By combining the finite difference time domain (FDTD) method with inverse optimization algorithm can break through the constraints of traditional design experience and realize integrated silicon ...components with much more compact sizes. In inverse design process of 2 × 2 3 dB optical power splitter, the direct binary search algorithm is very easy to fall into the local optimal solutions due to its off-centered input and initial refractive index distribution, which limits the performances of the device. In order to address this issue, a two-stage inverse design process is proposed to optimize a silicon 2 × 2 3 dB optical power splitter with compact size of 4.8×4.8μm which are greatly reduced in size compared to conventional 3 dB optical power splitter. The excess loss and split ratio at 1550 nm are about 1.15 dB and 0.97, which are greatly improved compared to the traditional single-stage inverse design process.
•We use a two-stage inverse design process to optimize a power splitter to avoid falling into the local optimal solutions.
In their seminal paper Sleator and Tarjan (1985) 15, the authors conjectured that the splay tree is a dynamically optimal binary search tree (BST). In spite of decades of intensive research, the ...problem remains open. Perhaps a more basic question, which has also attracted much attention, is if there exists any dynamically optimal BST algorithm. One such candidate is ▪ which is a simple and intuitive BST algorithm Lucas (1988) 11; Munro (2000) 12; Demaine et al. (2009) 6. Demaine et al. (2009) 6 showed a novel connection between a geometric problem and the binary search tree problem related to the above conjecture. However, there has been little progress in solving this geometric problem too.
Since dynamic optimality conjecture in its most general form remains elusive despite much effort, researchers have studied this problem on special sequences. Recently, Chalermsook et al. (2015) 2 studied a type of sequences known as k-decomposable sequences in this context, where k parametrizes easiness of the sequence. Using tools from forbidden submatrix theory, they showed that ▪ takes n2O(k2) time on this sequence and explicitly raised the question of improving this bound.
In this paper, we show that ▪ takes O(nlogk) time on k-decomposable sequences. In contrast to the previous approach, ours is based on first principles. One of the main ingredients of our result is a new construction of a lower bound certificate on the performance of any algorithm. This certificate is constructed using the execution of ▪, and is more nuanced and possibly more flexible than the previous independent set certificate of Demaine et al. This result, which is applicable to all sequences, may be of independent interest and may lead to further progress in analyzing ▪ on k-decomposable as well as general sequences.
•We propose a novel data hiding technique using adaptive difference recovery (ADR).•We design an efficient RDHEI method using the ADR-based technique.•The proposed RDHEI method outperforms some ...state-of-the-art RDHEI methods in payload.
Vacating room after encryption (VRAE) is a popular framework of reversible data hiding for encrypted images (RDHEI). Most VRAE based RDHEI methods do not make a desirable payload. To address this issue, this paper proposes a novel data hiding technique using adaptive difference recovery (ADR) and exploits this novel technique to design an efficient VRAE based RDHEI method. Specifically, the proposed ADR-based data hiding technique adaptively determines the range of original difference between a cover pixel and a reference pixel with correlation according to the marked difference generated by bit substitution technique. The cover pixel can be recovered losslessly with the range of original difference and the reference pixel. In the proposed RDHEI method, the encrypted image is generated by block permutation and block-based modulation so that spatial redundancy within encrypted image blocks is preserved. Then the ADR-based data hiding technique is applied to the encrypted blocks. Experiment results show that the proposed RDHEI method outperforms some state-of-the-art RDHEI methods in payload. The average embedding rates of the proposed RDHEI method on the BOSSbase, BOWS-2 and UCID datasets are 3.2045, 3.1145 and 2.4633 bpp, respectively.
The optical coupler can couple the light from the fiber into the waveguide, and the wavelength demultiplexer can split light into different wavelengths. Both devices play a significant role in ...optical chips, and combing them together can further reduce the chip footprint and improve the operating efficiency. In this work, based on the direct-binary-search (DBS) inverse design algorithm, we design two metamaterial couplers that can realize multi-wavelength demultiplexing. The two devices are based on silicon on insulator (SOI) and cover an ultra-compact footprint of 3.6 μm × 3.6 μm. The first device can couple and split 1310 nm and 1550 nm light into two separate waveguides with coupling efficiencies of 0.26 and 0.27, respectively. The second device can couple and split 1310 nm, 1490 nm, and 1550 nm light into three separate waveguides with coupling efficiencies of 0.25, 0.2, and 0.23, respectively. This effect is caused by the large number of guide-mode resonances in the device. The two couplers, especially the three-wavelength demultiplexing coupler, can be used as splitters for monolithically silicon-integrated transceivers at the commonly used wavelengths of 1310 nm, 1490 nm, and 1550 nm in the optical fiber communication, which potentially meets the low-cost and ultra-compact requirements for future passive optical networks.
•This study aims to create two optical couplers using the direct-binary-search (DBS) inverse design method for bi-wavelength and three-wavelength demultiplexing. The three-wavelength coupler is novel and can serve as a low-cost, compact splitter for silicon integrated transceivers operating at 1310 nm, 1490 nm, and 1550 nm. We believe that this paper will be of interest to the readership of your journal because of the great potential applications for such a device in optical interconnection on chip.
As a country that is rich in ethnic, cultural and linguistic diversity, Indonesia has 668 vernacular languages, one of them is Malay. West Kalimantan is one of the regions in Indonesia where majority ...of the population is Malay. The population used Malay language with a variety of dialects distinctive regional. The Ketapang Malay dialect is used in Ketapang Regency. Vernacular languages which are inherited from the ancestors should be preserved as an effort to maintain their function and position as ethnic identity, personality, as well as a means to show the variety of regional culture. Unfortunately, along with the times and influx of foreign cultural influences to Indonesia as an impact of globalization, many words of Malay Ketapang dialect underwent changes, developments and displacements, moreover leading to extinction. This research developed an Android-based application of Ketapang Malay Dictionary (KBMK) with the implementation of the binary search algorithm. Application was developed using following method, data collecting, application development, application testing, and system evaluation. Blackbox testing shows that the binary search algorithm is able to search the keyword correctly. Furthermore, the KBMK application was tested using a usability evaluation, evaluation obtained an average score of 4.48 indicating that the application is useful and effective in conducting searches, and providing user satisfaction.
The grasshopper optimization algorithm is one of the recently population-based optimization techniques inspired by the behaviours of grasshoppers in nature. It is an efficient optimization algorithm ...and since demonstrates excellent performance in solving continuous problems, but cannot resolve directly binary optimization problems. Many optimization problems have been modelled as binary problems since their decision variables varied in binary space such as feature selection in data classification. The main goal of feature selection is to find a small size subset of feature from a sizeable original set of features that optimize the classification accuracy. In this paper, a new binary variant of the grasshopper optimization algorithm is proposed and used for the feature subset selection problem. This proposed new binary grasshopper optimization algorithm is tested and compared to five well-known swarm-based algorithms used in feature selection problem. All these algorithms are implemented and experimented assessed on twenty data sets with various sizes. The results demonstrated that the proposed approach could outperform the other tested methods.
The structure of disordered gain media for a two-dimensional random laser was designed to obtain the specified spectrum of the emitted light. A scattering medium with a checkerboard structure was ...used to produce random lasing. Structural optimization was performed using a direct binary search method. The simulation results show that the emitted light can be concentrated at a single wavelength or within a specific wavelength range. The effect of the pump rate and manufacturing errors on the optimized spectrum of the laser emission was also examined. In this paper, we propose a new design scheme for achieving laser emission with any specified spectral shape by considering a multiple scattering medium as deterministic cavities.
•A new design scheme for achieving specified laser emission using random structures proposed.•Laser cavities with a checkerboard structure designed aiming for high figures of merit of the emission spectrum.•Effects of the pump rate and manufacturing errors examined.
This letter proposes a novel transport-layer encapsulation scheme, which integrates the permutation-based transmission and the packet grouping to improve spectral efficiency. For a group of packets, ...each data unit (DU) is divided into three portions: permutation-conveyed DU (PCDU), grouping-conveyed DU (GCDU), and conventionally conveyed DU (CCDU). The PCDU is conveyed through the selection among various lengths for GCDU plus CCDU. The GCDU is used for forming sub-groups so that, in each sub-group, the GCDU is encapsulated into the first packet only while removed from the other packets. Unlike CCDUs, the delivery of PCDUs and removed GCDUs does not consume any communication resource. To promote the improvement of spectral efficiency, an algorithm based on the binary search tree is proposed for the GCDU design in each sub-group, and a lower bound on the number of bits in the removed GCDUs is achieved in closed-form. Illustrative numerical results substantiate the spectral efficiency gain obtained by our permutation-based scheme in comparison with the conventional transport-layer encapsulation.
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