Many applications utilizing big data are being used every day, and the importance of data utilization is increasing day by day. Data spaces, a federated data management system, is gaining increasing attention in Europe and Japan. To promote data spaces into real applications and increase data exchange between companies and individuals, the data exchanged over data spaces must be well protected. To achieve that goal, we propose to apply homomorphic encryption scheme to data spaces, propose its architecture, and analyze its advantages. Furthermore, we also investigate the feasibility of the proposed architecture based on results of calculation of GHG emission of a self-driving electric vehicle in the real-world experiment.

Partial shading on a photovoltaic (PV) panel consisting of multiple substrings is known to trigger a significant reduction in power yield and the occurrence of multiple maximum power points (MPPs). Although differential power processing (DPP) converters can preclude the negative influences of partial shading, an additional DPP converter is separately required in addition to an existing step-up converter for panel control, resulting in increased circuit volume and system complexity. This paper proposes a novel integrated converter that realizes system simplification and circuit miniaturization by integrating a PWM step-up converter and a DPP converter. Laboratory and field tests were performed emulating partial shading and characteristic mismatch conditions. A local MPP successfully disappeared, and the extractable maximum power increased while boosting the panel voltage, demonstrating the efficacy of the proposed integrated converter.

The characteristic mismatch of photovoltaic (PV) substrings in solar roofs of PHEVs not only triggers a significant reduction in power generation but also malfunctions of maximum power point (MPP) tracking due to the occurrence of multiple MPPs. Differential power processing (DPP) converters based on a switched capacitor converter have been proposed to prevent negative influences of characteristic mismatch. However, a step-up converter is separately required to control panel voltage in addition to a DPP converter, resulting in the increased complexity of PV systems. This paper proposes an integrated converter that realizes system simplification by integrating a PWM step-up converter and a DPP converter. The step-up conversion ratio of the proposed integrated converter can arbitrarily adjust thanks to a tapped inductor. Experiments using a 200-W prototype for seven-substring solar roofs were performed emulating mismatched irradiance conditions, and the results demonstrated the step-up power conversion capability and enhanced power yield.

The front surface of the tablet style smartphone or computer is dominated by a touch screen. As a finger operation on the touch screen disturbs its visibility, it is assumed a finger touches the screen instantly. Under such restriction, use of the rear surface of the tablet for tactile display is promising as the fingers holding the tablet constantly touch it and feel the feedback steadily. In this paper, a slim design of tactile feedback mechanism that can be easily installed on the back of existing tablets is given and its mechanical performance regarding electricity consumption, latency and force is evaluated. Human capability in perceiving the tactile information on the display is also evaluated.

When we reuse a code fragment in an open source system, it is very important to know the history of the code, such as the code origin and evolution. In this paper, we propose an integrated approach to code history tracking for open source repositories. This approach takes a query code fragment as its input, and returns the code fragments containing the code clones with the query code. It utilizes publicly available code search engines as external resources. Based on this model, we have designed and implemented a prototype system named Ichi Tracker. Using Ichi Tracker, we have conducted three case studies. These case studies show the ancestors and descendents of the code, and we can recognize their evolution history.

In Open Source System (OSS) development, software components are often imported and reused; for this reason we might expect that files are copied in multiple projects (file clones). In this paper, we propose a file clone detection tool called FCFinder and show the analysis performed with it on the FreeBSD Ports Collection, a large OSS project collection. We found many file clones among similar or related projects, which are systematically introduced from base projects.

This paper proposes an improved lattice-reduction aided (LRA) MMSE detection based on the Gram-Schmidt (GS) procedure. The proposed detection reduces the column vectors of the MIMO channel matrix using the LLL algorithm and the GS procedure to create mutually purely orthogonal column vectors of the reduced channel matrix. Then the decision boundary becomes the same as that for the ML detection. Compared to the conventional LRA MMSE detector, the proposed detector achieves much closer BER performances to those for the ML detector in both the 4 × 4 MIMO and the 8 × 8 MIMO systems.

In this paper, we propose a control method of a P2P network based on a DHT with its maximum degree 4 for routing and its diameter lceillog2nrceil where n is the number of nodes. In previous methods, the maximum degree or the diameter is only probabilistically bounded. As the degree of a vertex is the number of the neighbor nodes, a node with a large degree suffers high load to transfer many queries. Even if the average degree is bounded, the loads of some nodes with large degrees are exponentially high. As the diameter of a network is the worst distance, a large diameter causes bad response time. Even if the average diameter is bounded, the performance between two nodes apart from each other is always bad. Therefore, it is important that the degrees and the diameter are always small. We show that the proposed method has this good property.