Cheng Zhang

Fully Human Monoclonal Antibodies Antagonizing the Glucagon Receptor Improve Glucose Homeostasis in Mice and Monkeys

Antagonizing the glucagon signaling pathway represents an attractive therapeutic approach for reducing excess hepatic glucose production in patients with type 2 diabetes. Despite extensive efforts, there is currently no human therapeutic that directly inhibits the glucagon/glucagon receptor pathway. We undertook a novel approach by generating high-affinity human monoclonal antibodies (mAbs) to the human glucagon receptor (GCGR) that display potent antagonistic activity in vitro and in vivo. A single injection of a lead antibody, mAb B, at 3 mg/kg, normalized blood glucose levels in ob/ob mice for 8 days. In addition, a single injection of mAb B dose-dependently lowered fasting blood glucose levels without inducing hypoglycemia and improved glucose tolerance in normal C57BL/6 mice. In normal cynomolgus monkeys, a single injection improved glucose tolerance while increasing glucagon and active glucagon-like peptide-1 levels. Thus, the anti-GCGR mAb could represent an effective new therapeutic for the treatment of type 2 diabetes.

A Methodology for Making a Three-Coil Wireless Power Transfer System More Energy Efficient Than a Two-Coil Counterpart for Extended Transfer Distance

A new methodology for ensuring that a three-coil wireless power transfer system is more energy efficient than a two-coil counterpart is presented in this paper. The theoretical proof and the conditions for meeting the objective are derived and practically verified in a practical prototype. The key features of the magnetic design are to: 1) shift the current stress from the primary driving circuit to the relay resonator; and 2) generate a large relay current for maximizing magnetic coupling with the receiver coil for efficient power transfer. Consequently, the current rating and cost of the driving circuit can be reduced and the overall quality factor and system energy efficiency are improved. This approach utilizes the combined advantages of the maximum efficiency principle and the use of relay resonator to overcome the energy efficiency problem for applications with extended energy transfer distances.

Two- and Three-Dimensional Omnidirectional Wireless Power Transfer

Nonidentical current control methods for 2- and 3-D omnidirectional wireless power systems are described. The omnidirectional power transmitter enables ac magnetic flux to flow in all directions and coil receivers to pick up energy in any position in the proximity of the transmitter. It can be applied to wireless charging systems for low-power devices such as radio-frequency identification devices and sensors. Practical results on 2-D and 3-D systems have confirmed the omnidirectional power transfer capability.

Basic Control Principles of Omnidirectional Wireless Power Transfer

This paper presents the basic control principles of omnidirectional wireless power transfer (WPT) based on the current amplitude control. The principles involve 1) an “omnidirectional” scanning process for detecting the power requirements in a 3-D space and 2) a “directional” power flow control for focusing the wireless power toward the targeted areas. Such principles apply to any WPT system comprising three orthogonal transmitter coils and multiple receivers with coil resonators. A current amplitude control method capable of generating a magnetic vector at a set of points evenly distributed on a spherical surface is explained. Based on the voltage and the current information in the transmitter circuit, the power involved in each vector over the spherical surface can be obtained. By scanning the vector over the spherical surface, the collective power flow requirements for the targeted loads can be determined. Based on the power requirements for the vectors over the spherical surface, a weighted time-sharing scheme is adopted to focus the wireless power toward the targeted areas. This method has been successfully applied to a hardware prototype. Both theoretical and experimental results are included to confirm these principles.

Modeling and Analysis of the Bendable Transformer

This paper presents a study of a bendable transformer for wearable electronics. Printed on a thin and bendable film, this transformer is bendable to wrap around body limbs such as the forearm. A model using a partial equivalent circuit theory has been developed to analyze the characteristic of an inductor and a bendable transformer. The mutual inductance and self-inductance for the bendable transformer over a range of bent curvatures have been calculated based on the model and compared favorably with measurements. Simulation and experimental results of applying the bendable inductor and transformer in dc-dc converters as a 5-V 500-mA power supply are included to confirm the usefulness of the transformer and the validity of the model.

Mathematic Analysis of Omnidirectional Wireless Power Transfer—Part-II Three-Dimensional Systems

Part-II of this paper focuses on the mathematical analysis of the 3-D omnidirectional wireless power transfer (WPT) and also addresses the general principle of load detection. It provides the mathematical forms of distributions of the input power vector and output power vector, and demonstrates that the geometry of such 3-D distributed space follows the revolution of the Lemniscate of Bernoulli along its longitudinal axis. It provides the mathematical proof that the direction of energy transfer for the maximum energy efficiency is always in line with that of the maximum load power path in the 3-D space. Experimental verification is included to confirm the 3-D omnidirectional WPT theory.

A Fast Method for Generating Time-Varying Magnetic Field Patterns of Mid-Range Wireless Power Transfer Systems

Visualizing the magnetic flux paths for wireless power transfer systems enables researchers and engineers to understand the operations and design the geometrical dimensions of the practical systems. However, time-domain transient simulations of 3-D electromagnetic fields of complex wireless power transfer systems with multiple coil-resonators are extremely time-consuming. This paper describes a fast hybrid approach that combines the time-domain coupled circuit modeling and the magnetostatic analysis to form a fast time-domain analytical tool for studying complex wireless power transfer systems. The proposed methodology has been successfully applied to several wireless domino-resonator systems. For the first time, the time-varying magnetic flux variations of wireless power domino-resonator systems can be visualized in computer simulations.

Omni-directional wireless power transfer systems using discrete magnetic field vector control

The majority of wireless power systems transfer power in a directional manner. Recently, 3-dimensional wireless power transfer has been addressed by several research groups. This paper describes a new discrete magnetic field control technique that can ensure omni-directional wireless power transfer in an efficient manner. The proposed control has been successfully implemented. Both theoretical and experimental results are included to confirm the validity of the control method.

Efficiency optimization method of inductive coupling wireless power transfer system with multiple transmitters and single receiver

In this paper, an analysis into the wireless power transfer system using inductive coupling with multiple transmitters and single receiver is presented. It is proved that, with certain total amount of input power from all of the transmitters, there is a maximal output power that can be delivered to the receiver. To achieve this optimal result, the electrical currents in all the transmitters shall be in-phase or 180-degree-out-of-phase. The magnitudes of the currents shall be controlled to match certain ratios. These ratios can be calculated from measurements in any known system. Experiments have been conducted to verify the theory in a wireless power transfer system with four transmitters and one receiver. The practical results match the simulated ones very well.

Power and efficiency of 2-D omni-directional wireless power transfer systems

This paper presents a mathematical analysis on 2-dimensional omni-directional wireless power transfer. It is shown that with the use of current control in the transmitter coils, magnetic field vector can be generated to point at all directions in a 2-dimensional sense. The theory allows the equations of the total input power and output power of the system to be determined at all angles of input magnetic field vector. Mechanisms for determining the load positions and directing wireless power them efficiently are proposed and practically realized. The theory has been verified with practical measurements.