In this paper, we propose Cloak—a new class of reliable timing channels—which is fundamentally di... more In this paper, we propose Cloak—a new class of reliable timing channels—which is fundamentally different from other timing channels in several aspects. First, Cloak encodes a message by a unique distribution of N packets over X TCP flows. The combinatorial nature of the encoding methods increases the channel capacity largely with (N,X). Second, Cloak offers ten different encoding and decoding methods, each of which has a unique tradeoff among several important considerations, such as channel capacity and the need for packet marking. Third, the packet transmissions modulated by Cloak could be carefully crafted to mimic the normal TCP flows in a typical TCP-based application session. Although Cloak’s basic idea is simple, we show in this paper how we tackle a number of challenging issues systematically. Our experiment results collected from PlanetLab nodes and a test bed suggest that Cloak is feasible under various network conditions and different round-trip delays.
International Journal of Radiation Oncology Biology Physics, 1998
To evaluate the efficacy of intraarterial 90yttrium (90Y) microspheres in nonresectable hepatocel... more To evaluate the efficacy of intraarterial 90yttrium (90Y) microspheres in nonresectable hepatocellular carcinoma (HCC). Patients with nonresectable HCC, but without extrahepatic disease, who also had lung shunting < 15% and tumor-to-normal ratio > or =2, as determined by simulation using (99m)technetium macroaggregated albumin, were entered into the study. The radiation dose delivered to the lungs, tumor, and normal liver was estimated by a partition model. 90Y microspheres were infused into the hepatic artery at the time of hepatic angiography or through an implanted arterial portacatheter under fluoroscopy. Repeated treatments were given for residual or recurrent tumor. Response to treatment was monitored by serum alpha-fetoprotein or ferritin levels, together with serial computed tomography. Seventy-one patients, including 20 patients with postoperative recurrence, were initially treated with an activity of 0.8 to 5.0 Giga-Becquerel (GBq) (21.6-135.1 mCi) (median 3.0 GBq or 81.1 mCi) of 90Y microspheres. There was a 50% reduction in tumor volume in 19 (26.7%) patients after the first treatment. However, the overall objective response in terms of changes in alpha-fetoprotein levels was 89% [partial response (PR) 67%, complete response (CR) 22%] among the 46 patients with raised pretreatment levels. The serum ferritin level in the other 25 patients dropped by 34 to 99% after treatment. Treatment was repeated in 15 patients. The maximum number of treatments was 5 and the maximum total activity was 13.0 GBq (351.4 mCi), given in 3 treatments. The estimated radiation doses to the nontumorous liver ranged from 25 to 136 Gy (median 52 Gy) in the first treatment and the highest total radiation dose was estimated to be 324 Gy. For the tumors, the estimated radiation doses ranged from 83 to 748 Gy (median 225 Gy) in the initial treatment and the highest cumulative dose reached was 1580 Gy. The residual tumors were resected in 4 patients. Two of these had complete histological remission, but only occasional viable tumor cells were found in the necrotic centers of the tumors resected from the other 2 patients. The median survival of the 71 patients was 9.4 months (range 1.8 to 46.4 months). Treatment was well tolerated and there was no bone-marrow toxicity, or clinical evidence of radiation hepatitis or pneumonitis. Selective internal radiation therapy using 90Y microspheres is effective for selected cases of nonresectable HCC and is well tolerated. The objective response rate in terms of drop in tumor marker levels is higher than that based on reduction in tumor volume shown by computed tomography. The nontumorous liver appears more tolerant to internal radiation than external beam radiation. Selective internal radiation treatment may convert nonresectable tumors to resectable ones.
In the current Internet landscape, a stub autonomous system (AS) could choose from a number of pr... more In the current Internet landscape, a stub autonomous system (AS) could choose from a number of providers and peers to advertise its routes. However, the route selection may not always result in a best choice in terms of end-to-end path performance. Instead of having an AS to monitor all possible paths, we argue that it is much more effective and beneficial for a number of neighboring ASes to cooperate in the path measurement. In this paper, we present a neighbor-cooperative measurement system in which each participating AS conducts measurement using their current routes for the same set of remote endpoints. A collation of the measurement results can help identify and correct poor routes, compare different providers' network services, and diagnose network performance problems. We report measurement results from an actual deployment involving eight neighboring universities for over a year.
International Journal on Interactive Design and Manufacturing (ijidem), 2007
Port container terminal operation requires a skill workforce who participates in performing a num... more Port container terminal operation requires a skill workforce who participates in performing a number major operation including container loading/unloading, task planning, scheduling of terminal resources, operating of crane systems, etc. in a highly coordinated manner. To facilitate the optimal design of terminal operation for both management and operators, and to provide a flexible environment for operator training and skill evaluation, a real-time distributed virtual environment that simulates container terminal operation is developed. The system includes an imseCAVE, which is a low cost fully immersive virtual reality system developed at the University of Hong Kong, together with several network computers that are linked to the imseCAVE for remote control and monitoring of terminal operations, and providing user interfaces that simulate the planning systems for terminal operations. The simulator recreates a vivid terminal operating environment that is found useful for both teaching and research in logistics and other related fields.
On two days during SUCCESS, the NASA DC-8 flew carefully designed flight tracks to sample wave cl... more On two days during SUCCESS, the NASA DC-8 flew carefully designed flight tracks to sample wave clouds downstream of the Rocky mountains. Wave morphology was deduced by applying linear perturbation theory to in-situ measurements of the Meteorological Measurement System (MMS) and remotely sensed isentrope profiles of the Micro-wave Temperature Profiler (MTP). Vertical winds from the MMS were consistent with updraft velocities derived from air parcel displacements estimated from the MTP. Derived wave characteristics and cooling rates are useful inputs to cloud microphysics models.
In this paper, we propose Cloak—a new class of reliable timing channels—which is fundamentally di... more In this paper, we propose Cloak—a new class of reliable timing channels—which is fundamentally different from other timing channels in several aspects. First, Cloak encodes a message by a unique distribution of N packets over X TCP flows. The combinatorial nature of the encoding methods increases the channel capacity largely with (N,X). Second, Cloak offers ten different encoding and decoding methods, each of which has a unique tradeoff among several important considerations, such as channel capacity and the need for packet marking. Third, the packet transmissions modulated by Cloak could be carefully crafted to mimic the normal TCP flows in a typical TCP-based application session. Although Cloak’s basic idea is simple, we show in this paper how we tackle a number of challenging issues systematically. Our experiment results collected from PlanetLab nodes and a test bed suggest that Cloak is feasible under various network conditions and different round-trip delays.
International Journal of Radiation Oncology Biology Physics, 1998
To evaluate the efficacy of intraarterial 90yttrium (90Y) microspheres in nonresectable hepatocel... more To evaluate the efficacy of intraarterial 90yttrium (90Y) microspheres in nonresectable hepatocellular carcinoma (HCC). Patients with nonresectable HCC, but without extrahepatic disease, who also had lung shunting < 15% and tumor-to-normal ratio > or =2, as determined by simulation using (99m)technetium macroaggregated albumin, were entered into the study. The radiation dose delivered to the lungs, tumor, and normal liver was estimated by a partition model. 90Y microspheres were infused into the hepatic artery at the time of hepatic angiography or through an implanted arterial portacatheter under fluoroscopy. Repeated treatments were given for residual or recurrent tumor. Response to treatment was monitored by serum alpha-fetoprotein or ferritin levels, together with serial computed tomography. Seventy-one patients, including 20 patients with postoperative recurrence, were initially treated with an activity of 0.8 to 5.0 Giga-Becquerel (GBq) (21.6-135.1 mCi) (median 3.0 GBq or 81.1 mCi) of 90Y microspheres. There was a 50% reduction in tumor volume in 19 (26.7%) patients after the first treatment. However, the overall objective response in terms of changes in alpha-fetoprotein levels was 89% [partial response (PR) 67%, complete response (CR) 22%] among the 46 patients with raised pretreatment levels. The serum ferritin level in the other 25 patients dropped by 34 to 99% after treatment. Treatment was repeated in 15 patients. The maximum number of treatments was 5 and the maximum total activity was 13.0 GBq (351.4 mCi), given in 3 treatments. The estimated radiation doses to the nontumorous liver ranged from 25 to 136 Gy (median 52 Gy) in the first treatment and the highest total radiation dose was estimated to be 324 Gy. For the tumors, the estimated radiation doses ranged from 83 to 748 Gy (median 225 Gy) in the initial treatment and the highest cumulative dose reached was 1580 Gy. The residual tumors were resected in 4 patients. Two of these had complete histological remission, but only occasional viable tumor cells were found in the necrotic centers of the tumors resected from the other 2 patients. The median survival of the 71 patients was 9.4 months (range 1.8 to 46.4 months). Treatment was well tolerated and there was no bone-marrow toxicity, or clinical evidence of radiation hepatitis or pneumonitis. Selective internal radiation therapy using 90Y microspheres is effective for selected cases of nonresectable HCC and is well tolerated. The objective response rate in terms of drop in tumor marker levels is higher than that based on reduction in tumor volume shown by computed tomography. The nontumorous liver appears more tolerant to internal radiation than external beam radiation. Selective internal radiation treatment may convert nonresectable tumors to resectable ones.
In the current Internet landscape, a stub autonomous system (AS) could choose from a number of pr... more In the current Internet landscape, a stub autonomous system (AS) could choose from a number of providers and peers to advertise its routes. However, the route selection may not always result in a best choice in terms of end-to-end path performance. Instead of having an AS to monitor all possible paths, we argue that it is much more effective and beneficial for a number of neighboring ASes to cooperate in the path measurement. In this paper, we present a neighbor-cooperative measurement system in which each participating AS conducts measurement using their current routes for the same set of remote endpoints. A collation of the measurement results can help identify and correct poor routes, compare different providers' network services, and diagnose network performance problems. We report measurement results from an actual deployment involving eight neighboring universities for over a year.
International Journal on Interactive Design and Manufacturing (ijidem), 2007
Port container terminal operation requires a skill workforce who participates in performing a num... more Port container terminal operation requires a skill workforce who participates in performing a number major operation including container loading/unloading, task planning, scheduling of terminal resources, operating of crane systems, etc. in a highly coordinated manner. To facilitate the optimal design of terminal operation for both management and operators, and to provide a flexible environment for operator training and skill evaluation, a real-time distributed virtual environment that simulates container terminal operation is developed. The system includes an imseCAVE, which is a low cost fully immersive virtual reality system developed at the University of Hong Kong, together with several network computers that are linked to the imseCAVE for remote control and monitoring of terminal operations, and providing user interfaces that simulate the planning systems for terminal operations. The simulator recreates a vivid terminal operating environment that is found useful for both teaching and research in logistics and other related fields.
On two days during SUCCESS, the NASA DC-8 flew carefully designed flight tracks to sample wave cl... more On two days during SUCCESS, the NASA DC-8 flew carefully designed flight tracks to sample wave clouds downstream of the Rocky mountains. Wave morphology was deduced by applying linear perturbation theory to in-situ measurements of the Meteorological Measurement System (MMS) and remotely sensed isentrope profiles of the Micro-wave Temperature Profiler (MTP). Vertical winds from the MMS were consistent with updraft velocities derived from air parcel displacements estimated from the MTP. Derived wave characteristics and cooling rates are useful inputs to cloud microphysics models.
Uploads
Papers by Rocky Chan