Payload Ratio Research Articles

Urban Air Mobility (UAM) Network. Case Study: Baku Metropolitan Area

The development and implementation of the Urban Air Mobility transportation system, using electric vertical takeoff and landing (e-VTOL) aircrafts are the most promising solutions to mitigate growing congestion in big cities. The multiple studies and assumed forecasts indicate a transformation of urban and regional transportation infrastructure while applying the air mobility concept. This study analyzes the feasibility of UAM operations focused on the selection of service segmentation with relevant use cases, which allows for define suitable air vehicle configurations for optimization of possible air network development for Baku city and suburban areas. The result of the study introduces air vehicle features, including flight range, payload ratio, as well as several aspects of weather condition for safe operations, and outlines approaches to defining suitable regulatory framework requirements for public departments. The findings provide a practical perspective for urban planners and involved single companies, which may be useful guidelines at the initial stages of UAM services and obtaining significant information about e-VTOL aircraft and their design configurations to overcome arising barriers in the implementation processes.

Multi-disciplinary optimization of single-stage hybrid rockets for lunar ascent

This study aims to determine the optimal design and ascent trajectory for a single-stage hybrid rocket in the context of a lunar ascent mission, with the objective of reaching a 100 km circular orbit on the Moon equatorial plane. A multi-disciplinary optimization problem is formulated, integrating flight design variables and launch vehicle design variables to achieve the best mission scenario. A zero-dimensional internal ballistics model is employed to estimate key parameters such as thrust, mass flow rate, and gross mass of the hybrid rocket, while a three-degree of freedom dynamical model is utilized to simulate the ascent trajectory. The resulting integrated optimization problem is solved using an in-house heuristic algorithm that combines particle swarm and genetic algorithms. Two propellant combinations, liquid oxygen/paraffin-wax and hydrogen peroxide (90%)/high-density polyethylene, are evaluated, considering both their performance in the integrated system and the feasibility of the proposed mission. After conducting a sensitivity analysis to investigate the influence of particle count in the optimization process, results for both propellant combinations are presented. While paraffin and oxygen provide the highest payload ratio, hydrogen peroxide and polyethylene entail a more feasible and flexible design for a lunar mission.

Design of a Tripod LARMbot Arm

A new design for humanoid arms is presented based on a tripod mechanism that is actuated by linear servomotors. A specific prototype is built and tested, with the results of performance characterization verifying a possible implementation on the LARMbot humanoid. The design solves the main requirements in terms of a high payload ratio with respect to arm weight by using a tripod architecture with parallel manipulator behavior. The built prototype is assembled with commercial components to match the expectations for low-cost user-oriented features. The test results show satisfactory operation characteristics both in motion and force performance, which will ensure a future successful implementation in the LARMbot humanoid structure.

Mission Profile Analysis of Point-to-Point Rocket Cargo Transportation System Using Trajectory Optimization

This paper proposes new concepts for the point-to-point rocket cargo transportation system (RCTS). The RCTS is a transportation system that can deliver cargo anywhere on Earth in an hour using reusable launch vehicle technologies. As a fundamental study of global transportation on Earth, we especially address the mission profiles for short-range transportation within hundreds of kilometers using small rocket engines, which are intended for logistics transportation within neighboring countries or domestic transportation in a country. Two mission profiles of the RCTS are introduced, and the flight phases of each concept are explained in detail. The trajectory optimization problem of the RCTS is formulated based on the mission profiles, incorporating the flight constraints, boundary conditions, and an objective function that aims to maximize the payload ratio. The explicit-guidance is employed during the landing burn phase to enhance the convergence of the optimization problem by expanding the feasible region. The coevolutionary augmented Lagrangian method, one of the evolutionary algorithms, is utilized to obtain the solution for the trajectory optimization problem. The optimal trajectory and state variables are presented through numerical simulations. Additionally, parametric studies are performed to determine the payload mass trend of the RCTS. The trajectory optimization results are summarized to provide an analysis and comparison of the proposed mission profiles.

An Exploratory Verification Method for Validation of Sea Surface Radiance of HY-1C Satellite UVI Payload Based on SOA Algorithm

To support the application of ocean surface radiance data from the ultraviolet imager (UVI) payload of the HY-1C oceanographic satellite and to improve the quantification level of ocean observation technology, the authenticity check study of ocean surface radiance data from the UVI payload was conducted to provide a basis for the quantification application of data products. The UVI load makes up for the lack of detection capabilities of modern ocean remote sensing satellites in the ultraviolet band. The UVDRAMS (Ultra-Violet Dual-band RadiAnce Measurement System) was used to verify the surface radiance data collected at 16 stations in the study area and the pupil radiance data collected by the UVI payload to establish an effective radiative transfer model and to identify the model parameters using the seeker optimization algorithm (SOA). The study of the UVDRAMS measurement system based on the SOA algorithm and the validation of the sea surface radiance of the UVI payload of the HY-1C satellite shows that 97.2% of the incident pupil radiance of the UVI payload is contributed by the atmospheric reflected radiance, and only 2.8% is from the real radiation of the water surface, while the high signal-to-noise ratio of the UVI payload of the HY-1C ocean satellite can effectively distinguish the reflectance of the water body. The high signal-to-noise ratio of the UVI payload of the HY-1C ocean satellite can effectively distinguish the amount of standard deviation in the on-satellite radiation variation, which meets the observation requirements and provides a new way of thinking and technology for further quantitative research in the future.

Effect of operating conditions of mine monorail locomotives on the durability of drive wheel polymeric rims

An increase in the rate of coal mining and a reduction of its prime cost can be ensured by comprehensive mechanization and automation of the system of mine auxiliary transport through the widespread introduction of overhead monorail tracks. The potential use of mine monorail tracks are conditioned by the following factors: low payload ratio of the train; reduction of the mine workings cross-section area due to transfer of auxiliary transport to the upper part of the workings; high operational safety; as well as the possibility of dismantling the track in the unused sections and subsequently installing it in new mine workings. The use of rubberized rollers in the drives of mine monorail locomotives enables the coefficient of adhesion of the wheel with the monorail to be increased. It also reduces dynamic loads and the noise level during operation. The purpose of this research is to assess the durability of polymeric rims of drive wheels for mine monorail locomotives, taking into account their operating conditions. Stress distribution over the contact area of the wheel rim with the monorail was determined, enabling the development of measures to increase the service life of drive wheels of mine monorail locomotives to be developed. It was established that the effect of the monorail track deformation has no significant impact on the durability of drive wheel rims of mine monorail locomotives. A mathematical model was obtained to determine the durability of drive wheel polymeric rims, taking into account the maximum dynamic forces arising during the contact of drive wheels with the monorail. The durability of wheel polymeric rims of mine monorail locomotives was assessed in accordance with the Bailey criterion with regard to the maximum values of dynamic contact loads arising during the monorail train movement. It was also established that an increase in the carriage mass from 20 to 47 kN leads to 32 % less durability of a monorail locomotive drive wheel rim (from 8700 to 5900 hours).

Introducing an efficiency index to evaluate eVTOL designs

The evolution of electric vertical takeoff and landing (eVTOL) aircraft as part of the Advanced Air Mobility initiative will affect our society and the environment in fundamental ways. Technological forecasting suggests that commercial services are fast emerging to transform urban and regional air mobility for people and cargo. However, the complexities of diverse design choices pose a challenge for potential adopters or service providers because there are no objective and simple means to compare designs based on the available set of performance specifications. This analysis defines an aeronautically informed propulsion efficiency index (PEX) to compare the performance of eVTOL designs. Range, payload ratio, and aspect ratio are the minimum set of independent parameters needed to compute a PEX that can distinguish among eVTOL designs. The distribution of the PEX and the range are lognormal in the design space. There is no association between PEX values and the mainstream eVTOL architecture types or the aircraft weight class. A multilinear regression showed that the three independent parameters explained >90 % of the PEX distribution in the present design space.

MI-STEG: A Medical Image Steganalysis Framework Based on Ensemble Deep Learning

Medical image steganography aims to increase data security by concealing patient-personal information as well as diagnostic and therapeutic data in the spatial or frequency domain of radiological images. On the other hand, the discipline of image steganalysis generally provides a classification based on whether an image has hidden data or not. Inspired by previous studies on image steganalysis, this study proposes a deep ensemble learning model for medical image steganalysis to detect malicious hidden data in medical images and develop medical image steganography methods aimed at securing personal information. With this purpose in mind, a dataset containing brain Magnetic Resonance (MR) images of healthy individuals and epileptic patients was built. Spatial Version of the Universal Wavelet Relative Distortion (S-UNIWARD), Highly Undetectable Stego (HUGO), and Minimizing the Power of Optimal Detector (MIPOD) techniques used in spatial image steganalysis were adapted to the problem, and various payloads of confidential data were hidden in medical images. The architectures of medical image steganalysis networks were transferred separately from eleven Dense Convolutional Network (DenseNet), Residual Neural Network (ResNet), and Inception-based models. The steganalysis outputs of these networks were determined by assembling models separately for each spatial embedding method with different payload ratios. The study demonstrated the success of pre-trained ResNet, DenseNet, and Inception models in the cover-stego mismatch scenario for each hiding technique with different payloads. Due to the high detection accuracy achieved, the proposed model has the potential to lead to the development of novel medical image steganography algorithms that existing deep learning-based steganalysis methods cannot detect. The experiments and the evaluations clearly proved this attempt.

Trajectory Optimization and Cost Estimation of Laser Propulsion Systems Considering Transmission Losses

We optimized the launch trajectory of an laser-sustained-plasma-type (LSP) laser propulsion rocket at an altitude of 500 km by considering transmission efficiency. The launch cost was calculated based on the results of trajectory calculations. The transmission loss was considered to be the effect of atmospheric turbulence and focusing the performance of the lens. In the optimization problem, the Legendre–Gauss–Lobatto (LGL) method was used for discretization, and the sequential quadratic programming method was used to solve the optimization problem. The payload ratio was 18.0% with a laser power of 200 kW. In the launch calculation, the costs of the laser, electricity, propellant, and airframe were considered for the experience curve effect. The calculation indicated the cost of 267,000 launches was 29.1% of the cost of chemical propulsion.

The ratio model between throughput and delay based on payload transmission time in wireless blockchain network

In wireless blockchain network (WBN), it is necessary to study the impact of delay performance on blockchain technology with different data rates, because the throughput performance is not the only goal. We propose an analysis model to evaluate network performance based on both delay performance and network performance. Firstly, we separate the communication process from business process in WBN, and package the business data into the payload in a frame. Secondly, we define throughput-time S_V as a ratio of throughput to data transmission rate and propose a ratio model of S_V to network delay. Then, we analyze the ratio model with the parameter of payload transmission time, which is defined as a ratio of payload in a frame to data transmission rate. Using the DATA/ACK type in IEEE 802.11, we learn that the optimal payload transmission time is independent of node number and only determined by some interframe space of access mechanism and propagation time. Finally, we analyze the performance of network delay and throughput between DATA/ACK type and RTS/CTS/DATA/ACK type based on payload transmission time. The simulation data verify the validity and accuracy of the proposed model.

A Fine-Grained Network Congestion Detection Based on Flow Watermarking

With the rapid development of the network, how to effectively reduce the dynamic delay and improve the performance of the network is an important and challenging problem. Specifically, network congestion is one of the key factors that hurt the network performance, so real-time detection of the network congestion is critical for recovering the network failure quickly. Current research in congestion detection mainly faces the problems of occupying extra bandwidth, decreasing the ratio of the effective payload of the packet, increasing the burden of the switches, etc. In this paper, we apply flow watermarking to network congestion detection and propose a fine-grained network congestion detection method based on flow watermarking. We also combine it with the eBPF (extended Berkeley Packet Filter) to improve the performance of congestion detection. Theoretical analysis and experimental results show that the changes in network status can be reflected in real-time and accurately in the watermark decoding information. The network congestion detection based on flow watermarking can detect network status on a small time scale and realize low-overhead and easily deployed congestion detection.

Optimum design of nuclear electric propulsion spacecraft for deep space exploration

Future space exploration is now focused on new field-deep space planets. Deep space exploration and the development and utilization of resources are inestimable strategic significance for the country to seize the initiative and command heights of deep space exploration. Nuclear electric propulsion (NEP) systems convert heat from the fission reactor to electrical power and then use the electrical power to produce thrust. Compared with traditional propulsion technology, the NEP system with variable Isp can be used for several applications. The NEP spacecraft is more suitable for deep space exploration missions due to the advantages of high specific impulse, high power, and long life. This paper analyzes the relationship between the transfer travel time, specific mass, power, and payload ratio of the NEP spacecraft through simple performance models. Use the mass optimization and specific mass optimization models based on the NEP system composition and small thrust orbit theory to maximize the payload ratio for a given transfer time and technological characteristics. Finally, applied this NEP model to discuss the feasibility of Mars, Jupiter, and Saturn transfer missions and compared it with the Tianwen-1, Juno, and Cassini–Huygens spacecraft, respectively. Results show that when the NEP spacecraft specific mass reaches 4.77 kg/kW, the Earth–Mars transfer time can be changed to 331.31 days, the payload increases to 1650 kg, the transfer time for Jupiter and Saturn mission would be shorted to 661.31 days and 1131.31 days, the corresponding payload significantly increases which achieved to 1270 kg and 2981 kg. The nuclear electric propulsion spacecraft dramatically improves the detection capability of the spacecraft and provides a reference for the feasibility demonstration and subsequent design of the deep space and the extrasolar planet exploration.

A New Kid on the Block: Sacituzumab Govitecan for the Treatment of Breast Cancer and Other Solid Tumors.

Human trophoblast cell-surface antigen-2 (Trop-2) is a membrane glycoprotein involved in cell proliferation and motility, frequently overexpressed in epithelial tumors. Thus, it represents an attractive target for anticancer therapies. Sacituzumab govitecan (SG) is a third-generation antibody-drug conjugate, consisting of an anti-Trop-2 monoclonal antibody (hRS7), a hydrolyzable linker, and a cytotoxin (SN38), which inhibits topoisomerase 1. Specific pharmacological features, such as the high antibody to payload ratio, the ultra-toxic nature of SN38, and the capacity to kill surrounding tumor cells (the bystander effect), make SG a very promising drug for cancer treatment. Indeed, unprecedented results have been observed with SG in patients with heavily pretreated advanced triple-negative breast cancer and urothelial carcinomas, and the drug has already received approval for these indications. These results are coupled with a manageable toxicity profile, with neutropenia and diarrhea as the most frequent adverse events, mainly of grades 1–2. While several trials are exploring SG activity in different tumor types and settings, potential biomarkers of response are under investigation. Among these, Trop-2 overexpression and the presence of BRCA1/2 mutations seem to be the most promising. We review the available literature concerning SG, with a focus on its toxicity spectrum and possible biomarkers of its response.

Parametric optimization of a cyclogiro aircraft design for efficient hover with aeroelastic considerations

A minimization procedure is proposed to orient the design of a vertical take-off and landing drone towards sustainability. The vehicle is a novel cycloidal rotor drone and the principal objective is to yield the best ratio of payload to power consumption. The drone blades, rotor arms, and frame are designed for fused deposition modeling additive manufacturing with polylactic acid. 10 variables for the geometry, operation parameters, and material infill percentages are explored in search of the optimum design. A special derivation procedure allows obtaining the symbolic equations for the weight and power consumption of the drone. This permits optimization with a hybrid genetic and gradient method and exploring a broad range of aircraft sizes. 7 constraint equations ensure that the necessary assumptions made for the derivation remain valid and that the structural strength is adequate. For each new configuration, this method allows to quickly find a new optimum design using a desktop computer. Also, modifying the constraints, variables, or objective function is straightforward. Finally, the resulting design has a power loading of 0.0876 N/W.

Comparative Analysis of Different Topologies of Linear Switched Reluctance Motor With Segmented Secondary for Vertical Actuation Systems

This paper presents the overall comparison of four possible topologies of linear switched reluctance motor with segmented secondary (LSRMSS) as candidates for vertical actuation systems. The analytical design approach which treats each unit of LSRM as independent force generator is applied to design the four machines. All the four machines can be seen as 2-unit force generator although they have different winding configurations and topologies. In this case, the four machines can be designed to have similar force profile due to the inherent modular characteristics of LSRMSS. Force production, active material mass, end effects, copper loss and thrust density have been considered as well as the dynamic performance. The results indicate that the topology with toroidally wound mover has the highest force density and payload ratio capability. This topology is finally chosen to be prototyped for a 1m long vertical propulsion actuator. The experiment is performed to validate the theoretical analysis above.

Analysis of fusion propulsion system for Earth-to-Mars mission

The high-performance space propulsion system is required for deep space exploration, such as Mars and Jupiter missions. The fusion propulsion system has an extraordinary performance of ultra-high specific impulse, high specific power, and moderate thrust, which can reflect its advantages in future deep space exploration missions. In this study, analysis has been conducted to investigate the technical requirements of the fusion propulsion system for the Earth-to-Mars mission. An analytical model based on Williams’s assumption was adopted and solved by using the MATLAB code. Critical parameters such as specific impulse, specific power, mission time, and payload ratio for Mars rendezvous missions were analyzed. The qualitative and quantitative analysis results show that in order to reach Mars within one month with a payload ratio higher than 10 %, the specific power ranging from 5 to 15 kW/kg and the specific impulse of 10000 s is required. These parameters will take entirely inherent advantage of the fusion propulsion system. Moreover, the fusion propulsion system can operate under the optimal condition, including a wide range of the specific power (1−100 kW/kg) and the specific impulse (10000–200000 s). Based on a comprehensive analysis of the space mission performance, it is possible to provide a significant reference for the development of the fusion space propulsion system.

Optimum design of a parallel robot using neuro-genetic algorithm

There are some advantages of parallel robots over serial ones, such as strong structure, big payload ratio with respect to the weight, and good dynamic response. The disadvantages of the parallel robots are the difficulty of solving the forward kinematics and the limited workspace. We apply the advantages of both neural networks and genetic algorithm, for the parallel robot design. With these two methods, we solve the problems of the maximum workspace and the forward kinematics. The design method we proposed in this paper uses the optimum algorithms such that the workspace volume of the robot is maximum. We successfully applied this method to the Stewart platform.

A Review on Applications and Effects of Morphing Wing Technology on UAVs

Unmanned aerial vehicles (UAVs) have excelled with their ability to perform the intended task on or without personnel. In recent years, UAVs have been designed for civilian purposes as well as military applications. Morphing wings are changeable wing applications developed as a result of the need for a different lift and drag forces in various phases of the flight of aircraft. It is an application that enables altering the wing aspect ratio, wing airfoil, wing airfoil camber ratio, wing reference area and even different angles of attack are obtained in different parts of the wing. Although morphing wing application has just begun on today’s UAVs, modern airliners already have morphing wingtip devices such as Boeing 777-X’s. The benefits of the use of morphing wings for UAVs make this technology important. UAVs with morphing wing technology; may increase its payload ratio, may achieve a shorter take-off distance, may land and stop in shorter distance, may take-off where runway clearance is limited, has more efficient altitude change at lower engine RPMs, can obtain higher cruise speeds, may decrease its stall speed, may lower its drag if necessary, thus; saving energy and time. This study concludes a review of literature over morphing wing technology.

Research on Armature Recovery of a Coil Launcher

At present, the boost payload of electromagnetic coil launcher mainly adopts integrated launching mode; that is, the armature and payload are integrated into a projectile to shoot out of the bore together. There are some problems with this kind of launching form, such as high parasitic mass and low efficiency of payload launching. In this article, a payload projection scheme of armature–load separation launching is proposed. When the armature and payload reach the peak velocity, the armature is separated from the payload by electromagnetic capture force, and the armature can be recovered and reused under certain conditions. A model of five-stage coil launcher is established and the interior trajectory characteristics of armature under the integrated launching and separation launching modes are compared by simulation. It is shown that the mass of armature will exaggerate the launching performance. The armature–load separated launching mode can effectively improve the launching efficiency. Then the armature recovery method is further proposed. The armature velocity is related to many factors such as mass ratio of armature and payload, driving voltage, and turns of the last coil stage. The study proves that under certain conditions, the armature can be recovered, which could improve the safety of launch.

Missions to Earth and Mars using a lunar launch facility

Many space agencies are working on solutions for manned operations on the Moon, both on its surface and in cislunar space. In such a scenario, with stable human presence, a launch facility would be needed and launch vehicles could take advantage of the benefits of the lunar environment. In the present paper missions to Earth (to a geostationary orbit) and to Mars (to an areostationary orbit), from a lunar launch facility, has been studied. The trajectories are analysed by using an ephemeris model, taking into account four attractive bodies (Earth, Moon, Sun and Mars). In the first phase of the two missions, the launcher places the spacecraft on a circular lunar orbit by using liquid, solid or hybrid propulsion systems. The latter solution is analysed assuming in situ propellant production using aluminum and oxygen, elements in which the moon is very rich. In the second phase of both the missions, a minimum energy trajectory is studied, which, exploiting the Luni-Solar perturbations, allows the spacecraft to escape the gravitational field of the Moon. In the mission to Earth, this manoeuver puts the spacecraft on a very high and inclined elliptical orbit. The last phase involves a circularization manoeuvre towards the GEO and transfers are studied for two different initial inclinations, using an electric engine. In the mission to Mars, the escape impulse is used to leave both the Earth-Moon and Sun-Earth systems. The interplanetary phase is analysed for several transfer final times and considering an electric engine with variable specific impulse. Finally, the performance of a lunar launch facility is compared to that of a traditional Earth facility, showing great advantages are obtained in terms of payload ratio.