Great Thrust Research Articles

Study on the transient cavitation characteristics in an axial flow tandem pump during the rapid starting period

Abstract In axial flow pump systems constrained by limited internal space, the advantages of axial flow tandem pumps are high space utilization, strong power capacity, and great thrust. The onset of cavitation during the rapid starting period poses a classic issue for tandem axial flow pumps, resulting in issues like noise, vibration, cavitation breakdown, and material damage. This article aims to investigate the transient cavitation characteristics of each flow passage component of an axial flow tandem pump during the rapid starting period by numerical simulation method. It is compared that the evolution laws of the cavity of each flow passage component. The evolution of the cavity in all flow passage components is strongly correlated with the flow rate change rate in each stage of the rapid starting period. Among all flow passage components, the first impeller firstly experiences cavitation, and its cavitation severity is also the most severe. The Effective Net Positive Suction Head (NPSHa ) can reduce the influence of transient effects on cavity prediction and better characterize the details of the cavity evolution in different impellers than the cavitation number σ during the rapid starting period. Meanwhile, The NPSHa of the second impeller inlet is always higher than that of the first impeller inlet, indicating superior cavitation performance for the second impeller.

Integrating electromagnetic cancer stress with immunotherapy: a therapeutic paradigm.

An array of published cell-based and small animal studies have demonstrated a variety of exposures of cancer cells or experimental carcinomas to electromagnetic (EM) wave platforms that are non-ionizing and non-thermal. Overall effects appear to be inhibitory, inducing cancer cell stress or death as well as inhibition in tumor growth in experimental models. A variety of physical input variables, including discrete frequencies, amplitudes, and exposure times, have been tested, but drawing methodologic rationale and mechanistic conclusions across studies is challenging. Nevertheless, outputs such as tumor cytotoxicity, apoptosis, tumor membrane electroporation and leak, and reactive oxygen species generation are intriguing. Early EM platforms in humans employ pulsed electric fields applied either externally or using interventional tumor contact to induce tumor cell electroporation with stromal, vascular, and immunologic sparing. It is also possible that direct or external exposures to non-thermal EM waves or pulsed magnetic fields may generate electromotive forces to engage with unique tumor cell properties, including tumor glycocalyx to induce carcinoma membrane disruption and stress, providing novel avenues to augment tumor antigen release, cross-presentation by tumor-resident immune cells, and anti-tumor immunity. Integration with existing checkpoint inhibitor strategies to boost immunotherapeutic effects in carcinomas may also emerge as a broadly effective strategy, but little has been considered or tested in this area. Unlike the use of chemo/radiation and/or targeted therapies in cancer, EM platforms may allow for the survival of tumor-associated immunologic cells, including naïve and sensitized anti-tumor T cells. Moreover, EM-induced cancer cell stress and apoptosis may potentiate endogenous tumor antigen-specific anti-tumor immunity. Clinical studies examining a few of these combined EM-platform approaches are in their infancy, and a greater thrust in research (including basic, clinical, and translational work) in understanding how EM platforms may integrate with immunotherapy will be critical in driving advances in cancer outcomes under this promising combination.

Strong Magnetic–Dielectric Synergistic Gradient Metamaterials for Boosting Superior Multispectral Ultra‐Broadband Absorption with Low‐Frequency Compatibility

AbstractThe construction of 3D porous structures and metamaterials (MMs) is the most promising approaches to achieve broadband electromagnetic wave (EMW) absorption. However, it is still a huge challenge to achieve multispectral ultra‐broadband EMW absorption properties compatible with low‐frequency band (L‐ and S‐band) due to its ultralong wavelength and strong bypass capability. Herein, magnetic–dielectric synergistic gradient MMs (MDSGM) consisting of oriented flaky carbonyl iron (FCI) film and periodical RGO/CNT/CNF aerogel (GTFA) array are demonstrated. Benefiting from the synergistic effect of strong magnetic–dielectric loss, structural loss, and excellent impedance matching, MDSGM harvests an exciting multispectral ultra‐broadband EMW absorption performance with a remarkable effective absorption bandwidth covering the whole measured frequency of 1–40, 50–110 GHz, and 0.1–2.0 THz for the first time. The minimum RL (RLmin) reaches −40.24 dB and average RL is up to −19.3 dB (98.8% EMW being absorbed) in microwave band. Moreover, this multispectral ultra‐broadband EMW absorption property is less affected by the incident angle. This work pioneered realization of multispectral ultra‐broadband EMW absorption compatible with low‐frequency, which provides a great thrust for the development of stealth technology in the upcoming smart era.

Late Cenozoic Cooling History of the Xigaze Fore-Arc Basin along the Yarlung–Zangbo Suture Zone (Southern Tibet): New Insights from Low-Temperature Thermochronology

Abstract The Tibetan Plateau is currently the widest and highest elevation orogenic plateau on Earth. It formed as a response to the Cenozoic and is still ongoing collision between the Indian and Eurasian plates. The Xigaze fore-arc basin distributed along the Indus–Yarlung suture zone in southern Tibet preserves important information related to the late Cenozoic tectonic and topographic evolution of the plateau. In this study, apatite fission track (AFT) thermochronology was carried out on twelve sandstone samples from the middle segment of the Xigaze basin and additionally on four sedimentary rocks from the neighboring Dazhuka (Kailas) and Liuqu Formations. Inverse thermal history modeling results reveal that the fore-arc basin rocks experienced episodic late Oligocene to Miocene enhanced cooling. Taking into account regional geological data, it is suggested that the late Oligocene-early Miocene (~27–18 Ma) cooling recognized in the northern part of the basin was promoted by fault activity along the Great Counter thrust, while mid-to-late Miocene-accelerated exhumation was facilitated by strong incision of the Yarlung and Buqu rivers, which probably resulted from enhanced East Asian summer monsoon precipitation. Sandstone and conglomerate samples from the Dazhuka and Liuqu Formations yielded comparable Miocene AFT apparent ages to those of the Xigaze basin sediments, indicative of (mid-to-late Miocene) exhumation soon after their early Miocene burial (> ~3–4 km). Additionally, our new and published low-temperature thermochronological data indicate that enhanced basement cooling during the Miocene prevailed in vast areas of central southern Tibet when regional exhumation was triggered by both tectonic and climatic contributing factors. This recent and widespread regional exhumation also led to the formation of the high-relief topography of the external drainage area in southern Tibet, including the Xigaze fore-arc basin.

Discovery and genesis of helium-rich geothermal fluids along the India–Asia continental convergent margin

Large-scale helium accumulations are rarely reported in tectonically active continental subduction zones. This study shows geochemical variations in helium and other volatiles (N2, CO2, Ne and Ar) in hot springs from the India–Asia continental convergent margin (Indus–Yarlung suture, IYS) to the intracontinental extensional region in southern Tibet and identifies a 1200-km-long helium enrichment zone (He > 5000 ppm) within 50 km north of the IYS. In total, 144 gas samples were categorized into four groups: Group A, with dominant N2 species and He concentrations (0.07–2.31 vol%) 1.4–23 times higher than industrial-grade He resources (0.05–0.1 vol%); Group B, with dominant CO2 species and high He concentrations (0.05–1.57 vol%); and Groups C and D, depleted in He (<0.05 vol%) and dominated by CO2 and N2, respectively. The gas mixtures exhibit systematic variations from the extensional zone to the continental convergent margin, changing from deep-origin, He-depleted, CO2-dominated fluids (Group C) to relatively shallow crust-derived, He-rich, N2-dominated gases (Group A). The former exhibits small but detectable amounts of mantle-derived He (2.3 ± 2.6%) and CO2 (<3.2%), primarily atmosphere-derived N2 (δ15N = 0.0 ± 0.6‰) and Ar (40Ar/36Ar = 307 ± 25), and crustal CO2 (82 ± 9% from carbonate and 17 ± 9% from sediments/metasediments) from the subducted Indian slab-carbonate and Tibetan crust. The low He flux of Group C matches the steady release of He from the 70-km-thick crust into the geothermal waters during 0.02–43.5 ka. Shallow calcite precipitation and dissolution reactions cause CO2 loss and slight He enrichment in the extensional zone. Group A samples at the convergent margin show pure crustal He, more radiogenic 40Ar (40Ar/36Ar = 330 ± 67), and higher sedimentary contributions of 28 ± 23% for N2 and 37 ± 11% for CO2. A high He flux near the IYS requires an external source with high 4He/N2 (∼0.05) and 4He/20Ne (103–105) to provide >62% of the total He flux. This finding is best explained by He production in the south-dipping Gangdese granitic belt and deep crust, accumulation below the accretionary wedge, and episodic liberation along Great Counter thrust structures since 0.7 Ma by Tibetan Plateau uplifts and intense hydrothermal activity. The He-rich fluids mix with the sedimentary and atmosphere-derived N2 from the accretionary wedge, forming He-rich N2-type gases. This study systematically reports large-scale He enrichment along the continental convergent margin for the first time and demonstrates that complex crustal-scale structures in the convergent margin significantly controlling gas geochemistry. These results have profound implications for potential helium resource exploration and He-CO2-N2 recycling in continental subduction zones.

Design and Computational Analysis of an Axisymmetric Contoured Supersonic Propulsion Nozzle

The design of supersonic axisymmetric nozzles to a required exit Mach number necessitates applying the Method of Characteristics (MoC) that reduces the partial differential equations system of hyperbolic form governing such internal flow-fields to two ordinary differential equations known as the characteristic and the compatibility equations. These relationships are then transformed into finite difference equations and solved using an appropriate predictor-corrector algorithm.The present study applies the MoC to the design of a contoured nozzle that accelerates the combustion gases to supersonic velocities. The selected configuration has a throat constituted of two circular arcs with the one downstream attached to a 2nd-order polynomial profile at the attachment point. The solution, in terms of the static pressure along the centerline and the wall is obtained. It was found that the flow expands gradually without any instability or possibility of shock waves. A gradual expansion represented by a decrease in pressure is noticed immediately downstream of the throat, the flow tending to expand gradually from the throat to the exit. Along the wall, the expansion is important immediately downstream of the throat while it tends to stabilize downstream to reach the ambient pressure at the outlet. In terms of performance, the thrust coefficient developed shows the great expansion process within the divergent supersonic section. The configuration is also found to develop a great specific thrust.

Variations Rake Angle Propeller B – Series Towards Performance and Cavitation with CFD Method

Fuel consumption is most widely used in ship propulsion system, therefore, in ship propulsion system must be considered and designed as efficiently as possible. Propeller is one of the mechanical components on a ship, which can run ships from one place to another. The most important thing in a propeller is the mechanical properties or strength of the propeller in accepting the load to be able to run the ship. Another factor that affects mechanical propeller properties is the propeller design itself. In propeller design, one thing that can be considered is the rake angle of propeller. The rake angle is the slope angle between the propeller blade and the propeller center. The rake angle on the propeller is used to increase the amount of mass water used to produce thrust that needed by ship. Reducing the rake angle can increase the efficiency of the B-Series propeller slightly. Previous research has analyzed the effect of variations in rake angle to determine the relationship between thrust and fluid flow in the B-series propeller, but for the cavitation that occurs in the propeller has not been analyzed. In this research, variations ware made from the B-Series propeller rake angle to obtain propeller thrust and cavitation values. The analysis carried out in this study is to use the CFD (Computational Fluid Dynamic) method and the results obtained from the simulation with greatest thrust and efficiency, that is in the 5º rake angle variations of 2310,273 KN and 70% efficiency, while the smallest thrust value is variation of rake angle 25º for 1110,933 KN. Then for the largest cavitation level in the variation of the 25º rake angle and the smallest at the 15º original rake angle.

Temperature field evolution and thermal-mechanical interaction induced damage in drilling of thermoplastic CF/PEKK – A comparative study with thermoset CF/epoxy

Although new generation carbon fibre reinforced thermoplastic (CFRTP) such as carbon fibre reinforced polyetherketoneketone (CF/PEKK) is a promising sustainable alternative to the conventional thermoset carbon fibre reinforced plastic (CFRP), there is a lack of literature regarding its machining performance. This is the first study unveiling the machining temperature evolution during drilling of CF/PEKK and its potential impact on the associated material damages. Through a comparative study with the thermoset CF/epoxy, the disparate drilling performance of the two composites has been uncovered, and the results were found to be closely related to the materials' thermal/mechanical properties. Specifically, CF/PEKK produces continuous chips due to its excellent ductility and thermal sensitivity, whereas CF/epoxy produces segmented chips due to its brittle nature. CF/PEKK generates up to 40 N (50.5 %) higher thrust force, 87.6 °C (98.9 %) higher hole wall temperature and 61.1 °C (48.8 %) higher chip temperature than that of CF/epoxy. This has been correlated to the longer tool-chip contact length of CF/PEKK and its unique chip morphology. Despite the greater thrust force/temperature generation, CF/PEKK shows 55.7 % lower delamination damage as compared to CF/epoxy, and this is owning to its excellent interlaminar toughness. This study establishes a more in-depth understanding into the drilling performance of thermoplastic CF/PEKK and thermoset CF/epoxy and also provides guidance on the high performance manufacturing of next generation composites.

Cenozoic kinematic histories of the Tidding and Lohit thrusts in the northern Indo-Burma Ranges: Implications for crustal thickening and exhumation of Gangdese lower arc crust along the Indus-Yarlung suture zone

Crustal thickening has been a key process of collision-induced Cenozoic deformation along the Indus-Yarlung suture zone, yet the timing, geometric relationships, and along-strike continuities of major thrusts, such as the Great Counter thrust and Gangdese thrust, remain inadequately understood. In this study, we present findings of geologic mapping and thermo- and geochronologic, geochemical, microstructural, and geothermobarometric analyses from the easternmost Indus-Yarlung suture zone exposed in the northern Indo-Burma Ranges. Specifically, we investigate the Lohit and Tidding thrust shear zones and their respective hanging wall rocks of the Lohit Plutonic Complex and Tidding and Mayodia mélange complexes. Field observations are consistent with ductile deformation concentrated along the top-to-the-south Tidding thrust shear zone, which is in contrast to the top-to-the-north Great Counter thrust at the same structural position to the west. Upper amphibolite-facies metamorphism of mélange rocks at ∼9−10 kbar (∼34−39 km) occurred prior to ca. 36−30 Ma exhumation during slip along the Tidding thrust shear zone. To the north, the ∼5-km-wide Lohit thrust shear zone has a subvertical geometry and north-side-up kinematics. Cretaceous arc granitoids of the Lohit Plutonic Complex were emplaced at ∼32−40 km depth in crust estimated to be ∼38−52 km thick at that time. These rocks cooled from ca. 25 Ma to 10 Ma due to slip along the Lohit thrust shear zone. We demonstrate that the Lohit thrust shear zone, Gangdese thrust, and Yarlung-Tsangpo Canyon thrust have comparable hanging wall and footwall rocks, structural geometries, kinematics, and timing. Based on these similarities, we interpret that these thrusts formed segments of a laterally continuous thrust system, which served as the preeminent crustal thickening structure along the Neotethys-southern Lhasa terrane margin and exhumed Gangdese lower arc crust in Oligocene−Miocene time.

Schooling benefits from a system of active and passive hydrofoils

Fishes school to swim more efficiently while not much of fish schooling is understood from the perspective of fluid–structure interactions. To understand the benefits of fish schooling, we investigate thrust, efficiency, and wake structure of a two-hydrofoil system where the upstream hydrofoil is forced pitching (active) and the downstream hydrofoil is free pitching (passive). The streamwise and lateral separations between the two hydrofoils are 0.109c and 1.0D, respectively, where c is the chord length and D is the diameter of the leading edge. The active hydrofoil pitches with normalized amplitudes A∗=0.55 – 0.80 and normalized frequencies StD=0.23–0.33. It is found that the upstream active hydrofoil undergoes up to 38% thrust enhancement in the presence of the downstream passive hydrofoil while the downstream passive hydrofoil achieves the same thrust as the upstream active hydrofoil under certain conditions. The maximum combined thrust and efficiency achieved for the two-hydrofoil system are 95% and 180% higher than those for a single isolated hydrofoil. These are some reasons for fish swimming in school. Three distinct flow structures (vortex impingement flow, vortex trapping flow, and vortex splitting flow) are identified in the A∗– StD domain, where the vortex trapping flow provides the greatest thrust and efficiency enhancement.

Design and Experimental Study of a Curved Contact Quadrupole Railgun

The railgun is a promising weapon, but suffers from poor contact and harsh magnetic field environment. We used the moment of inertia to measure the deformation resistance of the rail, studied the contact characteristics of the railgun by contact force, and compared the performances of different structures of the rail. The magnetic field environment in the bore and the thrust on the armature of different structure railguns were studied by FEM-BEM simulation, and the final structure of the hyperbolic augmented quadrupole railgun was determined. The new structure of the railgun possesses better deformation resistance and contact characteristics, and can provide an electromagnetic shielding area and greater thrust. The test results show that the proposed railgun exhibits less rail damage and less armature ablation after launch.

УВЕЛИЧЕНИЕ ТЯГИ ТУРБОРЕАКТИВНОГО ДВИГАТЕЛЯ ПУТЕМ МОДЕРНИЗАЦИИ СОПЛОВОГО БЛОКА

The study objective is the possibility of thrust augmentation of a turbojet engine due to upgrading the nozzle cluster by installing an external duct of the annular combustor on the engine case, acting as a nozzle. The problem to which the article is devoted is to get a new product with higher operating parameters at minimal cost by upgrading a mass-produced engine. The novelty of the work is in the introduction of an annular combustor into existing engines that are in serial production, thereby reducing the cost of producing a completely new product with greater thrust. During the research, a number of theoretical advantages of a new product based on a mass-produced engine are obtained, including increased thrust with minimal change in its weight, as well as the economic benefits of producing such units with minimal production changeover. At the stage of theoretical research of this topic, a retrofitted engine with an annular combustor has a number of advantages over the standard engine taken as a basis.

Late Oligocene - Miocene morpho-tectonic evolution of the central Gangdese batholith constrained by low-temperature thermochronology

The morpho-tectonic evolution of the Tibetan Plateau is controlled by complicated interactions between tectonic uplift and surface erosion. The Gangdese batholith in the southern Lhasa terrane is a key orogenic belt for exploring the complicated morpho-tectonic evolution of the Tibetan Plateau. In this contribution, we apply apatite fission track (AFT) thermochronology to constrain the thermo-tectonic evolution of the central segment of the Gangdese batholith. Twenty-four granitoid samples were collected from both river valleys (e.g., the Yarlung and Xiang Rivers) and from the internal batholith areas located farther from river drainage (and/or local faults) networks. All samples exhibit Miocene AFT ages between ∼19.9 and ∼ 6.1 Ma. Inverse thermal history modeling results reveal that the central Gangdese batholith underwent a two-stage accelerated basement cooling in the Miocene. The first cooling stage took place during the late Oligocene to middle Miocene (∼25–15 Ma), this period of moderate to rapid basement cooling coincides with activity along the Gangdese thrust and Great Counter thrust system, and the Oligocene-Miocene delamination of the Lhasa lithosphere and concomitant asthenosphere upwelling. These tectonic processes acted as first-order control on regional basement uplift, denudation and exhumation. Second, a middle-late Miocene (∼14–5 Ma) rapid cooling is widely recognized in the whole Gangdese batholith. We suggest that this middle-late Miocene cooling is due to exhumation in response to tectonic and surface erosion processes such as N-S normal faults and enhanced river incision induced by the intensification of Asian monsoon. Finally, in combination with published low-temperature thermochronological and paleoaltimetry data, it is deduced that the present-day low-relief landscape of the southern Lhasa terrane resulted from a long-term balance between intense regional tectonic activity and surface erosion.

Party system change and internal security: evidence from India, 2005-2021

ABSTRACT Has the consolidation of the Hindu nationalist Bharatiya Janata Party (BJP) as the dominant party at the national level since the 2014 Lok Sabha election affected internal security outcomes in India? This question assumes particular significance because of the primacy accorded to the use of force in the BJP’s counter-insurgency (COIN) strategy. Using sub-national data on insurgency-related fatalities from 2005–2021, I examine whether states where the BJP received the largest share of votes in the 2014 Lok Sabha election subsequently experienced any significant changes in the pattern of fatalities. Implementing a difference-in-difference econometric specification, I show that the BJP states experienced a relatively sharper decline in security force fatalities from pre-2014 compared to non-BJP states. However, there was no such effect on civilian fatalities or the total number of insurgency-related incidents. Taken together, these findings show that the greater thrust towards militarism in COIN strategy under the BJP, has, paradoxically, increased the security of military/police personnel involved in COIN operations, without commensurate changes in the security of those whom they are mandated to defend.

MRNA-based vaccine technology for HIV.

Human immunodeficiency virus (HIV) poses a major health problem around the globe, resulting in hundred-thousands of deaths from AIDS and over a million new infections annually. Although the standard treatment of HIV infection, antiretroviral therapy, has proven effective in preventing HIV transmission, it is unsuitable for worldwide use due to its substantial costs and frequent adverse effects. Besides promoting HIV/AIDS awareness through education, there is hardly an alternative for inhibiting the spread of the disease. One promising approach is the development of an HIV vaccine. Unfortunately, the high variability of envelope proteins from HIV subtypes, their frequency of mutation and the lack of fully understanding the mechanisms of protection against the virus constitute an obstacle for vaccine development. Efforts for developing successful anti-HIV vaccines have been underway for decades now, with little success. Lately, significant progress has been made in adopting the novel mRNA vaccine approach as an anti-HIV strategy. mRNA vaccines received a great thrust during the COVID-19 pandemic. Now, several mRNA-based HIV vaccines are undergoing clinical trials to evaluate their safety and efficacy. This review offers an overview of the pathogenesis and treatment of HIV / AIDS, previous efforts of HIV vaccine development and introduces mRNA vaccines as a promising and potential game changing platform for HIV vaccination.

Analysis of Linear Hybrid Excited Flux Switching Machines with Low-Cost Ferrite Magnets

Linear hybrid excited flux switching machines (LHEFSM) combine the features of permanent magnet flux switching machines (PMFSM) and field excited flux switching machines (FEFSM). Because of the widespread usage of rare-earth PM materials, their costs are steadily rising. This study proposes an LHEFSM, a dual stator LHEFSM (DSLHEFSM), and a dual mover LHEFSM (DMLHEFSM) to solve this issue. The employment of ferrite magnets rather than rare-earth PM in these suggested designs is significant. Compared to traditional designs, the proposed designs feature greater thrust force, power density, reduced normal force, and a 25% decrease in PM volume. A yokeless primary structure was used in a DSLHEFSM to minimize the volume of the mover, increasing the thrust force density. In DMLHELFSM, on the other hand, a yokeless secondary structure was used to lower the secondary volume and the machine’s total cost. Single variable optimization was used to optimize all of the proposed designs. By completing a 3D study, the electromagnetic performances acquired from the 2D analysis were confirmed. Compared to conventional designs, the average thrust force in LHEFSM, DSLHEFSM, and DMLHEFSM was enhanced by 15%, 16.8%, and 15.6%, respectively. Overall, the presented machines had a high thrust force density, a high-power density, a high no-load electromotive force, and a low normal force, allowing them to be used in long-stroke applications.

Role of Bioinformatics in the Development of Plant Genetic Resources

Bioinformatics plays a significant role in the development of many fields of biological science and plant genetic resources (PGR) is one of them. With the advent of high throughput sequencing technology, bioinformatics continues to make considerable progress in biology by providing scientists with access to the genomic information. There are many areas of plant genetic resources such as development of core set, trait associated gene discovery, genetic diversity analysis, Genome Wide Association Studies (GWAS), phylogenetic and evolutionary analysis, database development and its management etc. where bioinformatics plays important roles. Main role of bioinformatics is to provide computational algorithm and software tools to accelerate the research of PGR. Bioinformatics is a new paradigm in the genomic research, which provides PGR research a great thrust. However, there are many areas such as pan genomics, multi locus GWAS, Genomic Selection with epistasis effects where bioinformatics can play better role.

Experimental study on acoustic and aerodynamic improvement of the hemiptera-inspired propeller planform

The multi-rotors have a short working duration and produce excessive noise, which is insufficient for complicated jobs and has a negative impact on human and animal health. Nonetheless, their market is growing in popularity. As a result, low-noise products are more competitive, and aerodynamic and acoustic enhancements are essential. The goal of this research is to create a small bioinspired propeller with the same power input as a conventional propeller that achieves the same or better aerodynamic performance while reducing noise. Accordingly, an experiment looked at the effects of different operating circumstances and geometric factors on the aerodynamic and aeroacoustic performance of a small propeller with a distinctive planform shape inspired by Hemiptera. This propeller was run at eleven rotational speeds ranging from 3000 to 8000 RPM with no freestream velocity to simulate hover circumstances. When compared to the baseline propeller, the Hemiptera propeller produce greater thrust for the same power source, reduce harmonic and broadband noise, and offer a better noise level. This noise reduction might be attributed to a decrease in Hemiptera propeller force fluctuation. Furthermore, its rotational speed is lower and its figure of merit is higher than the baseline propeller at hover flying with 3N thrust. Moreover, at this force, the Hemiptera propeller shows a 2.8W power reduction and a 5 dB decrease in acoustic signature. When it comes to hover efficiency, the Hemiptera propeller outperforms the baseline propeller across the board, regardless of thrust.

Model Edukasi Bagi Ibu Rumah Tangga Dalam Mengelola Sampah Di Kecamatan Koto Tangah

The purpose of this study is to describe trash management in housewives, identify obstacles of managing trash and formulate an educational model in managing trash for housewives at the Koto Tangah District. The type of research used is research and development with a qualitative approach and supported by using ISM (Interpretative Structural Modeling) analysis techniques. The results showed that (1) trash management at the Koto Tangah District was still low. In general, housewives in Koto Tangah sub-district have less knowledge in terms of trash management (2) The obstacles faced by housewives at the Koto Tangah District include the development of technology that is still low lack of trash management to improve people's lives, lack of supervision and implementation of regulations related to trash management, lack of community participation in trash management. (3) The design of the educational model in trash management is formulated with ISM analysis. The results of the analysis of the data obtained, there are elements that have greater thrust in the design of the trash management educational model, namely: Independent trash management system, using the principle of 5R + 1FS and product results from the educational model in trash management is a brochure.

Preliminary identification of potential failure modes of a disc cutter in soil-rock compound strata: Interaction analysis and case verification

The reliability of a disc cutter is critical to shield tunneling performance in compound strata. In this regard, a series of three-dimensional models were developed to evaluate the interaction between the disc cutter and the soil-rock interface. The influences of the penetration depth and the tip width were also addressed. Then, this study presented a rudimentary identification method of disc cutter's potential failure modes in compound strata. The results convincingly indicated that the cutting coefficient could be separated into two stages at the interface of soil and rock: linear reduction stage and constant value stage. For a disc cutter with a tip width of 20 mm and 22 mm, about 1.5% and 1% increments were added to Cc,r as the disc cutter penetrated every millimeter deeper, respectively. It showed that a cutter ring was apt to fracture at the soil-rock interface. The risk of cutter ring fracture was mounting dramatically as the penetration depth raised. The fracture failure possibility at the soil-rock interface for a narrow cutter ring was higher under a great thrust. And it also revealed that the cutter ring of a disc cutter might be led to non-uniform wear due to the insufficient starting torque to rotate in soft layers. Overall, the conducted research could offer helpful guidance for TBM operation in the compound stratum.