Larger Payload Research Articles

Systemic design of the very-high-resolution imaging payload of an optical remote sensing satellite for launch into the VLEO using an small launch vehicle

The very low Earth orbit (VLEO), which includes orbits with altitudes of 100–450 km, has distinct advantages for remote-sensing spacecraft. Lower altitudes allow payloads with smaller dimensions, weight, and power to achieve performances similar to or better than larger payloads in higher orbits in remote sensing and Earth observation missions. The most important advantage of low orbits for optical imaging systems is the higher resolution these payloads can attain. The present paper systemically designs the very high-resolution imaging payload of an optical remote sensing satellite for operations in the VLEO. The aim of this design is to achieve a high spatial resolution of the optical imaging platform and reach a 1-m ground sampling distance (GSD) as reported. Therefore, considering an orbital altitude of 300 km and system calculations, the implementation of this method is described. The results obtained show that the proposed platform (VHR4) has better diffraction-limited ground resolution compared to several examples of operational satellite platforms under approximately equal orbital conditions. Also, by calculating and estimating the weight, power, and dimensions of the proposed imaging platform (VHR4), it is shown that the platform meets the requirements of a small satellite launcher in terms of weight, dimensions, and power.

Unmanned Helicopter Airborne Fourier Transform Infrared Spectrometer Remote Sensing System for Hazardous Vapors Detection

The rapid development of unmanned aerial vehicles (UAVs) provides a new application mode for gas remote sensing. Compared with fixed observation and vehicle-mounted platforms, a Fourier transform infrared spectrometer (FTIR) integrated in the UAV can monitor chemical gases across a large area, can collect data from multiple angles in three-dimensional space, and can operate in contaminated or hazardous environments. The unmanned helicopter has a larger payload and longer endurance than the rotary-wing drone, which relaxes the weight, size and power consumption limitations of the spectrometer. A FTIR remote sensing system integrated in an unmanned helicopter was developed. In order to solve the data acquisition and analysis problem caused by vibration and attitude instability of the unmanned helicopter, a dual-channel parallel oscillating mirror was designed to improve the stability of the interferometer module, and a robust principal component analysis algorithm based on kernel function was used to separate background spectrum and gas features. The flight experiment of sulfur hexafluoride gas detection was carried out. The results show that the system operates stably and can collect and identify the target spectrum in real time under the motion and hovering modes of an unmanned helicopter, which has broad application prospects.

The Autonomous Pipeline Navigation of a Cockroach Bio-Robot with Enhanced Walking Stimuli.

Tens of crawling bio-robots with cockroaches as the mobile platform have been developed with various functions. Compared with artificial crawling robots of the same size, they revealed better flexibility, larger payload, and stronger endurance. These features made bio-robots ideal for pipeline inspection scenarios because the advancements in locomotion mechanisms and efficient power systems are still hurdles for current artificial systems. In this study, we controlled the bio-robot to crawl in the confined dark pipeline and achieved autonomous motion control with the help of an onboard sensing system. Specifically, a micro-camera was mounted on the electronic backpack of the cockroach for image collection, and an IMU sensor was used to compute its body orientation. The electronic backpack transmitted images to the host computer for junction recognition and distance estimation. Meanwhile, the insect's habituation to electrical stimulation has long been an uncertain factor in the control of bio-robots. Here, a synergistic stimulation strategy was proposed to markedly reduce the habituation and increase the number of effective turning controls to over 100 times. It is also found that both the increase of payload and the application of stimulations could promote the metabolic rate by monitoring carbon dioxide release. With the integration of synergistic stimulation and autonomous control, we demonstrated the fully autonomous pipeline navigation with our cockroach bio-robot, which realized the cycle number of approximately 10 in a roll. This research provides a novel technology that has the potential for practical applications in the future.

Design, optimization and application of two-element airfoils for tactical UAV

Owning to the requirements for longer endurance, larger payloads as well as simpler mechanical structure of tactical UAV, the two-element airfoil technology is introduced. Firstly, the aerodynamic characteristics of five common low-speed airfoils are calculated and compared. The airfoil with good aerodynamic performance after segmentation is selected as initial airfoil. Then, the influence of different segmentation types on the aerodynamic characteristics of airfoils is analyzed, and the segmentation type which brings the best aerodynamic benefits is selected. The slot parameters are optimized by NSGA-II optimization algorithm under cruising, take-off, and a large angle of attack states to obtain a high-performance self-adaption tactical UAV airfoil. Finally, the new airfoil is applied to Sparrow-hawk tactical UAV, the CL1.5 /CD of acceleration state increases 15.5%, the CL of large angle of attack increases 20.4% and the CL1.5 /CD of cruising state after enlarge the aspect ratio increase12.3%.

Design and experiment of a new translational parallel manipulator with large payload and high repeatability

Parallel manipulators are known to have higher structural rigidity and end-effector speed than serial manipulators. However, the size, payload, rigidity, and repeatability of parallel manipulators highly depend on the types of active and passive joints used. Compared with other joint types, revolute joints are structurally simpler and have an unlimited rotation range. They can be easily preloaded to increase the stiffness and eliminate clearance. Hence, revolute joints are preferable for parallel manipulators that need to have a smaller size, larger payload, and higher reparability. This paper presents a new translational parallel manipulator (TPM) that uses only revolute joints as the active and passive joints. The kinematics, workspace analysis, and singularity analysis are provided to facilitate the design of the new TPM. Finite element analyses are given to evaluate the compliance contribution of the revolute joints and links of the new TPM. Compliance, payload, and repeatability experiments are provided to verify the merits of the proposed design. We expect that the proposed TPM can provide an alternative for selecting parallel manipulators to meet different industrial applications.

Sparse Optical Flow Implementation Using a Neural Network for Low-Resolution Thermal Aerial Imaging.

This study is inspired by the widely used algorithm for real-time optical flow, the sparse Lucas–Kanade, by applying a feature extractor to decrease the computational requirement of optical flow based neural networks from real-world thermal aerial imagery. Although deep-learning-based algorithms have achieved state-of-the-art accuracy and have outperformed most traditional techniques, most of them cannot be implemented on a small multi-rotor UAV due to size and weight constraints on the platform. This challenge comes from the high computational cost of these techniques, with implementations requiring an integrated graphics processing unit with a powerful on-board computer to run in real time, resulting in a larger payload and consequently shorter flight time. For navigation applications that only require a 2D optical flow vector, a dense flow field computed from a deep learning neural network contains redundant information. A feature extractor based on the Shi–Tomasi technique was used to extract only appropriate features from thermal images to compute optical flow. The state-of-the-art RAFT-s model was trained with a full image and with our proposed alternative input, showing a substantial increase in speed while maintain its accuracy in the presence of high thermal contrast where features could be detected.

Adaptive Reversible Data Hiding With Contrast Enhancement Based on Multi-Histogram Modification

Reversible data hiding with contrast enhancement (RDH-CE) is proposed to aim at improving the contrast of images while embedding data. After deeply analyzing and studying the RDH-CE method proposed by Jafar <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.</i> , it is found that there are three main problems in their method. Firstly, their method ignores the fact that the left-bottom neighbors of a pixel contribute to increasing the accuracy of the local-complexity evaluation. Secondly, Jafar <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.</i> ’s method employs K-means clustering in combination with one single feature to split pixels into five classes, leading to a weak clustering performance. Finally, Jafar <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.</i> ’s method uniformly embedded 1 bit into each pixel irrespective of the local complexity, and thus, the embedding capacity is limited. To this end, an improved RDH-CE method is proposed in this paper. Considering that the complexity evaluation plays a vital role in both contrast enhancement and payload increase, we improve embedding performance by including left-bottom neighbors of a pixel into complexity evaluation. Compared with one single feature in Jafar <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">et al.</i> ’s method, we extract multiple features to assist K-means clustering such that a better cluster performance is obtained. In addition, our method provides an adaptive pixel modification strategy based on the local complexity, in which we can adaptively embed 1 or 2 bits into a pixel according to the corresponding complexity. By these three improvements, our method is capable of achieving high capacity while enhancing contrast. The experimental results also show that our method achieves higher accuracy of the complexity evaluation, larger payload, and better local contrast enhancement than those existing RDH-CE related methods.

Android Head Units vs. In-Vehicle ECUs: Performance Assessment for Deploying In-Vehicle Intrusion Detection Systems for the CAN Bus

Following the numerous attacks that exploited vulnerabilities of Controller Area Networks (CAN), intrusion detection systems have become a topic of prime importance for in-vehicle buses. Newer in-vehicle communication layers, such as CAN-FD, despite the larger payloads which can easily integrate cryptographic elements, need similar attention. But detecting intrusions may call for demanding algorithms that are not computationally cheap while timely detection is necessary in order to process frames in real-time and take the appropriate actions. In this work we evaluate the performance of several binary classifiers on traditional in-vehicle Electronic Control Units (ECUs) and compare them to modern Android devices which have become widespread inside cars with the adoption of Android-capable infotainment systems. Needless to say, these modern devices benefit from higher computational and memory resources while cloud connectivity may alleviate computational costs even further. Contrasting between traditional controllers and Android devices has become necessary and so far there have been little efforts in this direction. To create a realistic testbed, we use collected in-vehicle CAN bus traffic from an SUV as well as more demanding logs from Advanced Driver-assistance Systems (ADAS) implemented on CAN-FD which we augment with adversarial activity.

Autonomous underwater videography and tracking of basking sharks

BackgroundBiologging studies have revealed a wealth of information about the spatio-temporal movements of a wide range of vertebrates large enough to carry electronic tracking tags. Advances in autonomous underwater vehicles (AUVs or UAVs) and unmanned aerial vehicles (commonly known as drones), which can carry far larger payloads of sensor technologies, have revealed insights into the environment through which animals travel. Some AUVs have been used to film target animals, but are generally limited to periods as long as a drone operator can actively follow an animal. In the present study, we use an AUV, the REMUS-100 SharkCam, paired with a custom transponder tag attached to the shark, to autonomously follow three basking sharks for a cumulative total of 10.9 h to collect video and environmental data on their sub-surface behaviour. The basking shark is the second largest fish in the world and is endangered globally, but despite being subject to various biologging studies, little is known of this species breeding ecology and their mating grounds remain unknown.ResultsWe detail the first successful autonomous tracking of basking sharks, comprising three missions that filmed basking sharks in mid-water and close to benthic habitats. Sharks spent very little time feeding, and travelled relatively close to sandy, rocky and algae-covered benthos. One basking shark was observed defecating. Conspecifics were not observed in the three missions, nor were courtship or breeding behaviours. AUV offset distances for videography were determined iteratively through tracking. These offsets varied depending on the trade-off of between water clarity and proximity of the AUV for obtaining useful video data and directly influencing shark behaviour.ConclusionsThe present study is the first successful use of an AUV to gain insight into the sub-surface behaviour of basking sharks.

Reversible data hiding for binary images based on adaptive overlapping pattern

Pattern substitution (PS) method (Ho et al., Comput. Stand. Interfaces 31:787–794, 2009) is a recent reversible data hiding method for binary images. It generates one pattern pair, the patterns in which are called PM and PF, and substitutes between them to embed one bit. Two types of PS have been proposed: non-overlapping PS and overlapping PS. However, Dong et al. (ETRI J. 37:990–1000, 2015) states that the overlapping PS sometimes cannot decode correctly, which is called as miscoding problem. Moreover, to the PS-based methods (Ho et al., Comput. Stand. Interfaces 31:787–794, 2009; Dong et al., ETRI J. 37:990–1000, 2015; Dong et al., Lect. Notes Comput. Sci. 6526:3516–3522, 2011), although chosen of two patterns to form the pattern pair which relates the embedding performance much, the previous methods only use a fixed pattern pair during the whole data hiding process. In order to overcome these two shortcomings, this paper proposes an adaptive overlapping PS method. Firstly, two modes of the embedding are proposed so that the miscoding problem can be solved. Secondly, one window which contains the context of current processing pixel is generated and updated when the process proceeds to the next pixel. Thus, the optimum pair of the local context for embedding can be chosen. Thirdly, in order to get a smaller location map, a three-round embedding mechanism is also proposed. With these three improvements, our method can embed larger payloads with less distortion than the previous works.

Encrypted images-based reversible data hiding in Paillier cryptosystem

Homomorphic public key technology effectively protects privacy, allowing algebraic operations directly in the cipher-text. Therefore, it has been extensively studied in the field of cloud computing. In this study, an encrypted image-based data hiding (EIRDH) algorithm with homomorphic public key cryptosystem is presented. The key contributions are these two sides. (1) An improved fast Paillier homomorphic public key cryptosystem system is proposed for encrypting image. It improves the efficiency of encryption operations greatly. (2) A difference expansion (DE) scheme is developed by exploiting the cover pixel to construct a new pair of pixels for data hiding. Compared with other methods, the experimental results show that, the proposed method has larger payload and higher stego-image quality. It accomplishes the image quality’s increasing instead of general decreasing.

Reducing Metadata Leakage from Encrypted Files and Communication with PURBs

Abstract Most encrypted data formats leak metadata via their plaintext headers, such as format version, encryption schemes used, number of recipients who can decrypt the data, and even the recipients’ identities. This leakage can pose security and privacy risks to users, e.g., by revealing the full membership of a group of collaborators from a single encrypted e-mail, or by enabling an eavesdropper to fingerprint the precise encryption software version and configuration the sender used. We propose that future encrypted data formats improve security and privacy hygiene by producing Padded Uniform Random Blobs or PURBs: ciphertexts indistinguishable from random bit strings to anyone without a decryption key. A PURB’s content leaks nothing at all, even the application that created it, and is padded such that even its length leaks as little as possible. Encoding and decoding ciphertexts with no cleartext markers presents efficiency challenges, however. We present cryptographically agile encodings enabling legitimate recipients to decrypt a PURB efficiently, even when encrypted for any number of recipients’ public keys and/or passwords, and when these public keys are from different cryptographic suites. PURBs employ Padmé, a novel padding scheme that limits information leakage via ciphertexts of maximum length M to a practical optimum of O(log log M) bits, comparable to padding to a power of two, but with lower overhead of at most 12% and decreasing with larger payloads.

Improved K-Pass Pixel Value Ordering Based Data Hiding

K-pass pixel value ordering (PVO) is an effective reversible data hiding (RDH) technique. In k-pass PVO, the complexity measurement may lead to a weak estimation result because the unaltered pixels in a block are excluded to estimate block complexity. In addition, the prediction-error is computed without considering the location relationship of the second largest and largest pixels or the second smallest and smallest pixels. To this end, an improved RDH technique is proposed in this paper to enhance the embedding performance. The improvement mainly lies in the following two aspects. First, some pixels in a block, which are excluded from data hiding in some existing RDH methods, are exploited together with the neighborhood surrounding this block to increase the estimation accuracy of local complexity. Second, the remaining pixels in a block, i.e., three largest and three smallest pixels are involved in data embedding. Taking three largest pixels for example, when the difference between the largest and third largest pixels is relatively large (e.g., > 1), we improve k-pass PVO by considering the location relationship of the second largest and largest pixels. The advantage of doing this is that the difference valued 3 between the maximum and the second largest pixel which is shifted in k-pass PVO, is able to carry 1 bit data in our method. In other words, a larger amount of pixels are able to carry data bits in our scheme compared with k-pass PVO. Abundant experimental results reveal that the proposed method achieves preferable embedding performance compared with the previous work, especially when a larger payload is required.

Image data hiding scheme based on spline interpolation and OPAP

In this paper we propose an image steganography method based on the spline interpolation. Firstly, digital images are often transmitted over the Internet which would arouse little suspicion. Secondly, the high correlation between pixels provides rich space for data embedding; in addition, optimal pixel adjustment procedure (OPAP) is employed to minimise the error between the input image and the output image in order to ameliorate the fidelity of the proposed steganography method. We propose image steganography methods in spatial domain by using a nearest neighbour, bilinear and bicubic spline interpolation technique, which can embed a large amount of secret data into images with imperceptible modification. The interpolation error, which is measured by distance between the maximum value and the predicted value, is used to embed the secret data. The experimental results show that the proposed schemes provide a larger payload and a good image quality.

A difference matching technique for data embedment based on absolute moment block truncation coding

In this paper, an optimized data embedding method based on Huang et al.’s work for absolute moment block truncation coding (AMBTC) is proposed. Huang et al.’s work successfully exploits the difference of quantization levels (QLs) for data embedment and has an excellent embedding performance. However, the modified QLs are not adjusted to minimize the distortion. In some rare cases, they might exceed the grayscale range. Moreover, the order of QLs in smooth blocks is not utilized for data embedment, losing the chance to embed one additional bit without deteriorating the image block. We propose a method to give analytical solutions to adjust QLs such that the distortions in both smooth and complex blocks are minimized. A subtle mechanism is also provided to ensure that no QLs will overflow or underflow. Moreover, the order of QLs is utilized in data embedment to further increase the payload without sacrificing the image quality. The experimental results reveal that the proposed method offers a better image quality over Huang et al.’s and other state-of-the-art works while providing a comparable or larger payload.

PENGARUH BEBAN KENDARAAN TERHADAP UMUR DESAIN PERKERASAN (STUDI KASUS JALAN NASIONAL LAMBARO – BATAS PIDIE PROVINSI ACEH)

Better capabilities of a vehicle (higher speeds, larger payloads) allows freight operators to perform "transport efficiency" (carrying goods as much as possible in one way that will provide benefits). This problem affects the cumulative equivalent standard axle (CESA) plan, which will experience a shift (Plans of CESA are reached before the service Period of the construction ends). The study is located on the eastern route of Aceh Province, especially on Lambaro-Pidie border. The purpose of this research was to know the relation of vehicle load with time, how to design pavement age and residual CESA value, in the service lifespan (time) of construction (10 years). The data used in this study was secondary data obtained from relevant agencies. The method used in this research was descriptive by doing comparison analysis to the relationship that happened. The data analysis and simulation were conducted in 3 scenarios, where Scenario 1 refers to the design data, Scenario 2 refers to the actual average daily traffic and the standard axle, and Scenario 3 refers to the actual LHR and actual axle load (Weigh in measurement results Motion-WIM). From the results of this study, it is known to simulate vehicle loads with time, Scenario 1 is y = 1,0794x - 2171,3, Scenario 2 y = 0,4935x2 - 1987,9x + 2E+06, and Scenario 3 y = 0,8605x2 - 3466,3x + 3E+06. The result of simulation lifespan of pavement design and CESA value, it is known that pavement design lifespan has decreased on average by 3.5 years, and CESA residual value is 42,138,92 thousand ESA.

Lipid Nanoparticles Enabling Gene Therapies: From Concepts to Clinical Utility.

Genetic drugs based on RNA or DNA have remarkable therapeutic potential as virtually any disease can be treated by silencing a pathological gene, expressing a beneficial protein, or by editing defective genes. However, therapies based on nucleic acid polymers require sophisticated delivery systems to deliver these macromolecules to the interior of target cells. In this study, we review progress in developing nonviral lipid nanoparticle (LNP) delivery systems that have attractive properties, including ease of manufacture, reduced immune responses, multidosing capabilities, larger payloads, and flexibility of design. LNP systems represent the most advanced delivery systems for genetic drugs as it is expected that an LNP-short interfering RNA (siRNA) formulation will receive clinical approval from the Food and Drug Administration (FDA) in 2018 for treatment of the hereditary condition transthyretin-mediated amyloidosis, a fatal condition for which there is currently no treatment. This achievement is largely due to the development of optimized ionizable cationic lipids, arguably the most important factor in the clinical success of LNP-siRNA. In addition, we highlight potential LNP applications, including targeting tissues beyond the liver and therapeutic approaches based on messenger RNA or Clustered Regularly Interspaced Short Palindromic Repeats/Cas.

A plan to seed life throughout the cosmos

The galaxy may contain billions of habitable but lifeless worlds. Claudius Gros at Goethe University Frankfurt, Germany, thinks that people should change it. He believes in directed panspermia: deliberately seeding life throughout the cosmos. To do so, he proposes people use a laser propulsion system that may not be technically out of reach. Breakthrough Starshot is an ambitious existing proposal to use giant lasers and light sails to send tiny probes to Alpha Centauri. The goal is to take pictures of this star. But these systems could also deliver much larger payloads, says Gros.

Frame error rate for single-hop and dual-hop transmissions in 802.15.4 LoWPANs

ABSTRACTIEEE 802.15.4 is a popular standard for personal area networks used in different low-rate short-range applications. This paper examines the error rate performance of 802.15.4 in fading wireless channel. An analytical model is formulated for evaluating frame error rate (FER); first, for direct single-hop transmission between two sensor nodes, and second, for dual-hop (DH) transmission using an in-between relay node. During modeling the transceiver design parameters are chosen according to the specifications set for both the 2.45 GHz and 868/915 MHz bands. We have also developed a simulation test bed for evaluating FER. Some results showed expected trends, such as FER is higher for larger payloads. Other observations are not that intuitive. It is interesting to note that the error rates are significantly higher for the DH case and demands a signal-to-noise ratio (SNR) penalty of about 7 dB. Also, the FER shoots from zero to one within a very small range of SNR.

Effect of static shape deformation on aerodynamics and aerothermodynamics of hypersonic inflatable aerodynamic decelerator

The inflatable aerodynamic decelerator (IAD), which allows heavier and larger payloads and offers flexibility in landing site selection at higher altitudes, possesses potential superiority in next generation space transport system. However, due to the flexibilities of material and structure assembly, IAD inevitably experiences surface deformation during atmospheric entry, which in turn alters the flowfield around the vehicle and leads to the variations of aerodynamics and aerothermodynamics. In the current study, the effect of the static shape deformation on the hypersonic aerodynamics and aerothermodynamics of a stacked tori Hypersonic Inflatable Aerodynamic Decelerator (HIAD) is demonstrated and analyzed in detail by solving compressible Navier-Stokes equations with Menter's shear stress transport (SST) turbulence model. The deformed shape is obtained by structural modeling in the presence of maximum aerodynamic pressure during entry. The numerical results show that the undulating shape deformation makes significant difference to flow structure. In particular, the more curved outboard forebody surface results in local flow separations and reattachments in valleys, which consequently yields remarkable fluctuations of surface conditions with pressure rising in valleys yet dropping on crests while shear stress and heat flux falling in valleys yet rising on crests. Accordingly, compared with the initial (undeformed) shape, the corresponding differences of surface conditions get more striking outboard, with maximum augmentations of 379 pa, 2224 pa, and 19.0W/cm2, i.e., 9.8%, 305.9%, and 101.6% for the pressure, shear stress and heat flux respectively. Moreover, it is found that, with the increase of angle of attack, the aerodynamic characters and surface heating vary and the aeroheating disparities are evident between the deformed and initial shape. For the deformable HIAD model investigated in this study, the more intense surface conditions and changed flight aerodynamics are revealed, which is critical for the selection of structure material and design of flight control system.