Structural Control Research Articles

Using Edge Detection Techniques on Aeromagnetic Data to Delineate Structures Controlling Orogenic Gold Deposits in the Sefwi Greenstone Belt, Ghana

ABSTRACT The orogenic-style gold deposits in the Sefwi greenstone belt are associated with quartz veins and occur along shear zones. Edge detection techniques (i.e., analytic signal, vertical, and tilt derivatives) were employed to delineate regional planar fabrics (e.g., shear zones, faults) using aeromagnetic data. The enhancing techniques aided the delineation of NE-SW striking lineaments associated with the Kenyase-Yamfo, Hwidiem, Ketesso, Bibiani, and Afema shear zones in the study area. These shear zones are within the Sefwi belt and at the contact zones between the belt and the adjacent metamorphosed volcano-sedimentary rocks of the Sunyani-Comoé and Kumasi-Afema basins. Low-displacement N-S to NNE-SSW trends which are oblique to the NE-SW shear zones, were also delineated. The local bend and offset along the NE-SW striking faults created by the cross-cutting N-S to NNE-SSW faults serve as favourable trap zones to focus fluids migrating along these shear zones. Fry analysis of known orogenic gold occurrences in the study areas shows that the NE-SW lineaments, with an azimuth of 40°-50°, are predominant in controlling the distribution of deposits. There is also a significant structural control in the N-S to NNE-SSW direction with azimuths 0°-10° and 10°-20°.

Integrating multispectral remote sensing and geological investigation for gold prospecting in the Borongo-Mborguene gold field, eastern Cameroon

Multispectral remote sensing data has great promise for mineral prospecting via regional-scale mapping of alteration zones and geological structures, once the method is calibrated using in-situ geological observations. The Borongo-Mborguene area, located in eastern Cameroon at the transition from sub-tropical to arid climates, hosts several alluvial gold deposits. In this investigation, maps developed by processing of Landsat-8 OLI images, ASTER satellite images, and SRTM DEM data were compared to results of a comprehensive field survey to locate zones of hydrothermal alteration and regional structural lineaments, and to verify the association of these features with gold mineralization. Specific Landsat-8 and ASTER band ratios, as well as principal component analysis of the multispectral images, were selected to isolate spectral signals that characterize particular groups of alteration minerals, such as clays, hydrated carbonates, hydrated sulphates, iron oxides, and iron hydroxides. Lineaments and their preferred orientations were extracted by filtering of the digital elevation data. A fuzzy logic approach was subsequently applied to the ensemble of resulting maps to highlight five areas of concentrated hydrothermal alteration and structural complexity as potential gold prospects (Mborguene, Boutila, Nandoungue, Borongo and Ouaden villages). Petrographic study of samples collected from the remotely-identified alteration zones revealed a hydrothermal ore assemblage of gold, galena, pyrite and hematite in mineralized quartz veins. Structural control of the alteration zones in the Borongo-Mborguene gold field was confirmed by field mapping along a shear zone. Hence, our petrographic and field studies indicate that the multispectral remote sensing data and data processing methods developed herein are appropriate for mineral exploration in remote sub-tropical areas of Africa. More generally, the computationally efficient and simple procedure developed here should yield accurate preliminary maps of the spatial distribution of hydrothermal halos and related mineral deposits in challenging mixed-type vegetated terrain around the globe.

A Tetracarbene Iron(II) Complex with a Long‐lived Triplet Metal‐to‐ligand Charge Transfer State due to a Triplet‐Triplet Barrier

Mixed N‐heterocyclic carbene (NHC) / pyridyl iron(II) complexes have attracted a great deal of attention recently because of their potential as photocatalysts and light sensitizers made from Earth‐abundant elements. The most decisive challenge for their successful implementation is the lifetime of the lowest triplet metal‐to‐ligand charge transfer state (3MLCT), which typically decays via a triplet metal‐centered (3MC) state back to the ground state. We reveal by variable‐temperature ultrafast transient absorption spectroscopy that the tripodal iron(II) bis(pyridine) complex isomers trans‐ and cis‐[Fe(pdmi)2]2+with four NHC donors show 3MLCT→3MC population transfers with very different barriers and rationalize this by computational means. While trans‐[Fe(pdmi)2]2+possesses an unobservable activation barrier, the cis isomer exhibits a barrier of 492 cm–1, which leads to a nanosecond 3MLCT lifetime at 77 K. The kinetic and quantum chemical data were analyzed in the context of semi‐classical Marcus theory revealing a high reorganization energy and small electronic coupling between the two triplet states. This highlights the importance of detailed structural control and kinetic knowledge for the rational design of photosensitizers from first row transition metals such as iron.

Impact of Environmental Factors, Organizational Structure, Conflict Management, and Internal Control on the Effectiveness of Islamic Schools in Banten

The rapid increase in the number of schools necessitates the evaluation of educational quality across all institutions, including both private and state-run schools, with a particular focus on Islamic schools. Organizational performance serves as a key indicator of an institution's effectiveness. This study aims to analyze the impact of organizational structure, conflict management, and internal control on the work environment and effectiveness of teachers in Islamic schools in Banten. The study population comprised teachers from Islamic schools in Banten, with a total sample size of 58 teachers. Data analysis was conducted using path analysis to assess the relationships between the variables. The analysis revealed that organizational structure, conflict management, and internal control positively influenced the teachers' work environment. Furthermore, the organizational structure was found to have a significant impact on work effectiveness. However, conflict management and internal control did not show a significant effect on teachers' work effectiveness. Additionally, the work environment had a positive effect on the effectiveness of the teachers' work. The findings indicate that a well-defined organizational structure enhances both the work environment and the effectiveness of teachers in Islamic schools. While conflict management and internal control are beneficial for improving the work environment, they do not directly influence work effectiveness. The positive correlation between the work environment and teacher effectiveness underscores the importance of fostering a supportive and well-structured organizational setting. This study underscores the critical role of organizational structure in enhancing teacher effectiveness in Islamic schools. While conflict management and internal control improve the work environment, their direct impact on effectiveness is limited. Creating a conducive work environment remains essential for maximizing the performance of teachers.

The Study of Levee Flood Control at Pengkol River - Meteseh, Tembalang Sub District - Semarang City

The Pengkol River, situated in Meteseh, Tembalang sub-district of Semarang City, underwent three significant flood occurrences from January to February 2023. An approach involving a structural flood control system, specifically a levee, was suggested as a solution to this issue. The objective of this research is to establish the arrangement and highest elevation of the levee flood control and evaluate its effectiveness in mitigating floods. To determine flood hydrographs, a hydrological analysis was carried out using the Rainfall-Runoff simulation with the SCS Curve Number method. Additionally, a hydraulic analysis was performed using Unsteady Flow simulation with HECRAS 1D/2D hydrodynamic models to define the river body, water profile, inundation, and levee design. The hydrologic analysis indicates that the flood discharge for the 50, 100, and 200-year return periods are 209.5 m³/sec, 225.1 m³/sec, and 240.6 m³/sec, respectively. Based on the hydraulic analysis, the maximum water levels resulting from these return periods' flood discharges are +35.62 m (Q50 years), +35.77 m (Q100 years), and +36.43 m (Q200 years). The Q200 years of return period was chosen for 2D modeling because it resembles documented flood occurrences. Using the HECRAS 2D Unsteady Flow model, it was found that before the levee implementation, the flooded area within the residential zone spanned 9462 m², with a peak water level of +37.3 m. With the levee application, using an existing layout with a total length of 230 m and a top levee level of +37.5 m, flooding was effectively prevented, reducing the maximum water surface elevation to +37.17 m. This demonstrates the levee's effectiveness in preventing floods.Keywords: levee, flood, HECRAS 1D 2D model, inundation. Unsteady flow.

A Site-Specific Cross-Linker for Visible-Light Control of Proteins.

There is a need for photochemical tools that allow precise control of protein structure and function with visible light. We focus here on the s-tetrazine moiety, which can be installed at a specific protein site via the reaction between dichlorotetrazine and two adjacent sulfhydryl groups. Tetrazine's compact size enables structural mimicry of native amino acid linkages, such as an intramolecular salt bridge or disulfide bond. In this study, we investigated tetrazine installation in three different proteins, where it was confirmed that the cross-linking reaction is highly efficient in aqueous conditions and site-specific when two cysteines are located proximally: the S-S distance was 4-10 Å. As shown in maltose binding protein, the tetrazine cross-linker can replace an interdomain salt bridge crucial for xenon binding and serve as a visible-light photoswitch to modulate 129Xe NMR contrast. This work highlights the ease of aqueous tetrazine bioconjugation and its applications for protein photoregulation.

Preparation Method and Application of Porous Poly(lactic acid) Membranes: A Review.

Porous membrane technology has garnered significant attention in the fields of separation and biology due to its remarkable contributions to green chemistry and sustainable development. The porous membranes fabricated from polylactic acid (PLA) possess numerous advantages, including a low relative density, a high specific surface area, biodegradability, and excellent biocompatibility. As a result, they exhibit promising prospects for various applications, such as oil-water separation, tissue engineering, and drug release. This paper provides an overview of recent research advancements in the fabrication of PLA membranes using electrospinning, the breath-figure method, and the phase separation method. Firstly, the principles of each method are elucidated from the perspective of pore formation. The correlation between the relevant parameters and pore structure is discussed and summarized, subsequently followed by a comparative analysis of the advantages and limitations of each method. Subsequently, this article presents the diverse applications of porous PLA membranes in tissue engineering, oil-water separation, and other fields. The current challenges faced by these membranes, however, encompass inadequate mechanical strength, limited production efficiency, and the complexity of pore structure control. Suggestions for enhancement, as well as future prospects, are provided accordingly.

Cycle-Based Control of Injection Moulding Process in Presence of Material Dual Sourcing Using Mass Feedback.

The low cost and precise tolerances of plastic injection moulded products are a major reason for the popularity of the manufacturing method. The tolerances are greatly influenced by the equipment, raw material and moulding process. One challenge is the raw material variation. This paper presents a production process using cycle based feedback of cycle mass, for control of part properties in the presence of material variation from dual sourcing. The part properties considered are part mass and outer dimensions. The process uses direct cycle mass feedback without additional process measurements in the proposed controller structure. The designed controller structure is tested in a multi-cavity mould while using raw materials from multiple vendors, encompassing five different grades. The results show a total decrease in part mass variance of approximately 50% and a decrease of length and width variance of approximately 40% compared to a moulding process with fixed settings.

Recent advances in Sb-based anodes for Li/Na/K-ion batteries and all-solid-state Li-ion batteries

In recent decades, lithium-ion batteries (LIBs) have emerged as a primary focus in the energy-storage field owing to their superior energy and power densities. However, concerns regarding the depletion of non-abundant lithium resources have prompted the exploration and development of emerging energy-storage technologies, such as sodium- (SIBs) and potassium-ion batteries (PIBs). In addition, all-solid-state LIBs (ASSLIBs) have been developed to address the issues of flammability and explosiveness associated with liquid electrolytes. Among the various alloy-based anodes, antimony (Sb) anodes exhibit high energy densities owing to their high theoretical volumetric capacities that are attributable to their high densities. However, Sb anodes exhibit poor cyclabilities owing to excessive volume changes during cycling. To mitigate this issue, researchers have investigated the use of diverse solutions, including solid electrolyte interface control, structural control, and composite/alloy formation. Herein, we review and summarize Sb-based anode materials for LIBs, SIBs, PIBs, and ASSLIBs developed over the past five years (2018-present), focusing on their reaction mechanisms and multiple approaches used to achieve optimal electrochemical performance. We anticipate that this review will provide a comprehensive database of Sb-based anodes for LIBs, SIBs, PIBs, and ASSLIBs, thereby advancing relevant studies in the energy-storage-systems field.

A Review: Structural Shape and Stress Control Techniques and their Applications

AbstractThis review article presents prior studies on controlling shape and stress in flexible structures. The study offers a comprehensive survey of literature concerning the adjustment and regulation of shape, stress, or both in structures and emphasizes such control’s importance. The control of systems is classified into three primary classes: nodal movement control, axial force control, and controlling the two classes concurrently. Each class is thoroughly assessed, showcasing diverse methods anticipated by various scholars. Furthermore, the paper discusses methods to reduce the number of devices (actuators) to adjust and optimize actuators’ placement to achieve optimal structural control, considering the cost implications of numerous actuators. Additionally, various actuators are presented in detail, their advantages and disadvantages are also discussed. Moreover, the applications of the presented techniques are reviewed in detail, the essential recommendations for future work are also suggested.

Insights into the Optimization of Catalytic Active Sites in Lithium-Sulfur Batteries.

ConspectusLithium-sulfur batteries (LSBs), recognized for their high energy density and cost-effectiveness, offer significant potential for advancement in energy storage. However, their widespread deployment remains hindered by challenges such as sluggish reaction kinetics and the shuttle effect of lithium polysulfides (LiPSs). By the introduction of catalytic materials, the effective adsorption of LiPSs, smooth surface migration behavior, and significantly reduced conversion energy barriers are expected to be achieved, thereby sharpening electrochemical reaction kinetics and fundamentally addressing the aforementioned challenges. However, driven by practical application targets, the demand for higher loadings and reduced electrolyte parameters inevitably exacerbates the burden on catalytic materials during their service. Additionally, given that catalytic materials contribute negligible electrochemical capacity, their incorporation inevitably increases the mass of nonactive components for reducing the energy density of LSBs. A meticulous insight into the lithium-sulfur catalytic reaction reveals that the conversion of LiPSs is dominated by active sites on the surfaces of catalytic materials. These microregions provide the necessary electron and ion transport for the conversion reaction of LiPSs, with their efficacy and quantity directly impacting the conversion efficiency. In light of these considerations, the strategic optimization of active sites emerges as a paramount pathway toward promoting the performance of LSBs while concurrently mitigating unnecessary mass. Here, we outline three strategies developed by our group to optimize active sites of catalytic materials: (1) Augmenting active sites by customizing structural modulation and precise dimensional control to maximize exposure. Emphasis has been placed on the approaches for material synthesis and the essence of reactions for achieving this strategy. (2) Regulating the microenvironment of active sites by integrating the coordination refinement, long-range atomic interactions, metal-support interactions, and other electronic regulation strategies, thereby providing an elevation in the intrinsic catalytic performance. (3) Implementing a self-cleaning mechanism for active sites to counteract deactivation by designing a tandem adsorption-migration-transformation pathway of sulfur contained within the molecular domain. Throughout this process, the intrinsic mechanisms driving performance enhancement through active site optimization strategies have been prominently emphasized, which encompass aspects such as electronic structure, atomic composition, and molecular configuration and significantly expand the comprehension of Li-S catalytic chemistry. Subsequently, considerations demanding heightened attention in future processes of active site optimization for catalytic materials have been delineated, including the in situ evolution patterns and resistance to the poisoning of active sites. It is noteworthy that given the similarity between Li-S catalysis chemistry and traditional electrocatalytic processes, this Account elucidates the concept of active site optimization by drawing insights from representative works and our own works in the field of electrocatalysis, which is relatively rare in previous reviews of LSBs. The proposed insights contribute to uncovering the intrinsic mechanisms of Li-S catalysis chemistry and introducing innovative ideas into active site optimization, ultimately advancing energy density and stability in LSBs.

Characterization and properties of phenolic resin doped modified lignin

Phenolic resins occupy an important position in industrial applications, but phenol, one of the raw materials for synthesis, is a non-renewable resource. Lignin, as a natural polymer containing phenolic hydroxyl groups, alcohol hydroxyl groups and other reactive groups, can replace some of the phenol in the synthesis of phenolic resins, which can reduce the amount of phenol, thus reducing the cost of phenolic resins, while effectively promoting the high value-added use of renewable biomass resources. Due to its low reactivity, alkaline lignin is usually discharged as production waste, unaware that lignin macromolecules can be modified. In this paper, the phenolic monomers were obtained by acid-catalyzed depolymerization of DES (choline chloride/p-toluenesulfonic acid or choline chloride/lactic acid) from waste alkaline lignin, and the recovery rate of the DES solution during the catalytic treatment was more than 85 %, in which the main monomer was 2-methoxy-4-(1-propyl) phenol. The degradation of alkaline lignin is still favorable after five times of DES solvent recovery. The depolymerized lignin monomer replaced phenol by 50 wt% and then ternary co-polymerized with phenol and formaldehyde to form a biomass phenol-based phenolic resin, providing a green route for phenolic resin production. The cost of resin preparation was economically calculated, and it was found that the cost of resin after accumulating 4 cycles of DES treatment was only 51.1 % of that of pure phenolic resin. The density functional theory (DFT) was used to simulate the possible radical reactions in the intermediate process of phenolic resin reaction, to explore the microscopic mechanism and competition, to provide theoretical reference for further experimental realization of resin structure control and optimization, and to improve the theoretical system of resin synthesis.

Control of the grain structure and wear behavior of a Y2O3 nanoparticle dispersed Stellite 6 alloy fabricated by laser-directed energy deposition

A nuclear reactor is operated with load following that generates more wear than the base load; therefore, the wear resistance of the Stellite 6 alloy should be further improved. This study fabricated a wear-resistant oxide dispersion-strengthened (ODS) Co-based Stellite 6 alloy by varying the amount of Y2O3 nanoparticles (0, 0.6, and 1.5 wt%). The feedstocks for the ODS Stellite 6 alloy samples were prepared via mechanical mixing and radio frequency plasma spheroidization. The samples were then prepared by laser-directed energy deposition to obtain a finer grain structure with superior wear properties. In the ODS Stellite 6 alloy samples, the addition of nanoparticles changed the grain structure from columnar to equiaxed and refined the maximum grain size by 68.9 % compared with that of the Stellite 6 alloy sample. In addition, the nanoparticles were dispersed in the interdendritic region of the ODS Stellite 6 alloy samples. The nanoparticles formed a layer in front of dendritic grains and inhibited the movement of the grains and diffusion of solute atoms. As a result, the ODS Stellite 6 alloy samples had a small equiaxed grain structure. Furthermore, a high density of nanoparticles had an Orowan dispersion-strengthening effect. Therefore, the ODS Stellite 6 alloy samples exhibited a maximum increased Vickers hardness value of 15.9 % and maximum reduced specific wear rate of 58.2 % compared with those of the Stellite 6 alloy sample. Moreover, the ODS alloys exhibited superior wear behavior than Stellite 6 alloy because Y2O3 reinforcement prevents the ODS alloys from being easily abraded or plowed from counterpart material. This study indicates that the ODS Stellite 6 alloys with the optimal amount of Y2O3 nanoparticles dispersed control the grain structure and exhibit superior wear behavior compared with other reported Co-based alloys.

Comparative analysis for optimal placement of piezoelectric actuators on smart thin plate

In contemporary smart structures, piezoelectric ceramic (PZT) actuators serve a crucial structural function. To construct a smart thin plate that integrates structural health monitoring (SHM) and active vibration control objectives, many placement methodologies were discussed. In current research, two positioning strategies of the attached PZT actuators are compared. The first strategy is a well-known controllability concept where PZT actuators’ optimum positions are obtained by maximizing the eigenvalues of the controllability Grammian matrix. The second strategy employs the energy concept to strategically position PZT actuators so that the utmost amount of exerted work is accomplished by the actuators. Thus, the optimal performance of actuators to provide energy for mitigating unwanted vibrations is maintained, as is the optimal excitation required for SHM in the designated modes. Kirchoff’s classical laminate plate theory (CLPT) is used to define displacements as well as the normal strains of this coupled electro-mechanical system, and then, using the Ritz solution, the modal eigenvalue problem is solved, and mode shapes are obtained. Consequently, normal strains are transformed into spatially dependent functions used to define both the virtual work and the controllability of the Grammian matrix for the PZT actuators as a function of their locations. Finally, iterative optimization based on a genetic algorithm (GA) is used to find the optimum actuator locations in the desired modes. The best location for the PZT actuator or actuators is explored for two specimen plates with different boundary conditions. The results for the two studied positioning strategies are then compared, showing the superiority of the proposed energy-based strategy. Further, a quantitative variance-based uncertainty analysis reveals a low variance of the output results for the proposed strategy.

Vertical vibration control of structures with tuned liquid column dampers

Conventional tuned liquid column dampers (TLCDs) can only be used to suppress structural vibrations in horizontal directions. However, in reality, the vibration-induced motion of civil engineering structures normally consists of both vertical and horizontal components. In this study, a TLCD-based vibration control system, which is composed of a pair of inclined U-shaped containers, springs, dashpots, as well as supporting slopes, is proposed to control the vertical vibration of an engineering structure. The proposed control system (denoted as vertical TLCD) successfully extends the application of TLCD-type devices to vertical vibration reduction. First, the general configuration and operating principle of the proposed vertical TLCD are illustrated in detail. Second, the equations of motion are derived based on the Lagrange dynamic equations and further verified by two-way fluid–structure coupling numerical simulations using finite element method and finite volume method. Subsequently, the closed-form solution is derived for the optimized design of the vertical TLCD in the frequency domain. The dynamic characteristics of an optimized vertical TLCD-structure system are revealed. The effects of mass ratio, excitation amplitude and structural damping ratio on the optimization results are elaborated, respectively. Under the same optimized parameters, the vertical TLCD is found to be superior, compared to the vertical tuned mass damper (TMD). Finally, the effectiveness of the proposed system is demonstrated by applying it to the control of a bridge experiencing vertical vibrations under seismic loads. The findings of this study provide a comprehensive understanding of TLCD’s capabilities and identify its potential for vertical vibration control, which contributes to the development of more effective and versatile vibration mitigation strategies for a wide range of structures under different engineering scenarios.

Using subtle variations in groundwater geochemistry to identify the proximity of individual geological structures: a case study from the Grimsel Test Site (Switzerland)

Understanding groundwater flow and the evolution of groundwater chemistry in networks of fractures in crystalline rock is of fundamental interest for geothermal projects, nuclear waste disposal, and groundwater resources. Groundwater chemistry at a given location is typically conceived of being of a specific ‘type’ (e.g. meteoric, juvenile, connate, marine), with associated chemical types controlled through water–rock interactions. Minor chemical variations between groundwater sample locations with the same chemical type are generally considered as ‘noise’ in the geochemical data. Here, we argue that this noise contains useful information on the mineral phases encountered by the groundwater as it travels through specific flow pathways. We analyse the spatial variability of groundwater chemistry around the Grimsel Test Site (GTS), Switzerland, where groundwater is hosted in two lithologies: the Central Aar Granite and the Grimsel Granodiorite, where flow occurs predominantly in a fracture network created by brittle reactivation of ductile shear zones. Groundwater chemistry is analysed using principal component and hierarchical cluster analyses, which identify two groundwater types based on their chemistry. The primary control on groundwater type is the host rock lithology (granite/granodiorite). While the spatial variability of groundwater chemistry within each of the two lithologies is small, statistical analysis of the data shows similar groundwater chemistry in borehole intervals that are crosscut by similar geological structures, implying a structural control on groundwater chemistry. Our research shows that subtle chemical variations in groundwater provide information on fracture network connectivity and the proximity of geological features, that specific volumes of groundwater has interacted with.

Bioinspired Nanolayered Structure Tuned by Extensional Stress: A Scalable Way to High-Performance Biodegradable Polyesters.

The nacre-inspired multi-nanolayer structure offers a unique combination of advanced mechanical properties, such as strength and crack tolerance, making them highly versatile for various applications. Nevertheless, a significant challenge lies in the current fabrication methods, which is difficult to create a scalable manufacturing process with precise control of hierarchical structure. In this work, a novel strategy is presented to regulate nacre-like multi-nanolayer films with the balance mechanical properties of stiffness and toughness. By utilizing a co-continuous phase structure and an extensional stress field, the hierarchical nanolayers is successfully constructed with tunable sizes using a scalable processing technique. This strategic modification allows the robust phase to function as nacre-like platelets, while the soft phase acts as a ductile connection layer, resulting in exceptional comprehensive properties. The nanolayer-structured films demonstrate excellent isotropic properties, including a tensile strength of 113.5MPa in the machine direction and 106.3MPa in a transverse direction. More interestingly, these films unprecedentedly exhibit a remarkable puncture resistance at the same time, up to 324.8Nmm-1, surpassing the performance of other biodegradable films. The scalable fabrication strategy holds significant promise in designing advanced bioinspired materials for diverse applications.

Structural control on formation of polygonal rims of impact craters in Thaumasia Minor, Mars

It has been known for almost a century that the surfaces of rocky planets contain polygonal-shaped, circular, or elliptical craters. Researchers have hypothesized that pre-existing structurally weak planes, such as faults or fractures, in the vicinity of the impact, are responsible for polygonal patterns of the crater rims. Thaumasia Minor, Mars, which is a heavily deformed late-Noachian terrain with craters of various morphologies, including polygonal impact craters (PICs), is the present area of study to understand the geological control behind the polygonal shapes of the crater rims. A population of 45 carefully chosen polygonal craters are mapped and compared with morphotectonic structures such as graben, wrinkle ridges, and dykes. To discern the relationship between the features, the study uses trends, statistical and spatial analyses of orientation data, and other parameters such as crater diameter and crater excavation depth. Also, to understand the factors affecting PIC formation, 12 earlier studied craters in East Coprates Planum, a region adjacent to the Thaumasia Minor, are studied again. The study proposes two possible geological controls on PIC formation. The study also suggests that graben have more control over smaller PICs while larger PICs are controlled by wrinkle ridges.

Optimization of column-in-column system based on non-conventional TMD concept

Previous studies showed that the non-conventional tuned mass damper (TMD) with large mass ratio outperforms the traditional one in respect to the structural vibration control efficiency and robustness. The authors recently proposed a novel control system based on the non-conventional TMD concept, namely the column-in-column (CIC) system, which was composed of a primary column, a secondary column and a series of interconnected springs/dashpots. In this novel system, the secondary column connected to the primary one with springs/dashpots could act as a large TMD to attenuate adverse vibration of the primary structure, and its control effectiveness was preliminarily verified through numerical investigations. However, the control robustness was found not sufficient based on the existing optimal formulae in the literature for CIC optimization. This paper presents a new design method for optimizing the CIC system for better harnessing its control effectiveness and robustness in reducing structural response. The CIC system consists of two columns with distributed mass and uniform flexural rigidity, connected by springs along the column height. The effective modal mass and modal stiffness of a specific vibration mode of the system can be straightforwardly calculated by using the Euler-Bernoulli beam theory. Considering the fundamental vibration mode of the system as the target response mode for vibration control, the multiple degree-of-freedom (DOF) CIC is simplified into a two DOF with three springs (2DOF3S) structural model, the design parameters, i.e., the optimal tuning frequency ratio and damping ratio of this system are derived to minimize the displacement response of the primary structure. To demonstrate the proposed design method, the effectiveness and robustness of the CIC system in controlling seismic induced structural vibrations are assessed in both the frequency and time domains. Results show that the derived optimum formulae are applicable for optimizing the TMD system with consideration of the distributed mass and deformation of the mass damper, i.e., a column in this study. The optimized CIC system has good control robustness even if the CIC is mistuned with its design parameters deviate from the optimal values by ±50 %. The conventional TMD system with lumped mass as the mass damper is a special case of the proposed CIC system. The optimized CIC system has favorable control efficiency in mitigating the seismic responses of structures with reduction ratios averagely varying within the range of 15 % ∼ 55 % with a probability of 92.67 %. It is concluded that the proposed method is reliable and can be used for the optimum design and control of the CIC system.

Overturning Children's Misconceptions about Ruler Measurement: The Power of Disconfirming Evidence.

Children have persistent difficulty with foundational measurement concepts, which may be linked to the instruction they receive. Here, we focus on testing various ways to support their understanding that rulers comprise spatial interval units. We examined whether evidence-based learning tools-disconfirming evidence and/or structural alignment-enhance their understanding of ruler units. Disconfirming evidence, in this context, involves having children count the spatial interval units under an object that is not aligned with the origin of a ruler. Structural alignment, in this context, involves highlighting what a ruler unit is by overlaying plastic unit chips on top of ruler units when an object is aligned with the origin of a ruler. In three experiments employing a pre-test/training/post-test design, a total of 120 second graders were randomly assigned to one of six training conditions (two training conditions per experiment). The training conditions included different evidence-based learning principles or "business-as-usual" instruction (control), with equal allocation to each (N = 20 for each condition). In each experiment, children who did not perform above chance level on the pre-test were selected to continue with training, which resulted in a total of 88 students for the analysis of improvement. The children showed significant improvement in training conditions that included disconfirming evidence, but not in the structural alignment or control conditions. However, an exploratory analysis suggests that improvement occurred more rapidly and was retained better when structural alignment was combined with disconfirming evidence compared to disconfirming evidence alone.