Key Stations Research Articles

Lymphatic Routes of Gastric Cancer Metastasis Elucidated by Triple Lymph Node Analysis

Background: Although the development of lymphatic invasion by gastric cancer has been solved using 'solitary lymph node metastasis' research, few facts are known about the sequential flow following the sentinel station.Aim: In this study, we investigate the lymphatic spread of gastric cancers using 'triple lymph nodes metastases' analysis.Methods: During January 2001 and December 2015, 402 subsequent patients with gastric cancer underwent gastrectomy with standardized lymph node dissection at our institute. Among them, lymph node involvement was revealed in 234 patients by a histopathological study. The lymphatic spread of gastric cancer was analyzed theoretically based on the probability of additional lymph node metastases from each station.Results: The numbers of cases were 64, 41, 17, 23, 17, 13 and 59 according to the number of metastases of 1, 2, 3, 4, 5, 6 and 7 or more, respectively. The lesser curvature lymph node (#3) was the key station and skip metastasis was sometimes seen in lymph nodes of the intermediate region at the solitary lymph node metastasis stage. Some lymphatic flows were demonstrated by double and triple lymph node metastasis analysis, especially many flows from perigastric toward intermediate regions.Conclusion: This study demonstrated theoretically a lymphatic route for gastric cancer cells using a novel methodology. The results may be applicable to making preoperative diagnosis and for deciding on optimal lymph node dissection in gastric cancer surgery.

A Transit Bottleneck Model for Optimal Control Strategies and its Use in Traffic Assignment in Paris

Control strategies are of crucial importance in operations of saturated transit lines. At a given bottleneck, delay propagates due to an excess of demand over supply. Operators therefore use optimal strategies (e.g. holding, fast-running, train-canceling etc.) in order to recover the level of service. While toolbox for train operation control system has thrived in past years, few traffic assignment models for large-scale transit networks on the planning side have touched on the impact of control dynamics: static macroscopic models perform quite well in simulating platform/vehicle saturation, but less so with bottleneck delay; dynamic models deal with dynamic passenger behavior under congestion, yet single vehicle runs are not explicitly considered either. The objective of this paper is to (1) capture the dynamic control features in a bottlenecked rail system; (2) provide a computation-friendly simulation approach to optimize the control; and finally (3) fit the bottleneck model in a static capacitated assignment model to improve its performance. The paper first provides mathematical formulae to describe bottleneck phenomena in a high-demand high-frequency transit line. Formulae are then cast into a control problem of dynamic system, to which we apply dynamic programming to reduce the dimension of decision variables. A numerical application to the Line RER A in Paris is followed, in which control strategies are optimized at key stations in a rolling horizon; on-platform passenger activities are simulated accordingly. Results are compared with both static model and real-life data, showing the effectiveness of the control-based assignment.

Capacity planning on key work stations in a hybrid MTO-ETO production system: a case-study on Siemens AG

The focus of this study is on tactical-level capacity management which refers to the determination of in-house workforce production capacity in an optimal cost-efficient manner in a multi-period mode. Two options for capacity planning are investigated for rapid prototyping with the help of a mixed-integer linear optimisation model: smoothing the capacity utilisation over time vs. a higher level of capacity availability. A sensitivity analysis based on real empirical data in Siemens AG is used for the revealing the impact of workforce and capacity flexibility on operational performance. The results suggest that the number of workers decreases if production orders have not to be completed within only one week. On the contrary, if the binary restriction on the order fulfilment within one week is released, the production orders can be split into different weeks and this results in a higher smoothing rate and thus in a higher capacity utilisation degree.

2016年长江洪水遭遇分析

本文利用数理统计方法，根据洪峰、洪量遭遇的时间、量级统计特征，分析2016年长江干支流洪水实况的遭遇情况。同时考虑梯级水库群调节作用，还原了长江流域干支流控制站的水位、流量过程，分析比较还原后的天然长江洪水遭遇情况。结果表明2016年长江流域主要为中下游洪水遭遇，长江流域梯级水库群的联合调洪对于减轻长江流域洪水遭遇起到了积极作用。 The encounter of floods in the main stream and tributaries of Yangtze River is studied by the statistic method, from the aspects of encounter time of the peak discharge and flood volume, and magnitude of the floods. Considering the operation effect the cascade reservoirs, the natural flow and water level of the key stations in the main stream and tributaries of Yangtze River are derived, to do the natural flood encounter analysis and comparison. The results show that the flood encounter mainly happened in the middle and lower reaches of the Yangtze this year, and the joint operation of the cascade reservoirs played a positive role in relieving the flood encounter in Yangtze River.

Hydrological alterations from water infrastructure development in the Mekong floodplains

AbstractThe Mekong floodplains, which encompasses the region from Kratie Township in Central Cambodia to the Vietnamese East Sea, is a region of globally renown agricultural productivity and biodiversity. The construction of 135 dams across the Mekong basin and the development of delta‐based flood prevention systems have caused public concern given possible threats on the stability of agricultural and ecological systems in the floodplains. Mekong dams store water upstream and regulate flow seasonality, while in situ flood prevention systems re‐distribute water retention capacity in the floodplains. The main aim of this paper is to evaluate possible impacts of the recent development of both hydropower dams and flood prevention systems on hydrological regimes in the Mekong floodplains. An analysis of measured daily and hourly water level data for key stations in the Mekong floodplains from Kratie to the river mouth in Vietnam was conducted. Hydropower dam information was obtained from the hydropower database managed by the Mekong River Commission, and the MODIS satellite imagery was used to detect changes in flooding extent related to the operation of flood prevention systems in the Vietnam Mekong Delta. Results indicate that the upper part of the floodplains, the Cambodian floodplains, may buffer upstream dam impacts to the Vietnam Mekong Delta. Flood prevention up to date has had the greatest effect on the natural hydrological regime of the Mekong floodplains, evidenced by a significant increase of water level rise and fall rates in the upper delta and causing water levels in the middle delta to increase. The development of flood prevention systems has also effected spatial distribution of flooding as indicated via a time series analysis of satellite imagery. While this development leads to increase localized agricultural productivity, our historical data analysis indicates that development of one region detrimentally affects other regions within the delta, which could increase the risk of future conflicts among regions, economic sectors and the ecological value of these important floodplains. Copyright © 2016 John Wiley & Sons, Ltd.

Arabian Peninsula wet season dust storm distribution: regionalization and trends analysis (1983–2013)

ABSTRACTA dust storm climatic regionalization of the Arabian Peninsula (AP) that aims to categorize the region into several cohesive sub‐regions is conducted. This approach was carried out by grouping together similar wet season climatological features of dust storm activity (DSA). A common period of 30 years (1983–2013) for 38 meteorological weather stations across the AP was utilized. The mathematical, statistical and subjective methods that are employed in the process of regionalization resulted in dividing the region into three sub‐regions. Each of the sub‐regions north, northwestern and central, northeast and south, west and coastal shows distinct features of its own. Subsequently, the temporal trend of the representative station (key station) for each sub‐region is examined. It is found that only the northeastern part of the region has a significant positive trend over the last 30 years. However, this positive increase in DSA is not associated with an increase in wind speed. This study assists future research in exploring the relationship between large‐scale forcing and the AP sub‐regional DSA. As well, this could enhance regional DSA forecast and future projections.

Toxigenic algae and associated phycotoxins in two coastal embayments in the Ebro Delta (NW Mediterranean)

Harmful Algal Bloom (HAB) surveillance is complicated by high diversity of species and associated phycotoxins. Such species-level information on taxonomic affiliations and on cell abundance and toxin content is, however, crucial for effective monitoring, especially of aquaculture and fisheries areas. The aim addressed in this study was to determine putative HAB taxa and related phycotoxins in plankton from aquaculture sites in the Ebro Delta, NW Mediterranean. The comparative geographical distribution of potentially harmful plankton taxa was established by weekly field sampling throughout the water column during late spring–early summer over two years at key stations in Alfacs and Fangar embayments within the Ebro Delta. Core results included not only confirmed identification of HAB taxa that are common for the time period and geographical area, but also provided evidence of potentially new taxa. At least 25 HAB taxa were identified to species level, and an additional six genera were confirmed, by morphological criteria under light microscopy and/or by molecular genetics approaches involving qPCR and next generation DNA pyrosequencing. In particular, new insights were gained by the inclusion of molecular techniques, which focused attention on the HAB genera Alexandrium, Karlodinium, and Pseudo-nitzschia. Noteworthy is the discovery of Azadinium sp., a potentially new HAB species for this area, and Gymnodinium catenatum or Gymnodinium impudicum by means of light microscopy. In addition, significant amounts of the neurotoxin domoic acid (DA) were found for the first time in phytoplankton samples in the Ebro Delta. While the presence of the known DA-producing diatom genus Pseudo-nitzschia was confirmed in corresponding samples, the maximal toxin concentration did not coincide with highest cell abundances of the genus and the responsible species could not be identified. Combined findings of microscopic and molecular detection approaches underline the need for a synoptic strategy for HAB monitoring, which integrates the respective advantages and compensates for limitations of individual methods.

Statistical downscaling of general circulation model outputs to precipitation, evaporation and temperature using a key station approach

Using a key station approach, statistical downscaling of monthly general circulation model outputs to monthly precipitation, evaporation, minimum temperature and maximum temperature at 17 observation stations located in Victoria, Australia was performed. Using the observations of each predictand, over the period 1950–2010, correlations among all stations were computed. For each predictand, the station which showed the highest number of correlations above 0.80 with other stations was selected as the first key station. The stations that were highly correlated with that key station were considered as the member stations of the first cluster. By employing this same procedure on the remaining stations, the next key station was found. This procedure was performed until all stations were segregated into clusters. Thereafter, using the observations of each predictand, regression equations (inter-station regression relationships) were developed between the key stations and the member stations for each calendar month. The downscaling models at the key stations were developed using reanalysis data as inputs to them. The outputs of HadCM3 pertaining to A2 emission scenario were introduced to these downscaling models to produce projections of the predictands over the period 2000–2099. Then the outputs of these downscaling models were introduced to the inter-station regression relationships to produce projections of predictands at all member stations.

A Bayesian network-based data analytical approach to predict velocity distribution in small streams

Developing a reliable data analytical method for predicting the velocity profile in small streams is important in that it substantially decreases the amount of money and effort spent on measurement procedures. In recent studies it has been shown that machine learning models can be used to achieve such an important goal. In the proposed framework, a tree-augmented Naïve Bayes approach, a member of the Bayesian network family, is employed to address the aforementioned two issues. Therefore, the proposed study presents novelty in that it explores the relations among the predictor attributes and derives a probabilistic risk score associated with the predictions. The data set of four key stations, in two different basins, are employed and the eight observational variables and calculated non-dimensional parameters were utilized as inputs to the models for estimating the response values, u (point velocities in measured verticals). The results showed that the proposed data-analytical approach yields comparable results when compared to the widely used, powerful machine learning algorithms. More importantly, novel information is gained through exploring the interrelations among the predictors as well as deriving a case-specific probabilistic risk score for the prediction accuracy. These findings can be utilized to help field engineers to improve their decision-making mechanism in small streams.

Modeling and application of mixed model assembly system complexity introduced by auto-body personalization

Assembly system complexity, especially welding system complexity introduced by auto-body product personalization is regarded as a major contributor of uncertainty in the system planning and designing. The welding system complexity is defined based on information entropy theory, the station-level integrated complexity model, and system-level complexity flow model are established to obtain the complexity source of welding system. Complexity source sensitivity indices are proposed to indentify key station and key equipment that contribute most to the complexity. Based on the application of auto-body side welding line case, the result indicates that the proposed complexity model and key complexity source identifying and diagnosing process can be used as the decision support tool of auto-body welding system.

Complex network theory, streamflow, and hydrometric monitoring system design

Abstract. Network theory is applied to an array of streamflow gauges located in the Coast Mountains of British Columbia (BC) and Yukon, Canada. The goal of the analysis is to assess whether insights from this branch of mathematical graph theory can be meaningfully applied to hydrometric data, and, more specifically, whether it may help guide decisions concerning stream gauge placement so that the full complexity of the regional hydrology is efficiently captured. The streamflow data, when represented as a complex network, have a global clustering coefficient and average shortest path length consistent with small-world networks, which are a class of stable and efficient networks common in nature, but the observed degree distribution did not clearly indicate a scale-free network. Stability helps ensure that the network is robust to the loss of nodes; in the context of a streamflow network, stability is interpreted as insensitivity to station removal at random. Community structure is also evident in the streamflow network. A network theoretic community detection algorithm identified separate communities, each of which appears to be defined by the combination of its median seasonal flow regime (pluvial, nival, hybrid, or glacial, which in this region in turn mainly reflects basin elevation) and geographic proximity to other communities (reflecting shared or different daily meteorological forcing). Furthermore, betweenness analyses suggest a handful of key stations which serve as bridges between communities and might be highly valued. We propose that an idealized sampling network should sample high-betweenness stations, small-membership communities which are by definition rare or undersampled relative to other communities, and index stations having large numbers of intracommunity links, while retaining some degree of redundancy to maintain network robustness.

Happy birthday, Rolf Mülhaupt!

Happy birthday, Rolf Mülhaupt!

Statistical downscaling of general circulation model outputs to evaporation, minimum temperature and maximum temperature using a key-predictand and key-station approach

A key-predictand and key-station approach was employed in downscaling general circulation model outputs to monthly evaporation, minimum temperature (Tmin) and maximum temperature (Tmax) at five observation stations concurrently. Tmax was highly correlated (magnitudes above 0.80 at p ≤ 0.05) with evaporation and Tmin at each individual station, hence Tmax was identified as the key predictand. One station was selected as the key station, as Tmax at that station showed high correlations with evaporation, Tmin and Tmax at all stations. Linear regression relationships were developed between the key predictand at the key station and evaporation, Tmin and Tmax at all stations using observations. A downscaling model was developed at the key station for Tmax. Then, outputs of this downscaling model at the key station were introduced to the linear regression relationships to produce projections of monthly evaporation, Tmin and Tmax at all stations. This key-predictand and key-station approach was proved to be effective as the statistics of the predictands simulated by this approach were in close agreement with those of observations. This simple multi-station multivariate downscaling approach enabled the preservation of the cross-correlation structures of each individual predictand among the stations and also the cross-correlation structures between different predictands at individual stations.

Delay Analysis of an Enhancing IEEE 802.11 Point Coordination Function MAC Protocol

The widespread use of multimedia networking applications has brought more requirements to the network, creating a need for end-to-end Quality of Service (QoS). The contention-free Point Coordination Function (PCF) with Round Robin scheme, where the Access Point controls all transmissions based on a polling mechanism, is defined in IEEE 802.11 standard to provide QoS service. This network suffers from inefficiency in the delay sensitive traffic and makes. It is difficult to provide priority-differentiated service. In this paper, a useful enhance mechanism is derived from a two-level-polling model with a parallel scheme between the polling and switch over processes. We consider two different polling schemes according to station classify: key station and normal station. This mechanism allows for a delay guarantee as well as priority service. An analytical is developed for evaluating the queuing length for the station and waiting time for the packets at nodes. Based on this model, we achieve several closed-form expressions for mean cycle time, mean queue length and mean waiting time. To verify the correctness of our analytical model, we also develop a simulator for the 802.11 PCF MAC. The simulation results well match the analytical results.

Applying Haar and Mexican Hat Wavelets to Significantly Improve the Performance of the New Zealand GeoNet P-Phase Picker for the 2008 Matata Region Swarm

Abstract The New Zealand GeoNet P ‐phase picker’s performance can be significantly improved, by up to 70%, when Mexican hat and Haar wavelet scale thresholding (WST) is implemented in the preprocessing stage of manually picked events. In total, 811 events with the required spatial and quality criteria from the 2008 Matata swarm were studied. The WST was applied to manually processed waveforms recorded by key stations, including 48 waveforms recorded by URZ; 47 by stations LIRZ, MARZ, and OPRZ; 64 by EDRZ; 33 by KARZ; and 47 by OPRZ. The signal‐to‐noise ratios of these key stations were dominated by additive noise rather than weaknesses introduced by the radiation pattern. We found that the Mexican hat WST produced the largest amount of retrieved and revised P onsets for station EDRZ (70.3%). The next best station was KARZ, which had 66.7% of picks showing improvement and only 3% of picks adversely affected. The main best scales (i.e., the wavelet’s degree of compression) for stations EDRZ and KARZ were scales 1 and 2, respectively. Haar WST for the OPRZ recordings resulted in a total improvement greater than 50%, with the lowest adversely affected picked onsets of 2.1%. Similarly, the Haar WST retrieved a considerable number of missed onsets at the TGRZ and LIRZ stations (25.5% and 20%, respectively), with a minor effect on the performance. The results confirmed that WST served to significantly enhance the performance of the GeoNet P picker for the chosen Matata earthquakes due to the frequency localization of the WSR compared to the current Butterworth filtering scheme. Online Material: Figure and table of quality of picks.

Detection of Quarry Blasts in the Koyna-Warna Region, Western India

Koyna-Warna is a seismically active region, characterized by earthquakes triggered by loading of artificial water reservoirs. In this region quarrying is ongoing and sometimes the quarry blasts are confused with triggered seismic events. About 410 events around a known mining area were ob-served during January 2007-October 2013. In general the quarry blasts are carried out mostly during the day time. Based on this fact a well known method of [1] is implemented, which has the capability of detecting the areas of quarry blast activity. Also, discrimination of quarry blasts from earthquakes has been achieved by studying waveforms at key seismic stations located close to the quarrying area. Further, distinction is achieved through spectral analysis in the frequency band of 3 - 15 Hz. Ratio of day-time to night-time events, waveform pattern and spectral analysis approach confirm the presence of quarry blasts aligned south-east of the Warna reservoir.

Impact of climate change on hydropower production within the La Plata Basin

ABSTRACTThis paper aims to estimate the variation of the combined dependable energy output of the set of major hydropower plants within the Brazilian part of the La Plata Basin due to possible climate changes during the twenty-first century. It uses and compares the predictions of two regional climate models, namely PROMES [Castro, M., Fernández, C., and Gaertner, M.A., 1993. Description of a mesoscale atmospheric numerical model. In: J.I. Díaz and J.L. Lions, eds. Mathematics, climate and environment. Rech. Math. Appl. Ser. Mason, 230–253; Gallardo, A., Galvan, C., and Mermejo, R., 2012. PROMES-MOSLEF: An atmosphere-ocean coupled regional model. Coupling and preliminary results over the Mediterranean basin. 4th HYMEX Workshop 2 2010] and RCA models [Rummukainem, M., 2010. State-of-the-art with regional climate models. WIREs Climate Change, 1, 82–96]. Rainfall and temperature predictions are converted into streamflow at key gauge stations using Variable Infiltration Capacity Model [Liang, X., Lettenmaier, D.P., Wood, E.F., and Burges, E.F., 1994. A simple hydrologically based model of land surface water and energy fluxes for general circulation models. Journal of Geophysical Research, 99, n. D7, 14,451–14,428]. The evaluation of the dependable energy output used the natural energy hydrograph method engineering consultants (Canambra Engineering Consultants, 1969. Power study of South Brazil. 13 v. Appendice XVII Final Report. Rio de Janeiro: Canambra Engineering Consultants), combined with the Monte Carlo simulation of synthetic series of natural energy. The main contribution of this paper is the consolidation of a methodology that provides estimates of the system's dependable energy as a function of the return period for both observed and future predicted streamflows. As a conclusion, a reduction of the dependable energy output of the hydropower plants within the La Plata Basin could be expected during the twenty-first century

The Development and Application of Small Watershed Hydrological Telemetry System

Small watershed floods have a short confluence time. Aiming at the demand of flash floods forecast, we do this research mainly around two key components, telemetry terminal and central station software. First, we design the telemetry terminal technology index, telemetry terminal circuit and GXU-1001 Hydrological Telemetry Terminal. They all based on equipment interface, communication channel, working mode, data sampling, solid-state storage, data query, parameter settings, power management, equipment, power consumption and other special technical requirements. Second, we developed central station software for GXU-1001, realize the telemetry terminal set parameters, received and compiled data, managed database, remote diagnosis and calibration, forwarded data, leak proof message, etc. The application in medium reservoirs of Baise, Guangxi, China shows the water level, rainfall, and images can be automatically acquired, transfered and processed. It provides timely and accurate hydrological data for the flood control and disaster mitigation.

Data Privacy Preservation in Wireless Sensor Networks Based on Multi-Secret Sharing Scheme

The Internet of things is widespread concerned by the whole society now. As an important component of the Internet of things, wireless sensor network has wide application prospect in various fields such as medical and health, military defense. The traditional data privacy protection technology of PKI system used in the WSN networks has its own weakness. This paper presents the secret key sharing mechanism to protect data privacy. The secret key, remote node and base station used to communicate, was divided into multiple secrets. The multiple secrets were distributed in the nodes which connect directly to the base station node. Only through collect more than threshold number of multi-secret that can decrypt the communication data between the base station and the remote node. To be safer, we used digital watermarking technology to protect the data transmission between the base station and the aggregate node. These techniques combined with the data slice, homomorphism encryption technology to protect data privacy, construct a safe and efficient wireless sensor networks.

Characterization of local wind patterns in complex mountain valleys

ABSTRACTIn this work, the wind patterns in high mountain areas with complex orography are characterized using hourly data provided by a network of weather stations. The key novelty of the study is the methodology. Data are grouped separately by wind speed and wind direction using two cluster analyses. The groups are analysed and described according to measurements at key stations in the network and their hourly presence. Both classifications are subsequently compared using contingency tables, and the main wind patterns are identified. The uncertainties associated with the average values of each wind pattern are quantified by principal component analysis of the wind vectors at each station. One year of data from nine stations located in the area of La Oroya, Peru was used to validate the proposed method. The local wind behaviour was characterized, the wind patterns were compared with respect to the seasons, and the winter morning transitions were analysed in detail. The methodology allows quantitative description of the local wind patterns and their temporal dynamics in complex mountain valleys. Both wind speed and direction were found to be relevant in wind pattern characterization. In particular, both parameters have proven helpful in identifying and quantifying the prevailing winds during cold dawns and thermal inversion periods.