Model reduction techniques for high-rise buildings and its reduced-order controller with an improved BT method

Chao-Jun Chen,Jun Teng,Zuo-Hua Li,Qing-Gui Wu,Bei-Chun Lin 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.78 No.3

An AMD control system is usually built based on the original model of a target building. As a result, the fact leads a large calculation workload exists. Therefore, the orders of a structural model should be reduced appropriately. Among various model-reduction methods, a suitable reduced-order model is important to high-rise buildings. Meanwhile, a partial structural information is discarded directly in the model-reduction process, which leads to the accuracy reduction of its controller design. In this paper, an optimal technique is selected through comparing several common model-reduction methods. Then, considering the dynamic characteristics of a high-rise building, an improved balanced truncation (BT) method is proposed for establishing its reduced-order model. The abandoned structural information, including natural frequencies, damping ratios and modal information of the original model, is reconsidered. Based on the improved reduced-order model, a new reduced-order controller is designed by a regional pole-placement method. A high-rise building with an AMD system is regarded as an example, in which the energy distribution, the control effects and the control parameters are used as the indexes to analyze the performance of the improved reduced-order controller. To verify its effectiveness, the proposed methodology is also applied to a four-storey experimental frame. The results demonstrate that the new controller has a stable control performance and a relatively short calculation time, which provides good potential for structural vibration control of high-rise buildings.

Opportunistic Scheduling of Randomly Coded Multicast Transmissions at Half-Duplex Relay Stations

Chen, Chao,Baek, Seung Jun,de Veciana, Gustavo Institute of Electrical and Electronics Engineers 2016 IEEE Transactions on Information Theory Vol. No.

<P>We consider the multicast scheduling problem for the block transmission of packets in a heterogeneous network using a half-duplex relay station (RS). The RS uses random linear coding to efficiently transmit packets over time-varying multicast channels. Our goal is to minimize the average decoding delay. Because of the half-duplex operation, at each time slot, the RS must decide to either: 1) fetch a new packet for encoding from the base station or 2) multicast a coded packet to wireless users. Thus, optimal scheduling hinges on exploiting multicast opportunities while persistently supplying the encoder (at the RS) with new packets. We formulate an associated fluid control problem and show that the optimal policy incorporates opportunism across multicast channels, i.e., the RS performs a multicast transmission only if the collection of channel conditions is favorable; otherwise, it performs a fetch. Based on the fluid policy, we propose an online algorithm. We prove that our algorithm asymptotically incurs no more than 4/3 and 2 times the optimal delay, for two-user and arbitrary number of user system, respectively. Simulation results show that, in fact, our algorithm's performance is very close to theoretical bounds.</P>

CO2 capture by amine-functionalized nanoporous materials: A review

Chao Chen,안화승,Jun Kim 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.11

Amine-functionalized nanoporous materials can be prepared by the incorporation of diverse organic aminemoieties into the pore structures of a range of support materials, such as mesoporous silica and alumina, zeolite, carbonand metal organic frameworks (MOFs), either by direct functionalization or post-synthesis through physical impregna-tion or grafting. These hybrid materials have great potential for practical applications, such as dry adsorbents for post-combustion CO2 capture, owing to their high CO2 capture capacity, high capture selectivity towards CO2 comparedto other gases, and excellent stability. This paper summarizes the preparation methods and CO2 capture performancebased on the equilibrium CO2 uptake of a range of amine-functionalized nanoporous materials.

Minimum Cost Data Aggregation for Wireless Sensor Networks Computing Functions of Sensed Data

Chen, Chao,Lee, Kyogu,Park, Joon-Sang,Baek, Seung Jun Hindawi Limited 2015 Journal of sensors Vol.2015 No.-

<P>We consider a problem of minimum cost (energy) data aggregation in wireless sensor networks computing certain functions of sensed data. We use in-network aggregation such that data can be combined at the intermediate nodes en route to the sink. We consider two types of functions: firstly the summation-type which includes<I>sum</I>,<I>mean</I>, and<I>weighted sum</I>, and secondly the extreme-type which includes<I>max</I>and<I>min</I>. However for both types of functions the problem turns out to be NP-hard. We first show that, for<I>sum</I>and<I>mean</I>, there exist algorithms which can approximate the optimal cost by a factor logarithmic in the number of sources. For<I>weighted sum</I>we obtain a similar result for Gaussian sources. Next we reveal that the problem for extreme-type functions is intrinsically different from that for summation-type functions. We then propose a novel algorithm based on the crucial tradeoff in reducing costs between local aggregation of flows and finding a low cost path to the sink: the algorithm is shown to empirically find the best tradeoff point. We argue that the algorithm is applicable to many other similar types of problems. Simulation results show that significant cost savings can be achieved by the proposed algorithm.</P>

SLAMF7 is critical for phagocytosis of haematopoietic tumour cells via Mac-1 integrin

Chen, Jun,Zhong, Ming-Chao,Guo, Huaijian,Davidson, Dominique,Mishel, Sabrin,Lu, Yan,Rhee, Inmoo,Pé,rez-Quintero, Luis-Alberto,Zhang, Shaohua,Cruz-Munoz, Mario-Ernesto,Wu, Ning,Vinh, Donald C.,Si Nature Publishing Group 2017 Nature Vol. No.

<P>Cancer cells elude anti-tumour immunity through multiple mechanisms, including upregulated expression of ligands for inhibitory immune checkpoint receptors(1,2). Phagocytosis by macrophages plays a critical role in cancer control(3-6). Therapeutic blockade of signal regulatory protein (SIRP)-alpha, an inhibitory receptor on macrophages, or of its ligand CD47 expressed on tumour cells, improves tumour cell elimination in vitro and in vivo(7-10), suggesting that blockade of the SIRP alpha-CD47 checkpoint could be useful in treating human cancer(11-14). However, the prophagocytic receptor(s) responsible for tumour cell phagocytosis is(are) largely unknown. Here we find that macrophages are much more efficient at phagocytosis of haematopoietic tumour cells, compared with non-haematopoietic tumour cells, in response to SIRP alpha-CD47 blockade. Using a mouse lacking the signalling lymphocytic activation molecule (SLAM) family of homotypic haematopoietic cell-specific receptors, we determined that phagocytosis of haematopoietic tumour cells during SIRP alpha-CD47 blockade was strictly dependent on SLAM family receptors in vitro and in vivo. In both mouse and human cells, this function required a single SLAM family member, SLAMF7 (also known as CRACC, CS1, CD319), expressed on macrophages and tumour cell targets. In contrast to most SLAM receptor functions(15-17), SLAMF7-mediated phagocytosis was independent of signalling lymphocyte activation molecule-associated protein (SAP) adaptors. Instead, it depended on the ability of SLAMF7 to interact with integrin Mac-1 (refs 18-20) and utilize signals involving immunoreceptor tyrosine-based activation motifs(21,22). These findings elucidate the mechanism by which macrophages engulf and destroy haematopoietic tumour cells. They also reveal a novel SAP adaptor-independent function for a SLAM receptor. Lastly, they suggest that patients with tumours expressing SLAMF7 are more likely to respond to SIRP alpha-CD47 blockade therapy.</P>

Multicast Scheduling for Relay-Based Heterogeneous Networks Using Rateless Codes

Chen, Chao,Baek, Seung Jun IEEE Computer Society 2017 IEEE TRANSACTIONS ON MOBILE COMPUTING Vol.16 No.11

<P>We consider the multicast scheduling problem in the heterogeneous network using a half-duplex relay station (RS). Our goal is to minimize the delay of transmitting a block of packets to users over time-varying channels using rateless codes. Due to half-duplex operation, at each time slot, the RS can choose to either multicast a packet to the users, or fetch a packet from the macro base station. We formulate a fluid relaxation for the optimal decision problem, and reveal that the optimal policy has a threshold-based structure so as to exploit the opportunism of multicast channel: the RS should multicast only when the channel quality is sufficiently 'high'. We propose an online policy based on the relaxation which does not require the knowledge of channel distribution. When the channel distribution is symmetric across users, we provide a closed-form expression of the asymptotic performance of our policy. For two-user systems, we prove that our scheme is asymptotically optimal. When the users' channels are independent, we derive a performance bound based on water-filling rate allocation which approximates the optimal policy well. Simulation results show that our scheme performs close to theoretical bounds, under correlated as well as independent fading channels.</P>

Nonlinear Model Predictive Control for Near-Space Interceptor Based on Finite Time Disturbance Observer

Chao Guo,Chen Song,Yu-Jie Zhao,Jun-Wei Wang 한국항공우주학회 2018 International Journal of Aeronautical and Space Sc Vol.19 No.4

This paper proposes a novel nonlinear model predictive control design method based on the finite time disturbance observer (FTDO) and dynamic control allocation (DCA) algorithm for the near-space interceptor (NSI). First, the FTDO is introduced to estimate the mismatched system disturbance. The nonlinear model predictive control scheme based on the estimation value is proposed to obtain the virtual control command, and the mismatched disturbance can be effectively removed from the output channels of the NSI by designing a feed-forward disturbance compensation term with an appropriate compensation gain matrix. Moreover, a new DCA method is given to distribute the above virtual control command among the corresponding actuators (reaction jets and aerodynamic fins). Finally, numerical simulations illustrate that the proposed control scheme can track the command signal with high precision and have strong robustness against the mismatched disturbance.

Cordycepsmilitaris polysaccharide triggers apoptosis and G0/G1 cell arrest in cancer cells

Cheng Chen,Mei-LinWang,Chao Jin,Huijuan Chen,Shao-Hui Li,Shu-Ying Li,Xing-Fan Dou,Jun-Qiang Jia,Zhong-Zheng Gui 한국응용곤충학회 2015 Journal of Asia-Pacific Entomology Vol.18 No.3

Although many studies have shown the antitumor properties of Cordyceps militaris (artificial cultivated from Bombyx mori pupa) polysaccharides, little is known regarding the mechanism of its effects. This study was conducted to determine the mechanism of antitumor effects of C. militaris polysaccharide extract by evaluating apoptosis rate and cell cycle progression status in human liver cancer cell SMMC-7721, stomach cancer cell BGC-823 and breast cancer cell MCF-7. Results showed that C. militaris polysaccharides inhibited proliferation of SMMC-7721, BGC-823 and MCF-7 cells with an IC50 of 192 ± 23.2 μg/mL, 237 ± 12.7 μg/mL and 165 ± 16.3 μg/mL, respectively. We also found that C. militaris polysaccharides at increasing concentrations induced apoptosis dose dependently in those cancer cells: apoptosis rates were 48.3%, 59.4% and 70.9% for SMMC-7721, 41.3% and 57.0%, 72.2% for BGC-823 and 61.3%, 66.9% and 80.6% for MCF-7 at 110, 156 and 323 mg/mL of C. militaris polysaccharides, respectively. C. militaris polysaccharides arrested SMMC-7721, BGC-823 and MCF-7 cells at G0/G1 and G2/M phases with corresponding decrease in S-phase. This study suggests that C. militaris polysaccharides may exert its antitumor effects in those cancer cells by suppressing its growth, arresting the G0/G1-phase, reducing DNA synthesis and inducing apoptosis.

Some completely monotonic functions involving the gamma and polygamma functions

Ai-Jun Li,Chao-Ping Chen 대한수학회 2008 대한수학회지 Vol.45 No.1

In this paper, some logarithmically completely monotonic, strongly completely monotonic and completely monotonic functions related to the gamma, digamma and polygamma functions are established. Several inequalities, whose bounds are best possible, are obtained. In this paper, some logarithmically completely monotonic, strongly completely monotonic and completely monotonic functions related to the gamma, digamma and polygamma functions are established. Several inequalities, whose bounds are best possible, are obtained.

Water and carbohydrate levels at different developmental stages and dynamics in hibernating pupae of Pieris melete (Lepidoptera: Pieridae)

Hai-Jun XIAO,JunHui CHEN,Chao CHEN,Fang-Sen XUE 한국곤충학회 2015 Entomological Research Vol.45 No.5

For insight into the physiological indicators of diapause in Pieris melete, water and carbohydrate (glycogen and trehalose) levels were measured under both natural and laboratory conditions. The highest water content (3.71–3.79 mg/mg dry weight) was found in larvae and developing pupae, which was substantially higher than in diapausing pupae (2.59 mg/mg dry weight). Water content was almost stable during diapause, except for individuals approaching diapause termination (3.43–3.58 mg/mg dry weight). The total carbohydrate level was significantly higher in pre‐pupae (47.41 μg/mg) compared to larvae (22.80 μg/mg) and developing pupae (21.48 μg/mg). The highest level of trehalose was detected in winter diapausing pupae, and no trehalose was found in larvae or developing pupae. Levels of glycogen were highest in pre‐pupae and lowest in diapausing pupae. Levels of total carbohydrate decreased as diapause proceeded, and no significant changes were found in trehalose levels for diapausing pupae under natural conditions or treated for 60–90 days at 5°C. Pupae treated at 20°C for 60–90 days had significantly lower levels of trehalose than those treated for 30 days. Glycogen content was relatively stable at 5°C, but increased after treatment under natural conditions and 20°C for more than 60 days. These results suggest that the dynamics of water and carbohydrate levels are potential physiological diapause indicators, which show metabolic differences between trehalose and glycogen during diapause development.