The imaging method of the mid-course missile is the key technique of the missile defense system.Because of the special precession character of the ballistic missile warhead,the inverse synthetic aperture radar method ...The imaging method of the mid-course missile is the key technique of the missile defense system.Because of the special precession character of the ballistic missile warhead,the inverse synthetic aperture radar method cannot realize phase compensation with the constant phase offset function,which leads to blurring of the image.In this paper,we propose a new narrowband radar imaging method for the precession cone-shaped targets.The method acquires the Doppler modulation of the precession target's scattering centers with high resolution time-frequency analysis method and extracts the Doppler parameter from the result of the time-frequency analysis with the general Radon transform,then reconstructs the scattering centers positions in the parameter domain.The experiment results with the anechoic chamber data of the representative cone-shaped object showed the effectiveness of the method.展开更多
A narrowband radio interferometer has been developed and used to locate the entire sources of VHF radiations from a negative cloud-to-ground (CG) lightning discharge which contains 19 strokes. This system uses five an...A narrowband radio interferometer has been developed and used to locate the entire sources of VHF radiations from a negative cloud-to-ground (CG) lightning discharge which contains 19 strokes. This system uses five antennas to form an array consisting of short- and long-baselines along two or- thogonal directions. The system error which comes from frequency conversion is reduced by phase detection through direct high frequency amplifying. An interactive graphic analysis procedure is used to remove the fringe ambiguities which exist inherently in interferometry and to determine the direction of lightning radiation sources in two dimensions (azimuth and elevation) as a function of time at a time resolution of microsecond orders. With the developed system, the whole progression process in time and space of a lightning flash can be reconstructed. In this paper, combining the synchronous data of electric filed change and VHF radiation, the whole processes of an example negative CG flash have been studied in detail. It is found that the preliminary breakdown event of the CG flash started from negative charge region and exhibited firstly a downward pregression and then an upward propagation. There were very intense and continuous radiations during stepped leaders which became much stronger when the first return stroke began. In contrast, there were less and only discrete radiations during dart leaders. Stepped leader and dart leader may transform to each other depending on the state of the ionization of the path. The progression speed of initial stepped leaders was about 105 ms?1, while that was about 4.1×106 and 6.0×106 ms?1 for dart leaders and dart-stepped leaders, respectively. M events produced hook-shaped field changes accompanied by active burst of radiations at their begin- nings. Followed these active radiation processes, M events appeared to contact finally into conducting main discharge channels. The mean progression speed of M events was about 7×107 ms?1, greater than that of the dart leaders and dart-ste展开更多
The topology of in-home power line communication(PLC) networks varies frequently, which makes traditional routing algorithms failure. To solve this problem, an end-to-end transmission time for remaining path(TTRP) met...The topology of in-home power line communication(PLC) networks varies frequently, which makes traditional routing algorithms failure. To solve this problem, an end-to-end transmission time for remaining path(TTRP) metric-based opportunistic routing(TTRPOR) is proposed. Since a local broadcasting scheme is adopted, the algorithm can find the optimal path for forwarding packets in a dynamic PLC network. The closed-form of the outage probability for a PLC channel is derived to estimate the TTRP. It is proved that the average throughput can achieve maximum as the metric TTRP is utilized to sort candidate forwarding nodes.Numerical results show that the end-to-end throughput of networks with TTRPOR, outperforms that of the network adopting DSR and EXOR, especially for the case of varying-topology in-home PLC networks.展开更多
BACKGROUND In recent years,two new narrow-band imaging(NBI)classifications have been proposed:The NBI international colorectal endoscopic(NICE)classification and Japanese NBI expert team(JNET)classification.Most valid...BACKGROUND In recent years,two new narrow-band imaging(NBI)classifications have been proposed:The NBI international colorectal endoscopic(NICE)classification and Japanese NBI expert team(JNET)classification.Most validation studies of the two new NBI classifications were conducted in classification setting units by experienced endoscopists,and the application of use in different centers among endoscopists with different endoscopy skills remains unknown.AIM To evaluate clinical application and possible problems of NICE and JNET classification for the differential diagnosis of colorectal cancer and precancerous lesions.METHODS Six endoscopists with varying levels of experience participated in this study.Eighty-seven consecutive patients with a total of 125 lesions were photographed during non-magnifying conventional white-light colonoscopy,non-magnifying NBI,and magnifying NBI.The three groups of endoscopic pictures of each lesion were evaluated by the six endoscopists in randomized order using the NICE and JENT classifications separately.Then we calculated the six endoscopists’sensitivity,specificity,accuracy,positive predictive value,and negative predictive value for each category of the two classifications.RESULTS The sensitivity,specificity,and accuracy of JNET classification type 1 and 3 were similar to NICE classification type 1 and 3 in both the highly experienced endoscopist(HEE)and less-experienced endoscopist(LEE)groups.The specificity of JNET classification type 1 and 3 and NICE classification type 3 in both the HEE and LEE groups was>95%,and the overall interobserver agreement was good in both groups.The sensitivity of NICE classification type 3 lesions for diagnosis of SM-d carcinoma in the HEE group was significantly superior to that in the LEE group(91.7%vs 83.3%;P=0.042).The sensitivity of JNET classification type 2B lesions for the diagnosis of high-grade dysplasia or superficial submucosal invasive carcinoma in the HEE and LEE groups was 53.8%and 51.3%,respectively.Compared with other types of JN展开更多
AIM： To evaluate the efficacy of non-sequential narrow band imaging （NBI） for a better recognition of gastric intestinal metaplasia （GIM）. METHODS： Previously diagnosed GIM patients underwent targeted biopsy fro...AIM： To evaluate the efficacy of non-sequential narrow band imaging （NBI） for a better recognition of gastric intestinal metaplasia （GIM）. METHODS： Previously diagnosed GIM patients underwent targeted biopsy from areas with and without GIM, as indicated by NBI, twice at an interval of 1 year. The authors compared the endoscopic criteria such as light blue crest （LBC）, villous pattern （VP）, and large long crest （LLC） with standard histology. The results from two surveillance endoscopies were compared with histology results for sensitivity, specificity, positive predic-tive value （PPV）, negative predictive value （NPV）, and likelihood ratio of positive test （LR＋）. The number of early gastric cancer cases detected was also reported. RESULTS： NBI targeted biopsy was performed in 38 and 26 patients during the first and second surveillance endoscopies, respectively. There were 2 early gastric cancers detected in the first endoscopy. No cancer was detected from the second study. Surgical and endoscopic resections were successfully performed in each patient. Sensitivity, specificity, PPV, NPV, and LR＋ of all 3 endoscopic criteria during the first/second surveillances were 78.8%/91.3%, 82.5%/89.1%, 72.8%/77.8%, 86.8%/96.1, and 4.51/8.4, respectively. LBC provided the highest LR＋ over VP and LLC. CONCLUSION： Nonequential NBI is useful for GIM targeted biopsy. LBC provides the most sensitive reading. However, the optimal duration between two surveillances requires further study.展开更多
Basaloid squamous carcinoma (BSC) is a rare variant of esophageal cancer. There are very few reports of “early” BSC. Here we report a case of early BSC with unusual findings by narrowband imagi...Basaloid squamous carcinoma (BSC) is a rare variant of esophageal cancer. There are very few reports of “early” BSC. Here we report a case of early BSC with unusual findings by narrowband imaging magnified endoscopy (NBI-ME). A 70-year-old man with a middle thoracic esophageal tumor was referred to our hospital. White-light endoscopy revealed a reddish depressed lesion 5 mm in diameter having a subepithelial tumor-like prominence with a gentle rising slope. NBI-ME revealed irregular loop-shaped microvessels coexistent with thick irregularly branched non-looped vessels. Iodine staining revealed a pale brown lesion. We performed endoscopic submucosal dissection for diagnostic treatment. Histologic examination showed the proliferation of basal cell-like hyperchromatic tumor cells in the lamina propria and with slight invasion into the submucosa at a depth of 320 μm. The tumor cells formed solid nests and microcystic structures, containing an Alcian blue-positive mucoid matrix. The surface was covered with squamous epithelium without cellular atypia. Thin vessels were observed in the intra-epithelial papilla and thick vessels were observed around the solid nests beneath the epithelium. Based on these findings together, we diagnosed the lesion as BSC. In this case, the NBI-ME findings differed from those of typical squamous cell carcinoma in that both non-invasive cancer-like irregular loop-shaped microvessels coexisted with massively invasive cancer-like thick non-looped vessels. We speculate that the looped and non-looped vessels observed by NBI-ME histologically corresponded to thin vessels in the intra-epithelial papilla and thick vessels around the tumor nests, respectively. These NBI-ME findings might be a feature of early esophageal BSC.展开更多
文摘The imaging method of the mid-course missile is the key technique of the missile defense system.Because of the special precession character of the ballistic missile warhead,the inverse synthetic aperture radar method cannot realize phase compensation with the constant phase offset function,which leads to blurring of the image.In this paper,we propose a new narrowband radar imaging method for the precession cone-shaped targets.The method acquires the Doppler modulation of the precession target's scattering centers with high resolution time-frequency analysis method and extracts the Doppler parameter from the result of the time-frequency analysis with the general Radon transform,then reconstructs the scattering centers positions in the parameter domain.The experiment results with the anechoic chamber data of the representative cone-shaped object showed the effectiveness of the method.
基金the Knowledge Innovation Program of the Chinese Academy of Sci-ences (Grant No. KZCX2-YW-206-2)the National Natural Science Foundation of China (Grant No. 40775004)the National Science Fund for Distinguished Young Scholars (Grant No. 40325013)
文摘A narrowband radio interferometer has been developed and used to locate the entire sources of VHF radiations from a negative cloud-to-ground (CG) lightning discharge which contains 19 strokes. This system uses five antennas to form an array consisting of short- and long-baselines along two or- thogonal directions. The system error which comes from frequency conversion is reduced by phase detection through direct high frequency amplifying. An interactive graphic analysis procedure is used to remove the fringe ambiguities which exist inherently in interferometry and to determine the direction of lightning radiation sources in two dimensions (azimuth and elevation) as a function of time at a time resolution of microsecond orders. With the developed system, the whole progression process in time and space of a lightning flash can be reconstructed. In this paper, combining the synchronous data of electric filed change and VHF radiation, the whole processes of an example negative CG flash have been studied in detail. It is found that the preliminary breakdown event of the CG flash started from negative charge region and exhibited firstly a downward pregression and then an upward propagation. There were very intense and continuous radiations during stepped leaders which became much stronger when the first return stroke began. In contrast, there were less and only discrete radiations during dart leaders. Stepped leader and dart leader may transform to each other depending on the state of the ionization of the path. The progression speed of initial stepped leaders was about 105 ms?1, while that was about 4.1×106 and 6.0×106 ms?1 for dart leaders and dart-stepped leaders, respectively. M events produced hook-shaped field changes accompanied by active burst of radiations at their begin- nings. Followed these active radiation processes, M events appeared to contact finally into conducting main discharge channels. The mean progression speed of M events was about 7×107 ms?1, greater than that of the dart leaders and dart-ste
基金supported in part by Open Research Fund of National Key Laboratory of Electromagnetic EnvironmentChina Research Institute of Radiowave Propagation (Grant No. 201500013)+3 种基金Open Research Fund of National Mobile Communications Research LaboratoryJiangsu Provincial Science Foundation Project (Grant No. BK20150786)Southeast University (Grant No. 2013D02)National Natural Science Foundation of China (Grants Nos. 61501238, 61271230, 61472190)
文摘The topology of in-home power line communication(PLC) networks varies frequently, which makes traditional routing algorithms failure. To solve this problem, an end-to-end transmission time for remaining path(TTRP) metric-based opportunistic routing(TTRPOR) is proposed. Since a local broadcasting scheme is adopted, the algorithm can find the optimal path for forwarding packets in a dynamic PLC network. The closed-form of the outage probability for a PLC channel is derived to estimate the TTRP. It is proved that the average throughput can achieve maximum as the metric TTRP is utilized to sort candidate forwarding nodes.Numerical results show that the end-to-end throughput of networks with TTRPOR, outperforms that of the network adopting DSR and EXOR, especially for the case of varying-topology in-home PLC networks.
基金Supported by Digestive Medical Coordinated Development Center of Beijing Hospitals Authority,No.XXZ015Capital Citizens Health Cultivation Project of Beijing Municipal Science&Technology Commission,No.Z161100000116084+1 种基金Medical and Health Public Foundation of Beijing,No.YWJKJJHKYJJ-B17262-067Science and Technology Development Project of China State Railway Group,No.N2019Z004.
文摘BACKGROUND In recent years,two new narrow-band imaging(NBI)classifications have been proposed:The NBI international colorectal endoscopic(NICE)classification and Japanese NBI expert team(JNET)classification.Most validation studies of the two new NBI classifications were conducted in classification setting units by experienced endoscopists,and the application of use in different centers among endoscopists with different endoscopy skills remains unknown.AIM To evaluate clinical application and possible problems of NICE and JNET classification for the differential diagnosis of colorectal cancer and precancerous lesions.METHODS Six endoscopists with varying levels of experience participated in this study.Eighty-seven consecutive patients with a total of 125 lesions were photographed during non-magnifying conventional white-light colonoscopy,non-magnifying NBI,and magnifying NBI.The three groups of endoscopic pictures of each lesion were evaluated by the six endoscopists in randomized order using the NICE and JENT classifications separately.Then we calculated the six endoscopists’sensitivity,specificity,accuracy,positive predictive value,and negative predictive value for each category of the two classifications.RESULTS The sensitivity,specificity,and accuracy of JNET classification type 1 and 3 were similar to NICE classification type 1 and 3 in both the highly experienced endoscopist(HEE)and less-experienced endoscopist(LEE)groups.The specificity of JNET classification type 1 and 3 and NICE classification type 3 in both the HEE and LEE groups was>95%,and the overall interobserver agreement was good in both groups.The sensitivity of NICE classification type 3 lesions for diagnosis of SM-d carcinoma in the HEE group was significantly superior to that in the LEE group(91.7%vs 83.3%;P=0.042).The sensitivity of JNET classification type 2B lesions for the diagnosis of high-grade dysplasia or superficial submucosal invasive carcinoma in the HEE and LEE groups was 53.8%and 51.3%,respectively.Compared with other types of JN
基金supported by the National Key R&D Program of China (2022YFA1203304)the Minstry of Science and Technology of China (2022YFB4200400 and 2019YFA0705900)the National Natural Science Foundation of China (21935007 and 52025033)。
基金Supported by The Gastroenterological Association of Thailand: grant for Gastroenterology Fellow 2007
文摘AIM： To evaluate the efficacy of non-sequential narrow band imaging （NBI） for a better recognition of gastric intestinal metaplasia （GIM）. METHODS： Previously diagnosed GIM patients underwent targeted biopsy from areas with and without GIM, as indicated by NBI, twice at an interval of 1 year. The authors compared the endoscopic criteria such as light blue crest （LBC）, villous pattern （VP）, and large long crest （LLC） with standard histology. The results from two surveillance endoscopies were compared with histology results for sensitivity, specificity, positive predic-tive value （PPV）, negative predictive value （NPV）, and likelihood ratio of positive test （LR＋）. The number of early gastric cancer cases detected was also reported. RESULTS： NBI targeted biopsy was performed in 38 and 26 patients during the first and second surveillance endoscopies, respectively. There were 2 early gastric cancers detected in the first endoscopy. No cancer was detected from the second study. Surgical and endoscopic resections were successfully performed in each patient. Sensitivity, specificity, PPV, NPV, and LR＋ of all 3 endoscopic criteria during the first/second surveillances were 78.8%/91.3%, 82.5%/89.1%, 72.8%/77.8%, 86.8%/96.1, and 4.51/8.4, respectively. LBC provided the highest LR＋ over VP and LLC. CONCLUSION： Nonequential NBI is useful for GIM targeted biopsy. LBC provides the most sensitive reading. However, the optimal duration between two surveillances requires further study.
文摘Basaloid squamous carcinoma (BSC) is a rare variant of esophageal cancer. There are very few reports of “early” BSC. Here we report a case of early BSC with unusual findings by narrowband imaging magnified endoscopy (NBI-ME). A 70-year-old man with a middle thoracic esophageal tumor was referred to our hospital. White-light endoscopy revealed a reddish depressed lesion 5 mm in diameter having a subepithelial tumor-like prominence with a gentle rising slope. NBI-ME revealed irregular loop-shaped microvessels coexistent with thick irregularly branched non-looped vessels. Iodine staining revealed a pale brown lesion. We performed endoscopic submucosal dissection for diagnostic treatment. Histologic examination showed the proliferation of basal cell-like hyperchromatic tumor cells in the lamina propria and with slight invasion into the submucosa at a depth of 320 μm. The tumor cells formed solid nests and microcystic structures, containing an Alcian blue-positive mucoid matrix. The surface was covered with squamous epithelium without cellular atypia. Thin vessels were observed in the intra-epithelial papilla and thick vessels were observed around the solid nests beneath the epithelium. Based on these findings together, we diagnosed the lesion as BSC. In this case, the NBI-ME findings differed from those of typical squamous cell carcinoma in that both non-invasive cancer-like irregular loop-shaped microvessels coexisted with massively invasive cancer-like thick non-looped vessels. We speculate that the looped and non-looped vessels observed by NBI-ME histologically corresponded to thin vessels in the intra-epithelial papilla and thick vessels around the tumor nests, respectively. These NBI-ME findings might be a feature of early esophageal BSC.
