Abstract

In our work, we propose a novel yet simple approach to obtain an adaptive learning rate for gradient-based descent methods on classification tasks. Instead of the traditional approach of selecting adaptive learning rates via the decayed expectation of gradient-based terms, we use the angle between the current gradient and the new gradient: this new gradient is computed from the direction orthogonal to the current gradient, which further helps us in determining a better adaptive learning rate based on angle history, thereby, leading to relatively better accuracy compared to the existing state-of-the-art optimizers. On a wide variety of benchmark datasets with prominent image classification architectures such as ResNet, DenseNet, EfficientNet, and VGG, we find that our method leads to the highest accuracy in most of the datasets. Moreover, we prove that our method is convergent. Index Terms—Adam, Image Classification, Optimization, Angle, Gradient Descent, Neural Networks, ResNet

Abstract

Extreme multi-label (XML) classification refers to the task of supervised multi-label learning that involves a large number of labels. Hence, scalability of the classifier with increasing label dimension is an important consideration. In this paper, we develop a method called LightDXML which modifies the recently developed deep learning based XML framework by using label embeddings instead of feature embedding for negative sampling and iterating cyclically through three major phases: (1) proxy training of label embeddings (2) shortlisting of labels for negative sampling and (3) final classifier training using the negative samples. Consequently, LightDXML also removes the requirement of a re-ranker module, thereby, leading to further savings on time and memory requirements. The proposed method achieves the best of both worlds: while the training time, model size and prediction times are on par or better compared to the tree-based methods, it attains much better prediction accuracy that is on par with the deep learning based methods. Moreover, the proposed approach achieves the best tail-label prediction accuracy over most state-of-the-art XML methods on some of the large datasets1 . Code: https://github.com/misterpawan/ LightDXML

Abstract

Over the years, the framework of Linear combination of unitaries (LCU) has been extremely useful for designing a plethora of quantum algorithms. In this work, we explore whether this widely applicable paradigm can be implemented on quantum computers that will be available immediately after the current NISQ stage. To this end, we develop three variants of LCU and apply each, to quantum algorithms of practical interest. First, we develop a physically motivated, continuous-time analogue of LCU (“Analog LCU”). This technique, implementable on hybrid qubit-qumode systems, is simpler than its discrete-time counterpart. We use this method to develop analog quantum algorithms for ground state preparation and quantum linear systems. We also develop a randomized quantum algorithm to sample from functions of Hamiltonians applied to quantum states (“Single-Ancilla LCU”). This approach repeatedly samples from a short-depth quantum circuit and uses only a single ancilla qubit. We use this to estimate expectation values of observables in the ground states of a Hamiltonian, and in the solution of quantum linear systems. This method is suitable for early fault-tolerant quantum computers. Our third approach stems from the observation that for several applications, it suffices to replace LCU with randomized sampling of unitaries according to the distribution of the LCU coefficients (“Ancilla-free LCU”). This is particularly useful when one is interested in the projection of a quantum state implemented by an LCU procedure in some subspace of interest. We demonstrate that this technique applies to the spatial search problem and helps establish a relationship between discrete and continuous-time quantum walks with their classical counterparts. Our work demonstrates that generic quantum algorithmic paradigms, such as LCU, can potentially be implemented on intermediate-term quantum devices.

Abstract

Throwing motion is known for phenomenally fast rearrangement, sorting tasks, and placing the object outside the limited workspace with less effort. However, in the robotics domain, despite many simple yet versatile, mechanically intelligent grippers reported earlier, they fo- cus primarily on achieving robust grasping and dexterous manipulation. This article presents a novel design of a sin- gle actuator driven hybrid gripper with mechanically cou- pled rigid links and elastic gripping surface; this arrange- ment provides the dual function of versatile grasping and throwing manipulation. The gripper comprises a latching mechanism (LM) that drives two passive rigid fingers by elongating/releasing the coupled elastic strip. Elongating the gripping surface enables the gripper to adapt to ob- jects with different geometries, vary surface contact force characteristics, and store the energy in the form of elastic potential. A mechanism to discharge the stored potential energy gradually or instantaneously is essential when the intended task is to place the object free from impact or away from the limited reachable workspace. The proposed LM can swiftly shift from a quick release to a gradual release of the stored elastic potential for greater object’s accelera- tion during throwing and no acceleration while placing. By doing so, the object can be placed at the desired location even farther than the manipulator’s reachable workspace. We report the proposed gripper’s design details, develop- ment, and experimentally demonstrate the versatile grasp- ing, impact-free placing, and throwing capabilities. Index Terms—Gripper design, multipurpose gripper, non- prehensile manipulation, throwing.

Abstract

Unmanned Aerial Vehicle (UAV) can be employed in various applications, including traffic control, and delivery application. However, these services are susceptible to various security attacks because sensitive data are exchanged through an open channel. Thus, a secure authentication scheme is essential for UAV. UAV has limited storage resources and computing capabilities. To overcome these problems, cloud computing is considered as a promising solution. Cloud computing provides various properties such as storage availability and scalability. Unfortunately, the cloud server’s database can be a major target for an adversary because it is a centralized system. If an adversary intrudes on the cloud server’s database, he/she may attempt to intercept or learn the stored data. To mitigate these issues, we design a secure and lightweight authentication and key agreement scheme for cloud-assisted UAV using blockchain in flying ad-hoc networks, called LAKA-UAV. LAKA-UAV utilizes blockchain technology to ensure access control and data integrity using log transactions and the cloud server securely manages collected data from UAV. We prove the security of LAKA-UAV based on informal security analysis and formal security verification implementation. Based on testbed experiments using MIRACL, LAKA-UAV provides about 2.13 times more efficient performance on average compared with related schemes in terms of computation. We present the blockchain implementation using Hyperledger Sawtooth platform

Abstract

Increasing use of electronic healthcare (eHealth) services demands efficient and secure solutions. Such solutions need to ensure the prevention of unauthorised access to the patient data and provide faster response. Fog computing is a viable solution to provide faster responses in eHealth systems. Key distribution and authentication play a major role in providing security to patient data. Existing centralized architectures are susceptible to single-point-of-compromise, that is, the entire system is vulnerable when the centralized authority keys are unexpectedly revealed to an adversary. In this paper, we present a fog-based semi-centralised architecture for key distribution and authentication, in which the key distribution service is delegated to individual fog-servers. Thus, the fog-servers become responsible for key distribution to the users without the involvement of the centralised authority, which forms a paradigm of multiple client-server architecture. Thus, achieving centralized trust by designing a single sign-on authentication in such environments is a challenging problem. We design a single sign-on authentication protocol for semi-centralized architectures to achieve centralized trust by ensuring that the user keys are independent of the centralized authority’s keys. A rigorous security analysis under the random oracle model is performed to prove that the proposed protocol is secure against single-point-of-compromise. We also conduct extensive experiments to show the practical perspectives of the proposed scheme. The results show that the protocol is suitable for eHealth applications, including emergency services.

Abstract

Cyber threat hunting proactively searches for cyber threats, which are undetected by the traditional defense mechanisms. It scans deep to identify malicious programs (ie, malware) that escape from detection. It is important because sophisticated cyber threats can bypass the cyber security mechanisms. The performance of the cyber threat hunting can be improved through artificial intelligence (AI), especially, explainable AI (XAI), which adds trust component to the cyber threat hunting process. Due to the inclusion of XAI, the security experts get the full explanations of the detected threats as the working of the detection model in XAI is known. Information, like, which one is a threat, how it has been detected, and why it has been detected, can be obtained very easily due to the inclusion of XAI in the cyber threat hunting. Therefore, an XAI-envisioned mechanism for cyber threat hunting has been proposed (in short, XAISM-CTH). The network and threat models of XAISM-CTH are designed and discussed. The conducted security analysis proves the security of XAISM-CTH against various potential attacks. XAISM-CTH also performs better than the other existing schemes. At the end, a practical implementation of XAISM-CTH has been provided to observe its impact on the performance of the system. KEYWORDS cyber threat hunting, explainable artificial intelligence (XAI), intrusion detection, privacy, security

Abstract

Due to high effectiveness and robust security proto- cols, lattice-based cryptography becomes a very broadly appli- cable optimistic post-quantum technique that is recently used in public key cryptosystem. An aggregate signature scheme enables a party to bundle a set of signatures together into a single short cryptographic signature, which can be verified by any verifier using the public information. In this paper, we provide a lattice- based aggregate signature scheme where the security depends on the difficulty of the Ring Learning-with-Error (Ring-LWE) problem. Next, we use the basic scheme in Internet of Drones (IoD) applications using the blockchain technology for secure and transparent data storage. The detailed security analysis and comparative study show that the proposed scheme provides superior security including resistance to quantum attacks and is efficient as compared to the existing state of art approaches. The testbed experimental results and the blockchain simulation demonstrate that the proposed scheme can be applied in real-life drones applications. Index Terms—Internet of Drones (IoD), unmanned aerial vehi- cles, lattice-based cryptography, aggregate signature, blockchain, security.

Abstract

Attribute-based encryption (ABE) is widely used for a secure and efficient data sharing. The predetermined access policy of ABE shares the data with intended data users. However, ABE is not preferable in many applications that require collaboration among data users. In such applications, an authorized data user may be interested to collaborate with another data user who does not adhere to the access policy. Fixed access policy of ABE does not allow an authorized data user (who satisfies the access policy) to collaborate or share the data with any unauthorized data user (who fails to satisfy the access policy). Thus, due to the static and predefined access policy, data collaboration in ABE is significantly challenging. In this work,

Abstract

We present three related schemes to generate novel molecules based on seed molecule; all the methods use as input the voxelized representation of the seed molecule to generate the SMILES representation of the novel molecule. At heart of these methods are two networks (a) a variational autoencoder that uses a Riemannian metric to encode the latent space of (hence named RHVAE) and can use pharmacophoric requirements as additional input for decoder and (b) attentive captioning network (a type of recurring neural network) that can efficiently focus, capture and use the ‘content’ of input to generate the SMILES output of novel molecules. We analyze the performance of the three proposed methods. We demonstrate the generation of meaningful new molecules, by generating shapes through an autoencoder network which can then be passed to our attentive captioning network, while requiring smaller data sets for training and retaining similar performance to existing state-of-art methods. Keywords. De Novo Drug Design; Chemical Modeling; Variational autoencoders, Attentive RNNs, Remannian