Observation Interval Research Articles

Reaction of rice varieties to rice leaf folder, Cnaphalocrocis medinalis Guenee in South Gujarat

The rice leaf folder, Cnaphalocrocis medinalis (Guenee) is a serious pest causing a great reduction in the yield of rice during the vegetative stage. In this study, ten rice varieties NAUR-1, GNR-2, GNR-3, GNR-4, GNR-5, GNR-6, GNR-7, GR-15, GR-11, and TN-1, were screened to assess their reaction against C. medinalis at the Main Rice Research Centre Farm, Navsari Agricultural University, Navsari, Gujarat, India during Kharif-2021. The infestation of C. medinalis was recorded in all ten rice varieties at 30, 40, 50, 60, 70, 80, 90, 100 and 110 Days After Transplanting (DAT). The lowest infestation of C. medinalis was recorded in GR-15, GNR-7, GNR-3, GNR-6, GNR-5, GNR-2 and NAUR-1 (score 3) and higher infestation was recorded in GNR-4 (score 5). Whereas the highest infestation was recorded in GR-11 and TN-1 (score 7), in all the observation intervals which were stated as state and national susceptible check.

An Interval Observer for a Class of Cyber–Physical Systems with Disturbance

This paper investigates the problem of interval estimation for cyber–physical systems with unknown disturbance. In order to realize the interval estimation of cyber–physical systems, two technical methods are adopted. The first one requires the observer dynamic error system to be non-negative, and the second one relaxes this limitation by coordinate transformation. The sufficient conditions are established using both Lyapunov stability and positive system theory. Furthermore, according to the Schur complement, the linear matrix inequality is solved to determine the observer gains. Finally, the effectiveness and feasibility of the designed interval observer are verified by one numerical simulation.

Direct Sequence Spread Spectrum Signal’s Parameters Estimation Bounds

The article discusses the problems of direct spread spectrum signal’s parameters estimation and estimation performance analyzing. The achieved estimation variances compared with the corresponding Cramer ‒ Rao bounds as a rule. The proposed approach makes it possible to determine the bounds for signals of various types of modulation and spectral characteristics. The dependences of the Cramer ‒ Rao bounds on the signal-to-noise ratio, the spread spectrum sequence length and the duration of the observation interval are presented.

ESTIMATION OF PROBABILISTIC AND STATISTICAL CHARACTERISTICS OF THE INFORMATIONAL STATE OF A COMMUNICATION CHANNEL

The methods for determining the informational state of a communication channel based on the assessment of probabilistic and statistical characteristics of errors at the channel output are presented. Adaptive information protection methods in digital communication systems, where encoder parameters change depending on the channel state, require the use of network quality control methods based on determining the statistical characteristics of the channel. It is shown that the bit error probability in the channel is constant for the presented error generation process and is independent of the method of dividing information into code blocks. The methods for assessing the statistical characteristics of the channel are based on the topological representation of error generation processes over the length of code blocks. It is demonstrated that, with a fixed code sequence length and a constant bit error probability at the output of the information channel, different error distributions correspond to sets of n-sequences. With a known number of states in the likelihood transition matrix, calculation of observation intervals for counting erroneous blocks is proposed. The presented method of researching statistical characteristics, based on the assumption of error independence, allows for the development of algorithms and procedures for assessing the state of discrete communication channels. The evaluation of potential bounds and statistical characteristics for the decoding error probability enables establishing a connection between the topological characteristics of error sequence partitioning and code parameters. The work confirms that the proposed method allows the synthesis of algorithms for determining code parameters, whose numerical values are determined based on minimizing potential decoding error probabilities.

Features of the coefficient of variation of parameters of the gas environment in fire in the premises

The object of the study is the selective coefficient of variation of dangerous parameters of the gas environment during the ignition of materials. The measure of the sample coefficient of variation of an arbitrary hazardous parameter of the gas environment observed at an arbitrary time interval is substantiated. The representativeness error of the measure of the sampling coefficient of variation, which depends on the value of the measure and the sample size, was determined. The measure allows you to numerically determine its value for an arbitrary observation interval. The difference in the measure at the intervals corresponding to the reliable absence and occurrence of ignition allows to detect the occurrence of ignition of the material. According to the results of laboratory studies, the measures of the sample coefficient of variation for carbon monoxide concentration, smoke density, and temperature of the gas medium in the laboratory chamber at intervals of absence and appearance of ignition of alcohol, paper, wood, and textiles were determined. It was established that the dangerous parameters of the gas environment at the intervals of absence and presence of ignition are characterized by different values of the increase in the measure of the sample coefficient of variation. For example, it is determined that the ignition of alcohol causes the maximum increase in the measure for carbon monoxide concentration from 0.135 to 0.441, for smoke density from 0.629 to 0.805, and for temperature from 0.001 to 0.115. When paper catches fire, the measure for carbon monoxide concentration and temperature increases from 0.0026 to 0.140 and from 0.0019 to 0.05, respectively. When burning wood, the measure for carbon monoxide concentration and temperature increases from 0.0072 to 0.177 and from 0.0067 to 0.016, respectively. The obtained results, provided that the hazardous parameters of the gas environment in the premises are measured and the sample coefficient of variation is calculated in practice, make it possible to use them in the creation of early fire detection systems

Genetic aspects in working with the kholmogory cattle breed in the arkhangelsk region

Monitoring of the genetic structure of cattle breeds allows conducting studies that provide information about the cross-section in the timeline by the frequencies of genotypes of blood groups. In particular, the study was carried out on 10 time intervals of observations in herds for the Kholmogorsky breed of breeding plants of the Arkhangelsk region (n = 10983). The dynamics is shown by the decrease and increase in the frequencies of individual alleles. The genetic structure of the herd becomes more homozygous, as the loss of alleles goes on. A similar situation has developed in the samples of cows of the first and ninth generations, their genetic structures are sharply different. According to the results of the research, it was found that the quantitative and qualitative composition of the allelofund of the Kholmogorsky cattle of the Arkhangelsk region has changed under the influence of breeding processes. It was found that the degree of homozygosity (theoretical) tends to decrease from 10.5% (3rd generation) to 6.5% (9th, 10th generation) in the context of the analyzed generations of females, and the number of effective alleles, respectively, increases from 9.4% to 15.4%. At the same time, it was revealed that the breeding stock of the herds of breeding plants of the Arkhangelsk region was heterogeneous according to the genetic panel of the EAV locus. The greatest genetic distance is shown by purebred cows of the Kholmogorsky breed of cattle of the 1-2 observation intervals with Holstein in the 9-10 intervals. Breeding work and assessment of genetic variability is a tool for successful breeding in cattle herds of breeding plants by generations. The event to create new and improve existing factory lines using genetic markers of breed affiliation is promising. This will reduce the negative consequences of related mating of parent pairs, as well as avoid an increase in the level of homozygosity in the controlled herds of the Arkhangelsk population of the Kholmogorsky cattle breed.

A Preliminary Study of Anti‐TNFα Therapy for Symptomatic Dolichoectatic Vertebrobasilar Aneurysms

Background Dolichoectatic vertebrobasilar aneurysms (DVBAs) carry high morbidity, and treatment options are limited. The tumor necrosis factor α signaling cascade is implicated in DVBA growth and rupture, but the role of anti–tumor necrosis factor α therapy in DVBA has not been studied. Methods A retrospective, case–control study of DVBA at a single institution was performed. Two patients with DVBA were treated with infliximab (tumor necrosis factor α inhibitor) as part of routine therapy for rheumatoid arthritis. Three additional patients diagnosed with DVBA were studied as a control group. Routine brain magnetic resonance imaging/magnetic resonance angiography were measured by 2 blinded neuroradiologists to assess DVBA growth. Baseline comorbidities and clinical outcomes were assessed by chart review. Results The groups were similar with respect to baseline characteristics, and all patients were symptomatic at the time of DVBA diagnosis. One patient who started infliximab during the study period showed a reversal in DVBA growth rate trajectory, with a relative decrease in growth rate by 37% (0.49–0.18 mm 2 /day). Mean interval DVBA growth rates were lower during infliximab therapy than during noninfliximab observation intervals (0.13 versus 0.50 mm 2 /day; P = 0.09). Two patients in the control group died during the study period and 1 had a poor outcome (modified Rankin scale = 4). Both patients in the infliximab group had unchanged functional status (modified Rankin scale = 1) and no adverse events related to infliximab. Conclusion This study presents the first investigation of anti–tumor necrosis factor α therapy for DVBA. Infliximab was associated with low and decreasing DVBA growth trajectories with no treatment‐related adverse events. The effect of infliximab on clinical outcomes remains uncertain.

Tampering attack detection for remote interval observer

In cyber–physical systems (CPSs), secure estimation observes the states of a physical plant remotely with potentially attacked data. Most attacks in CPSs are carefully designed such that they can not only ruin the estimation but also bypass the detector. These attacked estimations would corrupt decision-making and control, leading to decreased production efficiency and even equipment damage. Therefore, detecting these attacks is of great importance. It is noted that one of the reasons that these attacks can be successfully launched is that attackers can inject arbitrary false data into the communication channel at any time step, which makes it possible that the transmission data is tampered with by any designed attack sequences. In this paper, a modified data transmission mechanism is deployed to limit the attacker’s ability, and attack detectors are designed for detecting tampering attacks. Specifically, first of all, a one-bit event-triggered mechanism is deployed to binarize the transmitted data. Secondly, a primary detector is deployed to detect non-binary data received by the observer, and hence the attacker’s ability is greatly reduced. Thirdly, a main detector is designed, which definitely detects tampering attacks that can bypass the primary detector.The necessary and sufficient conditions for definite attack detection are given, with which the gain of interval observable and the threshold of the event-trigger mechanism are designed. Finally, simulation results are presented to verify the analysis.

Observer-based consensus of multi-agent systems under odd distributed impulsive control protocol

In this paper, for leader-follower Lipschitz nonlinear multi-agent systems (MASs) affected by external disturbances, observer-based distributed controller design problems are discussed in order to realize the MASs consensus. Firstly, to deal with unmeasured system states and the unknown disturbances, for each follower, a joint unknown input observer is proposed. To do so, through an interval observer, a mathematical relationship between the state and the disturbance is set up in advance. Secondarily, by using the estimations of the state and the disturbance, a local feedback controller is designed aiming at stabilizing the linear part of each follower. Thirdly, an odd distributed impulsive control method is proposed which is utilized to deal with the nonlinearity. Then the MASs consensus goal is realized by combining the local feedback controller and the distributed impulsive controller. At last, a simulation is discussed so as to display the effectivity of the raised scheme.

ACTIVITY CYCLES OF FK COM

New results of photometric observations of the chromospherically active star FK Com (a prototype of the group of the same name) performed during the past 5 years (2018–2023) at the INASAN observatories in Zvenigorod, Simeiz Observatory INASAN and Russian–Cuban Observatory in Havana, Republic of Cuba, are presented. In total during this observation interval we obtained 9060 estimates of the brightness of the star in V band. Our measurements as well as data from the literature and from the Kamogata Wide-field Survey (KWS) archive were combined into the array comprising 17 653 measurements in an interval of about 57 years. Based on the power spectrum constructed from these data, P values of the cycle activity have been established, which according to our estimate are equal to 2.4, 5.63, 8, 13.6, 30 and 49 years. The dominant is the P cycle lasting 5.63 years. It is shown that this dominant cycle with a period of about 5.63 years found by us according to more extensive data (5.4–5.8 years in other sources) can be traced in the results of the analysis of previous studies. The results on the activity cycles of FK Com are compared with data on the long-term variability of two more stars of the type under consideration – HD 199178 (V1794 Cyg) and ET Dra. Based on the data on the P cycle of other chromospherically active stars (according to literature sources and our measurements) a diagram \(\log (1{\text{/}}{{P}_{{{\text{rot}}}}}){\kern 1pt} - {\kern 1pt} \log ({{P}_{{{\text{cycl}}}}}{\text{/}}{{P}_{{{\text{rot}}}}})\) is analyzed. The conclusion about the comparability of the values of the activity cycles of the FK Com type stars with the data for stars of the RS CVn type is made.

Human-in-the-Loop Formation-Containment Control for Multiagent Systems: An Observer-Based Distributed Unknown Input Reconstruction Method

This paper studies the human-in-the-loop time-varying formation-containment tracking (TVFCT) control problem of general linear multiagent systems (MASs). The MASs consist of a non-autonomous tracking leader, multiple formation leaders and followers, and all agents are subject to unknown disturbances. A human operator is deployed to supervise and regulate the entire team by sending a command signal to the tracking leader. The control input of the tracking leader should be combined with the human operator but not available to other agents. First, a local observer associated with each agent is constructed to provide asymptotic state estimation, in which the observer error system is disturbance-free. Also, interval observers are established for the neighborhood TVFCT errors, where the disturbance of the current agent is aggregated with the disturbances and input signals of its neighbors into an unknown input. Meanwhile, a distributed asymptotic unknown input reconstruction (UIR) mechanism is proposed that decouples the control input of the current agent. The consequent human-in-the-loop TVFCT control protocol is designed by combining the local observer and distributed UIR scheme. Finally, the theoretical results are verified in multi-robot formation-containment control.

Observer design and interval estimation of time-delay discrete-time linear systems with external disturbance and measurement noise

Observer design and interval estimation of time-delay discrete-time linear systems with external disturbance and measurement noise

A flexible framework for coding and predicting acute hypotensive episodes using Markov chains

Over the past decade, the prediction of acute hypotensive episodes (AHEs) using computational models has gained significant attention. AHEs in patients admitted to intensive care units can lead to severe or life-threatening conditions. AHEs are defined as a drop in the mean arterial pressure (MAP) below a threshold during an observation period. However, adaptable AHE modeling approaches are required to account for patient-specific definitions caused by inter-patient variability. This study proposes a flexible three-stage framework for the AHE prediction problem capable of modeling different hypotension states. The initial stage involves encoding the MAP time series using the proposed scheme. A clustering process is then performed to determine the k≥2 hypotension states and transition probabilities between them. The proposed AHE prediction model is built using a cohort of 453 MAP waveforms from MIMIC-II. In the third stage, we use 173 MAP waveforms to validate the proposed prediction method. Given a patient’s MAP time series, we compute the initial probability distribution by considering (a) an encoded observation interval and (b) a similarity measure to determine the closest kth cluster (state) to the encoded interval. Based on the properties of the Markov process, we predict the most probable state for look-ahead times h ranging from 1 to 30 min. The proposed framework offers competitive performance for h=7 with an accuracy of 0.965, which is clinically relevant for medical practitioners. We also provide a comparative analysis to validate the effectiveness of the proposed approach, which exhibits a significant statistical difference (α=0.05) compared with other state-of-the-art methods.

Wavelet characterizing the non-stationary features of mountain valley winds both in frequency and time domain

This study aimed to quantify and evaluate the non-stationary characteristics of wind speed in mountain canyon terrain. A non-stationarity index was proposed based on continuous wavelet transform to quantitatively evaluate the non-stationarity of measured wind speed samples in both time and frequency domains. Subsequently, the effect of sample length and observation time interval of wind speed samples on the non-stationarity index was investigated. In addition, the non-stationarity of mountain canyon winds was compared with that of normal climate winds under the same sample length and observation time interval. The results indicate that the non-stationarity index based on wavelet transform can quantitatively evaluate the non-stationary characteristics of wind speed. With an increase in the sample length of wind speed series, the non-stationarity of wind speed increase gradually, and its probability distribution becomes more positively skewed. When the sample length of wind speed does not exceed 10 min, the probability distribution of non-stationarity index for mountain valley terrain and normal climate winds is not significantly different, which implies that it is reasonable for most countries to use a 10-min statistical length to calculate average wind speed. However, the difference in the probability distribution of non-stationarity index between mountain and normal climate winds significantly increases when the sample length exceeds 10 min. Besides, the non-stationarity index can reflect the non-stationary characteristics of wind speed series at different frequency components. Higher frequency components in wind speed exhibit stronger non-stationary characteristics. Moreover, mountain winds exhibit stronger non-stationary characteristics than normal climate winds in amplitude and frequency, especially the high-frequency components in wind speed series with long sample lengths.

Effects of urban expansion on the surrounding agricultural communities of the southern Ethiopian town of Jajura

ABSTRACT This study used a mixed research design for several reasons. Firstly, the researchers used longitudinal data from open-source remote sensing satellite imagery dating back at least 30 years to study urban expansion into rural farmland. Then, the researchers used cross-sectional data from household surveys, where data collection tools such as questionnaires and structured interviews were utilized. A simple sampling procedure was used to ensure the representativeness of homogeneous target group households. The survey data was analyzed with SPSS software, and the urban-to-farmland extent was investigated with Landsat satellite images and observation intervals every 10 years for the last 30 years. The key finding of this study was that urban expansion is encroaching onto farmland, negatively impacting household livelihoods. It is recommended that urban expansion should be managed and minimized and that cooperation with the communities in the study area is an important issue. The study emphasizes the significance of comprehending the implications of uncontrolled urban development on rural communities in Ethiopia, using a mixed research approach comprising both longitudinal and cross-sectional data. The research demonstrates that expanding cities are having a considerable impact on agricultural livelihoods and require delicate handling to mitigate their unfavorable influence.

Observer‐based event‐triggered consensus control for multi‐agent systems with nonlinearity and unknown inputs

AbstractThis article investigates observer‐based consensus issues for a class of Lipschitz nonlinear multi‐agent systems (MASs) with unknown input. To address the challenges because of the unmeasurable states and the unknown input of each agent system, an interval observer is utilized to design an unknown input observer (UIO). The UIO possesses the capability of generating asymptotically the estimations of both the system states and unknown input simultaneously. Subsequently, a distributed control protocol scheme is put forwarded. The distributed controller for each agent is designed by using the state estimation and the unknown input reconstruction (UIR). The unknown input is compensated thanks for the introduction of the UIR into the controller, and thus leads to a better control performance. Besides, the event‐triggered strategy is also considered such that agents communicate with each other discontinuously. In this way, an observer‐based event‐triggered distributed control protocol scheme is developed, and under the scheme, the asymptotic convergent MASs consensus is accomplished. Finally, the effectiveness of the proposed methods is verified by a simulation example.

The relationship between observation interval and prognosis in pancreatic cancer concomitant with intraductal papillary mucinous neoplasia

BackgroundIntraductal papillary mucinous neoplasia (IPMN) is a risk factor for pancreatic cancer (PC). PC concomitant with IPMN shows rapid progression similar to de novo PC, therefore, the appropriate observation interval (OI) is not yet clear. Patients and methodThis was a multicenter retrospective observational study, and patients with PC concomitant with IPMN were analyzed. OI was defined as the interval between the date of imaging at PC diagnosis and just before the diagnosis. Clinical factors of PC and prognosis were assessed according to OI. ResultsFrom January 2010 to December 2018, 73 patients from 11 institutions were enrolled. The images performed just before PC diagnosis were contrast-enhanced CT/magnetic resonance imaging/endoscopic ultrasonography in 44/27/2 patients, respectively. The median cyst size was 14.0 mm, and the median main pancreatic duct diameter was 3.0 mm. The median OI was 6.8 months. In OI 6 months or less (OI ≤ 6 M)/OI more than 6 months (OI > 6 M), the mean tumor size, the frequencies of metastatic PC, resectable PC and early-stage PC were 20.1/21.5 mm (P = 0.91), 12.1 %/32.5 % (P = 0.05), 72.7 %/52.5 % (P = 0.09) and 27.3 %/25.0 % (P = 1.00), respectively. The median overall survival was 35.5 months in OI ≤ 6 M and 16.2 months in OI > 6 M (P = 0.05). ConclusionIn OI 6 months or less, the rate of resectable PC was high, however, the rate of early PC was almost the same as that of OI more than 6 months. Approximately 10 % of cases found in the advanced stage with metastasis even if OI 6 months or less.

Relational-separable models of monitoring processes at variable and unclear observation intervals

The article is devoted to the development of combined models, methods and tools designed to solve the current problems of modeling and analysis of monitoring process data, which are repre-sented by time series and differ in variable or fuzzy observation intervals (CHRPNI). In the article, a new relational separable model (RSM) and a combined quantile algorithm are proposed to in-crease the accuracy and efficiency of modeling and analysis of the processes of CHRPNI. The rela-tional model is defined by a system of fuzzy relational relations of the first and second order ob-tained on the basis of the original sequence of data. In the combined algorithm, the results of calcu-lations obtained by SPM and models of fuzzy relational relationships were generalized with the op-timal selection of weighting factors for individual components. As a result of the conducted research by means of numerical modeling, it was established that the introduction of combined process models in the case of PNEU is rational and effective. Exam-ples of data analysis of monitoring processes of rehabilitation of diabetic patients showed certain possibilities of ensuring the accuracy of the results of the analysis of indicators and their short-term forecasting.

Determination of the Characteristics of Non-Stationary Random Processes by Non-Parametric Methods of Decision Theory

This article is devoted to methods of processing random processes. This task becomes particularly relevant in cases where the random process is broadband and non-stationary; then, the measurement of a random process can be associated with an assessment of its probabilistic characteristics. Very often, a non-stationary broadband random process is represented by a single implementation with a priori uncertainty about the type of distribution function. Such random processes occur in information and measuring communication systems in which information is transmitted at a real-time pace (for example, radio telemetry systems in spacecraft). The use of methods of traditional mathematical statistics, for example, maximum likelihood methods, to determine probability characteristics in this case is not possible. In addition, the on-board computing systems of spacecraft operate under conditions of restrictions on mass-dimensional characteristics and energy consumption. Therefore, there is a need to apply accelerated methods of processing measured random processes. This article discusses a method of processing non-stationary broadband random processes based on the use of non-parametric methods of decision theory. An algorithm for dividing the observation interval into stationary intervals using non-parametric Kendall’s statistics is considered, as are methods for estimating probabilistic characteristics on the stationary interval using ordinal statistics. This article presents the results of statistical modeling using the Mathcad program.

Interval Observers for Continuous-Time Systems with Parametric Uncertainties

Interval Observers for Continuous-Time Systems with Parametric Uncertainties