Threshold Estimation Research Articles

Decision-making analysis on collection and transportation distance of rural domestic waste: case study of Guangxi Province, China

There were two collection, transportation and treatment models for rural domestic waste management: urban–rural disposal model and area-based disposal model. In the urban–rural disposal model, rural domestic waste is collected in villages, transferred in towns, and disposed in centralized disposal sites of county, whereas area-based disposal model meant that each village built its own small-scale domestic waste facility. The threshold of transportation distance between urban centralized disposal sites and villages determined which of these two models would be more cost-effective. In this study, a distance decision-making model to obtain the threshold of collection and transportation distance was proposed. Besides, by application of this distance decision-making model supported by GIS software, 14588 villages of Guangxi Province, China were recommended to apply urban–rural disposal model or area-based disposal model. Results showed that (1) distance threshold decreases as the population of village increases; (2) when the population size of the village was up to 20000 people, it was more cost-effective choosing area-based disposal model; (3) a total of 10932 villages in Guangxi Province were recommended to select urban–rural disposal model, 71% of which should expand treatment scales of urban centralized disposal sites. In addition, 3554 villages were recommended to select area-based disposal model; (4) the parameters of amount of per capita domestic waste output, the average life of the facilities, cost of building new small-scale area-based treatment facilities, and cost of collection and transportation of waste have high sensitivity for distance threshold estimation.

Adaptive thresholding estimator for differential association structures in two independent contingency tables

In this paper, we consider an adaptive thresholding procedure to estimate the difference of association structures in two independent two-way contingency tables of the same order. Here, we assume that the class of paired association structures have an approximately sparse difference. Under $L_1$ and $L_2$ loss functions, we establish the corresponding risk's upper bounds for our differential association adaptive thresholding estimators. Moreover, we show that these estimators perform well in a simulated setting. In this line, we carry out a simulation study and compare two well-known independent social mobility datasets.

Wavelet-Based Quantile Density Estimation By Block Thresholding Method Under L2 Loss Function

In this paper, we consider an adaptive wavelet estimation for quantile density function based on block thresholding method and obtain it's convergence rate under L2 loss function over Besove function spaces. This work is an extension of results in Chesneau et. al. (2016) and shows that the block threshold estimator gets better convergence rate (Optimal) than the estimators proposed by Chesneau et. al. (2016). The performance of the proposed estimator is investigated with a simulation study.

Threshold Estimation for a Spectrally Negative Lévy Process

Consider a spectrally negative Lévy process with unknown diffusion coefficient and Lévy measure and suppose that the high frequency trading data is given. We use the techniques of threshold estimation and regularized Laplace inversion to obtain the estimator of survival probability for a spectrally negative Lévy process. The asymptotic properties are given for the proposed estimator. Simulation studies are also given to show the finite sample performance of our estimator.

Analysis of radio frequency spectrum usage using cognitive radio

This paper presents the analysis of radio frequency (RF) spectrum usage using cognitive radio. The aim was to determine the unused spectrum frequency bands for efficiently utilization. A program was written to reuse a range of vacant frequency with different model element working together to produce a spectrum sensing in MATLAB/Simulink environment. The developed Simulink model was interfaced with a register transfer level - software defined radio, which measures the estimated noise power of the received signal over a given time and bandwidth. The threshold estimation performed generates a 1\0 output for decision and prediction. It was observed that some spectrum, identified as vacant frequency, were underutilized in FM station in Benin City. The result showed that when cognitive radio displays “1” output, which is decision H1, the channel is occupied and cannot be used by the cognitive radio for communication. Conversely, when “0” output (decision H0) is displayed, the channel is unoccupied. There is a gradual decrease in the probability of detection (Pd), when the probability of false alarm (Pfa) is increased from 1% to 5%. In the presence of higher Pfa, the Pd of the receiver maintains a high stability. Hence, the analysis finds the spectrum hole and identifies how it can be reused

Nonparametric threshold estimation of spot volatility based on high-frequency data for time-dependent diffusion models with jumps

We construct a spot volatility kernel estimator of time-dependent diffusion models with jumps. Instead of idiomatic intraday return over an observation interval, in the proposed estimator, we use intraday range. Since the range represents the maximum difference among all observations within an interval, all data are used, and no information is lost. By setting a reasonable threshold and making the range not greater than it we effectively eliminate the negative effect of jump on volatility estimation. In this paper, we also prove the consistency and asymptotic normality of the estimator and testify its higher accuracy.

Estimation of maximum thermo-hygrometric index thresholds affecting milk production in Italian Brown Swiss cattle

It is known that heat stress affects dairy cow performance in multiple ways: physiological, behavioral, reproductive, and productive. The aim of the present study was to determine if a threshold of temperature-humidity index (THI) exists for multiple milk production traits (milk yield, fat-corrected milk, protein and fat yield and percentage, energy-corrected milk, cheese production, and cheese yield) in Italian Brown Swiss dairy cows from the period 15 d before the day of the Italian Breeders Association test-day sampling. A 10-yr data set (2009-2018) containing 202,776 test-day records of 23,296 Brown Swiss cows was matched with the maximum THI. In all parities considered, no THI thresholds were observed for milk yield in Brown Swiss. In contrast, a THI threshold of 75 was identified for fat-corrected milk. No THI threshold was found for fat percentage, but fat yield showed the highest THI thresholds in cows of first and second parity. Protein yield and cheese production were affected by heat stress with average THI threshold of 74. The THI thresholds identified indicate that the Brown Swiss breed has higher thermal tolerance versus literature values reported for Holstein cows. As THI rises, Brown Swiss cows tend to produce the same volume of milk, but with a decreasing quality with regard to components. Further study is necessary to estimate the genetic component of heat tolerance, in Brown Swiss cattle, considering that the correct estimation of THI thresholds represents the first step to identify components that could be included in selection procedures.

Challenges in urban stormwater management in Chinese cities: A hydrologic perspective

For managing the worsening urban water disasters in China, the Government of China proposed the concept of “Sponge City” in 2013 and initiated the strategy in 30 pilot cities from 2015. Despite the promise of the concept, there have been many challenges in implementing the “Sponge City” program (SCP). In this manuscript, we discuss the hydrology-related challenges in implementing the SCP. In particular, we consider two key challenges: (1) Determination of the “Volume Capture Ratio of Annual Rainfall” (VCRAR), as controlling urban stormwater runoff is one of the core targets of the SCP; and (2) Estimation of a proper rainfall threshold, which influences the layout of green-infrastructures in the SCP to achieve the core VCRAR target. To discuss these challenges, we consider the city of Beijing, the capital of China, as a case study. Our analysis shows that the trade-offs between the investment for the SCP and its potential economic benefits should be considered by undertaking a proper determination of VCRAR. The VCRAR estimated for Beijing from the present analysis is 0.73. This value is more reasonable than the empirical value of 0.80 that is presently used, as it can guarantee the positive rate of return on the investment. We also find that the nonstationary characteristics of rainfall data and their spatiotemporal differences are important for the estimation of the rainfall threshold in SCP. For instance, even using the daily rainfall data over a period of 30 years (1983–2012) in Beijing, as required by the National Assessment Standard, the estimated rainfall threshold of 27.3 mm underestimates the reasonable rainfall threshold that should at least be larger than 30.0 mm. Thus, the former cannot ensure the VCRAR target of 0.80. Based on these results, we offer proper approaches and key suggestions towards useful guidelines for delivering better SCP in the Chinese cities.

Assessing thermal sensitivity using transient heat and cold stimuli combined with a Bayesian adaptive method in a clinical setting: A proof of concept study.

Quantitative sensory testing of thermal detection abilities is used as a clinical tool to assess the function of pain pathways. The most common procedure to assess thermal sensitivity, the 'method of limits', provides a quick but rough estimate of detection thresholds. Here, we investigate the potential of evaluating not only the threshold but also the slope of the psychometric functions for cold and warm detection. A convenience sample of 15 patients with diabetes mellitus (DM) and 15 age-matched healthy controls (HC) was tested. Thirty brief (100ms) stimuli of each modality were applied to the volar wrist and foot dorsum. Cold and warm stimuli were delivered with a Peltier thermode and a temperature-controlled CO2 laser, respectively. Stimulus intensities were dynamically selected using an adaptive Bayesian algorithm (psi method) maximizing information gain for threshold and slope estimation. ROC analyses were used to assess the ability of slopes, thresholds and the combination of both to discriminate between groups. Assessment of the slope and threshold of the psychometric function for thermal detection took about 10min. The ability to detect warmth was not reduced in DM patients as compared to HC. Cold detection performance assessed using slope or threshold parameters separated DM from HC with good discriminative power. Discrimination was further increased when both parameters were used together (93% sensitivity and 87% specificity), indicating that they provide complementary information on patient status. The psi method may be an interesting alternative to the classical method of limits for thermal QST. Current QST protocols provide an incomplete and potentially biased estimate of sensory detection performance. We propose a method that estimates the slope and the threshold of the psychometric function, defining heat and cold sensory detection performance, in only a few minutes. Furthermore, we provide preliminary evidence that combining slope and threshold parameters of cold detection performance leads to a better discriminative ability than relying solely on the threshold.

A quick and reliable estimate of extended high-frequency hearing

ObjectiveTo encourage researchers to perform high-frequency threshold estimation using a technique outlined by Rieke and colleagues, described as fixed-level frequency threshold estimation. Their method used a Bekesy-style roving tone to estimate the highest audible frequency of a listener. The tone was fixed in its intensity (SPL) and changed in frequency as the participant indicated whether they could perceive the tone, or not. This was developed specifically for ototoxicity monitoring in the extended high-frequency region. Rieke and colleagues established that this approach to measuring hearing thresholds is both fast and reliable.DesignThe current article extends this approach to using a simple PC-soundcard-transducer setup and the method of limits to rapidly establish the highest audible frequency of a listener.Study sample: 24 listeners performed standard and fixed-level audiometry in the extended high-frequency range.ResultsThe method described is rapid and reliable and a single summary metric is obtained for each listener.ConclusionsThe advantage of the described approach over standard pure-tone audiometry in the extended high-frequency range is the time taken, the ability to avoid missing data points and the risk of distortions or electrical noise when close to maximal system output.

Time of arrival estimation based on clustering for positioning in OFDM system

In positioning research based on the orthogonal frequency division multiplex (OFDM) system, the observed time difference of arrival positioning method is a widely studied direction. The terminal measures the reference signal sent by the base station to calculate the time of arrival (TOA). Using TOA information, the location of the terminal can be identified. So the accuracy of the positioning is highly dependent on the results of the TOA measurements. Terminals often have difficulty measuring accurate TOA due to multipath channels and occlusion of obstacles. This study proposes two clustering-based TOA estimation methods. The cluster-based Max-peak estimator is used to solve the problem that the energy of the first-path is not the strongest in the case of multipath. Moreover, a cluster-based adaptive threshold estimator is used to estimate TOA when the power of the direct path is low. The joint estimator of the two methods is designed to improve estimation accuracy. The proposed method is tested in the OFDM localisation environment, and the results demonstrate that the proposed method has better performance than the conventional way.

Patient-Specific Analysis of Neural Activation During Spinal Cord Stimulation for Pain

Despite the widespread use of spinal cord stimulation (SCS) for chronic pain management, its neuromodulatory effects remain poorly understood. Computational models provide a valuable tool to study SCS and its effects on axonal pathways within the spinal cord. However, these models must include sufficient detail to correlate model predictions with clinical effects, including patient-specific data. Therefore, the goal of this study was to investigate axonal activation at clinically relevant SCS parameters using a computer model that incorporated patient-specific anatomy and electrode locations. We developed a patient-specific computer model for a patient undergoing SCS to treat chronic pain. This computer model consisted of two main components: 1) finite element model of the extracellular voltages generated by SCS and 2) multicompartment cable models of axons in the spinal cord. To determine the potential significance of a patient-specific approach, we also performed simulations with standard canonical models of SCS. We used the computer models to estimate axonal activation at clinically measured sensory, comfort, and discomfort thresholds. The patient-specific and canonical models predicted significantly different axonal activation. Relative to the canonical models, the patient-specific model predicted sensory threshold estimates that were more consistent with the corresponding clinical measurements. These results suggest that it is important to account for sources of interpatient variability (e.g., anatomy, electrode locations) in model-based analysis of SCS. This study demonstrates the potential for patient-specific computer models to quantitatively describe the axonal response to SCS and to address scientific questions related to clinical SCS.

A novel mechatronic system for evaluating elbow muscular spasticity relying on Tonic Stretch Reflex Threshold estimation.

Muscular spasticity represents one of the most common motor disorder associated to lesions of the Central Nervous System, such as Stroke, and affects joint mobility up to the complete prevention of skeletal muscle voluntary control. Its clinical evaluation is hence of fundamental relevance for an effective rehabilitation of the affected subjects. Standard assessment protocols are usually manually performed by humans, and hence their reliability strongly depends on the capabilities of the clinical operator performing the procedures. To overcome this limitation, one solution is the usage of mechatronic devices based on the estimation of the Tonic Stretch Reflex Threshold, which allows for a quite reliable and operator-independent evaluation. In this work, we present the design and characterization of a novel mechatronic device that targets the estimation of the Tonic Stretch Reflex Threshold at the elbow level, and, at the same time, it can potentially act as a rehabilitative system. Our device can deliver controllable torque/velocity stimulation and record functional parameters of the musculo-skeletal system (joint position, torque, and multi-channel ElectroMyoGraphyc patterns), with the ultimate goals of: i) providing significant information for the diagnosis and the classification of muscular spasticity, ii) enhancing the recovery evaluation of patients undergoing through therapeutic rehabilitation procedures and iii) enabling a future active usage of this device also as therapeutic tool.Clinical relevance- The contribution presented in this work proposes a technological advancement for a device-based evaluation of motion impairment related to spasticity, with a major potential impact on both the clinical appraisal and the rehabilitation procedures.

Gene Expression Thresholds Derived From Short-term Exposures Identify Rat Liver Tumorigens.

Traditional methods for cancer risk assessment are resource-intensive, retrospective, and not feasible for the vast majority of environmental chemicals. In this study, we investigated whether quantitative genomic data from short-term studies may be used to set protective thresholds for potential tumorigenic effects. We hypothesized that gene expression biomarkers measuring activation of the key early events in established pathways for rodent liver cancer exhibit cross-chemical thresholds for tumorigenesis predictive for liver cancer risk. We defined biomarker thresholds for 6 major liver cancer pathways using training sets of chemicals with short-term genomic data (3-29 days of exposure) from the TG-GATES (n = 77 chemicals) and DrugMatrix (n = 86 chemicals) databases and then tested these thresholds within and between datasets. The 6 pathway biomarkers represented genotoxicity, cytotoxicity, and activation of xenobiotic, steroid, and lipid receptors (aryl hydrocarbon receptor, constitutive activated receptor, estrogen receptor, and peroxisome proliferator-activated receptor α). Thresholds were calculated as the maximum values derived from exposures without detectable liver tumor outcomes. We identified clear response values that were consistent across training and test sets. Thresholds derived from the TG-GATES training set were highly predictive (97%) in a test set of independent chemicals, whereas thresholds derived from the DrugMatrix study were 96%-97% predictive for the TG-GATES study. Threshold values derived from an abridged gene list (2/biomarker) also exhibited high predictive accuracy (91%-94%). These findings support the idea that early genomic changes can be used to establish threshold estimates or "molecular tipping points" that are predictive of later-life health outcomes.

Establishing seasonal and alert influenza thresholds in Morocco

BackgroundSeveral statistical methods of variable complexity have been developed to establish thresholds for influenza activity that may be used to inform public health guidance. We compared the results of two methods and explored how they worked to characterize the 2018 influenza season performance–2018 season.MethodsHistorical data from the 2005/2006 to 2016/2018 influenza season performance seasons were provided by a network of 412 primary health centers in charge of influenza like illness (ILI) sentinel surveillance. We used the WHO averages and the moving epidemic method (MEM) to evaluate the proportion of ILI visits among all outpatient consultations (ILI%) as a proxy for influenza activity. We also used the MEM method to evaluate three seasons of composite data (ILI% multiplied by percent of ILI with laboratory-confirmed influenza) as recommended by WHO.ResultsThe WHO method estimated the seasonal ILI% threshold at 0.9%. The annual epidemic period began on average at week 46 and lasted an average of 18 weeks. The MEM model estimated the epidemic threshold (corresponding to the WHO seasonal threshold) at 1.5% of ILI visits among all outpatient consultations. The annual epidemic period began on week 49 and lasted on average 14 weeks. Intensity thresholds were similar using both methods. When using the composite measure, the MEM method showed a clearer estimate of the beginning of the influenza epidemic, which was coincident with a sharp increase in confirmed ILI cases.ConclusionsWe found that the threshold methodology presented in the WHO manual is simple to implement and easy to adopt for use by the Moroccan influenza surveillance system. The MEM method is more statistically sophisticated and may allow a better detection of the start of seasonal epidemics. Incorporation of virologic data into the composite parameter as recommended by WHO has the potential to increase the accuracy of seasonal threshold estimation.

An engineering estimation of fatigue thresholds from a microstructural size and Vickers hardness: application to wrought and additively manufactured metals

A novel empirical bi-parametric model based on the Vickers hardness HV and a microstructural length parameter, l, is proposed to estimate the fully-reversed threshold-Stress Intensity Factor for long cracks. The model was calibrated on fatigue data of wrought alloys taken from the literature and then extended to additively manufactured (AMed) metals. Experimental results, generated from testing AMed maraging steel 300 specimens containing natural defects as well as taken from the literature, were compared successfully with the estimation based on the El-Haddad model defined solely on the basis of the HV and l.

Do economic freedom matters for finance in developing economies: a panel threshold analysis

ABSTRACT Economic freedom is an important determinant of economic development, yet little academic research has considered its financial perspectives. Using a relatively new measure of finance, we find that a high-freedom environment fosters finance in developing economies. Unlike prior literature, the advanced panel threshold estimator shows a single significant economic freedom threshold level of 4.282 as a benchmark, where the relationship turns positive. The findings are robust to alternative estimators and split-sample analysis. The findings are useful for policymakers to attain optimal financial benefits by assuring a high-freedom environment.

Comparison between the geochemical response of BLEG and fine fraction stream sediments to mineralization in the Eastern Black Sea region, Turkey

Stream sediments are the preferred sampling method in regional geochemical exploration for Au deposits in regions displaying well-defined drainage systems. Analysis of either bulk leach extractable gold (BLEG) and aqua regia-extractable multi-element analysis of fine fraction sediments are two common analytical approaches. This study examines the efficiency of detecting known ore deposits and prospects using parametric (Q-Q) and nonparametric (U-spatial and C-A fractal) modeling of a large compilation of company stream sediment and rock chip geochemical data from exploration programs in the Eastern Black Sea region of Turkey, to identify geochemical patterns related to major precious and base metal deposits.The median and 95th percentile values for Au are similar across the different lithological groups, although BLEG values are high in granite and volcanic-dominated terranes. In general, C-A and U-spatial modeling of individual elements concentrations and PCA scores were more effective than Q-Q plots in separating populations associated with the effects of mineralization and delivered lower estimates for thresholds to the dominant “background” population. There is strong spatial association between the anomalous geochemical populations (especially for PCA scores) and the locations of the majority of known Au ± Ag and Cu ± Pb ± Zn deposits in the study area. Most of the known Au mineral deposits occur in catchments with marginal to strongly anomalous Au concentrations in BLEG or the <180 μm fraction. Known Pb and Cu deposits (of various genetic types) are generally contained in catchments displaying the third or higher C-A fractal or U-spatial populations. BLEG was marginally more effective than <180 μm in detecting catchments with known mineralization.

Nonlinear dynamics of a classical rotating pendulum system with multiple excitations**Project supported by the National Natural Science Foundation of China (Grant Nos. 11702078 and 11771115), the Natural Science Foundation of Hebei Province, China (Grant No. A2018201227) and the High-Level Talent Introduction Project of Hebei University, China (Grant No. 801260201111).

We report an attempt to reveal the nonlinear dynamic behavior of a classical rotating pendulum system subjected to combined excitations of constant force and periodic excitation. The unperturbed system characterized by strong irrational nonlinearity bears significant similarities to the coupling of a simple pendulum and a smooth and discontinuous (SD) oscillator, especially the phase trajectory with coexistence of Duffing-type and pendulum-type homoclinic orbits. In order to learn the effect of constant force on this pendulum system, all types of phase portraits are displayed by means of the Hamiltonian function with large constant excitation especially the transitions of complex singular closed orbits. Under sufficiently small perturbations of the viscous damping and constant excitation, the Melnikov method is used to analyze the global structure of the phase space and the feature of trajectories. It is shown, both theoretically and numerically, that this system undergoes a homoclinic bifurcation and then bifurcates a unique attracting rotating limit cycle. Finally, the estimation of the chaotic threshold of the rotating pendulum system with multiple excitations is calculated and the predicted periodic and chaotic motions can be shown by applying numerical simulations.

Estimation of rainfall thresholds for shallow landslides in the Sierra Madre Oriental, northeastern Mexico

Landslides induced by prolonged rainfalls are frequent mass movements along the northeastern portion of the Sierra Madre Oriental in Mexico, causing significant damage to infrastructure. In this work, we have studied the connection between rainfall and landslides in the Santa Rosa Canyon, a catchment located in the northeastern Mexico. A landslide database triggered by major storms and hurricanes that have hit the region over the past 30 years was analyzed. A total of 92 rainfall events in the Santa Rosa Canyon were studied to determine the amount of precipitation needed to trigger shallow landslides. For each event the duration (D, in hours) and the cumulated rainfall event (E, in mm) were determined by using historical rainfall data from weather stations located near the study area. We have proposed an ED threshold for rainfall-induced landslides with durations 0.5 < D < 120 hours to address the conditions that trigger these events in the study area. On analyzing the obtained threshold, it has been established that almost 60 mm of a daily rainfall accumulation is required to trigger shallow landslides in the study area. This estimation is consistent with other calculations made for areas close to the Santa Rosa Canyon. Finally, we validated the predictive capability of the threshold with a different set of rainfall data that did not result in landslides performing a straightforward receiver operating characteristic analysis. A good approach was obtained, especially for rainfall events with daily measurements. Results could be used as input information in the design of a landslide early warning system for the northeastern Mexico, and replicated for other landslide prone areas in the region.