Conic Research Articles

A Novel AGV Path Planning Approach for Narrow Channels Based on the Bi-RRT Algorithm with a Failure Rate Threshold.

The efficiency of the rapidly exploring random tree (RRT) falls short when efficiently guiding targets through constricted-passage environments, presenting issues such as sluggish convergence speed and elevated path costs. To overcome these algorithmic limitations, we propose a narrow-channel path-finding algorithm (named NCB-RRT) based on Bi-RRT with the addition of our proposed research failure rate threshold (RFRT) concept. Firstly, a three-stage search strategy is employed to generate sampling points guided by real-time sampling failure rates. By means of the balance strategy, two randomly growing trees are established to perform searching, which improves the success rate of the algorithm in narrow channel environments, accelerating the convergence speed and reducing the number of iterations required. Secondly, the parent node re-selection and path pruning strategy are integrated. This shortens the path length and greatly reduces the number of redundant nodes and inflection points. Finally, the path is optimized by utilizing segmented quadratic Bezier curves to achieve a smooth trajectory. This research shows that the NCB-RRT algorithm is better able to adapt to the complex narrow channel environment, and the performance is also greatly improved in terms of the path length and the number of inflection points. Compared with the RRT, RRT* and Bi-RRT algorithms, the success rate is increased by 2400%, 1900% and 11.11%, respectively.

Dietary arginine levels affect growth performance, intestinal antioxidant capacity and immune responses in largemouth bass (Micropterus salmoides)

This study explored the role of dietary arginine level (DAL) on growth, intestinal antioxidant status and immune response in juvenile largemouth bass (Micropterus salmoides), providing guidance for the optimization of commercial feed in largemouth bass. Six graded arginine levels in diets were fed to the fish for 8 weeks (1.96%, 2.28%, 2.52%, 2.81%, 3.09% and 3.35% diets). The findings were as follows: with increasing DALs, FW, WG and SGR increased first and decreased, and FCR showed the opposite trend. There was no difference in the contents of crude protein and ash among graded DAL (P > 0.05). DAL (3.09% and 3.35%) significantly increased the activities of plasma AST (P < 0.05). Certain range of dietary arginine levels could improve antioxidant ability by regulating intestinal antioxidant-related parameters including the activities of SOD, GPx, and the contents of GSH and MDA. The gene expression of Nrf2 was significantly increased in response to 2.52% DAL, while Keap1 expression was decreased (P < 0.05). Furthermore, 1.96% and 2.28% DALs significantly increased the gene expression of CAT and GPx (P < 0.05), and SOD expression was the highest in response to 2.52% and 2.81% DALs (P < 0.05). Compared with the control group, the relative expressions of IL-1β, IL-8, TNF-α and NF-κB were reduced that were fed 2.52%− 3.35% DALs. Moreover, the relative expression of IL-10 and TGF-β were peaked in response to 2.81% DAL (P < 0.05). The quadratic regression curve analysis according to the growth results of SGR and FCR, the expressions of IL-10 and TGF-β showed that the optimal dietary arginine requirement for largemouth bass were 2.40%− 2.63% (5.03%−5.46% of dietary protein), and could promote growth, intestinal antioxidant capacity and immune responses in juvenile largemouth bass.

CSD-RkNN: reverse k nearest neighbors queries with conic section discriminances

The reverse k nearest neighbors (RkNN) query is a prominent yet time-consuming spatial query used in facility siting, influential domain analysis, potential customer analysis, etc. Its aim is to identify all points that consider the query point as one of their k closest points. However, when k is relatively large (e.g. k = 1000), existing RkNN techniques often struggle to provide acceptable response times (within a few seconds). To address this issue, we propose a verification approach called conic section discriminance (CSD). This method serves to determine whether points belong to the RkNN set. With CSD, only a small fraction of candidates require costly k nearest neighbors (kNN) queries for verification, while the rest can be rapidly verified with O(1) complexity. Furthermore, we propose a Voronoi-based candidate generation approach to curtail the candidate set size. By leveraging the VoR-tree structure, we integrate these two approaches to form a novel RkNN algorithm named CSD-RkNN. A comprehensive set of experiments is conducted to compare CSD-RkNN with Slice as the state-of-the-art RkNN algorithm, and VR-RkNN as the original RkNN algorithm on VoR-tree. The results indicate that CSD-RkNN consistently outperforms the other two algorithms, especially when k is relatively large.

Exploring the impacts of spatial morphology of underground shopping mall atriums on natural lighting performance

ABSTRACT The natural lighting environment in the atrium space of an underground shopping street directly determines the spatial quality of the building. It has a significant impact on the quality of the indoor light environment, people’s mental experience, and the energy consumption of the building. Based on field research, this study combined Radiance and Rhino 7 software to construct realistic scene simulation models of the different shapes for each atrium’s underground shopping street. Daylight factor (DF) and useful daylight illuminance (UDI) were utilized as the evaluation metrics for assessing the natural lighting efficacy of the atriums. Simulation data were further processed and quantitatively analyzed with line charts and quadratic curve fitting methods. The results demonstrate that the DF of an atrium space in underground shopping streets declines rapidly as the height/width ratio (H/W) increases, followed by a gradual weakening trend. Meanwhile, as the aspect ratio (L/W) increases, the peak value of the DF gradually increases. The UDI of the atrium space in an underground shopping street will usually rise first and then fall as the height/width ratio (H/W) increases. Meanwhile, as the aspect ratio (L/W) increases, the UDI peak value gradually decreases. The experiment confirms that DF and UDI atrium space can be effectively improved by adjusting different combinations of the height/width ratio (H/W), aspect ratio (L/W), and lighting glass inclination angle. By doing so, this research provides architects with a theoretical foundation for the spatial morphology design of an atrium.

Effects of thickness and polishing treatment on the translucency and opalescence of six dental CAD-CAM monolithic restorative materials: an in vitro study

BackgroundComputer-aided design and computer-aided manufacturing (CAD-CAM) materials for prosthetic is gaining popularity in dentistry. However, limited information exists regarding the impact of thickness and roughening treatment on the optical properties of contemporary CAD-CAM restorative materials. This study aimed to quantitatively evaluate the translucency and opalescence of six dental CAD-CAM materials in response to different thicknesses and roughening treatments.MethodsSix dental CAD-CAM materials, lithium disilicate glass–ceramic (IPS e.max CAD, LS), polymer-infiltrated ceramic (VITA Enamic, VE), resin-nano ceramic glass–ceramic (LAVA Ultimate, LU), polymethyl methacrylate (Telio CAD, TE), and two zirconia reinforced lithium silicate (VITA Suprinity, VS, and Celtra Duo, CD), in shade A2 were prepared as 12 × 12mm2 specimens of four thicknesses (0.5mm, 1.0mm, 1.5mm, and 2.0mm) (N = 240, n = 10). After three different treatments (polished, roughened by SiC P800-grit, and SiC P300-grit), the translucency parameter (TP00) and opalescence parameter (OP) were measured with a spectrophotometer (VITA Easyshade V). The surface roughness was analyzed with a shape measurement laser microscope. The data were analyzed using a MANOVA, post hoc Tukey–Kramer test, the t test, and regression analysis (α = .05).ResultsThe TP00 and OP were significantly influenced by material type, thickness and roughening treatment (P < .05). TP00 showed a continues decline with increasing thicknesses, while the variations of OP were material-dependent. TP00 ranged from 37.80 (LS in 0.5mm) to 5.66 (VS in 2.0mm), and OP ranged from 5.66 (LU in 0.5mm) to 9.55 (VS in 0.5mm). The variations in TP00 of all materials between adjacent thicknesses ranged from 2.10 to 15.29, exceeding the acceptable translucency threshold except for LU. Quadratic and logarithmic regression curves exhibited the best fit for TP00 among the materials. Compared to polished specimens, rougher specimens exhibited lower TP00 and higher OP in all materials except for LS (P < 0.05). Roughening with P300-grit decreased TP00 and OP by an average of 2.59 and 0.43 for 0.5mm specimens, and 1.26 and 0.25 for 2.0mm specimens, respectively.ConclusionsVariations in translucency caused by thickness and roughening treatment were perceptible and may be clinically unacceptable. Careful consideration should be given to the selection of CAD-CAM materials based on their distinct optical properties.

Impact of magnetic resonance imaging-related geometric distortion of dose distribution in fractionated stereotactic radiotherapy in patients with brain metastases.

The geometric distortion related to magnetic resonance (MR) imaging in adiagnostic radiology (MRDR) and radiotherapy (MRRT) setup is evaluated, and the dosimetric impact of MR distortion on fractionated stereotactic radiotherapy (FSRT) in patients with brain metastases is simulated. An anthropomorphic skull phantom was scanned using a1.5‑T MR scanner, and the magnitude of MR distortion was calculated with (MRDR-DC and MRRT-DC) and without (MRDR-nDC and MRRT-nDC) distortion-correction algorithms. Automated noncoplanar volumetric modulated arc therapy (HyperArc, HA; Varian Medical Systems, Palo Alto, CA, USA) plans were generated for 53patients with 186 brain metastases. The MR distortion at each gross tumor volume (GTV) was calculated using the distance between the center of the GTV and the MR image isocenter (MIC) and the quadratic regression curve derived from the phantom study (MRRT-DC and MRRT-nDC). Subsequently, the radiation isocenter of the HA plans was shifted according to the MR distortion at each GTV (HADC and HAnDC). The median MR distortions were approximately 0.1 mm when the distance from the MIC was < 30 mm, whereas the median distortion varied widely when the distance was > 60 mm (0.23, 0.47, 0.37, and 0.57 mm in MRDR-DC, MRDR-nDC, MRRT-DC, and MRRT-nDC, respectively). The dose to the 98% of the GTV volume (D98%) decreased as the distance from the MIC increased. In the HADC plans, the relative dose difference of D98% was less than 5% when the GTV was located within 70 mm from the MIC, whereas the underdose of GTV exceeded 5% when it was 48 mm (-26.5% at maximum) away from the MIC in the HAnDC plans. Use of adistortion-correction algorithm in the studied MR diagnoses is essential, and the dosimetric impact of MR distortion is not negligible, particularly for tumors located far away from the MIC.

목표로서의 수학사를 위한 이차곡선의 교수·학습 자료개발

Objectives The purpose of this study is to develop a teaching and learning material of “Quadratic curve” using history of Mathematics as a Goal.&#x0D; Methods The direction of data development was determined after examining the type of mathematics history utilization and the method of mathematics history utilization in Korean textbooks. Materials were developed through the extraction of mathematical history contents that are acceptable for subject and purpose. Twelve math teachers with experience teaching high school students were tested for verifying the appropriateness of the developed material. After analyzing the test result, the material was revised and completed.&#x0D; Results The developed teaching and learning materials are organized according to the flow of time from ancient times to the present, in the order of etymological analysis of terms, discovery of ancient quadratic curves, relevance of modern analytic geometry and quadratic curves, development of modern astronomy, and use in modern earth science. While revealing the connection with other studies, the human side and usefulness of mathematics were revealed. A suitability test was conducted on the development materials, and positive responses were obtained from teachers of related subjects that they were developed well for the purpose of research.&#x0D; Conclusions In an environment where students' interest in mathematics is declining, the development type of using mathematical history as a goal can be a way to cope with the overall change in the educational paradigm of strengthening the curriculum centered on choice. It will be helpful for students' interest and choices if the human side of mathematics is emphasized through mathematics history.

The quasi-frame of the rational and polynomial Bezier curve by algorithm method in Euclidean space

PurposeFrames play an important role in determining the geometric properties of the curves such as curvature and torsion. In particular, the determination of the point types of the curve, convexity or concavity is also possible with the frames. The Serret-Frenet frames are generally used in curve theory. However, the Serret-Frenet frame does not work when the second derivative is zero. In order to eliminate this problem, the quasi-frame was obtained. In this study, the quasi frames of the polynomial and rational Bezier curves are calculated by an algorithmic method. Thus, it will be possible to construct the frame even at singular points due to the second derivative of the curve. In this respect, the contribution of this study to computer-aided geometric design studies is quite high.Design/methodology/approachIn this study, the quasi frame which is an alternative for all intermediate points of the rational Bezier curves was generated by the algorithm method, and some variants of this frame were analyzed. Even at the points where the second derivative of such rational Bezier curves is zero, there is a curve frame.FindingsSeveral examples presented at the end of the paper regarding the quasi-frame of the rational Bezier curve, polynomial Bezier curve, linear, quadratic and cubic Bezier curves emphasize the efficacy and preciseness.Originality/valueThe quasi-frame of a rational Bezier curve is first computed. Owing to the quasi frame, it will have been found a solution for the nonsense rotation of the curve around the tangent.

Study on Flight Dynamics and Heat Transfer Solidification of Metal Droplets during Centrifugal Spray Deposition Forming Process

Centrifugal spray deposition forming technology, which is used in the preparation process of near-net-forming billets, not only reduces the macroscopic segregation and refines the microstructures of billets but also has the characteristics of a rapid solidification structure. The trajectory, velocity, heat transfer and solidification of metal droplets granulated by the centrifugal force during flight will affect the shape, precision and microstructure of the billet. Therefore, it is necessary to study the dynamics and thermal history of droplets in flight. In this study, a single droplet is taken as the object. Considering the resistance of ambient gas, Newton’s second law, classical nucleation theory, Newton’s cooling law and the energy conservation equation were used to establish a dynamic model and heat transfer solidification model of liquid metal droplets during flight. The influence of the centrifugal disc speed on the diameter of granulated droplets was analyzed. The variation law of droplet flight trajectory and velocity was explored. The supercooling degree in metal droplet nucleation was quantified, and the influence of droplet diameter, superheat and other factors on heat transfer and solidification was revealed. The results show that the numerical calculation results are basically consistent with the previous research results. The trajectory of the droplet is parabolic during flight. The initial velocity of the droplet, the environmental gas resistance and the convective heat transfer coefficient are positively correlated with the rotating speed of the centrifugal disc; however, the droplet diameter is negatively correlated with the rotating speed of the centrifugal disc. The super cooling degree at the time of droplet nucleation and the flight time required for solidification are negatively correlated with the droplet diameter. Among them, the droplet diameter has a linear relationship with the solidification start time and a quadratic curve relationship with the solidification end time. The effect of superheat on the heat transfer and solidification of droplets is not obvious. The conclusions obtained can provide a theoretical basis for the determination of the preparation process parameters.

Validation of the fire dynamics simulator (FDS) model for fire scenarios with two liquid pool fires in multiple compartments

A validation study on the fire dynamics simulator (FDS) model for fire scenarios with multiple liquid pool fires occurring in multiple compartments was performed. For fire growth in the open simulation, the mass loss rate per unit area (MLRPUA) time curve obtained experimentally was used as the input. In the blind simulation, the pyrolysis model was used. For the ventilation flow rate curve, the supply/exhaust flow rate curve measured in the experiment was used as the input for the open simulation, whereas the quadratic fan curve model was used for the blind simulation. The time-averaged datasets of the output parameters from the FDS model and experiment were plotted as data points on scatter plots. In terms of bias factor and model standard deviation of output parameters, the scatter plots under the open simulation conditions were compared with those of NUREG-1824. Under blind simulation conditions, the bias factor and model standard deviation of output parameters increased significantly. A sensitivity analysis was performed on input parameters, such as the MLRPUA time curve, supply/exhaust flow time curve, compartment leak area, and maximum differential pressure in the compartment. Within the given ranges of the sensitivity input parameter values, only changing the MLRPAU time curve significantly affected the bias factor and model standard deviation of the output parameters.

A New Class of Trigonometric B-Spline Curves

We construct one-frequency trigonometric spline curves with a de Boor-like algorithm for evaluation and analyze their shape-preserving properties. The convergence to quadratic B-spline curves is also analyzed. A fundamental tool is the concept of the normalized B-basis, which has optimal shape-preserving properties and good symmetric properties.

Conditioning of Fourier sums on a quadratic curve

Conditioning of Fourier sums on a quadratic curve

Influence and prediction of oil film migration in submarine pipeline spills under multiple factors

Oil spills endanger the survival of marine species and the maritime environment. As a result, this study constructs a three-dimensional diffusion model of oil spills from pipeline ruptures and analyses the diffusion law of oil films created on the sea surface under various conditions. The model's accuracy was validated using actual oil spill tests, and the oil spill similarity model was further established using similarity theory. The results show that as the leaking aperture grows within 2–3 s, the high concentration centre area of the oil film on the sea surface expands, and the oil film protrudes to the right. From the inside out, the oil film produces a convex elliptical oil film with a high-low concentration form. As the leakage rate rises, a convex, elliptical, large-area oil film of low-high-low concentration forms. During this time frame, the oil leak has not yet developed an oil film at a flow rate of 0.3 m/s. This is due to the fact that horizontal migration speed has a large influence on vertical migration speed, increasing the horizontal migration distance underwater and lengthening the time needed to achieve the development of the sea surface oil film area. With increasing leakage aperture and leak rate, the lateral diffusion length, longitudinal diffusion breadth, and oil spill area of the oil film rise. However, when the velocity of the water flow increases, it decreases. Furthermore, the quadratic fitting curves of the longitudinal expansion length, longitudinal diffusion width, and oil spill area of the oil film were fitted under various influencing factors to predict the diffusion law of the oil film on the sea surface, which is critical for protecting the marine environment.

Primary aberrations theory in optical systems composed of Cartesian refracting surfaces

Among the main defects present in optical systems are geometric aberrations, which are well characterized for spherical and aspherical surfaces. Special cases of aspherical surfaces are the Cartesian surfaces since they exhibit rigorous stigmatism and also, for a subfamily of these surfaces, aplanatism. However, for objects outside the stigmatic points, these surfaces also present geometric aberrations, so to evaluate their performance, it is necessary to characterize them. Therefore, in this work, the geometrical aberrations presented in Cartesian surfaces are studied, where the formulation of the coefficients for primary aberrations includes the corresponding expressions for the conic sections of revolution refractive surfaces as particular cases, and likewise the spherical refractive surface.

Energy absorption of variable stiffness composite thin-walled tubes on axial impacting

In order to realize the engineering application of automated fiber placement for composite laminates, a method of the variable angle fiber placement was proposed to design the tube structures of variable stiffness composites based on the quadratic Bezier curve. The axial crushing responses were simulated to investigate the energy absorption characteristics of composite tubes. The results showed that the method of the variable angle fiber placement contributed to the improvement of the energy absorption effects. The maximum crushing force efficiency of the variable stiffness composite thin-walled tubes designed by the method was 49.04% which was 106.48% higher than the constant stiffness composite tube. The results could be helpful for the process of automated fiber placement and the design of the energy absorption for composite thin-walled structures.

Quadratic Curve Fitting-Based Image Edge Line Segment Detection: A Novel Methodology

In the field of computer vision, edge line segment detection in images is widely used in tasks such as 3D reconstruction and simultaneous localization and mapping. Currently, there are many algorithms that primarily focus on detecting straight line segments in undistorted images, but they do not perform well in detecting edge line segments in distorted images. To address this quandary, the present study introduces a novel method of line segment identification founded on the principles of quadratic fitting. The method proposed utilizes the inherent property of a linear projection in a three-dimensional space, whereby it appears as a quadratic curve in a distorted two-dimensional image. This approach applies an iterative estimation process to ascertain the optimal parameters of the quadratic form that aligns with the edge contour. This process is facilitated by implementing an assumption and validation mechanism. Upon deriving the optimal model, it is then employed to identify the line segments that are encompassed within the edge contour. The experimental assessment of this novel method incorporates its application to both distorted and distortion-free image datasets. The method eliminates the necessity for preliminary processing to discarding distortions, thereby making it universally applicable to both distorted and non-distorted images. In addition to this, the experimental results based on the dataset indicate that the proposed algorithm in this paper achieves an average computational efficiency that is 27 times faster than traditional ones. Thus, this research will contribute to line segment detection in computer vision.

Foliar Spraying of Nano-Silicate and Nano-Zinc on Wheat (Triticum aestivum L.) Under Salt Stress Conditions Enhances Productivity and Reduces the Optimal Nitrogen Fertilizer Rate

ABSTRACT Salinity stress poses a significant threat to agriculture, as it directly impacts crop growth and yield. The current study aimed at examining the role of foliar nano-silicate (nSiO2) and nano-zinc (nZnO) applications in increasing wheat productivity and nitrogen (N) use efficiency under salt stress conditions. A two-season field experiment was carried out on sandy soils irrigated with water from high-saline wells (4352 and 7040 mg L−1). The study was conducted in a split-plot design, with main plots assigned to three treatments of foliar application of nSiO2, nZnO, and control (nZero), and sub-plots assigned to six N fertilizer rates (0–300 kg N ha−1). The use of nSiO2 and nZnO increased wheat grain yield by 67 and 48% on average over nZero, respectively. When average wheat grain yields were plotted against increasing N fertilizer rates, a quadratic response curve was observed. Derivative solutions of the quadratic functions indicated that grain yield plateaued at 4641, 4560, and 3182 kg ha−1 for nSiO2, nZnO, and nZero treatments, respectively. The optimal N fertilizer rates for these yield levels were calculated to be 290, 353, and 386 kg N ha−1. When the net returns to N fertilizer and nano-material use were considered, nSiO2 had the highest net returns and the lowest optimal N fertilizer rate (229 kg N ha−1), followed by nZnO (272 kg N ha−1). The findings of the field experiment demonstrated that foliar spraying wheat with nSiO2 and nZnO under salt stress conditions enhances productivity as well as responsiveness to N fertilizer.

Effects of Tannic Acid Supplementation on the Intestinal Health, Immunity, and Antioxidant Function of Broilers Challenged with Necrotic Enteritis.

Clostridium perfringens causes necrotic enteritis (NE) after proliferation in the intestine of poultry, resulting in considerable losses to the poultry industry. This study aimed to investigate the impact of tannic acid on the antioxidant, immunity, and gut health of broilers with NE. In the experiment, 630 one-day-old Cobb500 male chicks were randomly divided into six treatment groups, with seven replicate cages and with fifteen birds in each cage. The treatment groups were as follows: control group (NC), challenged group (PC), and challenged NE chickens treated with 250, 500, 750, and 1000 mg/kg tannic acid (PTA1, PTA2, PTA3, and PTA4, respectively). To induce NE, coccidia vaccine and Clostridium perfringens were administered on day 19 and days 22-28, respectively. Indexes related to antioxidant, immune, and intestinal health were measured on days 28 and 35. During the infection period, we observed significant increases in fecal water content, D-LA, TNF-α, and malondialdehyde concentrations (p < 0.05). Conversely, significant decreases were noted in chyme pH and in T-AOC, IL-4, and IL-10 concentrations (p < 0.05). The addition of tannic acid exhibited a linear decrease in fecal water content and TNF-α concentration (p < 0.05). Furthermore, tannic acid supplementation resulted in a quadratic curve decrease in D-LA concentration and linear increases in T-AOC, IL-4, and IL-10 (p < 0.05). Cecal microbiological analysis revealed that Ruminococcaceae and Butyricimona were dominant in PTA3. In conclusion, the dietary addition of tannic acid may reduce the negative effects of NE by increasing antioxidant and anti-inflammatory capacity, improving the intestinal barrier, and regulating the intestinal flora.

Evaluation of optimal dietary protein levels and meat quality of adult hybrid abalone (Haliotis discus hannai♀ × H. fulgens♂) under two representative water temperatures

In this study, the optimal dietary protein levels for adult hybrid abalone (H. discus hannai♀ × H. fulgens♂) were evaluated at two representative temperatures, and the interactive influences of dietary protein and water temperature on abalone meat quality were examined. Six isoenergetic and isolipidic diets containing graded levels of protein (15%, 20%, 25%, 30%, 35%, and 40%) were fed to the hybrid abalone for 90 days. Based on the specific growth rate, the optimum dietary protein levels for adult hybrid abalone using a quadratic curve model were estimated to be 28.07% and 26.47% of the diet at 23 °C (optimum temperature) and 27 °C (high temperature), respectively. The amount of crude protein in the abalone body increased linearly with the dietary protein levels and water temperature. Antioxidation enzyme activities of abalone muscle, including GPx and GST were significantly affected by the interaction of dietary protein levels and water temperature. As for texture analysis, the abalone kept at 23 °C exhibited higher meat hardness than those fed the same diets at 27 °C. The n-3 PUFAs (particularly DHA and EPA) in abalone meat were significantly influenced by dietary protein levels, and the highest content was observed in the 30% dietary protein group. These levels were not affected by water temperature. In addition, higher dietary protein levels and water temperatures increased the total contents of free amino acids and flavor amino acids (Asp + Glu + Gly + Ala + Arg + Tau). The cooking loss of abalone meat was reduced with increased protein levels and was significantly lower in the 23 °C group, along with a higher meat postmortem pH value. The collagen fiber ratio and collagen content of abalone meat were higher in the 23 °C group. In summary, for multiple diet feeding strategies in practical production of abalone aquaculture, the balance between the seasonally specific feeds cost benefits and the abalone meat quality should be carefully evaluated.

The role of prior knowledge and need for cognition for the effectiveness of interleaved and blocked practice

AbstractInterleaved practice combined with comparison prompts can better foster students’ adaptive use of subtraction strategies compared to blocked practice. It has not been previously investigated whether all students benefit equally from these teaching approaches. While interleaving subtraction tasks prompts students’ attention to the different task characteristics triggering the use of specific subtraction strategies, blocked practice does not support students in detecting these differences. Thus, low-prior-knowledge students would benefit from interleaving rather than blocking as it guides them through the learning-relevant comparison processes. Because these comparison processes are cognitively demanding, students’ need for cognition (NFC) could influence the effectiveness of interleaved practice. The present study investigates the role of students’ prior knowledge and NFC for the effectiveness of interleaved and blocked practice. To this end, 236 German third-graders were randomly assigned to either an interleaved or blocked condition. Over 14 lessons, both groups were taught to use four number-based strategies and the written algorithm for solving subtraction problems. The interleaved learners were prompted to compare the strategies, while the blocked learners compared the adaptivity of one strategy for different mathematical tasks. A quadratic growth curve model showed that prior knowledge had a positive influence on students’ development of adaptivity in the blocked but not in the interleaved condition. Students’ NFC had a positive impact in the interleaved condition, while it had no influence in the blocked condition. However, the effects of prior knowledge and NFC did not differ significantly between the two conditions.