PROCEDURE AND ALGORITHM FOR DETERMINING THE COEFFICIENT OF THE FREIGHT WAGON STABILITY IN COMPLIANCE WITH CURRENT REQUIREMENTS

Improving the reliability of test results is achieved by applying more advanced methods of recording and processing the results. Therefore, an important part of the study of the strength of freight wagons is the choice of methods for obtaining, processing and analyzing experimental data. The article outlines the procedure and algorithms for determining the equivalent stresses under longitudinal and dynamic loads acting during operation. It is shown that algorithms for determining stresses generated by dynamic longitudinal and vertical forces are significantly different due to various load application schemes. Thus, the testing of freight wagons under dynamic longitudinal loads is carried out by the impact against an experimental wagon, and testing under dynamic vertical forces is performed during the wagon motion in the composition of the experimental train on the characteristic, pre-selected (planned) sections of the railway track at specified speeds. To estimate the level of loading of the freight wagon structureunder vertical dynamic loads, a method based on the replacement of a real random process is used by some schematized process, which in terms of the fatigue damage accumulation should be equivalent to a real process. From the whole variety of schematic methods, two methods stand out, i.e., the full cycle method and the rainflow method, which most fully represent the real process.The advantage of the rainflow method is the ability to process the process in real time. However, the algorithm of the rainflow method is quite complicated and does not allow processing large amounts of information. In this regard, a method of maximum discharge was proposed, which is a kind of full cycles method and allows you to process an unlimited amount of information online. An example specified in GOST 25.101 was used for a comparative analysis of the rainflow and maximum discharge methods. Analysis showed a satisfactory matching of both methods. Based on the procedure outlined, the block structure of the computational process is proposed to determine the equivalent reduced voltage amplitude. Each block displays the impact of the forces depending on the loading condition, that is, longitudinal impact force and dynamic forces when the wagon is moving on straight track sections, curves and switches of the railway track. Key words: wagon car, process, dynamic load, longitudinal load, voltage, amplitude, algorithm, equivalent stress, safety margin, strength.

The effect of flood on slope stability along downstream riverbank of MuaraBangkahulu River, Bengkulu City, Indonesia

The flood which occurred due to the rainfall intensity in Bengkulu City of Indonesia could inundate the downstream area of MuaraBangkahulu River, especially TanjungAgung Sub-District. In 2019, a huge flood had occurred in Bengkulu City and triggered the environmental effect to riverbank in TanjungAgung. This environmental effect is a massive slope failure on downstream riverbank in TanjungAgung. This study is therefore conducted to analyze the slope stability in the area during the normal and the critical conditions. A slope stability analysis using finite element method is performed. First, the maximum discharge of MuaraBangkahulu River is estimated. Furthermore, slope stability analyses are conducted by considering the normal condition and the increase of river water level due to the maximum discharge (the critical condition). Mapping of factor of safety for riverbank slope and soil deformation is conducted. The results showed that slope along downstream riverbank of MuaraBangkahulu could undergo slope failure under both normal and critical condition. The results also showed that the factor of safety decreases due to the increase of river water level. The results of this study could be used by local government to consider slope countermeasure in the study area

A Stochastic Dynamic Programming Model for Hydropower Scheduling with State-dependent Maximum Discharge Constraints

<div>We present a medium-term hydropower scheduling model that includes state-dependent environmental constraints on maximum discharge. A stochastic dynamic programming algorithm is used to enable modelling of nonconvex relationships in the problem formulation. The model is applied in a case study of a Norwegian hydropower system with multiple reservoirs. We find that the maximum discharge constraint significantly impacts the water values and simulated operation of the hydropower system. A main finding is that the nonconvex characteristics of the environmental constraint is reflected in the water values, implying a nonconvex objective function. Operation according to the computed water values is simulated for cases with and without the environmental constraint. Even though operation of the system changes considerably when the environmental constraint is included, the total electricity generation over the year is kept constant, and the total loss in expected profit limited to less than 0.8%.</div>

A Stochastic Dynamic Programming Model for Hydropower Scheduling with State-dependent Maximum Discharge Constraints

<div>We present a medium-term hydropower scheduling model that includes state-dependent environmental constraints on maximum discharge. A stochastic dynamic programming algorithm is used to enable modelling of nonconvex relationships in the problem formulation. The model is applied in a case study of a Norwegian hydropower system with multiple reservoirs. We find that the maximum discharge constraint significantly impacts the water values and simulated operation of the hydropower system. A main finding is that the nonconvex characteristics of the environmental constraint is reflected in the water values, implying a nonconvex objective function. Operation according to the computed water values is simulated for cases with and without the environmental constraint. Even though operation of the system changes considerably when the environmental constraint is included, the total electricity generation over the year is kept constant, and the total loss in expected profit limited to less than 0.8%.</div>

Analisis Pengaruh Perubahan Penggunaan Lahan terhadap Debit Sungai (Studi Kasus : Sub DAS Cikeas)

Land use change have an impact on infiltration capacity. There is often an annual flood on Kadumanggu District. When the rainfall is high so the river will be overflow. The outlet of Cikeas sub-basin was located on Kadumanggu District. This research aimed to determine the maximum discharge of the Cikeas River and analyze the relation between land use change and discharge of Cikeas River. The research was conducted by delineating the water catchment area, analyzing rainfall, making a land use map and modeling with HEC-HMS. Based on the modeling results, the maximum discharge of the Cikeas River in 2000 was 74.3 m3/s, in 2009 was 84.9 m3/s, and in 2018 was 91.7 m3/s. The catchment area with an extensive use as residential had a higher river discharge compared to the area with a large green area. It meaned that, land use changes greatly affected the river discharge.

Paleohydrology of the Stefanina Cave (Greece)

The development of hypergene Stefanina Cave, the hydrological conditions, and the maximum discharge of the paleo-flow are studied, based on its pattern in ground-plan, the geometry of the passage, and the peak flow velocity from the dimensions of the scallops. The village of Stefanina is located East of Thessaloniki and the cave NE of the village. A study was conducted measuring the orientation of the discontinuities of the rocks inside and outside the cave, the scallops in various sites to estimate the flow velocities, and in addition, were taken photographs for the full analysis of its cross-section. The cave-in ground-plan has a pattern of branches, which is often associated with recharging through karstic depressions. The shape of the passages is both curvilinear and angular, depending on the foliage and the fractures. The symmetrical phreatic passage shape has been evolved to a vadose canyon, forming a keyhole passage in cross-section. This is indicative of a water table drop. The scallops are visible in a meandering channel, where the discharge of the paleo-flow is estimated. The estimated peak flow velocity ranges from 0.4 to 2.7 m / s, while the area-specific peak flow discharge is estimated to be 2.2 m3/s. On the one hand, the scallops represent the peak flow velocity, on the other hand, the karst springs have a limited maximum discharge, regardless of the size of the catchment, making it impossible to use the calculated paleo-discharge to estimate the respective catchment area.

HEC-HMS Models for Urban Flood Analysis in Belik River, Yogyakarta, Indonesia

The rapid development of Yogyakarta has made city development increase. This construction continues to expand the reach of impervious surfaces. As a result, the surface runoff and maximum discharge have increased, overflowing up to urban drainage. This study aimed to analyze the maximum discharge of the watershed based on design storms with 2, 5, 10, and 25-year return periods, used for flood control considerations. The urban flood was modelled using HEC-HMS. The results showed, the contribution of discharge flow in each segment is influenced by the dominance of land use, in which the segment dominated by dense settlements has a high contribution to the maximum discharge. The flow contribution is due to the high CN value which corresponds to the high surface runoff.

EXPLORING THE POTENTIAL ENERGY OF LODAGUNG MINI-HYDROPOWER PLANT IN BLITAR, WEST JAVA, INDONESIA

Renewable energy in Indonesia is not optimally developed. Most existing renewable energy power plants come from water and geothermal, but the utilized capacity is far away from significant. Lodagung mini-hydro power plant was built by The Public Corporation, Jasa Tirta I with an installed capacity of 2x650 kW utilizing water from the Lodagung Irrigation Channel, Wlingi Dam to generate electricity in Blitar Regency, East Java. The plant has become the first to use Siphon technology in its operation. This study aims to analyse the potential power generated by Lodagung Mini-hydropower plant using primary and secondary data. The data processing was done by calculating the reliable discharge of the irrigation channel for three years since 2011 to 2013; calculating the water discharge in the siphon pipe; and calculating the estimated power generated by the plant. The findings indicate that the maximum discharge of the Lodagung irrigation channel is 13.78 m3/second, and the minimum discharge is 8.89 m3/second. The design discharge is 13.78 m3/second, and the maximum discharge in the siphon pipe is 3.96 m3/second/pipe. Based on the need, the expected power generated ranges from 16.48 kWh/day to 28.66 kWh/day.

Development of ANN model for discharge prediction and optimal design of sharp-crested triangular plan form weir for maximum discharge using linked ANN–optimization model

Triangular plan form weirs are advantageous over a normal weir in two ways. Within the limited channel width, use of such a weir increases the crest length and hence for a given head, increases the discharge and for a given discharge, reduces the head in comparison with a normal weir. In a previous study, researchers proposed an empirical equation to compute the discharge coefficient of a triangular plan form weir. The prediction error on the discharge coefficient was ±7% from the line of agreement. In the present study, an ANN model has been utilized to train randomly selected 70% data, with 15% tested and validation made for the remaining 15% data. The model predicts the discharge coefficient with a prediction error in the range of ±2.5% from the line of agreement, thereby decreasing the prediction error in Cd by 64%. Also, the sensitivity analysis of the developed ANN model has been performed for all the parameters (weir height, skew weir length and flow depth) involved in the study and the weir height was found to be the most sensitive parameter. Furthermore, the linked ANN–optimization model has been developed to find the optimal values of design parameters of a triangular plan form weir for maximum discharge.

The floods recorded in the North of Spain in October 2019. A paradigm of compound and multi-hazard event in the framework of climate and environmental change

&lt;p&gt;This contribution shows a multi-disciplinary forensic investigation of the catastrophic flood event that took place in the northern part of Spain between the 22&lt;sup&gt;nd&lt;/sup&gt; and 23&lt;sup&gt;rd &lt;/sup&gt;of October 2019. The case study has been selected for three reasons. Besides flash-floods and floods in several parts of the region of interest, the event also recorded windstorms, one tornado, snowfalls, thunderstorms, strong sea surges, and landslides, that made a good paradigm of a compound and multi-hazard event. The second reason is because the event has been analyzed from three approaches. Firstly, the hydrometeorological perspective, which includes monitoring through meteorological radar and observation stations, as well as the consequences on the surface. Second, from the socio-economic perspective, both in terms of economic impact and in terms of social perception, for which a citizen science experiment was designed with the FLOODUP tool and in collaboration with the Museu de la Vida Rural de l'Espluga de Francol&amp;#237; (a museum located in the village the event hit the most). FLOODUP is an App developed to improve the population risk awareness and sensibilization face to climate change, that can be also used to collect information. In this case it was used during the period of home confinement due to the pandemics to collect information about the emergency management and impacts. This part also includes the cascading effects, as well as what the Covid-19 pandemic meant in the difficulty of recovery. A third approach analyzes the early warning, emergency management and recovery, in addition to various human initiatives that were carried out. Finally, the third consideration follows the example of pair-events comparison developed in the framework of the IAHS Panta Rhei hydrological decade 2013- 2022 like (ex: Kreibich et al., 2017). In this case, the October 2019 event is compared with the floods of October 1994, specifically regarding the Francol&amp;#237; basin. Maximum precipitation recorded in this last event was 410 mm between 9 and 11 October, with a maximum discharge of the Francol&amp;#237; River of 900 m&lt;sup&gt;3&lt;/sup&gt;/s in Montblanc. As a consequence of it, 10 bridges were destroyed, 10 people lost their life and more than 230 &amp;#8364; millions in damages were produced. On the 2019 event maximum precipitation was of 293 mm between 22 and 23 October, the maximum discharge in Montblanc was of 544 m&lt;sup&gt;3&lt;/sup&gt;/s and 5 people lost their life and damages were above 44 &amp;#8364; millions. Finally, the event is contextualised in the flood trend observed in the region due to climate and environmental changes. &amp;#160;The presentation concludes with the discussion on the potential measures of adaptation that have been already applied or could be applied.&lt;/p&gt;&lt;p&gt;This work has been done in the framework of the M-CostAdapt (CTM2017-83655-C2-1&amp;2-R) research project, funded by the Spanish Ministry of Science and Innovation (MICINN-AEI/FEDER, UE).&lt;/p&gt;&lt;p&gt;Reference. Kreibich, H., S. Vorogushyn, J.C.J.H. Aerts, et al. 2017. Adaptation to flood risk &amp;#8211; results of international paired flood event studies. Special collection &amp;#8220;Avoiding Disasters: Strengthening Societal Resilience to Natural Hazards&amp;#8221; in the journal Earth&amp;#8217;s Future. Earth&amp;#8217;s Future,5,953&amp;#8211;965, doi:10.1002/2017EF000606&lt;/p&gt;