56 research outputs found
Optimal Scheduling and Power Allocation for Two-Hop Energy Harvesting Communication Systems
Energy harvesting (EH) has recently emerged as a promising technique for
green communications. To realize its potential, communication protocols need to
be redesigned to combat the randomness of the harvested energy. In this paper,
we investigate how to apply relaying to improve the short-term performance of
EH communication systems. With an EH source and a non-EH half-duplex relay, we
consider two different design objectives: 1) short-term throughput
maximization; and 2) transmission completion time minimization. Both problems
are joint scheduling and power allocation problems, rendered quite challenging
by the half-duplex constraint at the relay. A key finding is that directional
water-filling (DWF), which is the optimal power allocation algorithm for the
single-hop EH system, can serve as guideline for the design of two-hop
communication systems, as it not only determines the value of the optimal
performance, but also forms the basis to derive optimal solutions for both
design problems. Based on a relaxed energy profile along with the DWF
algorithm, we derive key properties of the optimal solutions for both problems
and thereafter propose efficient algorithms. Simulation results will show that
both scheduling and power allocation optimizations are necessary in two-hop EH
communication systems.Comment: Submitted to IEEE Transaction on Wireless Communicatio
Training Optimization for Energy Harvesting Communication Systems
Energy harvesting (EH) has recently emerged as an effective way to solve the
lifetime challenge of wireless sensor networks, as it can continuously harvest
energy from the environment. Unfortunately, it is challenging to guarantee a
satisfactory short-term performance in EH communication systems because the
harvested energy is sporadic. In this paper, we consider the channel training
optimization problem in EH communication systems, i.e., how to obtain accurate
channel state information to improve the communication performance. In contrast
to conventional communication systems, the optimization of the training power
and training period in EH communication systems is a coupled problem, which
makes such optimization very challenging. We shall formulate the optimal
training design problem for EH communication systems, and propose two solutions
that adaptively adjust the training period and power based on either the
instantaneous energy profile or the average energy harvesting rate. Numerical
and simulation results will show that training optimization is important in EH
communication systems. In particular, it will be shown that for short block
lengths, training optimization is critical. In contrast, for long block
lengths, the optimal training period is not too sensitive to the value of the
block length nor to the energy profile. Therefore, a properly selected fixed
training period value can be used.Comment: 6 pages, 5 figures, Globecom 201
Multi-frame Image Super-resolution Reconstruction Using Multi-grained Cascade Forest
Super-resolution image reconstruction utilizes two algorithms, where one is for single-frame image reconstruction, and the other is for multi-frame image reconstruction. Single-frame image reconstruction generally takes the first degradation and is followed by reconstruction, which essentially creates a problem of insufficient characterization. Multi-frame images provide additional information for image reconstruction relative to single frame images due to the slight differences between sequential frames. However, the existing super-resolution algorithm for multi-frame images do not take advantage of this key factor, either because of loose structure and complexity, or because the individual frames are restored poorly. This paper proposes a new SR reconstruction algorithm for images using Multi-grained Cascade Forest. Multi-frame image reconstruction is processed sequentially. Firstly, the image registration algorithm uses a convolutional neural network to register low-resolution image sequences, and then the images are reconstructed after registration by the Multi-grained Cascade Forest reconstruction algorithm. Finally, the reconstructed images are fused. The optimal algorithm is selected for each step to get the most out of the details and tightly connect the internal logic of each sequential step.This novel approach proposed in this paper, in which the depth of the cascade forest is procedurally generated for recovered images, rather than being a constant. After training each layer, the recovered image is automatically evaluated, and new layers are constructed for training until an optimal restored image is obtained. Experiments show that this method improves the quality of image reconstruction while preserving the details of the image
Binary Classification with Positive Labeling Sources
To create a large amount of training labels for machine learning models
effectively and efficiently, researchers have turned to Weak Supervision (WS),
which uses programmatic labeling sources rather than manual annotation.
Existing works of WS for binary classification typically assume the presence of
labeling sources that are able to assign both positive and negative labels to
data in roughly balanced proportions. However, for many tasks of interest where
there is a minority positive class, negative examples could be too diverse for
developers to generate indicative labeling sources. Thus, in this work, we
study the application of WS on binary classification tasks with positive
labeling sources only. We propose WEAPO, a simple yet competitive WS method for
producing training labels without negative labeling sources. On 10 benchmark
datasets, we show WEAPO achieves the highest averaged performance in terms of
both the quality of synthesized labels and the performance of the final
classifier supervised with these labels. We incorporated the implementation of
\method into WRENCH, an existing benchmarking platform.Comment: CIKM 2022 (short
Pattern formation of a pathway-based diffusion model: linear stability analysis and an asymptotic preserving method
We investigate the linear stability analysis of a pathway-based diffusion
model (PBDM), which characterizes the dynamics of the engineered Escherichia
coli populations [X. Xue and C. Xue and M. Tang, P LoS Computational Biology,
14 (2018), pp. e1006178]. This stability analysis considers small perturbations
of the density and chemical concentration around two non-trivial steady states,
and the linearized equations are transformed into a generalized eigenvalue
problem. By formal analysis, when the internal variable responds to the outside
signal fast enough, the PBDM converges to an anisotropic diffusion model, for
which the probability density distribution in the internal variable becomes a
delta function. We introduce an asymptotic preserving (AP) scheme for the PBDM
that converges to a stable limit scheme consistent with the anisotropic
diffusion model. Further numerical simulations demonstrate the theoretical
results of linear stability analysis, i.e., the pattern formation, and the
convergence of the AP scheme
DNN-Based ADNMPC of an Industrial Pickling Cold-Rolled Titanium Process via Field Enhancement Heat Exchange
The dynamic neural network based adaptive direct nonlinear model predictive control is designed to control an industrial microwave heating pickling cold-rolled titanium process. The identifier of the direct adaptive nonlinear model identification and the controller of the adaptive nonlinear model predictive control are designed based on series-parallel dynamic neural network training by RLS algorithm with variable incremental factor, gain, and forgetting factor. These identifier and controller are used to constitute intelligent controller for adjusting the temperature of microwave heating acid. The correctness of the controller structure, the convergence, and feasibility of the control algorithms is tested by system simulation. For a given point tracking, model mismatch simulation results show that the controller can be implemented on the system to track and overcome the mismatch system model. The control model can be achieved to track on pickling solution concentration and temperature of a given reference and overcome the disturbance
Pharmacokinetics and Pharmacodynamics of Once-Daily versus Twice-Daily Raltegravir in Treatment-Naïve HIV-Infected Patients
ABSTRACT QDMRK was a phase III clinical trial of raltegravir given once daily (QD) (800-mg dose) versus twice daily (BID) (400 mg per dose), each in combination with once-daily coformulated tenofovir-emtricitabine, in treatment-naive HIV-infected patients. Pharmacokinetic (PK) and pharmacokinetic/pharmacodynamic (PK/PD) analyses were conducted using a 2-step approach: individual non-model-based PK parameters from observed sparse concentration data were determined, followed by statistical analysis of potential relationships between PK and efficacy response parameters after 48 weeks of treatment. Sparse PK sampling was performed for all patients (QD, n = 380; BID, n = 384); selected sites performed an intensive PK evaluation at week 4 (QD, n = 22; BID, n = 20). In the intensive PK subgroup, daily exposures (area under the concentration-time curve from 0 to 24 h [AUC 0–24 ]) were similar between the two regimens, but patients on 800 mg QD experienced ∼4-fold-higher maximum drug concentration in plasma ( C max ) values and ∼6-fold-lower trough drug concentration ( C trough ) values than those on 400 mg BID. Geometric mean (GM) C trough values were similarly lower in the sparse PK analysis. With BID dosing, there was no indication of any significant PK/PD association over the range of tested PK parameters. With QD dosing, C trough values correlated with the likelihood of virologic response. Failure to achieve an HIV RNA level of <50 copies/ml appeared predominantly at high baseline HIV RNA levels in both treatment arms and was associated with lower values of GM C trough in the 800-mg-QD arm, though other possible drivers of efficacy, such as time above a threshold concentration, could not be evaluated due to the sparse sampling scheme. Together, these findings emphasize the importance of the shape of the plasma concentration-versus-time curve for long-term efficacy
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