Microscale droplet-based robotic systems have emerged as a promising platform for targeted drug delivery, minimally invasive surgery, and lab-on-a-chip applications. Here, we report a novel microrobotic swarm based on microdroplets of silicone oil-based ferrofluid, which exhibits excellent biocompatibility and chemical inertness. By modulating three-dimensional magnetic fields, we achieved reconfigurable self-organized patterns of an aggregated state, a dispersed state, and a chain state. We established a dynamic model and reproduced the three states via numerical simulations. Furthermore, we discovered two locomotion modes: sliding and rolling. Utilizing the sliding mode, we navigated the swarm through narrow and complex channels and accomplished directional transport of bubbles, enabling both translational and rotational movements.

With the rapid advancement of information technology, a large amount of high-value data have been generated. To exploit the potential value of big data and at the same time to protect individuals' sensitive information, a global combination and clustering based differential privacy (DP) mixed data publishing method is proposed in this paper. The main idea of the proposed method is to improve the truthfulness of the published data as well as to enhance the utility by shifting the sensitivity of query function from a single record to a group of records using$k$-median clustering algorithm. Specifically, to improve the accuracy and utility of categorical attributes, a global combination method is proposed to take the correlation among categorical attributes into account. The proposed combination method takes all categorical attributes as a unit and then applies the exponential mechanism to improve the data utility. Then we combine it with the$k$-median clustering with differential privacy to publish the mixed data. Theoretical analysis shows that the proposed method satisfies$\varepsilon$-differential privacy. Experimental results on real datasets illustrate that the proposed method has a much lower information loss and time overhead than the state-of-the-art approach for the same parameters.

Abstract Model‐based definition (MBD) containing all product and manufacturing information (PMI) has become the data source of future product development because of its incomparable advantages over traditional two‐dimensional drawings. In the whole life cycle of product development, it is an urgent problem to realize the sharing of geometric tolerance specification information of PMI among different CAx (CAD, CAE, CAM, etc.) and the automatic interpretation of its semantics by computer. In this paper, the semantic representation ontology of pattern and combined geometrical specification is studied based on the new generation GPS theory and the construction process is introduced in detail through an example. Benefiting from the logic‐based semantics of the web ontology language (OWL) and semantic web rule language (SWRL), the pattern and combined geometrical specification semantic can be interpreted directly by computer and has the advantages of clear, unambiguous, and consistent at different stages of the product life cycle. At the same time, it can automatically check the consistency of knowledge, reason new knowledge, and semantic query.

Summary In order to improve the assemblability and reduce the cost of the parts, the material requirements can be applied to the toleranced feature and the datum feature of the coaxiality at the same time in the practical application. How to realize the information exchange between different heterogeneous systems and how to read and explain the semantics of this complex tolerance specification automatically is one of the urgent problems to be solved in intelligent digital manufacturing. Ontology described in OWL2 DL and SWRL language has strict mathematical basis of description logic, and the knowledge represented by it has clear semantics and can be read and understood directly by computer. In addition, because of its consistency checking, knowledge reasoning, and flexible query ability, it becomes the most potential knowledge representation technology in the future. On the other hand, the semantic interpretation of tolerance specification by the new generation GPS theory based on skin model has the advantages of clear semantics, no ambiguity, and consistency at different stages of the product life cycle. In this article, the enhanced semantic representation ontology for this kind of coaxiality tolerance specification is constructed based on the advantages of the new GPS theory and ontology technology and the effectiveness of the method is verified and analyzed through a case.

The development and wide application of the internet technology produces a large amount of data, in order to storage and manage these massive data, NoSQL database technology comes into beings and develops rapidly, many manufacturers have introduced many different NoSQL storage solutions. In this context, the paper carries out the work about the testing method of the performance of NoSQL database. Firstly, the paper analyses the new features of the NoSQL database systems. Then, the paper proposes a general testing model for performance testing of the complicated system, which means that the architecture and its business should be considered when the testing work is carried out. Lastly, apply the model to perform the HBase's performance testing in the architecture level, mainly including some elements of the performance, such as the column-oriented data model, the spilt mechanism of the data table, the factor of the data replication. As to the every performance element, design the corresponding testing scenario and execute the testing procedure.

With the development and wide application of the computing technology, performance testing becomes more and more important. Real simulation of the user behavior becomes a concern of the performance testing. The paper introduces the potential model to establish the model of the visit amount which can be used in the performance testing. Firstly, the paper introduces the role of HBase in the search engine business and then illustrates the specific procedure about how to construct the visit amount model. Lastly, test the reading performance of HBase based on the model of the visit amount with the help of YCSB. At the same time, the paper simply introduces some applications of the potential cycle model in other contexts.

Survivability is crucial for computer systems that support critical infrastructures of our society. For those in paradigm of SOA where the computing settings are intrinsically open, traditional survivability model and safeguard mechanisms are no longer applicable. To rise to the challenge, we propose a formal definition and a corresponding framework to evaluate the survivability of SOA systems. We treat survivability as a multidimensional QoS property, and then give a holistic evaluation method based on the Hidden Markov Model.