The optimal position of solar panels depends on several factors:

• Season of year. The sun is lower in the sky during winter, so the slope should be greater. The significance of this factor varies with latitude, as does the slope itself.
• Value during day. Although demand may be greater at some times rather than others, the payment to you may not be, so what is best for you may not be what is best for the grid.

Tracking mechanisms work, but they are mechanical and can fail, and they cost money. It may be cheaper to add panels than to add trackers. For seasonal adjustment, some mounting hardware allows relatively easy manual adjustment of the slope.You don't have to change this but a few times a year.

I have been off the grid at home for ten years, depending mostly on solar but with a little wind. Our panels are pointed in three directions: Southeast to get power in the early morning when the batteries are lowest, south for use during peak sun, and southwest to end the daylight hours with fully charged batteries. We have home-made mounting, and it was cheaper to add a few extra panels than to add tracking hardware.

I would agree almost all the time. An error in doping, not being selective, would likely be obvious, because it would affect the other components on the same layer.

However, there is a small amount of boutique production which is done almost by hand, and more subject to errors. The chips are usually less complex, and given the right kind of circuit (such as the RNG from the paper) errors are more likely to slip through, especially if the circuit were to be confined, by itself, to layers not used in the interface electronics.This kind of specialty chip is sometimes used in obscure military and security devices. These are not chips you will find in mass-produced electronics.

The term, by hand, may be misleading. In fact, custom chip making is so well automated that a foundry can spit out dissimilar batches one after another, given instructions in electronic form. I've seen students design and make small batches of their own chips using commercial services. Here's the rub: all of the testing for a boutique chip must be defined for that chip, and if the designer/customer fails to specify the design or test correctly, a bad batch might emerge.

I've seen so many mistakes in my career, almost nothing surprises me now, although I'm sometimes amazed how long it takes to find them.

In semiconductor manufacturing, doping is the introduction of slight amounts of impurities into a semiconducting material, to create a condition of surplus or deficit electrons. Donors such as arsenic and phosphorus add electrons, creating n-type semiconductors, while acceptors such as boron and aluminum cause a deficit of electrons, making a p-type semiconductor. The terms surplus and deficit are relative to a state where all of the atomic orbitals are filled and the semiconductor has almost no conductivity. Thus, doping makes semiconductors into conductors.

Doping is commonly done by exposing the wafer of semiconducting material at high temperatures to a gas containing the dopant. The dopant diffuses into the surface of the wafer. A mask covers the wafer so that the diffusion only takes place where the wafer is uncovered. Note that the mask has microscopic detail, the quantities of dopants employed are low, and the chemicals used are nasty.

The circuit is created by the arrangement of the doped materials. For example, a p-type region adjacent to an n-type region makes a diode, while three adjacent regions in series make a bipolar transistor. The circuit is wired together using layers of metal (such as aluminum) deposited onto the surface and etched away in a pattern, done similarly to the way printed circuit boards are made.

Given Hanlon's razor, an accidental, rather than malicious, error in doping would be even more likely. If the chip were inadvertently doped incorrectly, it would pass visual inspections and even software tests without awareness of the defect. How many defective dice, not merely with RNGs but also with other circuits, are already in service due to inspection failures?

Although this paper shows how insidious a threat from a well-funded adversary might be, even more it shows the need for more comprehensive inspection mechanisms to discover misdoping which might go undetected by existing standard procedures.

BTW, the paper includes a well written and readable introduction to the context of the problem. Good job.

(1) plant drugs on enemy (2) use parallel construction to bust him (3) trail back to you is practically erased