Break Research Articles

Optimization of White Box Testing by Utilizing Branching and Repeating Structures in Java Programs Using Base Path

Software testing is a process created to detect anomalies in the operation of a program or system in order to achieve the expected results. White box testing is a software testing method that tests the internal structure, design and program code. This research aims to produce an optimization method for white box testing in Java programs by utilizing branching and repetition structures using the basis path method, as well as analyzing the effectiveness of the proposed method in generating test cases. The Java program tested in this research includes input function calls, loops, branching, and exception handling. Test case design is carried out by applying the basis path method to achieve comprehensive coverage. The test results show that the base path method is able to produce effective test cases for testing control structures without redundancy. Test case design is assisted by flowgraph and matrix graph modeling. It is hoped that this research can contribute to the optimization of white box testing techniques.

Continuous synthesis of calcium hydrogen phosphate dihydrate (DCPD) in an annular rotating flow loop reactor

The synthesis of calcium hydrogen phosphate dihydrate (DCPD) involves a gas–liquid-solid three-phase slurry system that poses challenges for precise control using traditional batch reactors to produce crystals with controlled morphologies and particle sizes. In this study, an annular rotating flow loop reactor (ARLR) was developed to continuously synthesize DCPD. The unique internal loop and annular rotating flow field of the reactor delivered exceptional plug-flow characteristics, ensuring that the obtained DCPD exhibited a controlled morphology and particle size. The morphology of DCPD was adjusted to be bowknot-shaped (BS) agglomerate crystals, reaching a length of 120 μm and a D50 size of 70 μm. The ARLR can achieve long-term stable operation with high-solid holdup slurries, outputting up to 125 g/h by maintaining precise and controllable flow and mixing conditions. Notably, ARLR marked a significant advancement in processing high-solid-holdup slurries, offering the adaptability to adjust the geometric design for various slurry systems and forecasting promising prospects.

Improved Reference Current Extraction Method for Electric Aircraft Active Power Filter Application

This paper proposes a robust reference current extraction method useful for active power filters (APFs) connected to the More Electric Aircraft (MEA) grid for addressing power quality issues. Hence, it is essential to investigate and develop better APF harmonic compensating control algorithms that can eliminate the impact of harmonics emerging from the nonlinear loads connected to the MEA grid. The proposed method envisages a half-cycle moving window discrete Fourier transform filter approach to rapidly extract the fundamental positive sequence (FPS) from a polluted three-phase grid voltage. Thus, allowing the harmonic cancelation method to generate desired clean reference current which is in phase with FPS component of the grid voltage. This reference current is used in conjunction with the hysteresis current controller to generate appropriate gate pulses for the current-controlled voltage source APF. The employment of the digital filter in the control structure of the APF ensures improved power quality for the MEA grid as compared to traditional filtering algorithms. The numerical and experimental results demonstrate that the proposed control solution helps to reduce the total harmonic distortion under abnormal grid disturbances, thus, indicating the potential benefits of the proposed work for addressing power quality issues in MEA applications.

Compliant variable admittance adaptive fixed-time sliding mode control for trajectory tracking of robotic manipulators

Abstract This paper presents a compliant variable admittance adaptive fixed-time sliding mode control (SMC) algorithm for trajectory tracking of robotic manipulators. Specifically, a compliant variable admittance algorithm and an adaptive fixed-time SMC algorithm are combined to construct a double-loop control structure. In the outer loop, the variable admittance algorithm is developed to adjust admittance parameters during a collision to minimize the collision time, which gives the robot compliance property and reduce the rigid collision influence. Then, by employing the Lyapunov theory and the fixed-time stability theory, a new nonsingular sliding mode manifold is proposed and an adaptive fixed-time SMC algorithm is presented in the inner loop. More precisely, this approach enables rapid convergence, enhanced steady-state tracking precision, and a settling time that is independent of system initial states. As a result, the effectiveness and improved performance of the proposed algorithm are demonstrated through extensive simulations and experimental results.

Facilely prepared Co-based MOF functionalized N, S-doped reduced graphene oxide for electrochemical non-enzymatic glucose sensing

Rational design of modified electrode materials is critical for electrochemical sensors. Metal-organic frameworks (MOFs), a novel sort of substance with porosity, has received widespread attention owing to various superior characteristics such as adjustable pore sizes, great surface area and controllable structures. Nevertheless, the poor charge transfer capability of MOFs leads to a general suppression of their electrochemical sensing performance. To solve this issue, compositing conductive substance with MOFs have been demonstrated to be an effective strategy. Herein, Co-based MOF (ZIF-67) functionalized N, S-doped reduced graphene oxide (N, S-RGO) heterostructure (ZIF-67/N, S-RGO) was fabricated through an in-situ synthesis method. The composite material was used in the modification of an electrode to construct a sensing platform for non-enzymatic glucose testing. The synergistic interaction of ZIF-67 and N, S-RGO not only provided more efficient active sites and larger surface areas, but also improved the electron transport efficiency and electrocatalytic performance. Under optimized conditions, the ZIF-67/N, S-RGO/GCE had a dynamic linear range of 1–3200 μM, with a detection limit of 0.33 μM (S/N = 3) for glucose detection. The sensing platform also provided excellent reproducibility, selectivity, and stability (70 % activity retained after 12 days). Furthermore, the sensor had the potential to apply for glucose determination in human serum. This work presented a novel strategy to the field of non-enzymatic glucose sensing and may provide effective coaching for optimizing the electrochemical sensing performance of other series of MOFs.

FLASH FLOODS: RISK ASSESSMENT AND MITIGATION

In recent years, United Arab Emirates has experienced several flash flood events and extreme cyclonic events that resulted in flooding various parts of the country. This in return raised concerns on the preparedness of the infrastructure to such events considering the damage caused by them. Roads were blocked from the excessive rainfall water leading to heavy traffic jams, houses were drowned and cars were swept away. Therefore, an in-depth study was performed on a selected area of interest in the city of Ras Al-Khaimah (UAE) to explore the risks associated with flash flood events and to propose solutions for flood management. Hydrological and hydraulic models were used to simulate precipitation runoffs and calculate flood magnitudes in order to plan and design new flood control and hydraulic structures. Using the output of the hydrologic and hydraulic models, a dam and a protection channel were proposed as possible solutions to resolve flood issues in the selected area. It was concluded that with proper hydrologic modelling, flash floods can be managed to a great extent and damage to the infrastructure can be minimized. It is even more important in context of climate change that such modelling techniques should be part of urban planning and design of infrastructure drainage systems for areas that are prone to heavy rainfall and floods.

Fabrication of carbon fiber/cement composites with controllable precise patterned structures via facile computerized embroidery

Carbon fibers exhibit good electrothermal performance; however, they break easily during the weaving process. This study used a facile computerized embroidery process to design and fabricate carbon fibers with controllable and precise patterned structures. The obtained carbon fiber/cement composites (CFCs) exhibited excellent electrothermal performance (100 ℃ under 30 V), low energy consumption (400 mW/℃), and homogeneous heat distribution with a unique heating element (carbon fibers) structure. The difference between the maximum and average surface temperatures improved, and the surface heat distributions of the CFCs under different structures were determined using a finite element simulation. CFCs with different complex heat element structures were successfully fabricated, and the mechanism regulating the heat distribution of the CFCs was revealed. Embroidery technology provides a novel strategy for the fabrication of carbon fiber/cement composite materials with a controllable carbon fiber structure, thereby significantly broadening the application of cement composites for electrothermal applications.

Comprehensive mathematical model for efficient and robust control of irrigation canals

Linear control-oriented models are important to represent canal dynamics for designing controllers. This study focuses on hydraulic control structure (gate) modelling to address the complex interdependent behavior inherent in irrigation canals. A comprehensive mathematical model that incorporates the water level with gate-opening to model discharge is introduced for single and multiple canal pool scenarios. The proposed model captures the hydraulic coupling within and among canal pools, a key finding. The model is evaluated extensively under uniform and non-uniform flows across three distinct canals, highlighting the model’s applicability to various systems. The uncertainty inherent within the nominal model is also assessed for varying operating conditions and hydraulic parameters. The proposed model is compared with the existing and the Saint-Venant (SV) model, showing improved accuracy in water-level predictions. This advancement in hydraulic modelling contributes to adaptable canal models essential in developing robust controllers to enhance water management in irrigation canals.

Efficient river hydrodynamics modelling in realistic river systems using a Fourier neural operator-based network

Effective river management relies heavily on the accurate simulation of river flow dynamics to develop scenario-based strategies and inform decision making. Deep learning (DL) models, as alternatives to conventional simulation techniques, offer a compelling blend of precision and efficiency. This study introduces FNOCL (Fourier Neural Operator with ConvLSTM units), a novel DL neural network for modelling unsteady natural river flows. The network is adept at handling the complexities of spatial and temporal variations. FNOCL builds upon the Fourier neural operator (FNO) by incorporating convolutional long short-term memory (ConvLSTM) layers, combining robust performance with high proficiency in terms of capturing spatiotemporal patterns. Notably, FNOCL accommodates complex river cross-section profiles, thus enabling the accurate modelling of flow dynamics within intricate river morphologies. Our study applies FNOCL to two distinct river networks with varying morphology complexity levels. With reference to the HEC-RAS model, FNOCL showcases its ability to attain high accuracy in model prediction tasks and superior generalization with regard to addressing the uncertainty associated with inflow variations and cross-sectional changes. In comparative analyses with benchmark models (i.e., FNO and ConvLSTM), FNOCL performs most efficiently during the training process and obtains the most accurate water level and river flow predictions in the spatiotemporal domain. Furthermore, FNOCL exhibits a substantial speedup over HEC-RAS, notably reaching up to 50 times in a complex river network. These results highlight FNOCL as an efficient surrogate for conventional simulators, facilitating precise analyses across various scenarios. It provides efficient computations for system responses within complex river flow networks, thereby enhancing applications in river management, such as flood risk assessment, flood control, and the planning and design of hydraulic control structures.

Self-Calibration Method of Displacement Sensor in AMB-Rotor System Based on Magnetic Bearing Current Control

Displacement sensors are the key components of the active magnetic bearing rotor (AMB-rotor) system to realize the closed-loop control of the rotor displacement. The aging and failure of the displacement sensor components will lead to the changes of sensor sensitivity and zero point, which can directly affect the suspension performance of the rotor and even cause the instability of the AMB-rotor system. Therefore, it is significant to calibrate the sensor regularly. This paper proposes a self calibration method based on the detection and control of the magnetic bearing current without additional calibration equipment and hardware circuits. In addition, a new control structure of the AMB-rotor system is proposed to achieve efficient calibration, which can control the rotor displacement based on current following control method. Finally, experimental results verify the effectiveness of the proposed method on the displacement sensor calibration.

ZIF-67 derived CoNi@carbon/RGO composites with abundant heterogeneous interfaces for electromagnetic wave absorption

The controllable structure design and composition regulation play a key role in the development of electromagnetic wave (EMW) absorbing material. Herein, CoNi@carbon/RGO absorbing materials were successfully prepared by direct pyrolysis of ZIF-67/Ni(OH)2/GO precursor. The CoNi@carbon/RGO-15 sample achieves an RLmin value of −46.14 dB and an effective absorption bandwidth (EAB) of 1.15 GHz (thickness 4.1 mm) at a low frequency with a filling amount of only 10 wt%. When the thickness is 1.5 mm, the RLmin reaches −41.09 dB and the EAB reaches 5.41 GHz, covering most of the Ku bands. After the pyrolysis, the carbon layer, Co and Ni nanoparticles, and RGO nanosheets form a three-dimensional porous structure, which builds up abundant heterogeneous interfaces and conductive networks. These factors can enhance impedance matching, dielectric, and magnetic loss. This indicates that CoNi@carbon/RGO is the potential lightweight EMW absorbing material with high performance.

Research and application of small-diameter hydraulic fracturing in situ stress measurement system

Abstract. Observation and estimation of the stress state in the deep crust is a crucial challenge in in situ stress measurement work. The hydraulic fracturing method is an important borehole-based technique for absolute in situ stress measurement. The small-diameter hydraulic fracturing in situ stress measurement system described in this article consists mainly of underground measurement components (serial small-diameter packers and dual-circuit connecting installation rods) and surface control components (hydraulic fluid control system, data acquisition system, and high-pressure oil pump with controllable flow). It enables series measurement of small-sized boreholes for in situ stress and provides a maximum measurement range of 30–45 MPa. The subsequent calculation of in situ stress data adopts a uniform design method to discuss the influence of various external factors on rock fracturing values. The small-diameter hydraulic fracturing in situ stress measurement system has the advantages of simple and lightweight structure, short testing time, high success rate, and low requirements for rock integrity and pressurization equipment. It has formed a series of small-diameter in situ stress measurement equipment which has been innovatively promoted to the field of underground tunnel safety assessment in coal mines and metal mining areas. It has an important practical value and economic significance in accurately determining the in situ stress state of deep development areas.

Enhancing computational thinking in early childhood education through ScratchJr integration

A plethora of programming platforms purports to teach preschool-aged children computational thinking (CT) and coding skills. However, the empirical evidence to support their effectiveness is still in its early stages. A three-week didactic intervention using ScratchJr was conducted to investigate its effectiveness in fostering CT and rudimentary coding skills in a cohort of preschool children (N = 34, aged 4–6 years). While the initial performance mean of the control group (M = 7.07, SD = 2.58) exhibits a statistically significant elevation t (22.64 = 2.23, p = 0.036) vis-à-vis the experimental group (M = 5.35, SD = 1.58), t (22.64) = 2.23, p = 0.0 the terminal performance means of both groups converge closely. However, meticulous data analysis unveils a statistically notable enhancement among preschool participants exposed to the educational intervention involving ScratchJr. Notably, both instructional modalities appear commensurate in nurturing elementary computational tenets, namely modularity and control structures. The experimental cohort outperforms the control group with statistical significance in comprehending potent ideational constructs encompassing representation, algorithms, and hardware/software interplay. Conversely, the control group performs better in grasping the debugging concept than their experimental counterparts. The outcomes lend substantive credence to the efficacy of the distinct programming milieu offered by ScratchJr, underscoring its effectiveness in cultivating CT and coding proficiencies within the preschool demographic.

Fabrication of biodegradable Poly(butylene adipate-co-butylene terephthalate) bead foams through solid utilization of chitin and controllable incorporation of porous structure

The pollution caused by waste plastics is becoming increasingly serious, and utilizing the biodegradable materials, that can be completely degraded in nature, is considered to be one of the most promising ways to solve this problem. Poly(butylene adipate-co-butylene terephthalate) (PBAT), as the commonly used biodegradable polymer material, is subjected to the problem of high cost, poor mechanical performance, and low melt strength at high temperatures. Herein, a novel strategy combining solid utilization of biomass material chitin and incorporation of porous structure was developed to fabricate the PBAT bead foams, relying on the solid-state shear milling (S3M) and supercritical carbon dioxide (scCO2) foaming technologies. Chitin scraps were super finely pulverized and uniformly combined with PBAT, and the PBAT-based bead foams with controllable cell structure, improved mechanical performance, and low cost after foaming the composite. When the content of chitin was 20%, the tensile strength and Young’s modulus of PBAT/chitin bead foam were 0.72 MPa and 2.14 MPa, respectively, much higher than that of neat PBAT bead foam, expressing the great significance to broadening the application field of degradable plastics.

A novel non-chemically amplified resist based on polystyrene-iodonium derivatives for electron beam lithography

To break the resolution limitation of traditional resists, more work is needed on non-chemically amplified resists (non-CARs). Non-CARs based on iodonium salt modified polystyrene (PS-I) were prepared with controllable molecular weight and structure. The properties of the resist can be adjusted by the uploading of iodonium salts on the polymer chain, the materials with a higher proportion of iodonium salts show better lithography performance. By comparing contrast curves and quality of the lithographic patterns, the optimum developing condition of 4-methyl-2-pentanone and ethyl alcohol (v:v = 1:7) was selected. The high-resolution stripes of 15 nm half-pitch (HP) can be achieved by PS-I0.58 in e-beam lithography (EBL). PS-I0.58 shows the advanced lithography performance in the patterns of 16 nm HP and 18 nm HP stripes with low line edge roughness (3.0 nm and 2.4 nm). The resist shows excellent potential for further pattern transfer, the etch selectivity of resist PS-I0.58 to the silicon was close to 12:1. The lithographic mechanism of PS-I was investigated by experimental and theoretical calculation, which indicates the polarity of materials changes results in the solubility switch. This work provides a new option and useful guidelines for the development of high-resolution resist.

Castor oil-based polyurethane Vitrimer modified asphalts regulated by dual dynamic reversible reactions and crosslinking density: Preparation, basic assessment and self-healing behavior

Thermosetting polymers, commonly used to improve asphalt properties, bring excellent pavement performance, but also pose significant challenges to the healing and recyclability of their modified asphalts after long-term service. An effective approach involves introducing dynamic bonds into the crosslinking networks to synthesize Vitrimer-modified asphalts with self-healing response. Due to the splendid mechanical properties, high elasticity, flexibility and easily controllable cross-linked structure of polyurethane, a novel castor oil-based polyurethane Vitrimer modified asphalt with disulfide bonds and Diels-Alder reactions was developed. Based on the prepared castor oil-based polyurethane Vitrimer (C-PUV, composed of components A and B) and its modified asphalts (C-PUVAs), a comprehensive study was conducted on the crosslinking density, mechanical properties, thermal stability, viscosity, compatibility, rheological properties, and self-healing behavior. The results indicated that C-PUVAs (C-PUVA1/C-PUVA2/C-PUVA3/C-PUVA4) exhibited sufficient retention times for viscosity, uniform phase distribution, and good high-temperature performance. The damaged C-PUVAs achieved a mechanical strength recovery rate more than 75 % after the first cycle of self-healing at 80 ℃ and 0.3 MPa. Furthermore, the crosslinking density of C-PUV was regulated by the segment length of component B. As the crosslinking density increased, C-PUV and C-PUVAs obtained higher mechanical strength while sacrificing part of self-healing efficiency. The mechanism is that increased crosslinking density altered the gel point distributions of the reversible crosslinked networks, resulting in a longer relaxation time and higher activation energy. In conclusion, the above findings provided valuable insights for developing bio-based polyurethane Vitrimer modified asphalts, and endosing thermosetting polymer modified asphalts with self-healing and recyclable properties.

A Survey on Cage‐based Deformation of 3D Models

AbstractInteractive deformation via control handles is essential in computer graphics for the modeling of 3D geometry. Deformation control structures include lattices for free‐form deformation and skeletons for character articulation, but this report focuses on cage‐based deformation. Cages for deformation control are coarse polygonal meshes that encase the to‐be‐deformed geometry, enabling high‐resolution deformation. Cage‐based deformation enables users to quickly manipulate 3D geometry by deforming the cage. Due to their utility, cage‐based deformation techniques increasingly appear in many geometry modeling applications. For this reason, the computer graphics community has invested a great deal of effort in the past decade and beyond into improving automatic cage generation and cage‐based deformation. Recent advances have significantly extended the practical capabilities of cage‐based deformation methods. As a result, there is a large body of research on cage‐based deformation. In this report, we provide a comprehensive overview of the current state of the art in cage‐based deformation of 3D geometry. We discuss current methods in terms of deformation quality, practicality, and precomputation demands. In addition, we highlight potential future research directions that overcome current issues and extend the set of practical applications. In conjunction with this survey, we publish an application to unify the most relevant deformation methods. Our report is intended for computer graphics researchers, developers of interactive geometry modeling applications, and 3D modeling and character animation artists.

ParDiff: Practical Static Differential Analysis of Network Protocol Parsers

Countless devices all over the world are connected by networks and communicated via network protocols. Just like common software, protocol implementations suffer from bugs, many of which only cause silent data corruption instead of crashes. Hence, existing automated bug-finding techniques focused on memory safety, such as fuzzing, can hardly detect them. In this work, we propose a static differential analysis called ParDiff to find protocol implementation bugs, especially silent ones hidden in message parsers. Our key observation is that a network protocol often has multiple implementations and any semantic discrepancy between them may indicate bugs. However, different implementations are often written in disparate styles, e.g., using different data structures or written with different control structures, making it challenging to directly compare two implementations of even the same protocol. To exploit this observation and effectively compare multiple protocol implementations, ParDiff (1) automatically extracts finite state machines from programs to represent protocol format specifications, and (2) then leverages bisimulation and SMT solvers to find fine-grained and semantic inconsistencies between them. We have extensively evaluated ParDiff using 14 network protocols. The results show that ParDiff outperforms both differential symbolic execution and differential fuzzing tools. To date, we have detected 41 bugs with 25 confirmed by developers.

Generalization of Direct Adaptive Control Using Fractional Calculus Applied to Nonlinear Systems

This paper presents a new direct adaptive control (DAC) technique using Caputo’s definition of the fractional-order derivative. This is the first time a fractional-order adaptive law is introduced to work together with an integer-order stable manifold for approximating the uncertainty of a class of nonlinear systems. The DAC approach uses universal function approximators such as multi-layer perceptrons with one hidden layer or fuzzy systems to approximate the controller. This paper presents a new lemma, which elucidates and clarifies the link between the Caputo and the Riemann–Liouville definitions. The introduced lemma is useful in developing a Lyapunov candidate to prove the stability of using the proposed fractional-order adaptive law. This is further explained by a numerical example, which is provided to elucidate the practicality of using the fractional-order derivative for updating the approximator parameters. The main novelty of the results in this paper is a rigorous stability proof of the fractional DAC approach for a class of nonlinear systems that is subjected to unstructured uncertainty and deals with the adaptation mechanism using a traditional integer-order stable manifold. This makes the control scheme easier to implement in practice. The fractional-order adaptation law provides greater degrees of freedom and a potentially larger functional control structure than the conventional adaptive control. Finally, the paper demonstrates that traditional integer-order DAC is a special case of the more general fractional-order DAC scheme introduced here.

Determining the Relevance of Commonly Used Hydraulic Parameters for Representing the Water Erosive Force in Rock Mass Erosion within Dam Spillways

Spillways are essential control structures in hydroelectric dams for evacuating excess water during periods of high-water flow. These structures are generally excavated within a rock mass, without lining, and they take the form of a flow channel or a plunge pool. Rock mass erosion is an important issue facing engineers when designing unlined spillways. Methods commonly used to analyze this phenomenon are based on the threshold line concept, i.e., the correlation between rock mass resistance and its destruction against the erosive force of water. Multiple indices have been proposed for both rock mass quality and water energy (or erosive force) to assess rock mass erosion. The selection of appropriate indices is critical when evaluating hydraulic erosion. The erosive force of water is often represented by energy dissipation; however, other parameters, including average flow velocity and shear stress at the bottom of the flow channel, may also be relevant. Thus, a critical question is framed: which index best represents the erosive force of water? Here, we develop an approach to assess the applicability of the various indices used to represent the erosive force of water by relying on erosional events at more than 100 study sites. We determine that the most relevant parameters are linked to water pressure, as pressure head and flow velocity better explain the erosive force of the water than shear stress and water dissipation energy.