Design Assumptions Research Articles

Appraisal of soil-cement columns load displacement behavior through full-scale tests database

Soil-cement columns are implemented in coastal areas to improve the capacity of loose, soft, and dredged soils, reduce settlement, and mitigate liquefaction effects. Static load testing is used for quality control and the verification of design assumptions. Given the greater reliability of full-scale testing results compared to physical and numerical modeling results and the lack of a database for soil-cement columns, 42 full-scale loading records on these columns were compiled to assess the behavior of these columns and identify the most influential factor in their behavior. The database contains columns ranging in length from 5 to 19 meters with diameters ranging from 40 to 120 cm, as well as soil profiles ranging from clay to sand and mixed soil. Their behavior was evaluated using a hyperbolic relationship. The results indicate that component materials, influenced by implementation technique, in-situ soil properties, and reinforcing, more significantly influence the behavior of columns than the columns’ length. The columns are categorized into three separate groups, which are separated due to their different equivalent unconfined compressive strengths and shapes. These categories allow for the prediction of the load-displacement ratio diagram range of the column based on initial information such as the column diameter, length, and properties of in-situ soil. The upper and lower bounds of categories were validated by the loading results of five soil-cement columns implemented in Iran coastal line.

The method of determining design assumptions for bogie platform

This article is devoted to the methods of designing running gear in compliance with recently changed requirements, regulations of rail authorities, technical specification for interoperability, and safety certification. Changes are focused on the certification process. According to ERA these changes are recommended for bogies holding IC certificate issued according to the former TSI WAG, without assessment of the strength of the bogie frame. The presented methods allow designing a bogie platform with a wide range of applications in regional, and long-distance trains. Issues related to calculations, and studies of bogie frames are described. Particular attention is paid to methods for determining loads applied to the bogie frame based on assumed axle loads, determining reference forces for the projected shock absorbers, and compiling computational cases for strength analysis of traction units.

The reliability assessment of the seismic demands of beams in chevron-braced frames and the factors affecting them

According to AISC 341–16, beams in chevron-braced frames should be designed for unbalanced forces. Several factors including the yield strength of steel materials, earthquake magnitude, the number of stories, and the details of the member connections affect the force applied to the beam. In this regard, the present study assessed the reliability of the seismic demand of beams in chevron-braced frames by considering the mentioned effective factors. First, 4-, 8-, and 12-story buildings representing low-, medium-, and high-rise buildings, respectively, were designed based on AISC 341–16. The beam-to-column connections and gusset plates were designed and modeled according to the capacity of the members. Then, one frame was selected from each building for stochastic seismic time-history analysis. For the stochastic analysis, 550 earthquake records were first chosen according to the considered characteristics of the site. Then, 100 ground motions were randomly selected and each braced frame was subjected to them. The yield and ultimate strengths of the steel materials were randomly selected based on the probability density function in each analysis. The results showed that a significant amount of the forces was generated in the beam-to-column connections contrary to the design assumptions. The results in the three frames showed that the resistance of the braced beams was on average higher than the demand forces. Moreover, the force distribution did not show an identical trend in different stories and the effect of the number of stories should also be considered in estimating the unbalanced forces of the braced beams.

Monitoring of Slopes and Retaining Structures Related to Infrastructures Case Study Hydroelectric Power Plant Jiu River Livezeni Romania

Abstract The Paper presents the results, interpretation and intervention measures obtained from inclinometer monitoring performed for a retaining structure built for the accomplishment of a hydrotechnical structure on Jiu River. The accomplishment of the hydrotechnical structure on Jiu River required a retaining structure of approximately 100m length adjacent to the slope which is crossed by the railway line Tg. Jiu - Simeria. The retaining structure made of 1500mm piles also keeps in safe condition the adjacent E79 Road section. Monitoring the behavior of the support structure and of the slope, the layout and the depth of the monitoring equipments, is the result of a complex analysis of the site, of the neighborhoods and the risks to be monitored and managed. This paper presents the “peak of the iceberg” related to site monitoring, being the result of several steps necessary to be performed in order to accomplish the monitoring program: establishing geotechnical or structural issues that require resolution / tracking, establishing the concept of monitoring systems and monitoring plan, establishment of: monitored points, equipment, frequency and type of data acquisition, processing methods, interpretation and issue resolutions for the data. The results of the geotechnical monitoring and topographical survey compared with the design assumptions can lead to intervention measures to ensure and restore structural stability for the construction during execution stage or exploitation stage.

Modelowanie hydrologiczne jako wsparcie dla projektowania i utrzymania infrastruktury

One of the many concerns related to climate change is its impact on infrastructure, for example in the case of structures such as bridges or culverts which are more frequently exposed to conditions like significant differences in water table levels or floods. Varying weather conditions can also cause deterioration of properties of the materials which they are made of, which coupled with higher loads (water, wind or temperature variation, depending on the structure) decreases their durability and hinders their operation. Existing infrastructure facilities were designed with the use of historical data, and those design assumptions can be out of date at the moment, moreover their validity decreases with further climate changes. In order to support the design of new infrastructure facilities and the maintenance of already existing ones, climate change should be taken into account. One of the means that can be used to assess the impact of climate change on bridges and other river infrastructure is hydrological modelling. In this paper, the authors present a hydrological model of the flow in the Ślęza River, a 78.6 km long, left- bank tributary of the Odra River, as well as in its tributaries, with a particular focus on the points where bridges are located. The model was performed with QSWAT software, taking into account two scenarios of climate change: SSP2-4.5 and SSP5-8.5 (obtained with the use of NorESM2-LM model) and calibrated with the use of historical meteorological data. The results of the model include daily flows for years 2023-2050, which allows to compare characteristic (statistical) flows and observe trends; also a change in the dynamics of the river caused by thaws can also be observed. A greater number of extreme events can be seen in the results for the SSP2-4.5 scenario, the values of flood flows are also higher for this scenario, whereas the average flows are higher for the SSP5-8.5 scenario, which is due to higher rainfall in this scenario – although the threat of short-term extreme events is lower, but nevertheless, due to increased flows, scouring development can occur in this scenario, which when left uncontrolled can pose great risks to bridges. The obtained results would be helpful for engineers who plan the maintenance of infrastructure facilities, as this analysis would provide additional data in order to choose optimal solutions for the costs of exploitation and for the environment.

Improving the operational durability of tangential-rotary picks for rock cutting with central spraying and hydrodynamic rotation

This article presents a proposal for a new solution of tangential-rotary picks intended for mining, especially hard rocks with roadheaders. The design of these picks is characterized by many innovative solutions aimed at significantly increasing their service life. The method to achieve this goal is to provide effective central spraying of the ring tip picks, crown picks, or similar types of picks while using the spray water to cause the picks to rotate as they contact the rock being mined. An important element of the work is to conduct extensive simulation studies using FEM to determine the stress distribution in the pick shank subjected to external load from cutting. The new design of the tangential-rotary pick is equipped with a reinforcing sleeve, in which a state of compressive stress is induced. This enables a significant improvement in the fatigue strength of the pick shanks. The conducted FEM comparative tests confirm the accuracy of the adopted design assumptions. They also determine the beneficial value of the tension nut torque, which tightens the reinforcing sleeve located on the pick shank.

Importance of Variable Turbine Efficiency in Run‐Of‐River Hydropower Design Under Deep Uncertainty

AbstractWhen less water is available, hydropower turbines are less efficient, or have to stop altogether. This reality is often neglected in recent work on the planning and operations of hydropower systems, despite widespread expected increases in drought intensity, frequency and duration. This paper is the first to integrate variable‐efficiency turbines into a hydropower plant design framework that accounts for design optimization as well as deep uncertainty in climatic and socio‐economic variables. Specifically, this framework focuses on leveraging multi‐objective robust decision making for the financially robust design of run‐of‐river hydropower plants, whose output is highly sensitive to flow variability. Application to five plants in Türkiye challenges two key design assumptions, use of net present value as a design objective and use of identical turbines. Instead, maximizing the benefit‐cost ratio yields plants with better financial viability over a range of plausible futures. They tend to have smaller capacity, and feature a small turbine that is well‐adapted to low‐flow periods. Another key insight is that socio‐economic uncertainties have as much or even more impact on robustness than climate conditions. In fact, these uncertainties have the potential to make many small hydropower projects too risky to build. Our findings are of considerable practical relevance at a time where 140 GW of unexploited small hydropower potential could help power the energy transition. They also highlight the need for similar research in reservoir‐based plants, considering over 3,000 such plants planned or in construction worldwide.

Enhancing Flow Batteries: Topology Optimization of Electrode Porosity and Shape Optimization of Cell Design

This research focuses on the improvement of porosity distribution within the electrode of an all‐vanadium redox flow battery (VRFB) and on optimizing novel cell designs. A half‐cell model, coupled with topology and shape optimization framework, is introduced. The multiobjective functional in both cases aims to minimize pressure drop while maximizing reaction rate within the cell. Topology optimization results reveal dependencies on initial value, porosity constraint, and flow rate. The distribution with lower porosity is preferred downstream of the inlet manifold. This design enhances active surface area, thus facilitating more effective conversion of incoming educts and improving mass transport of products. Compared to homogeneous electrodes, two‐part design demonstrates superior performance at specific porosity values. For combined porosities of 0.7 and 0.95, optimized distribution results in 81 % reduction in pressure drop, while conversion rate decreases by 7%. As regards various cell designs, optimization suggests a need to reconsider the vertical format of a rectangular cell. Horizontal cells are favored for nearly all porosities and flow rates. Trapezoidal and radial designs characterized by reduced downstream cross sections lead to higher pressure drops and are not preferred. This work provides further valuable insight into optimizing VRFB electrodes and challenges conventional cell design assumptions.

Dowel bars – reinforcing elements of cement concrete pavements

Our aim is to analyze the function of reinforcement elements (dowel bars) in cement concrete pavement to highlight the influence of these elements on the service life of the pavement as a whole and to find possible alternatives to existing products that are freely available on the Czech market. That is, how these elements in the form of dowel bars should work properly so that the function meets the design assumptions of a rigid pavement. We describe the procedure for inserting dowel bars during paving, which is directly related to the possibilities of using different dowel bars. Finally, we summarize the possibilities of using alternative materials, shapes, or sizes of dowel bars and the possibilities of their use in the Czech Republic.

Formula Student class electric vehicle energy storage - study and design assumptions

Formula Student class electric vehicle energy storage - study and design assumptions

Connected Automated and Human-Driven Vehicle Mixed Traffic in Urban Freeway Interchanges: Safety Analysis and Design Assumptions

The introduction of connected automated vehicles (CAVs) on freeways raises significant challenges, particularly in interactions with human-driven vehicles, impacting traffic flow and safety. This study employs traffic microsimulation and surrogate safety assessment measures software to delve into CAV–human driver interactions, estimating potential conflicts. While previous research acknowledges that human drivers adjust their behavior when sharing the road with CAVs, the underlying reasons and the extent of associated risks are not fully understood yet. The study focuses on how CAV presence can diminish conflicts, employing surrogate safety measures and real-world mixed traffic data, and assesses the safety and performance of freeway interchange configurations in Italy and the US across diverse urban contexts. This research proposes tools for optimizing urban layouts to minimize conflicts in mixed traffic environments. Results reveal that adding auxiliary lanes enhances safety, particularly for CAVs and rear-end collisions. Along interchange ramps, an exclusive CAV stream performs similarly to human-driven ones in terms of longitudinal conflicts, but mixed traffic flows, consisting of both CAVs and human-driven vehicles, may result in more conflicts. Notably, when CAVs follow human-driven vehicles in near-identical conditions, more conflicts arise, emphasizing the complexity of CAV integration and the need for careful safety measures and roadway design considerations.

Dynamic Modeling and Simulation of a Discrete Incremental Hydraulic Positioning System Controlled by Binary Valves

This article presents the conceptual design, operation principle, dynamic modeling, and simulation results of a discrete incremental hydraulic positioning system (DIHPS) intended for use in high-precision, heavy-load industrial automation solutions. An original solution for precise incremental step positioning using DIHPS is proposed, comprising an n-step linear double-acting hydraulic actuator (HA) with a double rod, cylinder sleeve with outflow gaps, binary valves (BVs) bleed-off into the tank, and fixed throttle valves (TRVs) at the inlets of the actuator chambers. The discrete incremental shift of the HA is determined by controlling the opening and closing of the individual BVs, and the step shift of the HA piston stops at the opening location of the BV. A dynamic model of incremental step shift for DIHPS is developed, considering the behavior and relationships of its individual elements. A dynamic model of HA with and without a hydropneumatic accumulator (HPA) is presented. HPA has been shown to effectively dampen piston vibrations and pressure peaks at the HA stop position. The design assumptions, dynamic models, and discrete incremental positioning of the DIHPS are verified by simulation tests and assessed with quantitative indicators. Innovative DIHPSs have significant practical potential in the discrete incremental positioning of heavy loads.

Reduced disclosure and default risk: analysis of smaller reporting companies

We examine the causal effect of reduced disclosure levels on the risk of default. Employing regression discontinuity (RD) design as our main identification strategy and the smaller reporting company rule (SRC rule) as the exogenous source of variation, we show that smaller reporting companies (SRCs), which are permitted to provide scaled disclosures in their 10-Ks, experience significantly and economically higher default risk. We demonstrate that, while there is no effect of information loss if a smaller reporting company voluntarily maintains its disclosure level by continuing to report its financial performance in full, there is an increase in its default risk due to the loss of commitment to mandatory disclosure. We also find that, compared to previously qualified SRCs, newly qualified smaller reporting companies face steeper increases in bankruptcy risk during their first year of eligibility. Our analysis indicates that strong external oversight mechanisms, better corporate governance, and credible audit quality attenuate the negative impact of reduced disclosure levels on the risk of default. Our results are robust to alternative model specifications, RD design assumptions, and measures of default risk.

The Role of Preference Formation and Perception in Unequal Representation. Combined Evidence From Elite Interviews and Focus Groups in Germany

Unequal representation can result from politicians’ biased perception of public opinion. Existing research has focused on the numerical accuracy with which politicians estimate preferences distributions in surveys. This method ignores politicians’ broader assumptions about public preferences; e.g. regarding their crystallization, salience, malleability, and measurability in surveys. We address these assumptions in a novel two-stage research design using redistributive tax policy in Germany as a case. Interviews with parliamentarians show that voters are perceived as uninformed, disinterested, and susceptible to anti-tax mobilization by business representatives. Support for taxing the rich in polls is dismissed as superficial and irrelevant for political behavior. In a second step, we verify these assumptions in twelve focus groups with high- or low-educated citizens. They largely confirm the assumed indifference and anti-tax attitudes. An education gap in tax preferences cannot be identified. Support expressed in previous surveys tends to disappear in conversations, which aligns with politicians’ experiences.

Koncepcja projektowania uniwersalnego jako element podnoszenia świadomości potrzeb osób z niepełnosprawnością wśród studentów. Z doświadczeń Uniwersytetu Jana Długosza w Częstochowie

The concept of universal design as an element of raising awareness of the needs of people with disabilities among students: the experience of the Jan Długosz University in Częstochowa The article is devoted to deepening students’ knowledge about the needs of people with disabilities. Its aim is to present the implementation of the project of the National Center for Research and Development entitled Universal Fields - Universal Society, implemented at the Jan Długosz University in Częstochowa, which focused on introducing mandatory classes in the field of accessibility and universal design into the study programs of selected fields. The article presents solutions implemented into the University’s teaching, in the form of traditional lectures, exercises, but also innovative workshops with people with special needs, simulations using specialized equipment and simulators, as well as study visits. The authors of this text also included the results of the classes and the opinions of students participating in them, pointing to the need to create an environment, services and products consistent with the assumptions of universal design.

Entropy Computation for Oscillator-based Physical Random Number Generators

In this paper, we provide a complete set of algorithms aimed at the design and security evaluation of oscillator-based True Random Number Generators (TRNG). While depending on some TRNG design assumptions, the proposed algorithms use as inputs the statistical parameters of the underlying random physical process such as the clock jitter originating from the thermal noise and give a lower bound of the entropy rate of the generated bit stream as output. We describe the general structure of a TRNG composed of multiple free-running oscillators and samplers, the outputs of which are post-processed by an entropy conditioner. Depending on the specification of the entropy conditioner, which can usually be any Boolean function, we describe several algorithmic optimizations. We then explain how to compute and efficiently manage the entropy rate at the output of such a post-processing block and at the output of the generator as a whole.

Development of a foam-filled steel web sandwich panel for the rehabilitation of timber floors

Lightweight sandwich panels offer a prominent solution for the rehabilitation of timber floors. This paper addresses the development of a solution capable of continuous production for a foam-filled steel web sandwich panel for floor rehabilitation. The newly designed flooring solution is tested in full-scale quasi-static flexural campaigns. The tests validate the analytical design's compliance with Ultimate limit state (ULS) and Serviceability limit state (SLS) requirements. Furthermore, the flexural behaviour is compared with analytical predictions for thin-walled members according to the effective width method, described in Eurocode 3. Different effective cross-section design assumptions are assessed to allow an accurate prediction of the panel's response.

Use of Augmented Reality as a Tool to Support Cargo Handling Operations at the CARGO Air Terminal.

(1) Background: A current trend observed in the logistics sector is the use of Industry 4.0 tools to improve and enhance the efficiency of cargo handling processes. One of the popular solutions is an augmented reality system that supports operators in everyday tasks. The article aims to present design assumptions for implementing an augmented reality system to support air cargo handling at the warehouse. (2) Methods: Research was carried out based on a five-stage analytical procedure, aiming to analyze the current state and identify the potential for implementing the AR system. The following methods were used to collect data: co-participant observations, process analysis, direct interviews, analysis of internal documentation, and applicable legal regulations. (3) Results: The conducted research allowed for identifying information flows accompanying cargo flows and developing a project to automate selected information flows. The obtained results made it possible to identify operations for which the AR system's implementation will increase their effectiveness and efficiency. (4) Conclusions: The obtained results identified the need to develop a hybrid algorithm for arranging cargo in the warehouse and to build a system supporting self-verification of markings on air cargo.

A metaheuristic‐based method for analysis of tensegrity structures

SummaryTensegrity systems are construction system that offers solutions for lighter designs compared with a standard truss system consisting of tension and compression elements. Due to their structure, they are recommended in the design of space structures due to the use of lighter and easy‐to‐assemble structural elements such as cables, ropes, and similar to provide the desired durability. In this study, energy minimization was carried out to solve the structural element displacements. It is expected to reduce the total potential energy of the system with minimization. By minimizing the total potential energy of the tensegrity system models, the displacement of each building element is found for the equilibrium condition. Tensegrity models were analyzed by minimizing energy via the adaptive harmony search (AHS) algorithm. In this research, two distinct tensegrity structure specimens were employed. One comprised a cantilever beam, while the other adopted a cyclic model, forming eight equal octagons from eight nodes at both the base and the top. Additionally, an examination was conducted on a two‐layer iteration of the cyclic model. The method is robust for both space and planar tensegrity structures, allowing the determination of deformed shapes under various loads without design assumptions. The TPO/MA method demonstrates superiority in handling nonlinear and barely stable systems, as evidenced by examples illustrating its efficacy in maintaining structural form under increasing loads and challenging conditions.

Integrated, multi-scale and multi-objective design of batch food processing plants. Part 2: Application to a mobile fruit and vegetable processing unit

The design of food processing plants that are plug-and-play, reconfigurable, modular, mobile and containerised is a complex task. The "Methodology for the integrated, multi-scale and multi-objective design of systems" can be used to design such systems. This was developed and the various tasks that make it up presented in a previous article by Savoure et al. (2023) (references to be specified). The aim of this study is to assess the potential of this methodology to design a mobile fruit and vegetable processing unit. Firstly, a design support tool was developed to (i) simulate the behaviour and estimate the performances of design solutions, (ii) convert their performances into desirability indices using the decision maker's preferences and (iii) search for the design solution(s) that best satisfy the decision maker's design objectives. The results were then visualised and analysed to ensure that the resulting design solution was a satisfying, feasible and coherent trade-off. This analysis also helped to understand (i) which design variables, models and assumptions drove the design decision the most and (ii) which final products, design objectives, performance indicators and preference models influenced the optimisation process the most. In particular, it showed that one of the products (okra puree) limited the performance of the design solution. Finally, this work increased the level of understanding of the design problem and challenged the preferences of the decision maker.