Inventory Management

Safety Stock: The amount of inventory carried in addition to the expected demand.

Stock Keeping Unit (SKU): A common term used to identify an inventory item.

Material Requirements Planning (MRP)

Available to Promise: A feature of MRP systems that identifies the difference between the number of units currently included in the master schedule and actual (firm) customer orders.

Bill of Materials (BOM): A computer file that contains the complete product description, listing the materials, parts, and components, and the sequence in which the product is created.

Closed-loop MRP: The use of actual data from the production system to continually update the MRP system. This feedback is provided so that planning can be kept valid at all... Continue reading "Key Terms in Production and Inventory Management" »

Git Commands and Concepts

Git key commands and concepts:

• add (stage changes)
• commit (with a message)
• head (most recent commit)
• branch (alternative history)
• checkout (enter/exit branch)
• merge (combine into master)
• stash (save without commit, -u for untracked files; latest stashes (0) at the top)
• pop (retrieve a stash)
• fork (copy code from the source into a repository)
• pull (pull remote changes and merge into master)
• revert (undo commits and create a new commit)
• log (history with most recent commits first, -p for patch details)
• rm (--cached to remove from staging)
• fetch (get changes from a remote repository to a local repository without merging them; useful for reviewing changes)
• pull (fetch + merge)
• rebase (create a clean/linear commit history by moving commits

Binding

Lifecycle Hooks

Pipes

Fixed-function Circuits

Fixed-function circuits. They are manufactured to implement a specified logic function that cannot be altered.

Programmable Logic

Programmable logic uses devices which are manufactured to be programmed and implement different logic functions (they are alterable).

SPLD, CPLD, FPGA

SPLD — Simple Programmable Logic Device. CPLD — Complex Programmable Logic Device. FPGA — Field Programmable Gate Array.

Common Programmable Array Combinations

• PROM / RAM (Programmable Read Only Memory / Random Access Memory) — also known as a LUT (look-up table).
• Fixed AND array and programmable OR array — FPLA / PLA (Fully Programmable Logic Array / Programmable Logic Array). Both arrays, AND and OR, are programmable.

Programming Links and

Binding Constraint: LHS equals to RHS at optimal ;  Non-binding constraint: LHS is not equal to RHS at optimal

Shadow Price: Amount by which OFV changes if RHS is increased by one unit

Basic Variable: A decision variable which has non-zero value at optimal ;  Non-basic Value: A decision variable which has a value of zero at optimal

Reduced cost: Amount by which the objective function coefficient needs to be decreased before the variable becomes basic

• Basic var: "Final Value" >0 and "Reduced cost"=0; With allow inc/dec, optimal solution (Final Value) doesn't change, OFV change by (change)*(Final Value); Beyond allow inc/dec, optimal solution and OFV changes by RESOLVE.
• Non basic var:  "Final Value"=0 and "Reduced cost"≠0; In a MIN,"Reduced

Port Sizing: Key Factors

Physical Factors

1. Oceanographic and Meteorological Conditions

These conditions define navigational restrictions. Wind conditions are classified as:

• Soft: Up to 36 kph
• Moderate: 36 - 63 kph
• Severe: 63 - 108 kph

2. Vessel Dimensions

Design vessel dimensions (LOA, breadth, freeboard, draft) are crucial for port design.

3. Vessel Maneuverability

• High: Light war vessels, cruises, bulk carriers, Ro-Ro vessels, first-generation containerships
• Medium: Modern war vessels, oil carriers (T-2), bulk carriers, second-generation containerships
• Low: Aircraft carriers, VLCC tankers, third and fourth-generation containerships, older or damaged vessels

4. Vessel Squat

Two main effects:

• Vertical movement (sinking)
• Longitudinal rotation

5. Vessel Movements

Tide... Continue reading "Port Sizing and Operations: Key Factors and Considerations" »

Relational Algebra and Relational Calculus

Relational Algebra and Relational Calculus are the formal query languages for a relational model. Both form the base for the SQL language which is used in most of the relational DBMSs. Relational Algebra is a procedural language. On the other hand, Relational Calculus is a declarative language. Relational Algebra and Relational Calculus can be further differentiated on many aspects, which I have discussed below with the help of a comparison chart.

31 Digital Switching Systems — Space Switching

Types and characteristics of space switching network

The space switching network operates with inputs and outputs organized in N time slots. Information from input time slots is routed from every input mux to a specific output mux without modification of the time position. Gates in crossbars are opened only for the duration of the corresponding time slot.

• Time slots: The network works at inputs and outputs with N time slots.
• Routing: Information of input time slots is routed from each input mux to a specific output mux without changing the time position.
• Crossbar gates: Gates in crossbars are opened only for the period of the time slot.
• Eight-bit words: Eight-bit words are carried through the space