Zheng Lu

The newly developed automorphism ensemble decoder (AED) leverages the rich automorphisms of Reed–Muller (RM) codes to achieve near maximum likelihood (ML) performance at short code lengths. However, the performance gain of AED comes at the cost of high complexity, as the ensemble size required for near ML decoding grows exponentially with the code length. In this work, we address this complexity issue by focusing on the factor graph permutation group (FGPG), a subgroup of the full automorphism group of RM codes, to generate permutations for AED. We propose a uniform partitioning of FGPG based on the affine bijection permutation matrices of automorphisms, where each subgroup of FGPG exhibits permutation invariance (PI) in a Plotkin construction-based information set partitioning for RM codes. Furthermore, from the perspective of polar codes, we exploit the PI property to prove a subcode estimate convergence (SEC) phenomenon in the AED that utilizes successive cancellation (SC) or SC list (SCL) constituent decoders. Observing that strong SEC correlates with low noise levels, where the full decoding capacity of AED is often unnecessary, we perform path pruning to reduce the decoding complexity without compromising the performance. Our proposed SEC-aided path pruning allows only a subset of constituent decoders to continue decoding when the intensity of SEC exceeds a preset threshold during decoding. Numerical results demonstrate that, for the FGPG-based AED of various short RM codes, the proposed SEC-aided path pruning technique incurs negligible performance degradation, while achieving a complexity reduction of up to 67.6%.

The Multiple Symbol Detection (MSD) algorithm can effectively lower the demodulation threshold in Frequency Modulation (FM) technology, which is widely used in aircraft wireless communications due to its insensitivity to large Doppler shifts. However, the high computational complexity of the MSD algorithm leads to considerable hardware resource overhead. In this paper, we propose a novel MSD architecture based on hybrid stochastic computing (SC), which allows for accurate signal detection while maintaining low hardware complexity. Given that the correlation calculation dominates the computational load in the MSD algorithm, we develop an SC-based, low-complexity unit to perform complex correlation operations using simple hardware circuits, significantly reducing the hardware overhead. Particularly, we integrate a flexible and scalable stochastic adder in the SC-based correlation calculation, which incorporates an adjustable scaling factor to enable high distinguishability in all possible correlation results. Additionally, for the symbol decision process of the MSD algorithm, we design a binary computing-based pipeline architecture to execute the computing process serially, which leverages the inherent low update rate of SC-based correlation results to further reduce the overall resource overhead. Experimental results show that, compared to an 8-bit quantization MSD implementation, our proposed hybrid SC-based MSD architecture achieves a comparable bit error rate while reducing the hardware resources to 69%, 45%, and 36% of those required for the three-, five-, and seven-symbol MSD algorithms, respectively.

Vehicle failure prediction technology is an important part of PHM (Prognostic and Health Management) technology, which is of great significance to the safety of vehicles and to improve driving safety. Based on the vehicle operating data collected by the on-board terminal (T-box) of the telematics system, the research on the state of vehicle failure is conducted. First, this paper conducts statistical analysis on vehicle historical fault data. Preprocessing procedures such as cleaning, integration, and protocol are performed to group the data set. Then, three indexes including recency (R) frequency (F), and days (D) are selected to construct a vehicle security status subdivision system, and K -Means algorithm is utilized to divide different vehicle categories from the perspective of vehicle value. Labeled information of vehicles in different security status are further established. Moreover, taking engine faults as an example, this paper uses gray correlation analysis method to extract key fault characteristic parameters. Based on self-organizing mapping network theory (SOM), the fault prediction model is built. And, by learning the fault data of the vehicles and obtaining the characteristic differences between different states, the prediction of fault and evaluation of vehicle condition is completed. Finally, test data is selected to verify the prediction accuracy of the model.

Objective: To compare the efficacy, advantages and disadvantages of endoscopic CO2 laser cauterization (ECLC) and open neck surgery in the treatment of congenital pyriform sinus fistula (CPSF). Methods: From September 2014 to March 2017, 80 cases with confirmed diagnosis of CPSF received initial treatment at Guangdong Provincial People's Hospital were prospectively analyzed, including 34 males and 46 females, aged 18 to 672 (194.17±141.18) months. They were consecutively divided into endoscopic group and open-surgery group, with 40 cases in each group. Both groups of patients received surgical treatment under general anesthesia. The endoscopic group was treated by endoscopic CO2 laser cauterization, and the open-surgery group underwent the following surgery: first, we performed suspension laryngoscopy examination to confirm the presence of fistula in the bottom of the piriform fossa, then open-neck resection of congenital piriform sinus fistula with recurrent laryngeal nerve and/or lateral branch of superior laryngeal nerve anatomy plus partial thyroidectomy were performed. The data between the two groups were compared, including the operative time, intraoperative blood loss, postoperative pain, average length of stay, neck cosmetic scores, complications and cure rates. All patients were followed up in outpatient clinics. Statistical analysis was performed using SPSS 20.0 software. P<0.05 indicates that the difference is statistically significant. Results: All patients were successfully completed the operation. The operative time, intraoperative blood loss, postoperative pain and average length of hospital stay in the endoscopic group were significantly less than those in the open group [(27.4±5.5) min to (105.8±52.5) min, (0.6±0.5) ml to (33.6±41.5) ml, (1.7±0.9) points to (4.6±0.7) points, (5.9±2.9)d to(8.9±3.3)d, t values were-9.400, -5.031, -16.199, -4.293, P values were all<0.01]; The neck cosmetic score in the endoscopy group was significantly greater than that of the open group [(9.9±0.4) against (5.8±0.9) points, t=25.847, P0.05). Three months after the first treatment, the cure rate in the endoscopic group (82.5%, 33/40) was significantly lower than that in the open-neck group (100.0%, 40/40), χ²=5.64, P<0.05. The follow-up time was 12 months after the last treatment. Eighty cases were followed up and none was lost to follow-up. During the follow-up period, the cure rate of the endoscopy group (97.5%, 39/40) was compared with that of the open group (100.0%, 40/40), and the difference was not statistically significant. Conclusions: In the treatment of CPSF, the two-surgical method each has their advantages. Compared with open-neck surgery, ECLC is simpler, repeatable. ECLC has shorter time in operation and hospital stay, less complications, and less postoperative pain and more precise cosmetic results. It could be preferred for the initial treatment of CPSF and relapsed cases after cauterization. But subject to relatively low cure rate of one-time cauterization and uncertain long-term efficacy, it cannot completely replace the open-neck surgery at present.

Upper gastrointestinal bleeding (UGIB) is common in liver cirrhosis. Although esophageal and gastric varices (EGV) is the main bleeding source, there were still a proportion of patients with peptic ulcer bleeding. Thus, this study aimed to analyze the characteristic of variceal bleeding and peptic ulcer bleeding in liver cirrhosis. Cirrhotic patients with confirmed UGIB by urgent endoscopy from July 2012 to June 2018 were enrolled, and classified into peptic ulcer bleeding group (n = 248) and variceal bleeding group (n = 402). Clinical and endoscopic characteristics, therapeutic efficacy and prognosis were evaluated, and independent risk factors for 42-day morality were determined. The mean age and gender ratio of peptic ulcer bleeding group were higher than those in variceal bleeding group (55.58 ± 11.37 vs. 52.87 ± 11.57, P < 0.01; 4.51:1 vs. 2.87:1, P = 0.023). Variceal bleeding group most commonly presented as red blood emesis and coffee grounds (67.16%), while peptic ulcer group primarily manifested as melena (62.10%). Hepatocellular carcinoma was more prevalent in peptic ulcer group (141 vs. 119, P < 0.01). Albumin level in variceal bleeding group was lower higher (P < 0.01), but serum bilirubin, creatinine and prothrombin time were significantly higher (all P < 0.01). Success rate of endoscopic hemostasis for variceal bleeding and peptic ulcer bleeding was 89.05% and 94.35% (P = 0.021). Univariate and multivariate analysis identified prothrombin time (P = 0.041, OR [95% CI] 0.884 [0.786–0.995]), MELD score (P = 0.000, OR [95% CI] 1.153 [1.073–1.240]), emergency intervention (P = 0.002, OR [95% CI] 8.656 [2.219–33.764]), hepatic encephalopathy before bleeding (P = 0.003, OR [95% CI] 8.119 [2.084–31.637]) and hepatic renal syndrome before bleeding (P = 0.029, OR [95% CI] 3.877 [1.152–13.045]) as the independent predictors for 42-day mortality. Peptic ulcer bleeding should be distinguished from variceal bleeding by clinical and endoscopic characteristics.

Although sudden death caused by digestive system diseases, accounting for about 7% of sudden death diseases, is not common compared with other diseases such as cardiovascular disease, it is also worthy of attention. Among them, sudden death caused by acute pancreatitis is the most common, accounting for 0.2%-0.5% of natural sudden death, and is one of the important causes of non-cardiac sudden death. This chapter mainly focuses on a series of sudden death related digestive system diseases, including ischemic bowel disease, variceal upper gastrointestinal bleeding in cirrhotic portal hypertension, hepatic encephalopathy, liver failure, acute suppurative cholangitis and acute pancreatitis. This type of disease is characterized by a rapid onset, a rapid progress, and a high mortality rate. Combining typical cases, this chapter describes the pathogenesis, diagnosis and treatment progress of the above-mentioned diseases that may cause sudden death.