Development of technology of high-speed digital-to-analogue converters to improve the efficiency of direct digital synthesis of radio-frequency signals

The importance of high-speed digital-to-analogue converters for the synthesis of high-frequency coherent signals is shown. A review of the main specialized modes of operation of high-speed digital-to-analogue converters is carried out, which make it possible to effectively use the side components of the spectrum that arose during the restoration of a signal from digital to analogue form. An RF2 reconstruction mode with a modified bipolar pulse sequence is proposed, which makes it possible to increase the amplitude of the images in the eighth and ninth Nyquist zones.

Near-channel classifier: symbiotic communication and classification in high-dimensional space

Brain-inspired high-dimensional (HD) computing represents and manipulates data using very long, random vectors with dimensionality in the thousands. This representation provides great robustness for various classification tasks where classifiers operate at low signal-to-noise ratio (SNR) conditions. Similarly, hyperdimensional modulation (HDM) leverages the robustness of complex-valued HD representations to reliably transmit information over a wireless channel, achieving a similar SNR gain compared to state-of-the-art codes. Here, we first propose methods to improve HDM in two ways: (1) reducing the complexity of encoding and decoding operations by generating, manipulating, and transmitting bipolar or integer vectors instead of complex vectors; (2) increasing the SNR gain by 0.2 dB using a new soft-feedback decoder; it can also increase the additive superposition capacity of HD vectors up to 1.7$$\times$$ × in noise-free cases. Secondly, we propose to combine encoding/decoding aspects of communication with classification into a single framework by relying on multifaceted HD representations. This leads to a near-channel classification (NCC) approach that avoids transformations between different representations and the overhead of multiple layers of encoding/decoding, hence reducing latency and complexity of a wireless smart distributed system while providing robustness against noise and interference from other nodes. We provide a use-case for wearable hand gesture recognition with 5 classes from 64 EMG sensors, where the encoded vectors are transmitted to a remote node for either performing NCC, or reconstruction of the encoded data. In NCC mode, the original classification accuracy of 94% is maintained, even in the channel at SNR of 0 dB, by transmitting 10,000-bit vectors. We remove the redundancy by reducing the vector dimensionality to 2048-bit that still exhibits a graceful degradation: less than 6% accuracy loss is occurred in the channel at − 5 dB, and with the interference from 6 nodes that simultaneously transmit their encoded vectors. In the reconstruction mode, it improves the mean-squared error by up to 20 dB, compared to standard decoding, when transmitting 2048-dimensional vectors.

Interlocking reconstruction-mode stem-sideplates preserve at-risk hips with short residual proximal femora

Aims We have evaluated the survivorship, outcomes, and failures of an interlocking, reconstruction-mode stem-sideplate implant used to preserve the native hip joint and achieve proximal fixation when there is little residual femur during large endoprosthetic reconstruction of the distal femur. Methods A total of 14 patients underwent primary or revision reconstruction of a large femoral defect with a short remaining proximal femur using an interlocking, reconstruction-mode stem-sideplate for fixation after oncological distal femoral and diaphyseal resections. The implant was attached to a standard endoprosthetic reconstruction system. The implant was attached to a standard endoprosthetic reconstruction system. None of the femoral revisions were amenable to standard cemented or uncemented stem fixation. Patient and disease characteristics, surgical history, final ambulatory status, and Musculoskeletal Tumor Society (MSTS) score were recorded. The percentage of proximal femur remaining was calculated from follow-up radiographs. Results All 14 at-risk native hip joints were preserved at a mean final follow-up of 6.0 years (SD 3.7), despite a short residual femur, often after proximal osteotomies through the lesser trochanter. Overall, 13 of 14 stems had long-term successful fixation. Eight patients required no reoperation. Three patients required reoperation due to implant-related issues, and three patients required reoperation for wound healing problems or infection. There were no dislocations or fractures. At final follow-up the mean MSTS score was 24.9 (SD 4.1). Nine patients required no ambulation aids, and only one had a Trendelenburg gait. Conclusion This interlocking, reconstruction-mode stem-sideplate reliably preserves native hip joint anatomy and function after large femoral resection with a short remaining proximal femur, both in the primary and revision setting. This is particularly important for preventing or delaying total femoral arthroplasty in young patients after oncological reconstruction. Hip abductor strength and function could be maintained by this method, and the risk of dislocation eliminated. The success of this technique in this modest series should be verified in a larger collaborative study and will be of interest to revision surgeons and oncologists. Cite this article: Bone Joint J 2021;103-B(2):398–404.

Diagnostic Value of Spectral CT Reconstruction Mode for Carotid Atherosclerotic Plaque Lesions

Objective: To investigate the diagnostic value of spectral CT reconstruction mode for carotid atherosclerotic plaque lesions. Methods: From January 2017 to January 2019, 70 patients with carotid atherosclerotic plaque lesions in our hospital were selected as the research object. All patients were diagnosed with cervical vascular color Doppler ultrasound and spectral CT scan under spectral CT reconstruction mode. Taking the results of coronary angiography as the “gold standard”, the clinical value of the two examination methods in the diagnosis of carotid atherosclerotic plaque lesions was compared and analyzed. Results: Coronary angiography diagnosis confirmed that 33 of 70 patients with suspected carotid atherosclerotic plaque lesions had vulnerable plaques and 37 had stable plaques. The accuracy of Spectral CT examination of carotid artery plaque was 87.14% (61/70), sensitivity was 90.91% (30/33), specificity was 83.78% (31/37), and the positive predictive value was 83.33% (30 /36), the negative predictive value is 91.76% (31/34), which is higher than that of cervical vascular ultrasonography (61.43%, 60.61%, 56.76%, 57.89%, 65.63%), the difference is statistically significant (P<0.05). Conclusion: The application of Spectral CT in the clinical diagnosis and treatment of carotid atherosclerotic plaque lesions with higher accuracy, sensitivity and specificity, is more significant and can provide a more reliable and effective imaging basis.

Urban Renewal Design-A Probe into the Reconstruction Mode of Urban Villages in Xi’an

Theproblemofvillagesinthecityisaproblemleftoverbythehistoryofdifferentstages of urban development.Itislikeapieceof” urban psoriasis”that affects the construction of the future city. How to explore a reasonable urban village reconstruction mode is of great significance for the future development of the city. In this paper, based on the investigation and analysis of the existing urban village construction environment in Xi’an, the author proposes the imagination of future living space mode of the village in the city, and explores how to transform the existing construction environment space of thevillageinXi’anCitytoreconstructthenewurbanpubliclivingspace,thus effectively driving the urban regional vitality, reasonably integrating villages in the City into the existing urban space development, and giving the village a new function and vitality.

Sustainable Development of Post-disaster Community: Comparative Study of Reconstruction Mode under Social Network Measure

The current urban environment is faced with the potential threat of frequent natural disasters, and the sustainable development of post-disaster community has become a global issue. As an intrinsic motivation influencing the social interaction and capital operation of community, social network is an important mechanism promoting such sustainable development. However, the difference in social network caused by different member structure, spatial arrangement and management mechanism of post-disaster communities in different reconstruction modes has influenced such sustainable development process. Therefore, reasonable selection of reconstruction mode is crucial. This paper applied analytic hierarchy process to comprehensively measure and compare the social network strength in post-disaster communities in the four reconstruction modes adopted by the government of China, i.e. unified planning and unified construction, unified planning and independent construction, in situ reconstruction and relocation resettlement, with communities after the 2008 Sichuan earthquake in Chengdu, China as study objects from the perspective of three social relations (the relations between residents and residents, residents and managers, and residents and servers). The results showed that strong connections are generally presented in the social network of post-disaster communities in unified planning modes, that the strength is significantly higher than that of those in non-unified planning modes, and that the strength of UPIC communities is the highest. Meanwhile, government intervention, residents&rsquo; free participation and market operation are positively correlated to government trust, community interaction and community service respectively. The positive impact of government intervention is the most significant, but it has a peak value. No government management and excessive government intervention will exert negative impacts. The coordination of government, society and market is the key contents of post-disaster community reconstruction. The reconstruction modes based on &ldquo;government leadership, resident participation and market operation&rdquo; may become a feasible path for such sustainable development.