Horizontal Resistance Research Articles

Analysis of Acinetobacter P-type type IV secretion system-encoding plasmid diversity uncovers extensive secretion system conservation and diverse antibiotic resistance determinants.

Acinetobacter baumannii is globally recognized as a multi-drug-resistant pathogen of critical concern due to its capacity for horizontal gene transfer and resistance to antibiotics. Phylogenetically diverse Acinetobacter species mediate human infection, including many considered as important emerging pathogens. While globally recognized as a pathogen of concern, pathogenesis mechanisms are poorly understood. P-type type IV secretion systems (T4SSs) represent important drivers of pathogen evolution, responsible for horizontal gene transfer and secretion of proteins that mediate host-pathogen interactions, contributing to pathogen survival, antibiotic resistance, virulence, and biofilm formation. Genes encoding a P-type T4SS were previously identified on plasmids harboring the carbapenemase gene blaNDM-1 in several clinically problematic Acinetobacter; however, their prevalence among the genus, geographical distribution, the conservation of T4SS proteins, and full capacity for resistance genes remain unclear. Using systematic analyses, we show that these plasmids belong to a group of 53 P-type T4SS-encoding plasmids in 20 established Acinetobacter species, the majority of clinical relevance, including diverse A. baumannii sequence types and one strain of Providencia rettgeri. The strains were globally distributed in 14 countries spanning five continents, and the conjugative operon's T4SS proteins were highly conserved in most plasmids. A high proportion of plasmids harbored resistance genes, with 17 different genes spanning seven drug classes. Collectively, this demonstrates that P-type T4SS-encoding plasmids are more widespread among the Acinetobacter genus than previously anticipated, including strains of both clinical and environmental importance. This research provides insight into the spread of resistance genes among Acinetobacter and highlights a group of plasmids of importance for future surveillance.

Experimental Study on Horizontal Resistance Parameter of Gravelly Soil Considering Slope Gradient Factor

Horizontal resistance can be significantly different for gravelly soil slope sites with different gradients. The impact of slope gradient on the horizontal resistance of soil based on a three-dimensional physical simulation test has been investigated, and the displacement of the pile top and soil pressure for four piles under various gradients (slope gradient 0–45°) was analyzed. The research reveals that ① The soil resistance exhibits a linear increase stage, non-linear steep increase stage, and gradually stabilizing stage with the increase in load. ② The ultimate soil resistance is significantly affected by depth and displacement, and hyperbolic variation characteristics related to the displacement stage. It has a slope weakening effect, and the steeper the slope gradient, the lower the ultimate soil resistance of the pile sides, which effect is negligible when the depth exceeds 0.6–0.7 times that of the pile buried depth. ③ Based on the characteristics of horizontal ultimate resistance-displacement-depth variation in soil, a gradient factor, which is only related to the slope gradient, was used to describe the impact of gradient on the soil resistance modulus (kini) and ultimate resistance (pu). kini is reduced close to the ground surface and gradually increases with depth until it becomes equal to the value of level ground. The ratio between pu in slope ground and level ground was determined for slope angles. The above horizontal resistance parameters were expressed as a function based on the test data to calculate the lateral ultimate bearing capacity of gravelly soil considering the slope gradient factor. The research results developed the theory of foundation design for building structures, promoting the reliability evaluation of pile soil systems towards a more scientific and rigorous direction.

Global meta‐analysis reveals the drivers of gut microbiome variation across vertebrates

AbstractShifts in gut microbial diversity and structure are one route by which vertebrate hosts adapt to local environmental conditions. However, recent studies have mostly been limited to a single species, small sample sizes, or restricted geographic ranges. Therefore, drawing a global picture of vertebrate gut microbiome diversity, community structure, and determinants for their adaptive shifts remains to be elucidated. We here collected 6508 samples from 113 vertebrate species covering diverse classes, feeding behaviors, and host habitats based on 16S rRNA gene sequencing. The results showed that host diet pattern had a significant impact on gut microbiome variation, which might drive taxonomic and functional contents of gut microbiome across vertebrates. Of note, the phylum Fusobacteria were enriched in carnivorous vertebrate gut while herbivorous vertebrate gut selectively increased the abundance of Verrucomicrobia. Also, climate factors were strongly associated with gut microbiome variation across vertebrates. Interestingly, we found that the abundance of microbiota belonging to Bacteroidetes increased gradually while the members from Proteobacteria showed a decreasing trend from high‐ to low‐latitude zones, potentially contributing to vertebrate adaptation to local climate condition. Additionally, we comprehensively deciphered the common antibiotic resistomes and their potential mobility between terrestrial vertebrate gut microbiome (n = 487) and their sympatric soil biological environment samples (n = 203) by integrating metagenomic sequencing datasets. Particularly, potential horizontal antibiotic resistance genes (e.g., bacA) transfers were detected between vertebrates gut microbiome and their sympatric soil biological environment. Together, our findings provide new evidence of how external environmental factors affect vertebrate gut microbiome variation.

Seismic behavior of lightweight steel frame with thin-walled steel skeleton-lightweight concrete wall

In this study, an innovative prefabricated lightweight steel frame with thin-walled steel skeleton-lightweight concrete composite wall structure (LSF-TSLC) is proposed. The proposed LSF-TSLC has the lightweight steel frame (LSF) as the vertical load-bearing system, whereas the thin-walled steel skeleton-lightweight concrete composite wall (TSLC) acts as the main component for horizontal earthquake resistance. A full-scale LSF specimen and three full-scale LSF-TSLC specimens were prepared considering the variables of wall installation method (embedded, external) and thin-walled steel skeleton distribution (frame type, truss type). The corresponding seismic behavior was experimentally investigated by evaluating the hysteretic characteristics, failure mode, ultimate bearing capacity, deformation performance, stiffness degradation, energy dissipation, and strain characteristics. The results showed that the plastic hinges appeared at the beam ends and column bases of LSF. Due to the shear failure, the embedded and external TSLC exhibited grid cracks and diagonal cracks, respectively. The LSF and TSLC had a good coordinating deformation capacity, while the LSF-TSLC structure had two seismic fortification lines. Compared with LSF, the ultimate bearing capacity and stiffness of LSF-TSLC were increased by 2.1 times and 5.1 times, respectively. The deformation capacity and energy dissipation of LSF-TSLC were significantly improved compared to LSF. The self-tapping nail joint of the embedded wall and the high-strength bolt joint of the external wall had reliable connectivity performance. The numerical simulation of LSF were conducted to verify the plastic analysis model for LSF. And the ultimate bearing capacity calculation method for the LSF-TSLC structure was proposed based on the Strut-and-Tie model.

Seismic design rules for lightweight steel shear walls with wood panel sheathing within the Eurocode format

Within the 2nd-generation of Eurocodes several new lateral force resisting systems (LFRS) typically used in lightweight cold-formed steel (CFS) buildings have been introduced, including shear walls with wood sheathing (SWWS). Therefore, extensive studies have been carried out to define the seismic design parameters according to the format of European code for seismic design, i.e. Eurocode 8. In current version of the 2nd-generation Eurocode 8 (prEN1998-1-2, CEN 2022), in case of SWWS the behaviour factor has been defined based on the FEMA P695 (FEMA, 2009) [3] methodology, whereas the other seismic design parameters have been set based on assumption validated with analyses on limited case studies. To overcome this lack, specific research devoted to defining the main seismic design parameters for SWWS belonging to Ductility class 3 (DC3) according to prEN1998-1-2 (CEN 2022) has been carried out at the University of Naples “Federico II”. The research shows that the Easley et al. (1982) method gives consistent in-plane horizontal wall resistance predictions if the shear resistance of wood panel-to-steel sheet screw connections (sheathing connections) is evaluated with reliable approaches and formulas for the evaluation of the shear resistance of sheathing connections have been calibrated. Based on the results obtained from this research, a partial safety factor for resistance evaluation of SWWS according to limit state design (LSD) equal to 1.3 is proposed and an overstrength (expected resistance) factor for the design of non-ductile elements according to capacity design equal to 1.7 is recommended.

A method based on GA solver for optimizing the design parameters of the right frustum resistance frame for indoor earthquake shelters

This paper proposes a new method to enhance the impact resistance of earthquake shelters. Traditional methods for protecting individuals during earthquakes focus on improving or reinforcing the building structures, which is time-consuming and inflexible. The SHELTER project developed an earthquake shelter using a conventional cubic frame. This study builds upon the SHELTER project by optimizing its frame structure to improve the shelter's impact resistance against falling debris during an earthquake. Firstly, a right frustum frame is selected as the basic geometric configuration for optimization (with the cuboid being a particular case of the frustum). Six critical design parameters serve as variables for optimization, establishing a mathematical model. Secondly, to maximize the permissible impact loads in both vertical and horizontal directions (F1 and F2), a multi-objective optimization using the NSGA-II algorithm is performed on the selected parameters, resulting in a Pareto front. Furthermore, to choose a solution from the Pareto front that meets the needs of this study, the relationship between the forces F1 and F2 applied to the shelter frame by falling debris during an earthquake is examined, converting the multi-objective optimization problem into a single-objective optimization problem. Finally, based on the relationship between F1 and F2, a single-objective optimization function is established and solved using the Genetic Algorithm (GA) to obtain the optimal parameters. The shelter frame manufactured with these optimal parameters exhibits better overall impact resistance than the cubic frame. This improvement is attributed not only to the geometric properties of the frustum, which results in a lower centre of gravity, but also to the optimization method, which enhances the frame's vertical impact resistance while maintaining good horizontal impact resistance.

Variable response of eastern filbert blight resistance sources in New Jersey.

Eastern filbert blight (EFB), caused by Anisogramma anomala, is the primary limiting factor for hazelnut (Corylus sp.) production in the United States. In this study, 82 cultivars and selections shown to be resistant or tolerant to EFB in Oregon were field planted in New Jersey in 2017 and 2019 and evaluated for their EFB response under high disease pressure. The trees carry known single resistance (R) genes with most mapped to their respective linkage groups (LG), including LG2, LG6, and LG7, or they express quantitative resistance (QR, horizontal resistance). Disease incidence and severity was documented, stem cankers counted and measured, and the proportion of diseased wood calculated. The EFB disease response of some cultivars/selections varied considerably between New Jersey and Oregon while others were consistent. Trends were observed in relation to resistance source origin and LGs, which provide insight into durability and usefulness of resistance. In striking contrast to Oregon, nearly all selections with R-genes mapped to LG6, including those carrying the 'Gasaway' resistance allele, exhibited severe EFB infections (232 of 266 [87%]). This finding is of consequence since the U.S. hazelnut industry currently relies solely on LG6 resistance for EFB resistance. Further, for the first time, EFB was observed on several selections carrying LG7 resistance, specifically offspring of 'Ratoli' from Spain. Interestingly, selections carrying LG7 resistance from origins other than 'Ratoli' remained free of EFB, with one exception, all selections carrying LG2 (n=9) resistance also remained free from EFB. Interestingly, the EFB responses of selections expressing QR (n=26) more closely resembled the disease phenotypes they exhibited in Oregon. Overall, the divergence in EFB response between Oregon and New Jersey, where pathogen populations differ, supports the presence of pathogenic variation in A. anomala and highlights potential limitations of using single R-genes to manage the disease. Results also suggest trees expressing QR may be more stable across pathogenic populations.

A Study on the Impact of Window Partition Walls on the Spread of Fire on Building Facades

This paper investigates the impact of window partition walls on the spread of fire on building facades under the impact of environmental wind through Fire Dynamics Simulator simulation experiments. A four-story building model was constructed using a Fire Dynamics Simulator incorporating six different wind speed conditions and six different partition wall widths. The fire-blocking performance of window partition walls of varying widths was systematically compared and analyzed, and the data indicated: (1) Under calm wind conditions, the installation of window partition walls is observed to facilitate the vertical spread of facade fires. Moreover, as the width of these partition walls increases, this facilitative effect becomes increasingly prominent; (2) Under wind speeds of 0 to 5 m/s, the temperature on the leeward side is lower when window partition walls are present than when they are absent. This indicates that window partition walls inhibit the horizontal spread of building facade fires, and wider window partition walls have better horizontal fire resistance performance.

Refinement of rice blast disease resistance QTLs and gene networks through meta-QTL analysis

Rice blast disease is the most devastating disease constraining crop productivity. Vertical resistance to blast disease is widely studied despite its instability. Clusters of genes or QTLs conferring blast resistance that offer durable horizontal resistance are important in resistance breeding. In this study, we aimed to refine the reported QTLs and identify stable meta-QTLs (MQTLs) associated with rice blast resistance. A total of 435 QTLs were used to project 71 MQTLs across all the rice chromosomes. As many as 199 putative rice blast resistance genes were identified within 53 MQTL regions. The genes included 48 characterized resistance gene analogs and related proteins, such as NBS–LRR type, LRR receptor-like kinase, NB-ARC domain, pathogenesis-related TF/ERF domain, elicitor-induced defense and proteins involved in defense signaling. MQTL regions with clusters of RGA were also identified. Fifteen highly significant MQTLs included 29 candidate genes and genes characterized for blast resistance, such as Piz, Nbs-Pi9, pi55-1, pi55-2, Pi3/Pi5-1, Pi3/Pi5-2, Pikh, Pi54, Pik/Pikm/Pikp, Pb1 and Pb2. Furthermore, the candidate genes (42) were associated with differential expression (in silico) in compatible and incompatible reactions upon disease infection. Moreover, nearly half of the genes within the MQTL regions were orthologous to those in O. sativa indica, Z. mays and A. thaliana, which confirmed their significance. The peak markers within three significant MQTLs differentiated blast-resistant and susceptible lines and serve as potential surrogates for the selection of blast-resistant lines. These MQTLs are potential candidates for durable and broad-spectrum rice blast resistance and could be utilized in blast resistance breeding.

A junction temperature model based on heat flow distribution in an IGBT module with solder layer voids

The presence of voids in a solder layer affects the thermal reliability of an insulated-gate bipolar transistor (IGBT). In this work, the effects of the size and fraction of solder layer voids and the power losses of chips on heat flow distribution, junction temperature and thermal resistance were investigated. It was found that it was difficult for the heat to flow through the voids due to the high thermal resistance of air. Therefore, the heat above the voids could only flow horizontally, and then avoid the voids and move downward in the solder layer and the following layers, leading to a temperature difference in the surface chip layer. An improved junction temperature model based on the heat flow distribution (HD) considering the solder layer voids was established, the horizontal thermal resistance and horizontal heat capacity are introduced to characterize the effect of the solder layer voids, and the parameter extraction method was proposed. The temperature difference on the surface of the module increased with the increase of the void fraction, and when the void fraction increased from 0 % to 40 %, the surface temperature difference increased from 9.591 °C to 109.86 °C. The results showed that the proposed model not only had a higher accuracy in the estimation of the junction temperature compared with the traditional Cauer model and the improved Cauer model, but also monitored the horizontal temperature differences in the chip layer precisely.

Effect of inter-module connection properties on structural sway of high-rise modular buildings

The modular steel building is a rapidly evolving prefabricated structural system, consisting of discrete volumetric modules assembled with inter-module connections. Despite numerous studies on the design optimization of inter-module connections, research on the development of realistic connection models and the correlation between connection properties and the overall structural behavior is relatively scarce. This paper introduces a multiple-spring inter-module connection model and supplies detailed property calculations of different load transfer components. The model can effectively simulate different stiffness and strength levels at inter-module connections and predict relative dislocations between assembled modules. The model is then applied to analyze the structural sway of modular buildings under seismic loads. Influences of connection modelling methods and the real connecting abilities on structural sway responses are investigated through comparative analysis of connection and module drift deformations when using conventional pin or rigid constraint connection models and the proposed realistic multiple spring model. Results indicate that simplified pin or rigid constraints cannot accurately represent the actual load transfer mechanisms at inter-module connections. The horizontal link determines the composition extent of horizontally assembled columns and modules. The horizontal shear resistance is closely related to column loads and follows the downwardly increased mode, which induces different structural sway and module drift levels in modular buildings.

Development and characterization of high friction polyurethane bearings for bridge engineering applications

In this study, a high friction polyurethane (HFPU) was prepared using PCL-210 N, MOCA, TDI, and silicone diols. HFPU bearings for bridges were manufactured by casting HFPU in layers onto steel plates. The chemical composition, microstructure, crosslinking strength, and viscoelastic properties of HFPU were characterized. The results demonstrated that HFPU possesses excellent mechanical properties and surface roughness. Mechanical tests showed that HFPU has a hardness of 84 HA, a tensile strength of 35.05 MPa, residual deformation of less than 5 %, and a shear modulus of 2.57 MPa. The HFPU bearings also exhibited excellent vertical load-carrying capacity, horizontal deformation resistance, and recovery capability. Additionally, the Bouc-Wen model accurately simulated the hysteretic behavior, indicating that the HFPU bearings can provide seismic damping effects in bridge structures. The high friction characteristics, characterized by both the Bouc-Wen and Dahl models, showed that the HFPU bearing could work stably within 0–250 % strain.

Effects of Short-Rest Interval Time on Resisted Sprint Performance and Sprint Mechanical Variables in Elite Youth Soccer Players

This study explored the impact of short rest intervals on resisted sprint training in elite youth soccer players, specifically targeting enhanced initial-phase explosive acceleration without altering sprint mechanics. Fifteen U19 soccer players participated in a randomized crossover design trial, executing two sprint conditions: RST2M (6 sprints of 20 m resisted sprints with 2 min rest intervals) and RST40S (6 sprints of 20 m resisted sprints with 40 s rest intervals), both under a load equivalent to 30% of sprint velocity decrement using a resistance device. To gauge neuromuscular fatigue, countermovement jumps were performed before and after each session, and the fatigue index along with sprint decrement percentage were calculated. Interestingly, the results indicated no significant differences in sprint performance or mechanical variables between RST2M and RST40S, suggesting that the duration of rest intervals did not affect the outcomes. Horizontal resistance appeared to mitigate compensatory patterns typically induced by fatigue in short rest periods, maintaining effective joint movement and hip extensor recruitment necessary for producing horizontal ground forces. These findings propose a novel training strategy that could simultaneously enhance sprint mechanics during initial accelerations and repeated sprint abilities for elite youth soccer players—a methodology not previously employed

The Analytical Model and Horizontal Resistance of the Column-Head Dou-Gong in the Traditional Chinese Timber Structure

ABSTRACT To study the horizontal resistance of the column-head Dou-Gong (CHDG) in the traditional Chinese timber structure, the analytical model of CHDG without or with horizontal gap was proposed in this study. According to the structural form analysis of CHDG, the analytical model of CHDG considers the contact relationship between the components. CHDG has several distinct layers, of which the first layer is modeled as a rotation spring element and the second layer and above of CHDG are modeled as shear spring elements. Then, the horizontal resistance of CHDG was analyzed, and the horizontal load-displacement relationship of CHDG with horizontal gap appears triple polyline, while CHDG without horizontal gap is bilinear. Finally, the effects of parameters, including the length or width of Dadou bottom, height of Mantousun (MTS), width of horizontal gap, and vertical load, on the horizontal resistance was analyzed. The horizontal resistance of CHDG increases significantly with the length or width of the Dadou bottom, height of MTS, and vertical load increase, while the horizontal resistance of CHDG decreases significantly with width of horizontal gap increases.

Numerical simulation of offshore monopiles with reinforcement in shallow soil layer

With the development of large-scale offshore wind turbines (OWTs), monopile foundations require larger diameter and greater embedded depth to satisfy the higher bearing requirements. Large-diameter monopiles for OWTs are mainly loaded horizontally, and the horizontal resistance provided by the shallow soil plays an important role in the loading of the monopile foundation. Therefore, shallow soil reinforcement (such as cement grouting and bio-grouting) is an effective method to improve the bearing capacity of the monopile. In this study, the lateral static loading mechanism of a shallow-layer reinforced monopile was investigated by finite element method (FEM). The effect of reinforcements with different stiffness values (elastic modulus), different strengths (cohesion and friction angle) and different reinforced ranges (width and depth) was analyzed on the lateral bearing capacity, deformations, soil resistances, and soil resistance per unit length to pile deflection (p-y) curves of monopiles. Based on the numerical results, an empirical formula was proposed for predicting the reinforcement coefficient of the bearing capacity. The effects of different reinforcement parameters on the distribution of soil resistance were analyzed, and the soil resistances obtained by FEM were compared with those from a theoretical formula. It was found that the resistance provided by the reinforced soil was clearly reduced at the interface with the unreinforced soil, and the resistance of the unreinforced soil was not significantly affected by the reinforced soil.

Breeding Programs Against Coffee Leaf Rust in Brazil: A Review

Leaf rust caused by Hemileia vastatrix Berk & Br. is the main disease that attack coffee plants all over the world. The disease causes 35-50% of yield loss in average in Brazil. The disease is present in all the countries that cultivate coffee (Coffea arabica L. and C. canephora L.). Resistance of coffee to leaf rust is the main method of disease control. But the great variability of the pathogen makes it very difficult. In the world and in Brazil there are more than 50 and 16 races of the pathogen, respectively. In Brazil there are seven research institutions that have been working with breeding programs against coffee leaf rust. The main source of resistance to coffee leaf rust used by all the research institutions in Brazil came from ‘Centro de Investigação das Ferrugens do Cafeeiro-CIFC’ in Oeiras, Portugal. They are: Híbrido de Timor (HdT) CIFC 832-1 and HdT CIFC 832 and HdT CIFC 2570. Crosses were made at CIFC with a variety Caturra and Vila Sarchi and sent to Brazil, Colombia and some countries of Central America and Caribean. The countries that received the germplasm of CIFC back crossed them with varieties Catuai and Mundo Novo. Crossing HdT with Caturra originated the group Catimor and HdT with Vila Sarchi the group Sarchimor. Other source of resistance to leaf rust came from Coffea canephora crossed with C. arabica originating the cultivar Icatu. But the great majority of the resistant cultivar came from Catimor and Sarchimor. More than 50 coffee varieties have been launched with resistance to the leaf rust in the last 40 years in Brazil. But only few of them remain with vertical resistance to all the races of H. vastatrix. Horizontal resistance is more common on C. canephora var. conilon and C. canephora var. robusta than in C. arabica. This revision has the purpose to relate to the scientific comunity the breeding programs against coffee leaf rust in Brazil.

Comparative Measurement of Horizontal Penetrometry with a Focus on the Degree of Soil Compaction in Real Work Conditions

Potential soil production is closely related to the physical and mechanical properties. The aim of this paper was to evaluate the effect of different levels of soil compaction created by tractor chassis. The total area of the experimental plot was 13.22 ha. Up until 2019, a conventional tillage system had been used. The measurements were carried out with an innovative measuring device that allows for the continuous measurement of the horizontal penetrometry for comparative measurements while driving, which was designed at the Slovak University of Agriculture in Nitra. The measuring device measured the soil resistance in the tire track (On-track) and out of track (Off-track) as well as in three (50 s) sequences within one tractor pass. Three lines were chosen, where in each a pair of combinations was made. The results were subjected, in addition to graphical evaluation, to single factor ANOVA analysis. When comparing individual passes (PH1 to PH6), the statistical analysis showed that the results of the horizontal resistance measurements proved to be statistically significant (p < 0.05) with respect to the weight, number of passes, and tire underinflation. The highest compaction was caused by the first pass, while the higher weight of the tractor during the next pass had a smaller effect. Underinflating the tires ensured a reduction in compaction. Reducing the tractor tire pressure to 0.15 MPa resulted in a reduction in soil compaction of up to 16%.

Оценка устойчивости перспективных гибридов цветного картофеля к фитофторозу

Abstract. Potatoes with pigmented tubers contain anthocyanins and other phenolic compounds that demonstrate antioxidant activity and have a beneficial effect on human health. The nutritional value and other consumer qualities of available potato varieties must be combined with resistance to various infections, primarily late blight, which leads to significant yield losses and considerable costs for chemical protection. The purpose of this work was to assess late blight resistance of 46 promising potato hybrids with different pigmentation patterns, both in the field and by laboratory methods, including molecular screening. The objectives of this study included obtaining promising hybrids of colored potatoes characterized by a set of economically importatnt traits, laboratory and field assessment of the resistance of leaves and tubers to the late blight pathogen Phytophthora infestans, as well as molecular screening of late blight resistance gene markers (Rpi genes). The production, cultivation and evaluation of the hybrid material was carried out using standard methods. Field and laboratory resistance of leaves and tubers was assessed on a 9-point scale. Molecular screening was carried out using PCR analysis. The scientific novelty of the work lies in the fact that for the first time a comprehensive assessment of the resistance to late blight of hybrid material of colored potatoes obtained on the territory of Russian Federation was carried out. According to the results obtained, the studied samples demonstrated a high level of resistance of tubers and leaves in field conditions and laboratory tests. However, the results of the study did not reveal a relationship between laboratory or field resistance and the presence of Rpi gene markers, which may be due to the influence of many independent factors that determine horizontal resistance.

Optimization and Experimental Study of Operation Parameters for Fertilizer Injection Drilling Device Based on Discrete Element Simulation

In addressing the challenges of high energy consumption and low efficiency in fertilization borehole drilling for clayey soils in southern orchards, this study utilizes the Discrete Element Method to establish a simulation model for clayey soils. Through this approach, we identify an optimal set of operational parameters that significantly reduces energy consumption. By utilizing simulation technology to model the drilling process, we analyzed the impact of rotation speed and feed rate on the torque and resistance of the drilling apparatus. Initially, this paper describes field measurements of particle parameters in soils from southern orchards. Subsequently, utilizing the Discrete Element Method and particle contact theory, we established a simulation model to represent the interactions between soil and soil, as well as soil and auger in the soil environment of the southern region. For the Southern orchard clay with a moisture content of 16.8% and a measured angle of repose of 35.55°, parameter calibration was performed. The contact model “Hertz-Mindlin with Johnson-Kendall-Roberts” was selected in EDEM. Using Design Expert, a regression model variance analysis was applied to the discrete element model parameters, leading to the determination of the optimal values for significant soil model parameters. The soil JKR surface energy is 5.85 J·m−2, with a soil–soil restitution coefficient of 0.65 and a soil–steel static friction coefficient of 0.5. Subsequently, discrete element simulation experiments on the drilling apparatus were conducted in EDEM, considering various rotation speeds and feed rates. The simulation analysis indicates that the torque consistently increases with higher rotation speeds, with a maximum relative error of 7%. The torque initially rises from zero to a maximum value, then gradually decreases to a low value, followed by a rapid increase to a higher value, and finally drops back down. This cycle repeats in the observed pattern. The total force experienced reaches its minimum average value of 200 N at a feed rate of 0.05 m/s. Simulation test results indicate that, among the three forces acting on the auger (vertical resistance, horizontal resistance, and lateral resistance), vertical resistance is the primary factor contributing to power consumption. As the rotation speed increases, the maximum value of vertical resistance continues to rise, while horizontal resistance and lateral resistance exhibit a declining trend. As the feed rate increases, the maximum values of resistance in all three directions also increase. When the feed rate exceeds 0.05 m/s, the maximum lateral resistance experiences a sharp increase. Through comprehensive analysis, the optimal operational parameters for borehole fertilization are determined to be a rotation speed of 100 r·min−1 and a feed rate of 0.05 m/s. The aim of this study is to reduce the energy consumption of borehole fertilization operations, minimize carbon emissions, and promote the sustainable development of orchard production.

Introduction: Verticality, radicalism, resistance

In recent decades urban scholarship has witnessed a ‘vertical’ or ‘volumetric’ turn that has advanced understandings of the multi-modal power asymmetries cutting through and organising urban space. Yet, this volumetric scholarship often remains locked into binary critiques – of success/failure, inclusion/exclusion, luxury/abjection, dispossession/accumulation, arborescent/rhizomatic, horizontal/vertical. This special issue tinkers with the limitations of these (unwittingly) binary urban geometries and volumetrologies – material as well as metaphorical ones. By building the etymological opposition of ‘the vertical’ with ‘the radical’ into the title of the volume (via the Latin root radix, meaning ‘root’), we seek to make the radical itself work with geometric and morphological associations. The papers in this special issue proffer diverse ethnographic, geographic and conceptual material for considering and theorising urban verticality in concert with rather than in opposition to its incumbent horizontalisms, diagonals, curls, zigzags and scattered planes. As we completed work on the special issue, the horrors of russia’s full-scale invasion of Ukrainian territory played out before our eyes. Accordingly, we make use of the introduction to reflect upon the insight that the war in Ukraine brings to bear on the intersection between domains of the urban, the vertical and the radical in the fraught, tense, vicious, fragile – but resistant – urban worlds of today. In doing so, we seek not only to render more clearly visible the violent effects of power verticals on lives, worlds and cities, but also to find seeds of hope in emergent, insurgent forms of (vertical as well as horizontal, and neither vertical nor horizontal) resistance.