Brain Image Assessment Using Displacement and Divergence Maps
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Solution Overview
Problem
LED drivers experience unwanted peak-currents when switching between LED groups with different forward voltages, potentially damaging the switched LED group.
Innovation Solution
An LED driver with a control unit that switches LED groups between nominal and transition modes, using a capacitor and resistors to manage current flow during transitions, reducing peak currents by controlling gate-to-source voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If switching is performed between LED groups with different forward voltages, then color pattern generation is enabled, but peak currents occur that may damage the switched LED group
Solution Approach 1:
The capacitor is pre-charged to the forward voltage of the first LED group before switching occurs. When switching to the second LED group, the capacitor's stored energy provides a voltage ramp that prevents peak current by gradually transitioning the voltage level rather than abruptly changing it.
Solution Approach 2:
The capacitor acts as an intermediary element between the LED groups with different forward voltages. It mediates the voltage transition by being charged to an intermediate voltage level, thereby smoothing the switching process and preventing direct high-current injection into the second LED group.
2Stability of the object's composition
If a capacitor is added in parallel to reduce high frequency current, then current ripple is reduced, but device complexity increases
Solution Approach 1:
The capacitor serves multiple functions simultaneously: it acts as a smoothing capacitor to reduce high-frequency current ripple, and as a voltage-ramping element to prevent peak currents during switching transitions between LED groups with different forward voltages. This multi-functionality justifies the added component.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Mitigates peak currents during LED group transitions, ensuring safe and efficient operation of LED fixtures by limiting current flow during voltage changes.
Implementation Method 1
an LED fixture comprising a plurality of LED groups, each LED group comprising at least one LED forming a series connection with a switch, wherein the plurality of LED groups are arranged in a parallel connection, the LED fixture further comprising a capacitor arranged in a parallel connection to the plurality of LED groups
Implementation Method 2
control the operation mode of the switch of the LED group between a nominal mode, wherein the switch operates in a closed nominal state or an open nominal state, and a transition mode, wherein the switch operates in a semi-closed state, wherein the gate to source voltage of the switch of the LED group is lower than the gate to source voltage of the respective switch when operated in the nominal mode
Data Source
AI summary
A method of assessment of medical images of a brain is described. The method is for patients with a lesion of the brain. Lesion tissues are segmented using automated methods and a region of interest in the peri-lesion area is defined based on dilation operations. The method includes estimating the displacement field within each consecutive image pair within the stack of longitudinal medical images and then computing magnitude and divergence maps from the estimated displacement fields. This is done by computing the magnitude of the displacement field to characterise pixelwise displacement within the image field of view and divide it by the time between their associated consecutive image pair; and computing the divergence of the displacement field to characterise pixelwise compression and/or expansion phenomena within the image field of view and dividing by the time between their associated consecutive image pair.