrete Allan variances ...An identification method using Allan variance and equivalent theorem is proposed to identify non-stationary sensor errors mixed out of different simple noises. This method firstly derives the discrete Allan variances of all component noises inherent in noise sources in terms of their different equations; then the variances are used to estimate the parameters of all component noise models; finally, the original errors are represented by the sum of the non-stationary component noise model and the equivalent m...展开更多
基金The authors gratefully acknowledge the support of the National Natural Science Foundation of China(No.11574250).
文摘Underwater acoustic signal processing is one of the research hotspots in underwater acoustics.Noise reduction of underwater acoustic signals is the key to underwater acoustic signal processing.Owing to the complexity of marine environment and the particularity of underwater acoustic channel,noise reduction of underwater acoustic signals has always been a difficult challenge in the field of underwater acoustic signal processing.In order to solve the dilemma,we proposed a novel noise reduction technique for underwater acoustic signals based on complete ensemble empirical mode decomposition with adaptive noise(CEEMDAN),minimum mean square variance criterion(MMSVC) and least mean square adaptive filter(LMSAF).This noise reduction technique,named CEEMDAN-MMSVC-LMSAF,has three main advantages:(i) as an improved algorithm of empirical mode decomposition(EMD) and ensemble EMD(EEMD),CEEMDAN can better suppress mode mixing,and can avoid selecting the number of decomposition in variational mode decomposition(VMD);(ii) MMSVC can identify noisy intrinsic mode function(IMF),and can avoid selecting thresholds of different permutation entropies;(iii) for noise reduction of noisy IMFs,LMSAF overcomes the selection of deco mposition number and basis function for wavelet noise reduction.Firstly,CEEMDAN decomposes the original signal into IMFs,which can be divided into noisy IMFs and real IMFs.Then,MMSVC and LMSAF are used to detect identify noisy IMFs and remove noise components from noisy IMFs.Finally,both denoised noisy IMFs and real IMFs are reconstructed and the final denoised signal is obtained.Compared with other noise reduction techniques,the validity of CEEMDAN-MMSVC-LMSAF can be proved by the analysis of simulation signals and real underwater acoustic signals,which has the better noise reduction effect and has practical application value.CEEMDAN-MMSVC-LMSAF also provides a reliable basis for the detection,feature extraction,classification and recognition of underwater acoustic signals.
基金supported by the National Science Foundation of China (No.61371169)the Aeronautical Science Foundation of China(No.20120152001)
文摘The problem of two-dimensional(2 D)direction of arrival(DOA)estimation for double parallel uniform linear arrays is investigated in this paper.A real-valued DOA estimation algorithm of noncircular(NC)signal is proposed,which combines the Euler transformation and rotational invariance(RI)property between subarrays.In this work,the effective array aperture is doubled by exploiting the noncircularity of signals.The complex arithmetic is converted to real arithmetic via Euler transformation.The main contribution of this work is not only extending the NC-Euler-ESPRIT algorithm from uniform linear array to double parallel uniform linear arrays,but also constructing a new 2 Drotational invariance property between subarrays,which is more complex than that in NCEuler-ESPRIT algorithm.The proposed 2 DNC-Euler-RI algorithm has much lower computational complexity than2 DNC-ESPRIT algorithm.The proposed algorithm has better angle estimation performance than 2 DESPRIT algorithm and 2 D NC-PM algorithm for double parallel uniform linear arrays,and is very close to that of 2 D NC-ESPRIT algorithm.The elevation angles and azimuth angles can be obtained with automatically pairing.The proposed algorithm can estimate up to 2(M-1)sources,which is two times that of 2 D ESPRIT algorithm.Cramer-Rao bound(CRB)of noncircular signal is derived for the proposed algorithm.Computational complexity comparison is also analyzed.Finally,simulation results are presented to illustrate the effectiveness and usefulness of the proposed algorithm.
基金Supported by the National Natural Science Foundation of China (61072098 61072099+1 种基金 60736006)PCSIRT-IRT1005
文摘A new direction finding method is presented to deal with coexisted noncoherent and co- herent signals without smoothing operation. First the direction-of-arrival （DOA） estimation task is herein reformulated as a sparse reconstruction problem of the cleaned array covariance matrix, which is processed to eliminate the affection of the noise. Then by using the block of matrices, the information of DOAs which we pursuit are implied in the sparse coefficient matrix. Finally, the sparse reconstruction problem is solved by the improved M-FOCUSS method, which is applied to the situation of block of matrices. This method outperforms its data domain counterpart in terms of noise suppression, and has a better performance in DOA estimation than the customary spatial smoothing technique. Simulation results verify the efficacy of the proposed method.
文摘The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained experimentally through tests on specimens under multiaxial loading with that calculated by the variance method. In the statistical approach criteria, several methods have been developed but we have presented only one method, namely the variance method using the equivalent stress. She assumes that the fracture plane orientation is the one on which the variance of the equivalent stress is maximum. Three types of equivalent stress are defined for this method [1]: normal stress, shear stress and combined normal and shear stress. The results obtained were compared with experimental results for multiaxial cyclic stress states, and it emerges that the variance method for the case of combined loading is conservative as it gives a better prediction of the fracture plane.
文摘Working toward an efficient duration and timeline for the preconstruction phase should be one of the main objectives for project owners.Failing to plan for and coordinate preconstruction decisions in order to control preconstruction duration and manage time variances can lead to financial insecurities,incomplete contract documents,permitting issues,and unrealistic schedules and resource allocation during this phase.To minimize time variances and ensure a productive decision-making process,project owners should be familiar with critical elements in a project that cause variances in the preconstruction phase timeline.In this study,the impacts of eleven critical preconstruction elements on time variances were analyzed.These eleven preconstruction elements are considered critical in how they impact time variances during the preconstruction phase.They were determined to be critical based either on significantly impacting time variance during the preconstruction phase or believed to be critical from findings from previous studies,however,the findings from this study showed no significant impact on the time variances.In most previous studies focusing on the elements impacting project schedules,data were collected by surveying construction professionals.In this study,objective and quantitative data related to project preconstruction elements were used as opposed to self-reported data.Using the results of this study,project owners and stakeholders will be able to evaluate the critical preconstruction elements impacting the timing of their projects and prioritize decisions related to the critical elements early on during the preconstruction phase.
基金supported by the Ministry of Education,Singapore,under its Academic Research Fund Tier 2 Grant MOE-T2EP20222-0003.
文摘The valuation of financial derivatives often assumes risk neutrality with respect to the risk-neutral martingale measure,which prevents arbitrage opportunities.However,casual traders may still incur substantial losses when trading at this risk-neutral price,especially when the price has to be paid now and the payoff is only realized in the future.This study proposes a new valuation framework that provides risksensitive investors with an additional safeguard.The proposed framework embraces a worst-case perspective while exploiting the underlier’s stochastic process,representing a combination of robust optimization and stochastic programming.Notably,it aims to mitigate losses in the likelier scenarios of the underlying asset’s prices.When the underlier’s returns are independent and lognormally but not necessarily identically distributed,our approach for pricing variance and volatility swaps could be greatly simplified,benefit from parallel computing,and be solved by a two-dimensional grid search.We further derive a closed-form solution in some special stationary cases and provide experimental results to highlight the effect of risk aversion on fending off sizable trading losses.
基金supported by the National Natural Science Foundation of China(No.42174011)。
文摘In the variance component estimation(VCE)of geodetic data,the problem of negative VCE is likely to occur.In the ordinary additive error model,there have been related studies to solve the problem of negative variance components.However,there is still no related research in the mixed additive and multiplicative random error model(MAMREM).Based on the MAMREM,this paper applies the nonnegative least squares variance component estimation(NNLS-VCE)algorithm to this model.The correlation formula and iterative algorithm of NNLS-VCE for MAMREM are derived.The problem of negative variance in VCE for MAMREM is solved.This paper uses the digital simulation example and the Digital Terrain Mode(DTM)to prove the proposed algorithm's validity.The experimental results demonstrated that the proposed algorithm can effectively correct the VCE in MAMREM when there is a negative VCE.
基金supported by the National Key Research and Development Plan of China(Grant No.2022YFB3207402)the National Natural Science Foundation of China(Grant Nos.U1833104 and 61735011).
文摘In traditional sensing,each parameter is treated as a real number in the signal demodulation,whereas the electric field of light is a complex number.The real and imaginary parts obey the Kramers-Kronig relationship,which is expected to help further enhance sensing precision.We propose a self-Bayesian estimate of the method,aiming at reducing measurement variance.This method utilizes the intensity and phase of the parameter to be measured,achieving statistical optimization of the estimated value through Bayesian inference,effectively reducing the measurement variance.To demonstrate the effectiveness of this method,we adopted an optical fiber heterodyne interference sensing vibration measurement system.The experimental results show that the signal-to-noise ratio is effectively improved within the frequency range of 200 to 500 kHz.Moreover,it is believed that the self-Bayesian estimation method holds broad application prospects in various types of optical sensing.
基金supported by the National Natural Science Foundation of China(62371225).
文摘The Global Position System(GPS)is a reliable method for positioning in most scenarios,but it falls short in harsh environments like urban vehicular scenarios,where numerous trees or flyovers obstruct the signals.This presents an unprecedented challenge for autonomous vehicles or applications requiring high accuracy.Fortunately,vehicular ad-hoc networks(VANET)offer an effective solution,where vehicle-to-vehicle(V2V)and vehicle-to-infrastructure(V2I)communications are used to enhance location awareness.In V2I communications,the roadside units(RSU)transmit beacon packets,and the vehicle receives numerous packets from different RSUs to establish communication.To further improve localization accuracy,a cross-covariance matrices-alternating least square(CCM-ALS)algorithm is proposed.The algorithm relies on ALS of the CCM for obtaining the position of vehicles in V2I communications.The algorithm is highly precise compared to traditional angle of arrival(AOA)positioning and not inferior to direct position determination(DPD)approaches while being low in complexity,which is crucial for moving vehicles.The numerical results verify the superiority of the proposed method.
文摘Increases in climate variability, including extremes, may be expected with anthropogenic climate change, but some evidence is contrary. The issue is important because the consequences of variability can be critical for ecosystems. It has long been known and often rehearsed that ecological consequences of increased variability may be greater than those that result from expected changes in mean temperature and precipitation. Tree rings have been useful indicators of ecological response to climate change and used as proxies for climate variability;work in the Rocky Mountains, USA, has been particularly informative. Chronologies from two high elevation species ranging over 2500 km were analyzed for changes in variance through time. These spatially extensive and disaggregated tree ring records do not show a consistent pattern of change in variance over the past 500 or 100 years; heteroscedasticity has recently been greater. A lack of consistent response in growth over a period encompassing changes in mean climate indicates that mountain environments, with inconsistent trends in temperature and precipitation,may be too complex to act as sentinels.
基金support from various sources,including the National Natural Science Foundation of China(Grant Nos.81570774,82070872,92049118,and 82370854)the Junior Thousand Talents Program of China,and the Nanjing Medical University Startup Fund(All awarded to J.L.)support provided by Jiangsu Province's Innovation Personal as well as Innovative and Entrepreneurial Team of Jiangsu Province(Grant No.JSSCTD2021)(All awarded to J.L.).
文摘V-raf-leukemia viral oncogene 1(RAF1),a serine/threonine protein kinase,is well established to play a crucial role in tumorigenesis and cell development.However,the specific role of hypothalamic RAF1 in regulating energy metabolism remains unknown.In this study,we found that the expression of RAF1 was significantly increased in hypothalamic AgRP neurons of diet-induced obesity(DIO)mice.Under normal chow diet feeding,overexpression of Raf1 in AgRP neurons led to obesity in mice characterized by increased body weight,fat mass,and impaired glucose tolerance.Conversely,Raf1 knockout in AgRP neurons protected against diet-induced obesity,reducing fat mass and improving glucose tolerance.Mechanistically,Raf1 activated the MAPK signaling pathway,culminating in the phosphorylation of cAMP response element-binding protein(CREB),which enhanced transcription of Agrp and Npy.Insulin stimulation further potentiated the RAF1-MEK1/2-ERK1/2-CREB axis,highlighting RAF1's role in integrating hormonal and nutritional signals to regulate energy balance.Collectively,these findings underscore the important role of RAF1 in AgRP neurons in maintaining energy homeostasis and obesity pathogenesis,positioning it and its downstream pathways as potential therapeutic targets for innovative strategies to combat obesity and related metabolic diseases.
文摘In this paper, a new feature space for PD （partial discharge） signal separation is presented. Three typical PD defects were experimentally reproduced in a laboratory for obtaining independent PD sources. Signals were acquired with a digital storage oscilloscope and then post-processed with DWT （discrete Wavelet transform） for de-noising. The new feature space for PD source separation was constructed with the variance of each Wavelet coefficient vector and was compared with an established feature space for PD source separation; based on the energy of DWT coefficient vectors. After a space reduction by mean of PCA （principal components analysis）, the separation capability among them was measured by comparing the final classification error after training a neural network Results showed that with this new feature space it is possible to separate different sources of PD signals. Later, the feature space proposed was used to separate two PD sources from a real equipment tested. Further analysis on the reduced feature space has shown the band location of PD signals information for separating purpose.
基金supported by the Wellcome Trust(grant No.103852).
文摘The nervous system function requires a precise but plastic neural architecture.The neuronal shape dictates how neurons interact with each other and with other cells,being the morphology of dendrites and axons the central determinant of the functional properties of neurons and neural circuits.The topological and structural morphology of axons and dendrites defines and determines how synapses are conformed.The morphological diversity of axon and dendrite arborization governs the neuron’s inputs,synaptic integration,neuronal computation,signal transmission,and network circuitry,hence defining the particular connectivity and function of the different brain areas.
基金supported by the College of Oral Medicine,Taipei Medical University,Taipei,Taiwan(Grant No.TMUCOM202502)supported by Taipei Medical University Hospital,Taipei,Taiwan(Grant No.114TMUH-NE-05).
文摘This narrative review examines recent advances in salivary biomarkers for oral squamous cell carcinoma(OSCC),a major subtype of oral cancer with persistently low five-year survival rates due to delayed diagnosis.Saliva has emerged as a noninvasive diagnostic medium capable of reflecting both local tumor activity and systemic physiological changes.Various salivary biomarkers,including microRNAs,cytokines,proteins,metabolites,and exosomes,have been linked to oncogenic signaling pathways involved in tumor progression,immune modulation,and therapeutic resistance.Advances in quantitative polymerase chain reaction,mass spectrometry,and next-generation sequencing have enabled comprehensive biomarker profiling,while point-of-care detection systems and saliva-based omics platforms are accelerating clinical translation.Remaining challenges include variability in salivary composition,lack of standardized collection protocols,and insufficient validation across large patient cohorts.This review highlights the mechanistic relevance,diagnostic potential,and translational challenges of salivary biomarkers in OSCC.
基金funded by the Yancheng Municipal Health Commission 2024 Medical Research Project(YK2024166).
文摘Objective:To investigate the anti-atherosclerosis effect of chikusetsusaponinⅣ(CSⅣ)against high-fat diet-induced atherosclerosis in rats.Methods:A high-fat diet was used for the induction of atherosclerosis in rats,and the rats received oral CSⅣor atorvastatin.The body weight,organ weights,food intake,calorie intake,lipid parameters,3-hydroxy-3-methylglutaryl coenzyme A(HMG-CoA)/mevalonate ratio,collagen,free fatty acid,cardiac parameters,apolipoprotein(A and B),antioxidant parameters,inflammatory cytokines,and inflammatory parameters were assessed.The mRNA expressions of interleukin-1β(IL-1β),tumor necrosis factor-α(TNF-α),IL-6,IL-17,PI3K,AKT,and mTOR were estimated.Results:CSⅣsignificantly modulated food intake,body weight,organ weight(liver,kidney,and heart),and calories(P<0.05).Total cholesterol,triglycerides,very low-density lipoprotein cholesterol,low-density lipoprotein cholesterol,cardiovascular risk index-1,and cardiovascular risk index-2 were decreased,while high-density lipoprotein cholesterol and anti-atherogenic index were increased significantly in the CSⅣgroup(P<0.05).Besides,CSⅣsignificantly restored the level of HMG-CoA/mevalonate ratio,collagen,free fatty acid,cardiac parameters(creatinine kinase-MB,lactate dehydrogenase,cTnT,cTnI),apolipoprotein(apolipoprotein A and apolipoprotein B),antioxidant parameters(MDA,CAT,GPx,GSH,SOD),inflammatory cytokines(TNF-α,IL-1β,IL-6,IL-10),inflammatory parameters(COX-2,TGF-β,NF-κB),intercellular adhesion molecule-1,vascular cell adhesion molecule-1,and monocyte chemoattractant protein-1.CSⅣalso decreased the mRNA expression of IL-1β,TNF-α,IL-6,IL-17,PI3K,AKT,and mTOR.Conclusions:This study showed the anti-atherosclerosis effect of CSⅣagainst high-fat diet-induced atherosclerosis in rats via alteration of NF-κB/COX-2 and PI3K/AKT/mTOR signaling pathway.
基金Supported by the State Key Laboratory of Acoustics and Marine Information Chinese Academy of Sciences(SKL A202507).
文摘Accurate time delay estimation of target echo signals is a critical component of underwater target localization.In active sonar systems,echo signal processing is vulnerable to the effects of reverberation and noise in the maritime environment.This paper proposes a novel method for estimating target time delay using multi-bright spot echoes,assuming the target’s size and depth are known.Aiming to effectively enhance the extraction of geometric features from the target echoes and mitigate the impact of reverberation and noise,the proposed approach employs the fractional order Fourier transform-frequency sliced wavelet transform to extract multi-bright spot echoes.Using the highlighting model theory and the target size information,an observation matrix is constructed to represent multi-angle incident signals and obtain the theoretical scattered echo signals from different angles.Aiming to accurately estimate the target’s time delay,waveform similarity coefficients and mean square error values between the theoretical return signals and received signals are computed across various incident angles and time delays.Simulation results show that,compared to the conventional matched filter,the proposed algorithm reduces the relative error by 65.9%-91.5%at a signal-to noise ratio of-25 dB,and by 66.7%-88.9%at a signal-to-reverberation ratio of−10 dB.This algorithm provides a new approach for the precise localization of submerged targets in shallow water environments.
基金supported by grants from NIH T32(DK007260,to WC)the Steno North American Fellowship awarded by the Novo Nordisk Foundation(NNF23OC0087108,to WC)+6 种基金STI2030-Major Projects(2021ZD0202700,to HY)the National Natural Science Foundation of China(32241004,to HY)the Natural Science Foundation of Zhejiang Province of China(LR24C090001,to HY)Key R&D Program of Zhejiang Province(2024SSYS0017,to HY)CAMS Innovation Fund for Medical Sciences(2019-12M-5-057,to HY)Fundamental Research Funds for the Central Universities(226-2022-00193,to HY)the Non-profit Central Research Institute Fund of Chinese Academy of Medical Sciences(2023-PT310-01,to HY)。
文摘Type 2 diabetes mellitus has central complications:Diabetes,a metabolic disorder primarily characterized by hyperglycemia due to insufficient insulin secretion,or impaired insulin signaling,has significant central complications.Type 2 diabetes mellitus(T2DM),the most prevalent type of diabetes,affects more than 38 million individuals in the United States(approximately 1 in 10)and is defined by chronic hyperglycemia and insulin resistance,which refers to a reduced cellular response to insulin.
文摘Protein aggregates,mitochondrial import stress and neurodegenerative disorders:A salient hallmark of several neurodegenerative diseases,including Parkinson’s disease,is the abundance of protein aggregates(Goiran et al.,2022).This molecular event is believed to lead to activation of stress pathways ultimately resulting in cellular dysfunction(Eldeeb et al.,2022).Accordingly,many lines of research investigations focused on dampening the formation of protein aggregates or augmenting the clearance of protein aggregates as a potential therapeutic strategy to counteract the progression of neurodegenerative diseases,albeit with little success(Costa-Mattioli and Walter,2020).Cell stress cues such as the accumulation of protein aggregates lead to the activation of stress response pathways that aid cells in responding to the damage.Despite the notion that the transient activation of these pathways helps cells cope with stressors,persistent activation can induce unwanted apoptosis of cells and reduce overall tissue strength as well as lead to an accumulation of aggregation-prone proteins(Hetz and Papa,2018).Mutations in proteins involved in stress signaling termination can cause conditions like ataxia and early-onset dementia(Conroy et al.,2014).Therefore,it is crucial for stress response signaling to be turned off once conditions have improved.Nevertheless,the mechanisms by which cells silence these signals are still elusive.
基金National Basic Research Program of China (JW132006093)
文摘An identification method using Allan variance and equivalent theorem is proposed to identify non-stationary sensor errors mixed out of different simple noises. This method firstly derives the discrete Allan variances of all component noises inherent in noise sources in terms of their different equations; then the variances are used to estimate the parameters of all component noise models; finally, the original errors are represented by the sum of the non-stationary component noise model and the equivalent m...
