Java排名算法

TopicRank.java

import blade.kit.DateKit;

public class TopicRank {
	
	/**
	 * 计算帖子权重
	 * @param stars		点赞数
	 * @param comments	评论数
	 * @param sink		下沉数
	 * @param create	创建时间
	 * @return			返回帖子得分
	 */
	public static double getScore(int stars, int comments, int sink, long create){
		int score = Math.max(stars - 1, 0) + comments - sink;
		// 投票方向
		int sign = (score == 0) ? 0 : (score > 0 ? 1 : -1);
		// 帖子争议度
		double order = Math.log10(Math.max(Math.abs(score), 1));
		// 1459440000是项目创建时间
		double seconds = create - 1459440000;
		return Double.parseDouble(String.format("%.2f",order + sign * seconds / 45000));
	}
	
	public static void main(String[] args) {
		
		System.out.println(getScore(0, 0, 0, DateKit.getUnixTimeByDate(DateKit.dateFormat("201604192000","yyyyMMddHHmm"))));
		System.out.println(getScore(0, 0, -1, DateKit.getUnixTimeByDate(DateKit.dateFormat("201604202000","yyyyMMddHHmm"))));
		System.out.println(getScore(10, 2, 0, DateKit.getUnixTimeByDate(DateKit.dateFormat("201604202000","yyyyMMddHHmm"))));
		System.out.println(getScore(0, 2, 0, DateKit.getUnixTimeByDate(DateKit.dateFormat("201604202000","yyyyMMddHHmm"))));
		System.out.println(getScore(20, 0, 0, DateKit.getUnixTimeByDate(DateKit.dateFormat("201604202000","yyyyMMddHHmm"))));
		
	}

}

这个下沉数是什么意思？